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My adventures in tuning the vq35de

Old 02-08-2019, 03:02 PM
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fflipski
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Default My adventures in tuning the vq35de

Newbie here. I was wondering if people are checking out this subforum and if people would be interested in me posting my progress in tuning my car on the link ECU platform.

Last year, I was able to replicate Nissan OEM ECU and get 248whp and 232wtq. My de is a 2003 with 134k miles. Right now I am preparing my car and doing a retune using modelled mode so I only have to tune my ve table only once before I upgrade injector/fuel system.

My goal is to have a vq with the best mid-range torque for the Shenandoah circuit in summit point WV.

Let me know if you are interested.

Disclaimer: My post are for my specific engine, with my specific mods, with my specific lack of knowledge and my willing to explore an area of engine tuning that I understand but that I am not qualified to perform on a professional basis. Please DO NOT TRY THIS AT HOME . This is for curious mind only

Last edited by fflipski; 02-08-2019 at 05:23 PM. Reason: Adding Disclaimer warning.
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Old 02-08-2019, 05:21 PM
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fflipski
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Default input configurations

OK, so where do I start.

Engine inputs configurations

The linkECU #350z is a plug and play unit that plugs into the oem ecu harness. It is very easy to install. It does includes a 4bar MAP sensor which is more than plenty for NA applications and low boost applications.
Since I didn't want to rely on Nissan sensors only, i decided to install it with the map sensor connected to the intake plenum. while keeping the maf connected since the intake temperature sensor is inside the MAF sensor. The goal is to use the intake manifold pressure difference as the main load axis of the tune. I did check that the sensor is stable and provide accurate load information. Of course , the MAP data doesn't mean anything without having the surrounding atmospheric air pressure. This is detected using a internal sensor called BAP and needs to be calibrated every time the ECU is reset.

One thing about my 2003 DE is that it only comes with narrowband sensors. later 07+ do have wideband but I wasn't so lucky. So I ordered a Innovate LC2 Wideband controller and plugged the analog output to an auxiliary input on the Link ECU. connectors are easily available at Linkecu.com or on digikey.
Link already have the mapping table for the innovate sensors. Just needed to make sure they are matching the output configuration of the lc2 controller.


OK, so now that we have the sensors connected, I just make sure the other analog inputs ( IAT, ECT , TPS, APS , etc...) are all configured.

Next step is to calibrate the APS ( accelerator pedal sensors) , the TPS ( throttle position sensors). There is a quick menu to do that in the software ( no more pedal dance for me). Once calibrated, I made sure the mapping between throttle and accel Pedal is linear. The software enables to change the mapping to whatever linearity you want.

Ok, so now the throttle , accelerator, manifold pressure and wideband are set, what else needs to be done.

Triggers

Well, the ECU needs to know the position of the engine so it can fire the plugs and injectors are the right time. This is done using triggers inputs. By combining the signals of 1 camshaft sensor and the main crankahsft sensor.
The VQ35DE has 3 sensors.Those sensors are plugged into digital input of the link ecu. we just need to make sure the sensors are "timed" correctly. For that the ecu software has several screens for that.

The first one is the crank position sensor. So I had to buy a timing light. Yes, some places still sell them ( they will look at you funny because most modern engine don't need a timing light any more). Also I fabricated a plug wire that enable to get the timing light on the wiring to the plug instead of the wiring to the coil. Everything setup , it is now time to fire up the car for the first time and let it idle to warm up temps. Suprisingly , the base map worked out of the box. So ,using the timing light, I flash the crank pulley and there is 3 marks on it. The left most one is TDC, then 15ATDC and then 20ATDC. Just input the value of the 15deg in the configuration screen and make sure the timing light shows the 15atdc mark aligned with the arrow on the lower timing cover-cover. Then while reving up the engine, adjust the delay to stabilize the timing mark.
Once the main timing is set, we need to setup the timing offset of the camshafts. Link provides a way detect the offsets of both camshafts. this has to be done once the main timing is set, otherwise , you'll have to redo it again.

OK, so now the ecu has good information, it knows accel pedal position, tb position, manifold pressure, exhaust AFR, and knows precisely where the engine is into it cycle.

Next post, I will dive into setting up the ecu for VE tuning.

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Old 02-08-2019, 06:06 PM
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Default Hello world!

