PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

What to look into & log?

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Old Oct 24, 2007 | 08:06 AM
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Default What to look into & log?

Using HPTuners, for the most part the Trans AM is running great!

The only issue I'm seeing is 1st thing in the morning. I'll start-up the car and let it idle for 2-3 minutes before driving off to work. I seem to be able to back out of the driveway okay, but once I start to drive forward (M6) it seems to have a not just a lack of power, but a little bucking...more like hesitating.

So I'll be driving away getting up to speed, 1st gear, 2nd, 3rd, etc. Once up to speed on that road (about 45mph), then cruise along okay. By the time I hit the 1st stop light, stop then drive off again, the car is running fine, A+. For the rest of the day, it'll run great, no problems. Even after it sits at work all day long, 8 hours.

At first I thought it might be something in Open Loop, but temp might be playing into it. I'm not sure. Any thoughts?
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Old Oct 24, 2007 | 08:29 AM
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Originally Posted by Michael02hawk
Using HPTuners, for the most part the Trans AM is running great!

The only issue I'm seeing is 1st thing in the morning. I'll start-up the car and let it idle for 2-3 minutes before driving off to work. I seem to be able to back out of the driveway okay, but once I start to drive forward (M6) it seems to have a not just a lack of power, but a little bucking...more like hesitating.

So I'll be driving away getting up to speed, 1st gear, 2nd, 3rd, etc. Once up to speed on that road (about 45mph), then cruise along okay. By the time I hit the 1st stop light, stop then drive off again, the car is running fine, A+. For the rest of the day, it'll run great, no problems. Even after it sits at work all day long, 8 hours.

At first I thought it might be something in Open Loop, but temp might be playing into it. I'm not sure. Any thoughts?
Sounds like it may be a little too lean. Are you using a wideband?
PS, the adjustment would depend on alot of things. Do you have a log?
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Old Oct 24, 2007 | 08:55 AM
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Temperature drives open loop fuel adders and spark
too. Log the EQ ratio and the NBO2 voltage, see what
the PCM is commanding for fuel and whether the O2s
agree that's what's happening (wideband, even better).
Log the ECT and you can at least run a finger through
the tune file to see what's being laid on you.

Cammed cars idle at MAP levels which the stock EQ vs
ECT vs MAP (OLFA) table has big enrichment values for,
especially cold. Oddly I see later truck tunes with much
less over-the-top enrichment. You have to look at the
F-body LS1 as GM's "learning experience" and one not
really completed.

Logging FTC will tell you about closed loop / open loop
too.
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Old Oct 24, 2007 | 11:04 AM
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Looking at my current EQ ratio table (its stock) I think you got me in the right area.

Thanks! I'll scan and look into it more this weekend.
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