just as added info to the above post... the intake valves do not close before the piston begins its travel upward. the inertia of the incoming air can overcome the beginning of the compression stroke for a brief moment.

Anyway, the heat of compression combined with the heat of ignition can cause secondary burns to start on there own... read spontaneous combustion. so while the sparks primary flame front is already going about its duty, another flame front can begin. When this happens, your peak cylinder pressure will hit before optimum crank angle. This sounds like **** and blows up your engine

Extra fuel can keep things cool enough to prevent all this nastiness... to a certain extent. This is why OEM turbocharged cars runs so very very rich. If OEM turbo cars with lower compression are tuned so rich... why would we think we can safely go leaner with a high compression engine with horribly small and defenseless ring lands that just cannot evacuate the heat quickly enough.?!?

 

Absolutely, that boundary layer is only a few molecules thick and easily broken down whereupon heat into the piston etc etc

 

the coolant was all over the ground and coming out of the bottom of the radiator.

 

+1

i certainly can't claim to have 1/100th the in-depth knowledge of phunk, and even though there are many variables / differences, i bust my brothers chops all the time because of the terrible mileage his STi gets. at best, highway cruising is in the 25mpg range (ie, get gas on highway, set cruise @ 70 until empty, refill). typical mix of city/highway typically nets 18-20mpg. in order to make that motor last, it is set pig rich. i'd surmise his a/f to be closer to 10:1 than 11:1. and this on a 8.2:1 CR (although running ~14psi). totally stock motor (decatted downpipe). when i finally get my damn car to a tuner, i'm shooting for 10.5:1 under WOT (@ APS ST stock boost - 8psi?).

ahm

 

I appreciate all the info that you guys have posted and will definately take into consideration to bring the A/F below 11.5, as I also don't feel comfortable with the A/F being this lean to begin with. I just didn't really question AAM's tuning because of all the sucessful tunes they have given to fellow Z members.

Now my question is... why would they tune my car like this knowing(or maybe not) that it's dangerous for my car? I paid alot of money to get a good tune and now I have to travel back down to Maryland in order for them to fix it again!? As of now, I really feel like I'm either really bad luck with this car or people are just out to screw me. I paid to install a fuel return locally and have to pay AAM to do the fuel pump assembly over. I paid for my Emanage to be installed locally and have to pay AAM again to soder it correctly. I get a tune locally and it turns out to be crap. Everything is always done more than once on this freaking car.

At first I was excited that I got my car tuned by a really experienced shop, but now I don't know what to think anymore. So this will be the third attempt to tune this car already. I surprised my engine didn't blow yet.*Knock on wood* If what Phunk said is totally true, which I believe BTW, I should definately get reimbursed for my time+gas+toll down back to AAM again. Do you guys agree?

 

Consider it a learning experience. What is your Wideband saying? Were you watching the runs from inside? Talk to the guys while they are tuning the car. Ask them what you should do when it gets colder since it will run leaner. Ask them what trouble signs to look for. Ask them their tuning strategy and ask questions till you understand it totally. It took me a good 5 years of being around turbocharged cars to really understand the different schools of thought on tuning. I am in no way an expert but I know how to tune safely. I may not be able to squeeze as much power out of a vehicle as some of the other guys on here but I like doing things myself and I know how to be safe. You're paying those guys good money to tune the car and most of the time they'll be happy to share/show off their knowledge. Also, it gets pretty boring making a pull, looking at the logs while it cools down, making adjustments and starting over. Half the fun of having a tuner car is actually tuning it. When this cool weather starts it will be nice to be able to make fine adjustments to get the car dialed in perfectly. Let them worry about the timing(that's a little harder to learn and this is where a dyno comes in handy) but even an idiot like me can dial in AF ratios.
Also if you plan on doing minor tuning yourself invest in something to monitor knock visually such as the unit by MSD. This isn't as necessary if you don't plan on touching the timing but a good idea even if you don't.

 

well i wouldnt say that AAM really owes you a refund and that is because they are the only ones that know what they are doing since they are the only ones that were actually there when it happened. from where we all sit at the computer, all we can do is imagine what the actual circumstances are.