In computer programming, the sentence "Hello world!" was used a lot to test the printouts of your application. Well , in my case, firing the engine for the first time was that check.
The ECU comes with PCLink software that has some "base maps" for the 350z. 1 with dual VVT camshaft and 1 for quad VVT camshaft for the revup model. 1 is for Auto and 1 is for a manual.
Both basemaps uses the traditional tuning method where the fuel maps dictate the amount of fuel being pushed by the injectors. Basically, injector size and fuel pressure are "Baked" into this table. So if you ever change injectors or change the fuel pressure, you will have to retune the whole table. There is a target AFR table but it is not used by the traditional method.

Until recently, I wasn't trusting myself enough to be able to tune using another method. It was a great starting point and now I feel more confident into my tuning abilities. ( which are still very poor per professional standard).

So for this thread , I will talk about the different fueling method that the link ecu is capable of.

1. Traditional mode. is where the fuel table dictate the amount of fuel.
2. Modelled mode is the next step into tuning. This method extract the fuel injector, fuel pressure, fuel system type, engine displacement, various temperatures ( IAT, fuel temp, etc..) out of the main fuel table. What this means is that the main fuel table becomes a Volumetric efficiency table that capture how much fuel needs to be injected to match the target AFR table.
3. Modelled multi-fuel is the last step into tuning. compared to the modelled mode, the multi-fuel enables to create various tuning changes based on what type of fuel is getting into the fuel rails. ( this also means having a fuel sensor setup )

Since I have no plan on getting multi-fuel setup since I am staying N/A. I will stay with the Modelled mode. One great advantage of this mode is that once the main fuel table is tuned. you can quickly change the AFR by just changing the target AFR table. no more dealing with the fuel table. Another advantage is that if I decide to change the injectors or the fuel system, I can simply change those values instead of retuning the whole table.

Ok, so before I continue I probably need to do some engine theory for some clarification.

The VQ35DE is a sequential port injected engine ( injector are actually fire individually inside the intake runner before the intake valves). it has 6 cylinder firing in order 1,2,3,4,5 and 6. ( cyl 1 is the front passenger side one, cyl 6 is the driver side rear most cylinder). Ignition is direct spark which means that each coils are activated individually in order to provide spark to each cylinder. Furthermore the VQ35DE is equipped with an intake variable valve timing. what this means is that the camshafts that open and close the intake cam can be advanced to allow the intake valve to open earlier or later in the intake cycle.

So what does all that means. Well, in order to tune the car, we need to configured all those different items.

So we are going to work on Fuel and Injector timing, ignition timing and VVT timing.
Basically, an engine will be run under 2 configurations. 1. Power mode where the engine will provide the most torque/hp. 2. cruise mode: where the engine will run at its most fuel efficient way.

Ok, enough for now. see you next time.

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Old 02-08-2019, 07:03 PM
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Link as in Link G4+ from New Zealand?
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Old 02-09-2019, 01:50 AM
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Originally Posted by bealljk View Post
Link as in Link G4+ from New Zealand?
Yes, this is the G4+ in a #350z enclosure.
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Old 02-09-2019, 03:28 AM
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Default Fuel ! baby , Fuel !

In my Last post, I talked about the 2 different modes a engine will run. Power and cruise. so let's talk about an important aspect of tuning : "The Load Axis".
"Load" is the amount of force you apply to the engine crankshaft, there is several ways to measure this load. On the 350z oem ecu, the load is measured by the amount of air the engine is "sucking" in. For this, it uses the Mass Air Flow sensor or MAF. you could use the Accelerator pedal position or the Throttle position sensor. In my case, I've decided to use the manifold pressure differential or the MGP since the link g4+ has the internal sensors to provide that information.

So Why using the manifold pressure ? Well, there is 2 advantages to it. 1. The MAF works with a specific housing. Change the housing and you'll have to change the calibration. 2. Manifold pressure capture the engine load with better speed and accuracy if it is stable. Fortunately for the VQ, the small plenum volume coupled with the "large number of cylinders" provides a very good reading.

Without a load, a healthy vq engine should create -12 to -13 psi. this means the engine is creating vacuum. How ? Well, at no load, the throttle body plate is almost closed , seriously restricting the amount of air flowing thru the plenum. But the Engine is still breathing in air so a vacuum is created. When a load is applied to crankshaft, the engine will compensate by burning more fuel/air. this means more air will be sucked in, which means more air pressure will be present in the manifold. In a N/A engine , this means the manifold pressure difference will rise to the normal atmospheric pressure. in boosted application, this means we will get into positive manifold pressure where the pressure inside the manifold is greater than the outside pressure.

