goosegoose

iTrader: (8)

Here is the AFR section of the MPS Log Map taken on Aug 30.
Temp was about 85F.
As you can see, the AFR values in MAP column 0 are all between 14 and 15.


Here is the AFR section of the MPS Log Map taken on Aug 30.
The temp was about 85F.
As you can see, the AFR values in MAP column 0 are all between 14 and 15.


Here is the MPS Log Map taken tonight, Nov 7.
The temp was about 45F.
I am alarmed to see the AFR values lean all the way to 21.



Is something seriously wrong here?

Whenever this happens, I feel a serious loss of power, the engine sometimes bogs down, and the car will slow down at constant throttle. The condition even happens at idle, when the car will jutter, before correcting itself several seconds later.

I'm guessing it is not the UTEC that is at fault here, since column 0 is strictly when the OEM ECU is in control. Also, the fact that all my AFR values are good under higher load, when the UTEC is in control, seems to suggest that there is nothing wrong with the UTEC. But I guess I could be wrong?

What else could be the problem here? Bad MAF sensor? Plenum leak? I'm sure this is not happening simply because of the drop in temperatures.

HELP!

athenG

iTrader: (2)

Goose,
I just got back home since I did a test run since it is colder. I was running so lean that I was knocking at high load with 6% correction. I had to bump it up to 8% just to get my A/F at load 80 down to 11's. I cant really explain why on ECU control that you are leaning so much. What was your IAT temp tonight? It was around 41F here and my IAT is around 2C-4C and at around mid 50F my IAT is around 12C-15C with my TS bumper.



Anyways here's a snapshot of my last log at 8% correction on Fuel.

QuadCam

iTrader: (8)

are you sure if is not taking those readings on decelleration? when you let off the throttle, the ecu shuts off the injectors and the A:F shows super lean numbers, but it is nothing to worry about.

goosegoose

iTrader: (8)

I am positive that these numbers do not occur at deceleration. These numbers occur when throttle is gently applied, and RPMs hold steady between 2000-3000.

I reset the OEM ECU last night, but that has made no difference on these super lean numbers.

gothchick

iTrader: (12)

Wow. That did go lean. Can you richen up the 0% column a little via Utec, or is your ecu driving the injectors in the 0% column?

This might sound a little corny, but maybe some fuel injector cleaner gas additive might help. It kinda looks like your injectors aren't opening up enough until you get into the higher load columns...

Maybe a fuel pump starting to give out?

I think the change in cooler ambient temps is just a coincidence in this case...

goosegoose

iTrader: (8)

I am almost certain the ECU is driving the injectors in the 0% column. In the logs, the MAP column reads ECU wherever it goes lean.

I've actually never tried fuel injector cleaner products before. Do these things actually work? I don't mind giving it a shot since it seems simple enough.

athenG

iTrader: (2)

Goose,
Do you have an old copy of your 0 Column? try comparing them and see if anything got changed.

Edit: I didn't see Gothchick's post

goosegoose

iTrader: (8)

I just checked my previous and existing tunes. The 0% columns on all the tunes are completely identical.

It doesn't look like a tuning issue. But maybe I'm wrong?

gothchick

iTrader: (12)

It has to be mechanical then. I bet some injector cleaner will help. Might want to check/ replace your fuel filter too (can't hurt). If those don't help, maybe your pump is starting to go.

Edit: Would a plenum leak (unmetered air) make it go lean like that in the 0% column? Does it idle okay?

goosegoose

iTrader: (8)

For the last several nights, it did not idle ok. It would hover around 15-16 AFR, randomly jump to 18-19AFR, boggle the engine a bit, and then correct itself a few seconds later.

Does this point to a plenum leak?

gothchick

iTrader: (12)

Yeah, I think it sounds more like a plenum leak now... Even NA cars (like mine) idle rough when they have a plenum/ intake leak... It's the unmetered air messing with the tune.

With the engine running (idling) just spray some carb cleaner around all the mated surfaces, gaskets, etc... If the engine suddenly races or boggs, you found your leak.

Or you can have a local shop do a smoke test on it. They fill the intake and plenum with compressed smoke. Pretty easy to spot a leak that way too.

goosegoose

iTrader: (8)

I can certainly check for leaks near the throttle body and the plenum entrance. But to diagnose problems in the plum body, I'm assuming I will have to take it apart and examine the seals and gaskets?

Also, would a plenum leak cause problems only at 0% Load, and not at higher MAP loads?

athenG

iTrader: (2)

quick way to check is get some carb cleaner, and spray the edge of the plenum with the car is running. When the cars idle changes then there is a leak.

goosegoose

iTrader: (8)

How exactly does this work? If there is a leak point, the area in question, will suck in the the carb cleaner and make the idle more rich or more lean?

athenG

iTrader: (2)

Well this will just tell you if there is a leak, if there is none then you can move on to troubleshoot something else. When you spray and there is a leak then your idle will change or you'll see that your car will bog down.

QuadCam

iTrader: (8)

mine does that too. always has. i THINk it has more to do with the larger injectors not liking to idle as well when scaled back so far.

goosegoose

iTrader: (8)

Problem is I've had these injectors for months, and have not had these problems until now. Also, all the other drivers with the STS setup and the exact same injectors don't seem to have this issue.

athenG

iTrader: (2)

My A/F always stay around 13.5-15 part throttle even on this colder weather. Lately my RPM does go dip every now and then but the car doesn't die I think I need to up my Idle a little. The only thing I'm curios is that my 0 column look different than his. We should (I hope) have the same size and kind of injector so I'm curious why we have different values.

Julian@MRC

iTrader: (28)

If your AF stayed at part throttle in the normal range, even during the cooler weather, and just now it seems to be doing this out of nowhere It concearns me.If adding some Temp correction in the parameters does not solve it, then you could try adding some fuel in those cells. Keep in mind part throttle is done in a % of MAF offset, so add smaller amounts like 3-5 at a time, and see if it corrects it. If it does not, then to me would seem like an injector is faulting..

athenG

iTrader: (2)

Isn't that temp correction is a global parameter? His problem is only on the 0 column and seem to be fine once he hit load. Does Utec Temp Compensation also affect the 0 Column? I'm also curious why his 0 Fuel Column is way different than mine. My 0 column is around -4.3 to -4.5 and his is around -12 to -16. My Idle and part-throttle under no boost/load has an A/F from 13-15.