Help me decipher TL info

[DKREDT]

First time I have hooked up TL. I saved the idle info after the car had warmed up. Car runs decent, but seems to stumble low end.

Here are some of the numbers that seem to deviate from the normal values I have read about.

Idle values, car warm

TPS .36
o2 cross 0
O2 volts 738 mv
IAC index 0 # 0%

Car has a Thrasher 92 chip with FP set to 45 psi line off.

Do I need a new 02 sensor based on the cross counts? What is up with the IAC index? Is the TPS set too low?

Thanks,

Joel

(TL rookie)

 

[kenmosher]

At a glance, TPS is a bit low (which can aggrevate a low end stumble). I'd raise it a bit to ~0.40-0.42. See:

http://www.gnttype.org/techarea/maintenance/TPS.html

O2 volts indicate that car is really rich at idle (assuming that's an average?)

O2 xcnts indicate it is staying rich (there should be 10-25 crosscounts at idle with a good active O2 sensor).

IAC indicates that you might benefit from resetting the minimum idle air set screw (on the side of the throttle body). See:

http://www.gnttype.org/techarea/faq/IACresetscan.html

After doing the adjustments, see how things work. If that cures the stumble and things look better, you're done. If not, I'd start looking for the following:

• A Vacuum leak
• A hole in the flexible MAF hose, leaking air around the MAF
• Bad PCV
• Bad MAF
• Leak around the intercooler hoses
• Leak around the TB hoses
• Intake manifold leak

 

[TurboDave]

Originally posted by DKREDT
First time I have hooked up TL. I saved the idle info after the car had warmed up. Car runs decent, but seems to stumble low end.

Here are some of the numbers that seem to deviate from the normal values I have read about.

Idle values, car warm

TPS .36
o2 cross 0
O2 volts 738 mv
IAC index 0 # 0%

Car has a Thrasher 92 chip with FP set to 45 psi line off.

Do I need a new 02 sensor based on the cross counts? What is up with the IAC index? Is the TPS set too low?

Thanks,

Joel

(TL rookie)

Trying to diagnose any kind of a problem from idle data while there's a thrasher chip installed is going to be next to impossible, since the thrashers are open loop idle chips.
That's the reason you're seeing no O2 cross counts and a high idle O2 value

Your TPS is a little low, try and get it up to something closer to .40-.42

Your IAC's at 0 indicate your minumum air screw needs a little adjusting to bring them up. But to raise IACs you need to go CCW on the adjust screw, which is going to take your TPS value even lower, so get the TPS set better first, then any IAC adjustments you need to make wont take your TPS WAY out of range.
When you do find a good IAC number (15-20 in park idling, warm) then give your TPS it's final tweek.

 

[kenmosher]

Good catch Dave!

I missed the Thrasher chip ... ignore the "rich at idle" part, Dave's right, that's the way a Thrasher is supposed to work, since it's open loop.

Just do the TPS and IAC adjustment (TPS first as Dave suggests, then IAC, then tweak TPS, as Dave suggested).

Sorry for the confusion, I missed the Thrasher chip...

 

[DKREDT]

Dave and Ken.. thanks for the help. I appreciate it!

Joel

 

[WSLN 6]

I agree with pretty much everything....except for the crosscounts comment.
I run a Thrasher 100 chip all the time, and the crosscounts were pretty much zero. I replaced the O2 with another AC Delco and the crosscounts were back and very active.
Something to check after all the basic adjustments are done............