Some tuning shops will ONLY tune a car with a wideband that is in the test pipe, and the tailpipe sniffer for the graph printouts hardly gets proper maintenance because it doesnt matter... if they tuned your car using a different wideband than the one attached to the dyno, then it really could be that your car isnt actually that lean.

There are just too many variables... but if they have their tune down and they have a way thye have been tuning the Z and they dont blow up the way they do it... then hey, who are we to critisize... whatever works and keeps your engine together is what matters.

 

My wideband tells me the same...the A/F looks to be around low 12's and occasionally hit high 11's. I never saw anything in the low 11's at WOT. I usually tend to ask alot of questions and would like to know everything thats going on with my car. However, I was just to tired/exhausted to even be enthusiastic about it. As I have mentioned before, I drove the night before starting at 3am and got there around 8'ish. Went to book a room at a near by Holiday Inn because that was the only way my g/f would go with me. Went to the Holiday Inn to find out that all the rooms are booked! Somehow I managed to talked them into giving me a room, but they told me it wouldn't be available until 11am. I literally slept 1 hour or so and had to drive to AAM. During the time I was there, I literally feel asleep on the chair while Mike was Dynoing the car. LoL

I wish I had the talent like you to tune a car. Unfortunately, I'm only the average mechanic that can perform basic bolt-ons.

FYI, the whole trip down to AAM cost me a little over $1600(including gas,hotel,tolls) to get my car tuned. I really would think that the money I spent was well worth it. But, to find out that the tune is not safe and having to spend another $200+ to drive back down to AAM. I'm just starting to feel, once again, that I'm being jerked.

 

Phunk, I'm not asking for a refund, as I know Mike put alot of effort to tune my car, and I really appreciate it. I am in no way, trying to knock on AAM's ability to tune the car correctly, as I know that there are many happy customers on this board. It's just that feeling that you've paid good money to get something done right, just to find out that it needs a little tweaking. I just want it done correctly the first time. I just feel a little annoyed that I have to drive down there again to get this thing done right when it was suppose to be done right the first time around. Feel me?(or am I alone on this one)

 

Queenz350z, if you have a wideband gauge, you can possibly save yourself a lot of time and money by just jacking up your fuel pressure 1 or 2 psi. The cars closed loop cycle will compensate under part throttle and light load depending on how high your pressure already is.

If you decide to try it, start the engine and take off the vacuum line that goes to your fuel pressure regulator, and use your finger or a screw to plug the vacuum line temporarily... then take a perfect note of exactly where the pressure is before you adjust it. then put the vacuum line back on after you set the new pressure. The reason you remove the line is because your pressure will return to base before you adjust, where as if you left it on it can move around a little as engine vacuum can vary a tad bit from day to day, hour to hour.

typically you can get away with a couple psi change leaving your tune equally flat, and just raise or lower it with pressure... but sometimes, depending on circumstances, you cant always get away with it. but it might be worth a shot.

 

A slightly different take on why you should not go too lean:
EDITED-> I think the article was WRONG so pulled it

 

Damn, that why my fuel pressure always fluctuate 1psi up and down. I adjusted it without disconnecting the vacuum line. Why do you recommend the fuel pressure at idle be set to? I am a tad off from 42psi right now.

 

well i know that when my car went to AAM and was put on the dyno it was reading lean but, i know that my car is rich. i was told that, because they use the sniffer that goes into the tail pipe it doesn't read as accurate as an O2 sensor that goes into a bung before the cats.

 

jpc350z told me in another thread that tail pipe method would only bias it by between .3 and .5 at any reasonable RPMs (>500) - at very low RPM, the discrepancy could be much greater due to mixing of exhaust gas with air at tailpipe

If you have an exhaust (do you guys call it a muffler?) leak, that would explain a very lean value using the tail pipe sniffer method

 

If you have been tuned and you are not trying to change that tune, do not alter your fuel pressure. I recommend you set the fuel pressure to wherever it was when shariff tuned your car!