Ok, so for my application, the full range of PSI reading should go from -13psi to 0psi. Since the ecu provides table with 16 points for the load axis, I kept the already configured table to -13 to 1.5psi , the 1.5psi row should never apply but I kept it there "Just in case".

Ok, so now , we have our load axis, let's talk about the engine speed. Every engine will behave differently at 1500 rpm than at 6000rpm. its power output varies greatly depending on its speed. Let's make the analogy of a person on a bicycle. The person has a set amount of lung capacity and when rotating the pedal slowly on a flat road, he/she won't need to breath in lot of air. The faster he/she rotates the pedal, the more oxygen that person will require to keep its muscles happy. Well, an engine is the exact same way. at low rpm, the engine will require less air per rotation than at full rpm. Add load to the equation ( equivalent of going up hill on a bicycle) and the amount of air required varies even more.

So ECU's have 2D Tables for this.



This is how the fuel table looks like. Don't pay attention to the numbers for now. But basically, what this table does is to tell the ECU how much % of total air capacity the engine will "suck in". A perfect engine will have a smooth curve and should breath in 100% of its displacement under full load around the rev limit point. You can see the value getting closer to 100 towards the bottom right of the table. So by using this values, the ECU can calculate exactly how much fuel it needs to spray down the intake runners to reach a target AFR. If the engine falls between 2 cells , the ECU will interpolate the value in between. Smart !

Remember me mentioning Power mode and Cruise mode ? I am getting there.

AFR or air fuel ratio is an important aspect of engine management. It measure the left over of the combustion process. We all heard of the Stoichiometry ratio. that famous 14.7. Well, this number will provide a complete combustion of the air and fuel. meaning no more fuel is left to burn and no more oxygen is left to burn. This provide good fuel economy and good power results and great emissions ( if temperatures are right). So in cruise mode, an engine will be required to provide good power at good fuel efficiency. There is no point to provide more fuel that than since all the oxygen will be burn.
Under Power mode ( high loads), the AFR could still be left at that ratio but the temperatures inside the combustion chambers start getting close to the melting point of aluminium. And we don't want to melt our aluminum pistons, don't we ? So, how do we keep temperatures in check ? Fluids are in-compressible, which means that only the by replacing some of the air-fuel mixture with more fuel , we end up with lower overall temperatures before ignition as less air will be present in the chamber to heat up. So instead of running a 14.7 AFR, N/A engine will run around 13 to 12.5 AFR under power and boosted engine will run in the 11 to 11.5.
So let's have a look at our target AFR ? should we ?




As you can see, in a no load situation ( the first 3 rows) , the target AFR is set to 14.7 to get best fuel economy. but as you increase load on the engine, the AFR is lowered to 13 to provide enough cooling. We do loose power potential since we are forcing more fuel in the cylinders but we are not melting the pistons, so I'll take that. As with the fuel table , value between cells will be interpolated to provide a smooth transition between them.


Finally, the fuel is delivered in the lower intake manifold in each runner by an injector. The ECM can "inject" the fuel at different time , This is called Injector timing. the Link G4+ provide a way to time the injector at begining of injection or end of injection. End of injection seems to me to be better since you can synchronise it better with the opening of the intake valve.

0 degree , piston at tdc , end of compression cycle. both valves are now closed.
180 degree , piston at bdc, end of power cycle. exhaust valve opens up.
360 degree , piston at tdc, end of exhaust cycle. exhaust valve closes and intake valve opens up
520 degree , piston at bdc, end of intake cycle., intake valve closes.
720 degree , pistong at tdc, end of compression cycle. round we go again.

So when would you fire the injectors ? for port injected engine, I was told the best time to inject is when the intake valve is closed but is about to open up as you don't want the mixture to be robbed away by another cylinder. so 360 degree seems a good time for that for now. Good thing it was already configured in the software to run this way. I will play a little more with those values as tuning progresses as I believe ( I can be wrong and was wrong before) than ending the injection while the valve is open could create better atomization at the top of the cylinder.

But wait ? how much time do we need to open the injectors ?

Well, its complicated while being simple. The time you need to open the injector is proportional to the pressure difference between the fuel rail and the intake runner air pressure and how much fuel you need to inject.
Basically, in order to calculate , the ECU will need the injector rated flow, their deadtime and fuel rail pressure. It seems the 350z has oem injector rated at 285cc at 50psi and has a returnless fuel system working at 50psi. So I just configured them in the software and we should be set.

