KR elimination

[superchargedSSEi]

Check your fuel pressure with a mechanical gauge even if the headers fix the KR problem. The positive LTFT could be a sign that something isn't right with your fuel system, especially with 141k on the car, and the last thing the motor needs is for you to go WOT with low fuel pressure.

[TommyGloves]

You might also need to change your fuel filter. That could also reduce your fuel presure.

[99ssei]

Fuel filter was changed in March (I think). Need to check my documents.
EDIT: Fuel filter changed 4/06/08
Could the factory sending unit be an issue? I've never had it fixed. (problem is it's reading full, but after 1/2 tank, gauge is unreliable: sometimes reads full when on empty). I know to fill up every 280 miles and have been doing so for 4 years.

[BillBoost37]

That sounds like a sender.

Easy way to check is get 110 ohm and 220 ohm resistors and put one between (I think..need to check) pins B & D on the sender connector by the tank. Your gauge should be 0-220 ohm (or something close to that). 110 would be half full and 220 is empty (IIRC)

[2000Silverbullet]

Fuel level sensor will have nothing to do with KR.

[willwren]

Fuel level sensor will have nothing to do with KR.

Correct. You can rip out the sender and your fuel gauge and it doesn't matter. How much fuel is indicated on that gauge has no effect on how the motor runs.

[99ssei]

Check your fuel pressure with a mechanical gauge even if the headers fix the KR problem. The positive LTFT could be a sign that something isn't right with your fuel system, especially with 141k on the car, and the last thing the motor needs is for you to go WOT with low fuel pressure.

What should the LTFT be?
I was watching the short trim and it was fluctuating between negative (no throttle) and positive numbers (throttle).

EDIT: I was researching and found this great article: http://www.c5forum.com/diy/ltft.php
I'm definitely running lean. Now, should I look at my MAF? If I'm flowing more air, should I look into get a MAF translator?

[99ssei]

Just rest the fuel trim through the scangauge and went for a test drive to see the results.
I did the reset in park, at idle. The STFT and LTFT immediate cleared to 0.0 and I felt the car's idle change.
At less than 50% throttle, LTFT is between 7 and 10.
At WOT, LTFT went down to 0.0, but never negative.
I still saw KR hit 7. Grrr

EDIT: KR was ONLY at WOT.

[99ssei]

I asked Aeroforce about the fuel trim reset and what it does...exactly.

"I have my WOT timing tables advanced 3 degrees. Will this feature reset it back to stock settings?"

Aeroforce response: "No, it will just reset the learned fuel trims to 0.0, and clear any historical DTC's. Once you start driving around the PCM will start learning again and adjust the fuel trims. Some people will reset the fuel trims before running at the track because they can have an effect on WOT fueling. If the car has a tune it will not account for this and can be bad if the car is then pulling fuel in open loop (Wide Open Throttle)."

[superchargedSSEi]

What should the LTFT be?
I was watching the short trim and it was fluctuating between negative (no throttle) and positive numbers (throttle).

The LTFT should be as close to zero as possible without it being positive (lean). The LTFT value is how much the pcm is correcting the injector pulse width, +7 means 7% longer injector pulses. Without a tuner there's not much you can do to get it close to zero. The STFT isn't really useful for anything unless you are trying to figure out when your fuel trims are relearned.

EDIT: I was researching and found this great article: http://www.c5forum.com/diy/ltft.php
I'm definitely running lean. Now, should I look at my MAF? If I'm flowing more air, should I look into get a MAF translator?

You aren't flowing anywhere near enough air to peg the factory MAF sensor. In the L67 circle MAF translators are usually only used if you're pegging a 85mm MAF sensor (LT1, LS1, LQ4 etc.). Unless your MAF readings are getting *dang* close to 11.5k Hz you don't need to upgrade.

Just rest the fuel trim through the scangauge and went for a test drive to see the results.
I did the reset in park, at idle. The STFT and LTFT immediate cleared to 0.0 and I felt the car's idle change.
At less than 50% throttle, LTFT is between 7 and 10.
At WOT, LTFT went down to 0.0, but never negative.
I still saw KR hit 7. Grrr

It usually takes anywhere from 50-200miles of mixed driving to relearn the fuel trims. WOT or even 50% throttle runs right after resetting them .

The WOT LTFT will occasionally default to 0 during the relearn period so what you saw today does not mean that your fueling is perfect. The fact that you are still running as lean as you are at part throttle right after resetting the fuel trims points to a fuel delivery problem. Putting your shiny new headers on the car might fix your KR now but it WON'T fix your lean condition which could result in even more KR down the road or worse. Fixing this lean condition needs to be your top priority.

[BillBoost37]

A friend once explained to me that fuel trims take two drive cycles to start relearning. A drive cycle was explained as an up to operating temp 10 minute drive. At that point you'll want to turn the car off and restart for at least another 10 minutes.

The best measurement is over a good period of time as your trims will change based on the driving (city/hwy) etc. When you WOT, the LTFT is where it's all at.

[TommyGloves]

The WOT LTFT will occasionally default to 0 during the relearn period so what you saw today does not mean that your fueling is perfect. The fact that you are still running as lean as you are at part throttle right after resetting the fuel trims points to a fuel delivery problem. Putting your shiny new headers on the car might fix your KR now but it WON'T fix your lean condition which could result in even more KR down the road or worse. Fixing this lean condition needs to be your top priority.

x2

[99ssei]

Update...Headers put in Friday, but with some minor issues:
http://www.pontiacbonnevilleclub.com/fo ... =12&t=3192

Right after I had them installed, I immediately reset the fuel trim.
With the main fan out, I've driven it with caution (low pro arrives Tuesday and will be installing it ASAP).
I've been able to make some WOT runs today and it's getting better.

Air temp - 79 (low humidity)
Intake temp - 82
1st run - (0-45) 0.0 KR
2nd run - (0-50) 0.0 KR up to 4500 RPM, 2.3 KR @ about 5k RPM
3rd run - (0-45) same as above, but hit 2.3 KR @ 5K, LTFT was at 9.3
(all three runs were consecutive at operating temp 160-65).

Still looks like I'm running lean.
Will be looking at fuel pressure this week to see what's going on there. Since this is only WOT, can I test pressure while in park and rev the motor to see results or do I have to strap my buddy to the hood as I make a run?

[superchargedSSEi]

If everything checks out while testing the pressure in the driveway you'll need to go for a test drive with your buddy strapped to the hood.

[BillBoost37]

I picked up a piece of hose with fittings and use it to extend the FP tester.

[99ssei]

Wondering if it's an electrical issue:
http://www.3800performance.com/Merchant ... t_Count=11

[99ssei]

What is the desired fuel pressure for my car?

[willwren]

41 psi at idle, as close to 47 psi at idle with the vac line pulled off the FPR.

Those are minimums.

[99ssei]

Tested with mechanical gauge:
Just kicking on the pump (ignition forward) - 48
At idle - 42
Rev'd - hit 58

Side note, DTC PO440 came on. Found the hose going to the EVAP canister was cracked. (is that connected to the EVAP solenoid?) Tried local parts store for the hose and they don't carry formed hose.

[willwren]

That COULD run you lean. Depends on the leak.

You can use standard non-preformed vac line there. Just make sure it doesn't kink when you bend it around that tight. Or go to the wrecker or dealer.