 

Yeah, it's too late. MY a/f has to be tweaked. When I drove the car to Sharif I had the EVO II exhaust. For some reason that piece of chit would not let my car make more than 430whp. The more boost that was added the less power the car made. Sharif and Eric tried to figure out for a week WTF was causing this. They decided to take the exhaust off the car and do a run and WALA......543whp. The car was tuned with no exhaust and dump tubes to a/f of no higher than 11.7. It was tuned passed 11.5 thinking that once the the 3" was intsalled it would restrict the flow a little (as compared to no exhaust), but it restricted more than they thought, thus the car runs rich (better rich than lean I guess). With the 3" exhaust the car runs an a/f of 9.9 to 1 after 3700 RPMS at WOT. I lowered the fuel pressure a little to try and lean it out and it worked for a few days. I went into the high 10's, but then 1 day the car started running in the high 12's. I rasied the fuel pressure again and I am back at 9.9 to 1. Since I am 750 miles away from Sharif, I couldn't really take the car back so he could touch up the a/f after I had the exhaust installed.

 

hey queenz, why did'nt you take your ride to xx tuning in connecticut. they tune unichip and have a dynapack and dynojet plus it closer, right?. the reason i ask is i'm about to get my kit tuned and i want to make sure i go to the most capable tuner.

 

FYI some reading to educate..

The UTEC is a User Tunable Engine Computer. This doesn't mean you have to tune this unit yourself. We supply the tools you will need to tune your car or just to keep an eye on your vehicle. This is where the Tuner comes into play. It allows you to append AFR into your data logs and also input additional logging of sensor like Exhaust Gas Temp and Intake Temp.

When running the E-manage on a Forced Induction application you typically over run your Mass Air Flow sensor at about 7-9 Psi. The work around for this is to clamp your Mass Air Flow sensor at a certain voltage (usually 4.9v). If you clamp your Mass Air Flow sensor, you are also clamping the ability to recognize the amount of Mass that your car is ingesting. This voltage is usually expressed as gm/sec (gram of air per sec). So you tune your vehicle to reach your target of 11.3 to 1 Air to Fuel Ratio on the 85 Degree day with an arbitrary number of 4.5ms for injector on time at peak torque. Everything is consistent when the temperature is rather close. What happens when the weather is colder?

Let's talk about the Hot-wire style Mass Air Flow sensor. The is a sensor that can make a density calculation of it's own by heating the hot wire element to pre defined temperature then as the air passes the element it can calculate the amount of air flow by the required current draw to keep the element at the set temperature. With the voltage clamped or pegged you have no means of calculating the air density. As soon as you encounter a cooler day than the 85 degrees, you will see an immediate change in your air to fuel ratio. Why? Cold air is denser than warmer air, fact! If your mass is colder, that means your motor is ingesting more air. Within the factory ECU's limits of the Mass Air Flow Sensor you would be able to calculate longer ms on times for a certain AFR target.

Unfortunately, you have over run your Mass Air Flow Sensor and to keep you from activating limp mode you clamped your Mass Air Flow voltage. The outcome of this work around is that your Mass Air Flow Sensor is no longer being used to accurately calculate load and you are ingesting more air un-metered. Do you remember on that 85 Degree day that you tuned 11.3 to 1 Air to fuel ratio? Now it is 60 degrees and yes you are adding more air but you locked into your E-manage ms on time of 4.5. The function alone of temperature can lean your car out immensely. A Lean Air to fuel ratio can be the cause of high exhaust gas temperatures, increased cylinder pressures and usually lead to Detonation. When using the E-manage you do not know how or when you are knocking.

The UTEC will employ a hybrid fuel control system Mass Air Flow and Speed Density. This allows you to use your Mass Air Flow Sensor for the simple drive-ability portion and when you are pushing the limit's it will become speed density. The use of speed density as fuel control gives the UTEC an ability that the E-manage does not have, which are temperature compensations. Speed Density systems take many variables into account like engine rpm, intake temperature, map sensors, throttle position and volumetric efficiency. If your temperature changes you have a temperature compensation. This combination of sensors can be found in the GM Ecotec Supercharged Engines.

Ignition Timing- The UTEC gives you complete control of timing. This is not done on the basis of offsets or altering the crank signal as some engine management systems use. The load reference we use is RPM vs. Manifold Absolute Pressure. This allows the Ignition Timing table to be adjusted at each of the 250 rpm resolution with over 10 different load sites from zero to rev limit. When you enter a value into the Ignition Map you are actually typing in Degrees Before Top Dead Center. The UTEC fires the coils based on these values. No more wondering if the stock ecu is going to advance or retard timing.