Ok, so now , we have a base fuel config, we have our fuel system and injectors configured. I think its time we go ride a bicycle again.

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Old 02-09-2019, 03:56 AM
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Default push ! push ! push !

Let's go back to the bicycle rider. But let's imagine there is only 1 pedal on 1 side and his/her leg needs rest every other rotation, we've all experienced that, didn't we ?

So when do you push with your leg/foot. Do you push while the pedal is at the top or do you wait for it to start going down ? Well, an engine is the same way. you don't want to start pushing before the piston starts going down in the power cycle. I've read a lot of forums and 15degree ATDC is a good time to start pushing down to get maximum torque.

Since combustion takes time. we need to start the combustion process before that point. This is where the Ignition table fall into.
Like for the fuel, ignition timing falls under 2 modes. Power mode and cruise mode. in cruise mode, less fuel/air is in the cylinder, so we know we won't make much power so we plan on pushing on the cylinder a little earlier to keep the rotation speed. This timing is called advanced because we apply power to the piston past the 15 degrees point. Under power , we "retard" that timing to push the piston close to the 15degree mark by starting the combustion a bit later ( in the compression cycle). The main reason is that since more fuel is in the chamber, the faster it will burn and you don't want it to start pushing before the piston is past the TDC point.

simple enough ? Well, I've already tuned my car with a safe table , so I kept it as is for now.




Again, this is my own tuning, those values were tuned on the road without a knock device but the engine seems to like them ! :-) You can see how the timing is retarded under the power mode ( bottom rows ) versus the cruise mode ( center and top rows).

Link ECU provides huge number of tools to configure the timing for each cylinder. This is too complicated for now but could be use to extract every single little bit of power out of each cylinder. Maybe I'll look at it during next off season.

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Old 02-11-2019, 03:02 AM
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Default VVT what !

the VQ35DE has variable intake valve. basically, the timing chain synchronize the crankshaft and all 4 camshafts. the exhaust camshafts are on fixed sprockets while the intake cams have a special kind of sprocket that can advance the rotation of the camshaft. This is done by sending hot, sticky and gooey oil thru the mechanism. Send a little and you'll get a bit of an advance, Send a lot and you'll get a lot more. So on top of the special sprockets, our engine has 2 solenoids that controls how much oil is sent to the cam "phasers".
This sounds quite complicated to setup but the Link ECU already has all the info and even has a specific program for the VVT for our DE. So this makes it very easy, well, the controlling part , it is.

Now we need to figure out what we should do about those cams ?

After searching online for a lot of info on cam tuning , it all comes down to the overlap between the intake and exhaust valve. First , a bit of a warning, the VQ is a interference engine, which means there is a way for the intake valve to "kiss" the piston. Is there a risk of advancing the intake cam too much ? I do not know and it depends a lot on the cam lobe profile. (if someone knows , let me know). Basically, you don't want to have the intake valve fully open while the piston is getting to TDC. 40degrees seems to be the max in the base tunes, so I'll keep it there for now.

Overlap.

At low speed the engine uses a smaller amount of fuel/air, which results in faster exhaust gases thru the valve. This results in a tiny vacuum in the combustion chamber. This tiny vacuum could be use the start to "suck-in" more air before tdc . more air = more power , yeah! so it makes sense to have overlap in low to mid rpm.
At higher rpm, it does take more time for the exhaust gases to exit, which means that if the intake valve opens before the exhaust valve closes, you might end up with some exhaust going back to the intake runner. This is a very ineffective way to create a EGR effect. So for now, VVT will be disabled at high rpm.




So, for now, I will be using this table as a starting point. as you can see , with increase in load, I create more overlaps by advancing the cams in the mid to low rpm. high rpms will be zero'd out until I can get some dyno time.

Ok, next time, we go for a run. a log run!




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Old 02-11-2019, 04:03 AM
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Default More than meet the eyes.

To plagiarized the movie Transformer, the Link ECU G4+ is a little more than just a tiny box. A lot of things are going on inside and a lot of tools are given to the tuner to help him/her do her job.
From engine protection to fuel corrections, those tools are great help to finalize a tune but they do go against the tuner to initialize a good fuel table..... sorry VE table.




