lanceccs

Stock Engine HKS SC setup with Uprev tune. Been running fine until the following happened...

Was raining heavily and my car went thru a few isolated puddle of shallow water. Exhaust started to sound different and engine started to bog. I drove abit more to a good place and had my car towed to my workshop. Found out that one of the rear O2 sensor was ripped off, the bung was ripped off as well leaving a hole in the test pipe. My work shop then patched the broken test pipe removed the other remaining O2 sensor planning to run without them (rear O2 sensor).

(No sanity check perform yet since restoration)

I've taken this opportunity to put on the GTM smaller pulley and extended cold air intake which I have purchased earlier since my tuner is available. Post installation, exhaust has a lot of black smoke (Running Rich)? Engine continues to bogs and we decided to go up to the dyno to find out what is happening.

Couldn't complete the tune due to strange behaviour...

- Engine running very rich at idle 10.5.
- Engine cuts off at ~4100 rpm, suspect fuel cut.
- Engine internal seems to be fine, making almost same power all the way until engine cuts off at ~4100 rpm

Now, this is what we suspect could be wrong...

1. Hydrolock when I drove past the water.
Unlikely we think. The HKS SC setup filter is far from where the water is able to reach.

Water might have entered from the broken test pipe.
Unlikely as well, as the engine is still making almost the same among of power and engine sounds fine on the dyno.

2. Removal of the rear O2 sensors.
Unlikely. Anyone can confirm this?

3. MAF sensor. I know that HKS SC setup tends to cover the MAF sensor with oily dirt. Changing to the GTM cold air intake setup might have changed the intake condition resulting in problem.

4. HKS SC Power Package upgrade
Adding 90mm pully and the cold air intake. Don't think that would cause any problem. http://www.gtmotorsports.com/product...cat=258&page=1


We believe MAF sensor is the main suspect causing the engine to be running rich thus bogging. We will try to clean, if not replace the MAF sensor.

If that doesn't fix, we will put back the both rear O2 sensor but we don't think this could be it.



Any input will be very much appreciated. Thank you in Adv!

Vas_Z33

iTrader: (39)

I would start with the MAF..

lanceccs

Taking the MAF out from HKS SC is a *****! Sigh.

swishh

hmm dont mean to hijack the thread
do u happen to experience a complete shut down of the engine after some sprited driving?
ie when i dump the clutch for another gear ive had the revs just drop to zero and stalled the engine ..
Im using a tuned version of the fcon is btw..
i will look into that MAF asap.

swishh

btw how is your belting holding up ill put some pics up
after less than 20 000 km on the install the wear looks pretty bad lots of ribs gone .. how long do i wait to change it out ..

Vince@R/TTuning

iTrader: (7)

def suspect the MAF sensor...we had a TT car that got some water in the intake system and it just collected in the pipes. The customer drove it for several days an just couldn't get the water out and keep soaking the maf sensor. We ended up driving it on the dyno with the MAF pipe hooked up and the outlet pipe of the intercooler disconnected and it took about ten minutes to blow all the water out....

cdoxp800

iTrader: (12)

Question did you add this yet?

If so you maybe maxing out your OEM MAF. Have you logged your MAF voltages?

Next I would invest in this pipe from GTM. This is a far better location for the MAF that I came up with way back when.
http://www.gtmotorsports.com/product...cat=322&page=1
1. It moves the MAF after the intercooler. This allows for cooler AIT
2. This should allow you to run the MAF and keeping it under 5v do to the slower moving air across it.
All my ideas are in this thread:
https://my350z.com/forum/forced-indu...tallation.html

Next The GTM intake you have came from one of my prototypes, but I whet a different route with my last design. I have attached the Pics.

Please let us know about your MAF voltage. keep in mind this 5 volts is on some throttle of WOT. Also what engine managment are you running?

lanceccs

I am running on Uprev custom pro tune.

Yes, right after the raining incident. I added the GTM package. The sad is that i didn't test the car to take a baseline of how it is doing before adding the GTM kit.

Yes, I will have a similar pipe customed. The reason is the MAF is located under the SC, it is a pain to take it out. What is the easiest way, anyone?

Now that I have driven the car a few days I am much more familiar to comment about the problem.

1. The car bogs when moving off from idle. After moving off, rest of the acceleration or deacc is fine.

2. When I WOT the car pulls as expected and then engine cuts off (@ ~4-5k RPM) and follow by limp mode until you restart the car. When in limp mode, the RPM won't go past 3k rpm. See youtube video.

http://www.youtube.com/watch?v=SbY3z...bBkQm84nJRdDOA

http://www.youtube.com/watch?v=G3qzU...mRv8wonyePNPcw

I don't believe is due to maxing out the MAF because 1 week before all these happened I had the car going into limp mode as well. It was happened after 100 miles of cuising in very heavy rain, after toll I WOT and bang! (limp mode).

I strongly suspects it has something to do with water. Maybe Vince is right, water is being collected somewhere. I will get the MAF and TB cleaned and see how it goes. If it warrants, I will take out the whole intake system.

Any further input is welcome.

lanceccs

After reading 33 pages of your SC post. Seem like maxing out MAF is a know issue.

If I understand correctly I have 2 solutions,

1. Get PMAS 6 Pin Drop in style sensor and software. As seen here http://www.atomicperformance.com/bro...-Software.html

2. Relocate the original MAF sensor to TB?
Q: has this solution been tested and proven.
Q: this new piping has to be 3"? Smaller or bigger make any diff?

Which solution do u suggest.

