Adjusting idle and part throttle

[Silver02]

I just logged about 15 minutes of driving time. What and where should I look to be sure the car is running correctly. I had the car tuned but a vacuum hose was disconnected during the tune.

[Blacky]

1. Take a look at your LTFT matrix in the Scan Tool, menu option: LS1/LS6->Long term fuel trim cells. If any cell is more than +/- 10% then that indicates a potential fueling issue at that operating condition. If any cell is +/- 25% then there is a definite problem and that would usually be accompanied by a check engine lamp and malfunction code.
A disconnected vacuum hose (as will most intake manifold and exhaust leaks) will show up as skewed fuel trim cell values.

2. Display the EPA test results to make sure all the supported tests are complete.
Menu option: Info->Retrieve all test results.
Then on the [OBDII (F7)] tab page, just select each sub page in turn to view the test results.

3. Does your car "feel" like it idles and drives well at part throttle. That is sometimes the best indication of whether anything is wrong or not. Sometimes idle/part throttle is not necessarily wrong, it just isn't the way *you* like it. If you like the way your car idles/drives at part throttle and the above test results show no problems then sit back, turn off the radio and listen to the sweet music of your LS1...

Regards
Paul

[joecar]

Also, look at the following sensors for sane numbers:

IAT should be close to ambient or underhood temp.
ECT should be above your thermostat but but below 220.
TPS should follow accelerator pedal motion.
MAP should be low at idle and should be approx barometric at WOT.
MAF should be low at idle and should increase with throttle opening.

If any one of these does not behave as described, then you got a problem
(each one of these is easy to fix).

[Silver02]

One thing I did last night was something I got from ls1tech.com I turned the throttle screw in until the sensor said 3% then I unplugged the sensor and it reset to 0. Now it idles a little faster. Will the computer relearn and adjust the idle lower after a while or do I need to make other adjustments. I'll also check for what was said on the posts above.

[Dirk Diggler]

3% was prolly too much and the car is getting too much air you need to move smaller than that 1% increments. Do you think the car isnt getting enough air for some reason.

[Silver02]

Cold start idle was terrible and just a little rough idle when warm. They have a sticky post on ls1tech.com that says that will make the car idle nice. I'm very new to tuning so maybe I need to back off from the 3% or I need to check the other adjustments first.

[Silver02]

backed off the idle screw about 1/2 way and reset the the sensor. Now it starts up fine cold and doesn't idle fast. I think it's pretty darn close.