Ok, so we have the following fuel corrections.
Cold Start. I won't need to change this since I will make sure I am tuning while warmed up. So I'll keep it unchanged for now.
Fuel corrections. Ideally, the temperature outside should be at 70F, well, unless I drove all the way to Florida, it won't happen around here. So I am disabling the IAT fuel correction for now.
Accell Enrichment. Every time you press on the accelerator, the engine needs time to react. This section helps push more fuel in every time the accelerator pedal is pressed. I'll turn that off for now.
Overrun fuel cut. When you let off the accelerator, the throttle body closes, so the g4+ can decide to turn off the fuel delivery after a short period. I'll turn that off until my VE table is tuned.
Closed loop lambda and Ind. cyl corrections will be turned off too. This way, the only variable will be the value in the fuel table.

So, off we go. Turn engine on. Let is warm up until ECT reaches 155F , oil temp reaches 160F, time to go for a drive.

Link G4+ has 2 logging facilities. 1 when the computer is plugged in and 1 where the ecu simply log in its internal memory. For now , I will be using the "PC" Log since it capture a lot more information than the ecu log.
So after warmup is done, I started the recording on the PC and Off we go.
As a first time , I am making sure I am driving in flat roads in a very slow pace with minimal sudden changes in throttle , speed and load. This enable to get a smooth log to validate and start making changes to the Fuel Table.


Once, I logged the data, I stop on the side of the road in a safe place and start looking at the log.
In this picture, I looked at the cell close to 3000rpm and -8psi load. my target afr is 14.11, but my wideband is telling me I am at 13.67. I am able to log the fuel data to 66.7% , so in order to correct the cell in the fuel table, I need to decrease the amount of fuel by decreasing the value to 13.67 divided by 14.11 = 0.98xxx times 66.7% = 64.6.

Rinse and repeat for every cells that shows a stable log long enough to get a stable afr reading. It does take time to read the afr. most sensor needs a few tenths of a second to stabilize.

This process is very long, but it does not cost dyno time. next time I'll talk about the "Mixture map" which is a way to quickly accelerate this process.



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Old 02-13-2019, 04:10 AM
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fflipski
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Default The Lazy way !

the PCLink Software that comes with the ECU is quite impressive and has a lot of functionalities that I couldn't find with Haltech but that comes with Motec ecu ( which are way more expensive).
From motorsports datalogging to tuning tools, It is very easy to find a way to improve your tuning skills. Once of the way is the Mixture Map.



Basically, this window will gather the data from a log file and pull information on the AFR , its target for the cell and the number of sample data that matches the engine load/speed cell.

By just double clicking on a cell, the software automatically makes the correction in the fuel table to get a AFR close to the target value. It is like a "manual" Automatic learning.
But now , we have to be carefull on how the data is populated. Remember when I disable all the fuel corrections ? well, this is because I am using this tool to dial in the fuel tuning before spending too much time on the dyno. If a fuel correction is active, the fuel table will end up recording the corrections and later on, if the corrections is no longer , needed, the fuel table will be inaccurate.
Another warning is the number of sample, a cell with 10 samples will have inaccurate results compare to a cell with 100 samples. fortunately, the Mixture map can be configured to only include cells where a sample count is given, this greatly reduce the manual decision making if a cell can be updated or not. You could also apply filters to make sure you are excluding records where the throttle is closed, where the load is too low, etc.. etc...




As you can see, there is quite a bit of options to help you tune out bad samples and keep only the one that interest you.

So since I disables all corrections, I just input 40 records in the minimum sample count, start the logging, go for a 20 minutes drive trying to smooth inputs to each rpm/load levels and stop and update the mixture map and force the resulting corrections. Then I repeat this process until the corrections smooth themselves out. This is a long process but I am having fun doing it. Once I'll get on the dyno, I'll further smooth out the fuel since I'll be able to sustain each cell more efficiently.

Basically, I am saving time on the dyno by doing this. It is not a perfect method, but It works for me.
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Old 02-13-2019, 06:01 AM
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Subscribed to the very informative, excellent post ! (well, from what I can see from a quick glance)
Thank you for sharing your adventures
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Old 02-13-2019, 10:03 AM
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Originally Posted by RobPhoboS View Post
Subscribed to the very informative, excellent post ! (well, from what I can see from a quick glance)
Thank you for sharing your adventures
thank you!
just trying to give back a little to this great online resource. Without my350z this would not have been possible.
Hopefully people can correct me if I am wrong and if this help another person, I'll be happy.
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Old 02-28-2019, 03:42 AM
  #13  
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Default Road tuning early observations

The weather currently is cold ! which means that my tuning is based on intake temps in the 30's to 40's.

