Ltrims out of wack! - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 10-04-2004, 06:10 PM   #11
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Well I almost had it fixed. I started the car up for work this morning and the check engine light still came on, but after 1 minute it turned off! The whole 15 minute drive to work it didn't come back on so I thought the stud I put in the header fixed it. Well I started it up to leave work at 3:30 and TA DA!...there was the friggin' CEL again.

We checked something else that night at the track...it might have been IAC. I remember numbers 20 and 40 having a significance. I had the "bad" number and wanted the other number. So I either had a 20 and want a 40 or vice versa.

One other thing I've noticed, but I've noticed this for some time before headers. The boost gauge will jump/fluctuate from -10 to -8ish when braking or coming to a stop.
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Old 10-04-2004, 08:30 PM   #12
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Were you getting the +16.4 LTFT reading at idle or at highway cruising speed?

Cheers,
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Old 10-04-2004, 09:19 PM   #13
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16.38% at idle in D with parking brake on.

Scott suggests a leak near the EGR tube. Any tips for getting that plate flush with the headers (considering there is only 1 bolt on one end of the plate)? I ask because the top of my plate has a small slit.
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Old 10-04-2004, 10:09 PM   #14
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He definitely has a leak somewhere, his IAC counts at idle were 15.

btw, I was the one who scanned your car. I found your forum

Thanks,

Joel
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Old 10-04-2004, 10:24 PM   #15
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Quote:
Originally Posted by Allmachtige
16.38% at idle in D with parking brake on.
But that'* what it should be...no? Both my OEM PCM and my INTENSE PCM run at +16.4 LTFT at idle. What is your value at highway cruising speed?

Cheers,
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Old 10-04-2004, 10:36 PM   #16
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Do you have an aftermarket cam? If so, for some cams its normal to have your Ltrims maxed at +16.4% at idle.

My L-Trims at idle range from +2.6% - -2.6% at idle, this is after tuning with the Mini-Afc 2.0. Before tuning my L-trims at idle were around +10% - +11%

Thanks,

Joel


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Originally Posted by Foghorn
Quote:
Originally Posted by Allmachtige
16.38% at idle in D with parking brake on.
But that'* what it should be...no? Both my OEM PCM and my INTENSE PCM run at +16.4 LTFT at idle. What is your value at highway cruising speed?

Cheers,
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Old 10-04-2004, 10:42 PM   #17
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Quote:
Originally Posted by jk99gtp
Do you have an aftermarket cam? If so, for some cams its normal to have your Ltrims maxed at +16.4% at idle.

My L-Trims at idle range from +2.6% - -2.6% at idle, this is after tuning with the Mini-Afc 2.0. Before tuning my L-trims at idle were around +10% - +11%

Thanks,

Joel


Quote:
Originally Posted by Foghorn
Quote:
Originally Posted by Allmachtige
16.38% at idle in D with parking brake on.
But that'* what it should be...no? Both my OEM PCM and my INTENSE PCM run at +16.4 LTFT at idle. What is your value at highway cruising speed?

Cheers,
I don't have a cam or rockers. I'm guessing from your screen name Joel that you have a 99 GTP, did you check the LTFT on yours before tuning with the AFC?

My 2000 GTP also had idle LTFT values of +16.4% on an OEM PCM.

The high value at idle is normal as far as I know Joel. Do you happen to have the rest of the values from your scan(*).

Cheers,
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Old 10-04-2004, 10:48 PM   #18
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I'm going out to check my car now.
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Old 10-04-2004, 10:51 PM   #19
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I do have a 99 GTP, before tuning with the Mini-Afc I was seeing around +10%-+11% Ltrims. I had to add around 3% on the Mini-Afc on the 1Khz-3Khz ranges, this brought my L-trims down to around +2.6% - -2.6%. My cruise L-trims were around +5-+6%, so I added 1% of the Mini-Afc to get them around the same values as above.

I found this article to be a really good start on tuning your L-trims (Granted it is an article for a Mini-Afc 2.0, but it does give a good idea on what to look for

http://www.stlclubgp.com/tech/afc20/

Here is some info from the article regarding LTFT'*:

"LFT1 – LFT1 is used for tuning with the AFC 2.0 at Cruise and Idle. WOT uses O2L which we will talk about later. If you are see large negative (-) numbers here, you will most likely want to turn your fuel down (take fuel away). The reverse goes for large positive (+) numbers as here is when you want to add Fuel.

Large Positive (+) LFT1 = TOO LEAN
Large Negative (-) LFT1 = TOO RICH

You want your LFT1 reading as close to 0 as possible but +/- 5 is an acceptable level. I have found that a 1% Increase/Decrease on the AFC 2.0 Equals about 2-4 Increase/Decrease on the LFT1 reading. "

We did not check Kyle'* LTFT'* at cruise since we didnt have much time at the end of the day. But hopefully we can get some scans in for him, so we can see his KR, IPW, Ignition Timing, O2, etc...

Thanks!

Joel



Foghorn Wrote:
I don't have a cam or rockers. I'm guessing from your screen name Joel that you have a 99 GTP, did you check the LTFT on yours before tuning with the AFC?

My 2000 GTP also had idle LTFT values of +16.4% on an OEM PCM.

The high value at idle is normal as far as I know Joel. Do you happen to have the rest of the values from your scan(*).

Cheers
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Old 10-04-2004, 11:00 PM   #20
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Initial car start (cold) was 1.7% - 2.5% Once car reached temp (160) LTFT was 4.7%.

My IAC count was 80 cold and 60 warm though, not sure about this, have to look into it tomorrow.
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