For those who have been following my build so far, i now have 500 miles on the motor... mechanically everything feels like its running right... however, ive noticed a few things with the computer that i would like to know if they are fixable with HPT...
First off all, the car was tuned at idle before i really started driving it and now for the most part the car runs stoich... it maintains between 13.6 - 16.9 AFR with it mostly around 14.7 at both idle and cruising... at WOT it stays around 10 (which i know is rich, but WOT hasn't been tuned yet at all)... however on occasion, it randomly decides to run pig rich and the wideband stays locked at 10. During this time the car makes very little power, and black fuel smoke comes out the exhaust. (It smells like a gas station behind the car)... after i shut it off, let it sit for a few, it'll start back up at 14.7 and drop down from there... it took a few times reving the engine for it to slowly come back to stoich... from what ive noticed it doesnt happen that often, but it has happened multiple times, and twice today (i put 300 miles on from friday to today).... the first time it happened today i was crusing in the city between 45 - 55 MPH and had several stoplights.... the second time happened while i was sitting in the car with it idling runing the AC, after 15 minutes it reved up, and after a few seconds it reved down and the AFR was locked at 10. (this is when i called Clyde, and after starting it up twice and revving it, it went back to stoich)
So basically its just randomly running rich.
My second issue is on a lot of occasions, the car will try to hold 3000 RPM. For example, i'm driving, i shift, it'll rev up, shift again, rev up... pull out of gear, it'll hold 3000, or if im driving it, and in gear the car will accelerate slightly even when my foot is not on the gas. heres the part that makes me think this is computer related... when its doing it, the instant i hit around 5 MPH, it'll rev down.... everytime... it doesnt matter if it takes me 20 seconds or 1 minute to slow down to 5 MPH, it will hold the rev perfectly at 3000 until around 5 MPH, then it will idle normally... It doesn't do this all the time, but quite often it does.
Speedline02 (GME Chat!!) wrote:For those who have been following my build so far, i now have 500 miles on the motor... mechanically everything feels like its running right... however, ive noticed a few things with the computer that i would like to know if they are fixable with HPT...
My second issue is on a lot of occasions, the car will try to hold 3000 RPM. For example, i'm driving, i shift, it'll rev up, shift again, rev up... pull out of gear, it'll hold 3000, or if im driving it, and in gear the car will accelerate slightly even when my foot is not on the gas. heres the part that makes me think this is computer related... when its doing it, the instant i hit around 5 MPH, it'll rev down.... everytime... it doesnt matter if it takes me 20 seconds or 1 minute to slow down to 5 MPH, it will hold the rev perfectly at 3000 until around 5 MPH, then it will idle normally... It doesn't do this all the time, but quite often it does.
This sounds like it COULD be idle air control related...
the IAC valve is brand new (i replaced it first thinking this could have been the problem, before realizing that the RPM was exactly holding at 3000 and dropped exactly around 5 MPH (maybe 7... its always slightly above the 5 MPH mark on the speedo)
Edited 1 time(s). Last edited Sunday, April 25, 2010 7:02 PM
well when you say it was just tuned at idle and now your driving it did you go into further tuning for the ve and pe enable? sounds like something is up with your ve....
no we simply tuned the idle in the parking lot...first the injector constant (for the LSJ injectors), and then the values in the idle table... when its acting right, it idles exactly where it should (in terms of AFR)...
at that point in time i only had 100 ish miles on the motor and did not street tune any other part of the ECM yet...
My tuner is really good with HPT, but he's much more experienced with the Cobalts, and the Cavalier ECM is new to him.. so any knowledge that may assist him would be appreciated..
I think you should go in and at those specific rpm points you have issues and try and change the values. Or even try and do a low to mid rpm ve tune you have a wideband does he have hpt pro or the regular one
he has hpt pro... i'll be talking to him wednesday so he'll come out somewhere around then
Hey bro im sure you have already checked this already but this same exact problem happened to me after I installed my LE5 intake manifold. I had a small vacuum leak from the brake booster hose. Once i bought another new hose, my issues went away. As for yours running rich randomly, mine does that too and it's driving me nuts. I installed cams last year and i was thinking maybe my exhaust cam got 1 tooth off....