First some observations.

1. VVT timing. I've noticed a drop in power on the upper rpm from my butt dyno. It looks like I am being too aggressive on the VVT during that range. I've decided to drop the advance to zero at 4500rpm. So from 4500 and over, the intake cams will be zero'd out. Also, I've reduced the amount of advance on the low to mid range. Originally 40deg, I dialed it down to 36deg, somehow, it allowed a much faster response from the solenoids. This resulted in a increase power at high rpm and no loss in the lower range. My butt dyno is happy.

2. AFR Targets. After initial VE tuning, I've decided to dial up the fuel during WOT. It looks like my fuel value are good since changing the AFR target , actually changed the results to the new targets. I've found that running 12.5-12.7 at WOT is making my engine happy. I needed to dial down the timing just a tad ( 2% decrease) to prevent knock noises ( from the link ecu knock monitoring). I don't have a knock headphone yet and knock config should be done on a dyno anyway. but after doing those corrections, I am feeling good power coming from the engine from 3500rpm to redline.

3. Redline. The ECU link is very conservative on the rpm limit. I need to figure out why setting the limit at 6600 rpm only allow the engine to rev to 6400rpm. I've raised the limit to 6800 and now I am able to reach 6600rpm. I still need to tweak the rev limiter since it only cut fuels as of now. but for now, it will do. I just need to make sure to not hit the rev limit while on track as it is a hard cut off.

Road tuning take a lot of time. From logging to update the mixture map , to re-running the same roads and comparing the results. But it is fun to do. Sometimes , things go the wrong way, sometimes , they do go the right direction. Just have to be patient.

I will not be able to dyno my car before the first track session of the event as I won't have a day off for that. but I do feel my engine is responding to the initial road tune. I will be running the engine a little dialed back on timing until I get it on the dyno.

Question for those tuners out there ? 2750 rpm. it looks like this engine speed really decrease the VE of my engine. 2500rpm is higher, 3000 is higher. so why the dip in efficiency. If I try to smooth out the fuel, I am getting too rich in this speed , which decrease the throttle response. That is weird. I might run some calculations to see if this is a intake issue or a exhaust issue. But my first guess is on the exhaust side.


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Old 02-28-2019, 06:30 PM
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Does your fuel rails have built in dampers? I would have to do so digging but i recall a thread talking about a rich/lean (can't remember) condition due to no dampers at a specific rpm.

Originally Posted by fflipski View Post
The weather currently is cold ! which means that my tuning is based on intake temps in the 30's to 40's.

First some observations.

1. VVT timing. I've noticed a drop in power on the upper rpm from my butt dyno. It looks like I am being too aggressive on the VVT during that range. I've decided to drop the advance to zero at 4500rpm. So from 4500 and over, the intake cams will be zero'd out. Also, I've reduced the amount of advance on the low to mid range. Originally 40deg, I dialed it down to 36deg, somehow, it allowed a much faster response from the solenoids. This resulted in a increase power at high rpm and no loss in the lower range. My butt dyno is happy.

2. AFR Targets. After initial VE tuning, I've decided to dial up the fuel during WOT. It looks like my fuel value are good since changing the AFR target , actually changed the results to the new targets. I've found that running 12.5-12.7 at WOT is making my engine happy. I needed to dial down the timing just a tad ( 2% decrease) to prevent knock noises ( from the link ecu knock monitoring). I don't have a knock headphone yet and knock config should be done on a dyno anyway. but after doing those corrections, I am feeling good power coming from the engine from 3500rpm to redline.

3. Redline. The ECU link is very conservative on the rpm limit. I need to figure out why setting the limit at 6600 rpm only allow the engine to rev to 6400rpm. I've raised the limit to 6800 and now I am able to reach 6600rpm. I still need to tweak the rev limiter since it only cut fuels as of now. but for now, it will do. I just need to make sure to not hit the rev limit while on track as it is a hard cut off.

Road tuning take a lot of time. From logging to update the mixture map , to re-running the same roads and comparing the results. But it is fun to do. Sometimes , things go the wrong way, sometimes , they do go the right direction. Just have to be patient.