Anything? What could be causing the moving bogging issue?

djamps

iTrader: (1)

If you have a stock MAF and recently added more boost that could easily cause limp mode, because the MAF is now maxing out where it didn't before. You should also get retuned ASAP since your original tune wasn't dialed into your new PSI. Upgrading your MAF requires a retune anyways, keep it in mind.

cdoxp800

iTrader: (12)

I would get this for a MAF if I was to upgrade my MAF again.
http://uprev.com/secure/accessories/uprev-maf-gt.html

2. Relocate the original MAF sensor to TB?
Q: has this solution been tested and proven.
Q: this new piping has to be 3"? Smaller or bigger make any diff?
I never got to fully test this myself. I will still recommended doing this first over the MAF. This larger pipe, being located after the supercharger has some benefits.
1. the Air coming a cross the MAF is not so turbulent, like it is now being located right in front of the SC.
2. The Relocation of the MAF and Lager Pipe diameter will cause the Air slower across the MAF and also lower Air intake Temps due to being after the intercooler.

As for what I would do, I would do Both the uprev-maf-gt and the new piping and get a retune. Even if you do one of them your still going to have to get re-tuned, So do both for all the added benefits for the longevity of my motor.

You can always call GTM and ask Sam to be 100%. He can be hard to get a hold of at time, but he is real helpful.

Now djamps knows his stuff, he created a Uprev log analysis tool.
https://my350z.com/forum/tuning/5112...ysis-tool.html

Best wishes and Happy New Year,

C

lanceccs

Update on the troubleshooting progress...

1. Took off the 90mm and put back the stock 95mm pulley. The car is still going into limp mode at 4-5k rpm. In fact, I suspect the limp mode comes at certain boost, not RPM specific. I am going to play around with the accelerator to see if it that is really the case.

Conclusion>>> The limp mode is NOT caused by maxing out MAF. 95mm stock pulley is not known to max off MAF. At this stage, the only difference before I experienced all these problems are

a. Cool Air Intake extension from GTM and new filter
b. the delete of of both the O2 sensors after the water incident

2. MAF and TB cleaned. Still going into limp mode at 4k+ RPM. I wanted to change out the MAF but it was New Year Eve and all stockies are closed at that hour.

Conclusion>>> The limp mode is NOT caused by dirty MAF or TB. However this doesn't rule out the possibility where the MAF is faulty.


Next I will try will be changing out the MAF.

Question, should I buy a stock MAF or an upgraded MAF?

FYI I am having a STOCK HKS SC, planning to run on 90mm pulley subsequently. Not having a GTM mod'ed blower.



cdoxp800>>> Greatly appreciate your input so far.

lanceccs

New observation:

1. Car sputters at moving off RPM. Suspects due to running rich.

2. Fuel comsuption is real bad now, I used to get ~250KM with half tank. I am only getting ~120KM. That is halved.

Also found a member with different setup but experiencing the same symptons.

https://my350z.com/forum/maintenance...2-sensors.html

jerryd87

iTrader: (4)

replace the rear 02 sensors, without them the vehicle has no idea if the corrections the front ones are making are correct so it throws it into limp mode. this is to protect the engine since the ecu has no idea if the front sensors are pulling too much fuel or giving too much fuel.

if your worried about this happening again then get o2 sims and mount them somewhere they wont get ripped out, the vehicle NEEDS that signal. while you MIGHT be maxxing the maf you where having problems before the upgrade however intermittent so that must be fixed first before you try and figure out problems you may or may not have because of the upgrades.

edit: i need to go to bed cant think right >.<

lanceccs

Yes I have been reAding about the purpose of downstream O2 sensor. They seems to be evidence they does more than just monitoring the Cat. They seem to have a role in fuel trimming as well.

I will Put them back first since they are the cheapest and easilest

djamps

iTrader: (1)

They do more than control the check engine light. Exactly how much is up for debate. In my case a 'bad' reading from them caused un-tunable rich condition at part throttle closed loop operation. They do not seem to have much if anything to do with WOT/open loop..

jerryd87

iTrader: (4)

they assist the front ones to alter short term fuel trim. the front onces bounce fuel between rich and lean to make the cats work properly even if you dont have them. the downstream monitor this and if it sees improper voltage vs what the front one is doing it will calculate what needs to be changed to get proper voltage and then both the front and back will work togeather to achive the proper short term fuel trim. if you get one of the high end like snap on scanners that can alter short term fuel trim you can scope the rears and modify short term fuel trim a little and it will kick on a check engine light then the rears will tell the computer and it makes a change to short term to put it back where it needs to go.

my boss when i worked at a smaller shop showed me that was pretty interesting but he was trying to send me to a ASE advanced OBD2 class because i was quick to pick up on the electronics and emissions stuff.

if you dont care much just get some simulators then it dosnt even matter because they will tell the computer the voltage is correct regardless of what actual readings are.

pez1111

iTrader: (2)

If you are revup '06. Try looking into the CEL code P2A00 /P2A03 do a search. I just recently threw this code and it got me doing a heap of checks all relating to the 02 sensors. Problems are usually leaking cats , exhaust system. Mine ended up being faulty sensor 1 bank 2.Your symptoms sound very much like mine, heaps rich and bogging down. Looked like a diesel zed the smoke was so thick. I am HKS S/charged running stock maf with a local tune here in Sydney on the factory ecu. I re-located my intake just like cdoxp800 and it's running sweet. I still may get the maf into that post IC location as well. Good luck.

lanceccs

Update...

I put back both(new) the downstream O2 sensor connecting to the test pipes (without non fouler). Problem persists...

Back to looking at the MAF. Ordered upRev GT MAF, pending arrival.

Should I try changing the spark plugs too?

pez1111

iTrader: (2)

Check your entire exhaust system for any cracks and leaks . They may not be visible but you need to eliminate any leaks because the rear sensors may be seeing too much oxygen and dumping fuel.