So this thing is running really good now and I've got it tuned pretty close. I've had PCM for Less send me a computer and made a second tweek at it. It idles normal and runs smooth but after about an hour of driving the idle will start to pick up and aim for 2000 when driving. It will settle back to normal 1000 after the car comes to a complete stop. What is causing this and how do I fix this?

I have been tweeking with the idle adj screw on the tb which seemed to help for a bit the first time but the problem returned. I'm not sure if it's requiring more or less air at idle. Before the second tune, it was really bad and as soon as the car warmed up, it would do it. Any clues?

 

Throttle Cracker values probably too high.

Dixit

 

I would agree, look at the throttle cracker values under 2200 rpm, I set mine all at zero from 1800 rpm down and my engine drops right to idle when I push the clutch in now, before it would hang and take up to thirty seconds to fall.

 

Alright, I'll have to talk to brian at pcmforless. I drove it all last night and it was fine and then started to hang again. I gave the throttle screw a quarter turn and it has been better but every once in a while will hang around 1500 or so but at the same time, it will drop around 600 if I push the clutch in. Drivability is fine and seems to run great but the idling issues are getting annoyting. I also am getting the SES light from one code that says mass air circuit low. It has been on a while but when I restart the pcm, it stays off until the next time I turn the key on and start.

 

Its your cracker for sure. But also make sure your base RAF is dialled in and you don't have too high spark advance on your main spark map on decel and the upper 0.04-0.16g/cyl cells.

 

Did you ever find out what it was?

 

To dial in the base RAF, do you typically need to increase the values after cam install?

 

not always the throttle cracker

if you tb set screw is open too far it may see tps > 0% and you may have the iac steps already at 0 so it nolonger controls the idle. get the idle airflow right, then make sure the cracker doesnt have crazy high values (like the stock 2000 table). make sure at idle your iac steps arent any lower than 30 or so when fully warm.

 

yes, in general. it all depends on the car

 

The cam will decide whether the values need to increased or decreased. I haven't seen a cam install yet that didn't require these values to be changed. Every cam I've seen so far required decreasing these values.

 

it also depends a lot on the rpm you are idling at, should mention that as well. 2 guys with the same cam could have totally different tables depending on how they like their idle