Active Knock Control- This feature allows you to help keep your motor in one piece. The UTEC contains default knock thresholds but can be adjusted at 1000 rpm increments up to 9000 rpm. It also contains a Knock Count threshold that allows you to define how many counts of knock before the UTEC will respond with a Knock Retard Step. The Knock Retard Step is the amount of ignition timing that will be pulled per knock count to a defined Knock Maximum Retard. Knock Maximum Retard relates to the maximum degrees of timing the UTEC will retard per knock event. When a knock count is registered the UTEC will hold the retard for a set number of crank cycles this is called Knock Retard Duration. The UTEC also has the ability to apply a global Knock Correction to the entire map once a knock event is evident. This will help ensure that you keep your high compression monster together. All of these features are the UTEC’s safety net. They should be used pro-active not as a reactive measure.

Datalogging- The UTEC’s Datalogging function helps you to keep an eye on your engines vitals. Using the logger gives you all the information you want to know about your vehicle. You can take multiple logs of your vehicle whether it’s simple drive-ability or all out racing. You can be sure the UTEC is keeping an eye out when you can’t. The main logger (Number1) contains rpm, map, maf voltage, tps, load site, afr, ignition timing, injector duty cycle, modified fuel (fuel control) and more. Logs can be output into text files or csv files for easy comparison. When the UTEC is used with a TXS Tuner model it can also supply you with w/b afr readings in your logs as well. The combination of our tuning tools gives you the ultimate tuning solution.

Remote Map Selector- The remote selector gives you the capability to switch between your UTEC maps. It also allows you to revert back to full stock ecu control on map 0 (when stock sized injectors are used). Maps 1 through 5 are your UTEC tunable map locations. Map 7 is your security mode, the car will not start. The car cannot be bump started or jumped when security mode is enabled.

Auxiliary Outputs- The UTEC can control several accessories like a Boost Control Solenoid, Fuel Pump, Water Injection System and more. You will have the ability tune them with high resolution, up to 36 rpm points with over 10 different load sites.

The first two features are what makes the UTEC a new breed of Engine Management. I wanted to highlight some major points before going further. The UTEC also has an on-board canbus, which is just a few things that this new breed of Engine Management bring to the table.

Jermaine@turboxs.com

 

Julian, welcome back...I thought you were banned?

Phunk, I am not trying to second guess AAM's tune, which is why I mentioned that 12:1 CAN be safe if the tuner knows what he is doing.

Take a read here...written by Innovate's engineers...probably well qualified to speak to this. In summary...gasoline is a horrible "coolant" and provides minimal benifits in cooling the combustion chamber. http://www.innovatemotorsports.com/resources/rich.php

And Julian, thanks for posting Jermaine's comments in this thread for discussion. But also note, that the EU has intake temp and coolant temp correction maps. So you can add fuel as as coolant temps rise, or add fuel as intake temps rise. No worries.

 

i have read that article in the past, and i have a lot of respect for the writer.

However, I trust no ones judgement more than the manufacturers of our cars. They are the ones building and tuning engines to last 100,000+ miles of abuse.

We do not currently have the datalogging equiptment available to moniter everything that is required to perfectly tune an engine like that. Innovate does. Maybe in a year or two when they release some of their upcoming product, we will all be able to log the required data to tune more aggressively.

I dont base my tuning methods on web articles... its from what I have done that has yet to result in me melting a customers piston.

The thing to keep in mind here... that article promotes making the best power. The facts stated in the article promote that a richer mixture does work to help prevent detonation... which is the entire goal here. So why not run safe timing, AND make it richer? I dont think anyone here with 400+ RWHP is concerned about the gas mileage under full throttle and boost... we all want our engines to last, even if that means sacrificing 10hp.

we need room for error with the currently available and popular tuning methods. None of them are proven to provide any type of consistency in dramatic environmental changes. Just cause you CAN tune it leaner, is not a very good reason... you are shruging off any room for inconsistency in environment, gasoline quality, engine temps, etc. These are street cars, not race cars. When tuning for max power with racing fuel and full engine control, tune 12:1 with high compression and boost all you like!