ITP

I have been helping a friend tune his 08 GSR. And we have run across a very interesting situation. Once the car gets heat soaked,it starts to run very lean.

The car....
-Built motor
-FP Black
-FIC 1680's
-Kelford 214b's
-Primo 3.5 intake
-Dual fuel pumps on hobs switch

Think those are all the major components. The car is built correctly.

Heres the issue. You can start the car cold,let it warm up a minute or so and drive away. Drive the twenty minutes to work with no issues. AFR's are fine and happy.

Now...Let the car sit for half or longer and the car will be very lean after a hot start. I'm not talking about the Hot Restart issue that others have experienced upon cranking. The car will run so lean that it may stall. And also runs lean for an undetermined amount of time.

So I did a test. I started the car from stone cold and let it run for about 45 minutes at idle. Same thing. AFR's were happy then it started leaning out. By the end of the 45 minutes the car had gone from -5% LTFT to maxxing out the STFT and LTFT. Hitting the gas pedal would almost stall the car it was so lean.

The AIT and MAT got up to about 160deg during the test. Which is completely understandable for a car idling in 90deg temp for so long. It is also not just Closed Loop that is affected. Open Loop is as well.

Letting the car cool of for a few hours....and all is back to normal.

This leads me to believe that there are compensation tables or switches that are causing the issues. I have never noticed this type of issue on a EvoX anywhere from stock to bolt-ons. Or even on the same car with smaller turbo and injectors.

The rom and xml is a combo of Tephra and Goledevo def's. And there are zero fuel or timing trims related the air or coolant temp. Other than the Cranking fuel table. Which is not the issue. I tried adjusting the MAT vs MAP Fuel Comp map. No dice.

I am open to advice on the issue. Ultimately,finding these trim tables,or switches if that happens to be the case,would be a huge help.

tephra

iTrader: (6)

There are literally a bazillion ECT compensation tables in the ECU.

Are you disabling the "LTFT-Mid" from affecting WOT? (https://www.evolutionm.net/forums/ev...t-fueling.html)

tephra

iTrader: (6)

I would love to see a log of this... send it to me - I love data haha

I suspect you can learn quite a lot from graphing "load and IPW vs time" and also ECT/MAT/MAFIAT in another graph..

ITP

Yes. The LTFT-mid has disables and adjusted to 300g/s.

I have noticed the IPW over time does not change dramatically over the course of these conditions. Atleast at idle. You can literally watch the hot soak issue start to happen with minimal change in IPW. Doing the calculation for the required "new" IPW does not reflect in the actual IPW that is being logged. Which is what is leading me to believe a compensation is being applied.

I will take another log later a shoot it over for you Tephra.

tephra

iTrader: (6)

are you logging 2byte IPW?

that *should* be the IPW being sent to the injectors, ie a last step.

so if your are going lean then you *should* see it in the IPW..

ITP

Not logging 2-byte. If you can give me the formula and address,i will add it into the logger.

flagg77

subscribed for an interesting issue

hotstix

iTrader: (3)

What does maf voltage look like?

01CBR929

iTrader: (8)

I'm going to have to keep an eye on this thread.... My car has acted up in the summer heat.

Golden

iTrader: (1)

If IPW does not decrease during this time, then it has to be that air is getting into the car from somewhere. Like say the manifold is expanding and causing a leak in the gasket somewhere. That leak is then sealed when the manifold cools down. This could apply to any physical piece after the MAF.


Edit, I just realized that the corollary to more air would be less fuel. So, have you made sure that your base fuel pressure is the same at idle when hot?

Golden

iTrader: (1)

If your IPW does go down as the car heats up, you may want to look into changing this table.

Heck, you can change it now and it should patch the issue.

tephra

iTrader: (6)

For 526800xx: 2byte IPW = 2380A944, ResponseBytes = 2, Eval=x/1000

RazorLab

iTrader: (8)

Doesn't that show richer mixtures for higher MAT temps?

ITP

Maf is pretty stable and doesn't seem affected by the heat.

ITP

I did not consider a vac/boost leak. But if this is the case AFR's should go back to richer under boost conditions.
Fuel psi is stable

Tried this didn't help at idle or Closed loop conditions. And I commanded 2 points richer. Did not check if it helped in Open Loop because by this time in testing in the car ran so lean that it would barely move.