I will not be able to dyno my car before the first track session of the event as I won't have a day off for that. but I do feel my engine is responding to the initial road tune. I will be running the engine a little dialed back on timing until I get it on the dyno.

Question for those tuners out there ? 2750 rpm. it looks like this engine speed really decrease the VE of my engine. 2500rpm is higher, 3000 is higher. so why the dip in efficiency. If I try to smooth out the fuel, I am getting too rich in this speed , which decrease the throttle response. That is weird. I might run some calculations to see if this is a intake issue or a exhaust issue. But my first guess is on the exhaust side.
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Old 02-28-2019, 06:30 PM
  #15  
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Does your fuel rails have built in dampers? I would have to do so digging but i recall a thread talking about a rich/lean (can't remember) condition due to no dampers at a specific rpm.

Originally Posted by fflipski View Post
The weather currently is cold ! which means that my tuning is based on intake temps in the 30's to 40's.

First some observations.

1. VVT timing. I've noticed a drop in power on the upper rpm from my butt dyno. It looks like I am being too aggressive on the VVT during that range. I've decided to drop the advance to zero at 4500rpm. So from 4500 and over, the intake cams will be zero'd out. Also, I've reduced the amount of advance on the low to mid range. Originally 40deg, I dialed it down to 36deg, somehow, it allowed a much faster response from the solenoids. This resulted in a increase power at high rpm and no loss in the lower range. My butt dyno is happy.

2. AFR Targets. After initial VE tuning, I've decided to dial up the fuel during WOT. It looks like my fuel value are good since changing the AFR target , actually changed the results to the new targets. I've found that running 12.5-12.7 at WOT is making my engine happy. I needed to dial down the timing just a tad ( 2% decrease) to prevent knock noises ( from the link ecu knock monitoring). I don't have a knock headphone yet and knock config should be done on a dyno anyway. but after doing those corrections, I am feeling good power coming from the engine from 3500rpm to redline.

3. Redline. The ECU link is very conservative on the rpm limit. I need to figure out why setting the limit at 6600 rpm only allow the engine to rev to 6400rpm. I've raised the limit to 6800 and now I am able to reach 6600rpm. I still need to tweak the rev limiter since it only cut fuels as of now. but for now, it will do. I just need to make sure to not hit the rev limit while on track as it is a hard cut off.

Road tuning take a lot of time. From logging to update the mixture map , to re-running the same roads and comparing the results. But it is fun to do. Sometimes , things go the wrong way, sometimes , they do go the right direction. Just have to be patient.

I will not be able to dyno my car before the first track session of the event as I won't have a day off for that. but I do feel my engine is responding to the initial road tune. I will be running the engine a little dialed back on timing until I get it on the dyno.

Question for those tuners out there ? 2750 rpm. it looks like this engine speed really decrease the VE of my engine. 2500rpm is higher, 3000 is higher. so why the dip in efficiency. If I try to smooth out the fuel, I am getting too rich in this speed , which decrease the throttle response. That is weird. I might run some calculations to see if this is a intake issue or a exhaust issue. But my first guess is on the exhaust side.

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Old 03-01-2019, 01:58 AM
  #16  
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Originally Posted by Conway_160 View Post
Does your fuel rails have built in dampers? I would have to do so digging but i recall a thread talking about a rich/lean (can't remember) condition due to no dampers at a specific rpm.
I am running the oem returnless system. So yes it has dampers and I can see why it would do that at high duty cycle. Thank you for the tip!
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Old 03-01-2019, 02:37 AM
  #17  
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It wasn't in high duty cycle area's it was some where between 2500-3200 Ill do some digging today to see if i can find the thread.

Originally Posted by fflipski View Post
I am running the oem returnless system. So yes it has dampers and I can see why it would do that at high duty cycle. Thank you for the tip!
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Old 03-01-2019, 03:26 AM
  #18  
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I found some threads about fuel dampers issue with fuel return systems at around 2400rpm. someone even mentioned that the oem dampers are prone to fail. I don't have a fuel pressure gauge so I won't be able to monitor this. for now, I am going to tune this out and keep an eye on it. I know it is not optimal but I don't have a driveability issue so far. torque curve seems to be smooth enough for me. Once I get to compete at higher level, I'll look into the fuel system as I build a engine for track.

I have the oem injectors for now and the variance is not that big as other have experienced. But this is a interesting reading and I love to learn new thing about our vq. Thank you.
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