Idle issues after tune. Does something need replaced? What can I test?
06-16-2016, 10:31 AM
#1
Idle issues after tune. Does something need replaced? What can I test? I just had my car tuned after changing out a bunch of parts and the tuner couldn't get it to idle right after a start.
When you turn the key and start it the idle falls until it dies. If you blip the throttle a little before it dies it will idle fine after that. He messed with it for a couple hours and finally told me the car just needed to relearn. He told me to drive it for a few days and not to let it die and it would resolve it. Well, after 7 or 8 restarts it still dies. One time it did start and idle fine without any assist but hasn't since.
Today a new problem crept in. I put the transmission in neutral to come to a stop and as soon as I let off the clutch the idle went up to 2000rpms and stayed there. I stopped at a gas station to fill up and and re-started and it did the same thing all the way home.
I also noticed when the ac is turned on now the idle doesn't raise any. It doesn't die, but doesn't blip up like it did on the last tune.
I've also had an issue a long time ago where every once in a while if I start the car it wouldn't idle at all. The rpms just fell until it died. I would unplug everything in the engine bay and replug it in and it would be fine. Never could figure that out and it eventually ceased to be a problem.
I drove the car with the new mods on the old tune for the last 500 miles and it didn't exhibit any idle problems. I figured all was well and had it tuned. That's when the idle problems listed in the beginning started.
Previous tune and setup was and 227/235 .614/.621 113+2 cam only build with 42# injectors, drilled throttle body blade, and long tube headers. It was EFI Live tuned in SD.
Mods added since old setup/tune are:
POTZ ported stock Throttle Body with bumpstop mod and non-drilled blade (transferred sensors over from old throttle body)
243 heads, milled to 63cc chambers
226/234 .612/.595 112+2 cam
3/8" Pushrods
Morel 5315 lifters
1 7/8" headers (old were 1 3/4")
High flow cats
Racetronix 255lph fuel pump with hotwire
Maf tuned with HP Tuners
Is there a sensor I can test/replace that could be contributing to this problem? I hesitate to blame it on the tuner because that particular tuner has a solid reputation around here for making these car run great. In fact, driveability is awesome now, almost stock. Whereas the last setup and tune there was a lot of low speed low rpm drive ability issues. He spent several hours doing both a street tune and a loaded dyno tune. At one point, when he was trying to fix the idle, he came in asked me if I had jacked with my throttle-body or idle screw because the numbers were all over the place.
When you turn the key and start it the idle falls until it dies. If you blip the throttle a little before it dies it will idle fine after that. He messed with it for a couple hours and finally told me the car just needed to relearn. He told me to drive it for a few days and not to let it die and it would resolve it. Well, after 7 or 8 restarts it still dies. One time it did start and idle fine without any assist but hasn't since.
Today a new problem crept in. I put the transmission in neutral to come to a stop and as soon as I let off the clutch the idle went up to 2000rpms and stayed there. I stopped at a gas station to fill up and and re-started and it did the same thing all the way home.
I also noticed when the ac is turned on now the idle doesn't raise any. It doesn't die, but doesn't blip up like it did on the last tune.
I've also had an issue a long time ago where every once in a while if I start the car it wouldn't idle at all. The rpms just fell until it died. I would unplug everything in the engine bay and replug it in and it would be fine. Never could figure that out and it eventually ceased to be a problem.
I drove the car with the new mods on the old tune for the last 500 miles and it didn't exhibit any idle problems. I figured all was well and had it tuned. That's when the idle problems listed in the beginning started.
Previous tune and setup was and 227/235 .614/.621 113+2 cam only build with 42# injectors, drilled throttle body blade, and long tube headers. It was EFI Live tuned in SD.
Mods added since old setup/tune are:
POTZ ported stock Throttle Body with bumpstop mod and non-drilled blade (transferred sensors over from old throttle body)
243 heads, milled to 63cc chambers
226/234 .612/.595 112+2 cam
3/8" Pushrods
Morel 5315 lifters
1 7/8" headers (old were 1 3/4")
High flow cats
Racetronix 255lph fuel pump with hotwire
Maf tuned with HP Tuners
Is there a sensor I can test/replace that could be contributing to this problem? I hesitate to blame it on the tuner because that particular tuner has a solid reputation around here for making these car run great. In fact, driveability is awesome now, almost stock. Whereas the last setup and tune there was a lot of low speed low rpm drive ability issues. He spent several hours doing both a street tune and a loaded dyno tune. At one point, when he was trying to fix the idle, he came in asked me if I had jacked with my throttle-body or idle screw because the numbers were all over the place.
06-16-2016, 01:52 PM
#2
Well I went home on lunch and tested some things. Key on, engine off the tps reads .62 throttle closed and 4.63 throttle blade open. With the engine running it averages .54 but bounces around erratically from .13 to .67.
Also, i started the car with the iac unplugged and it acted the same as when plugged in. While unplugged, after 30 seconds or so of running the car started reving up to 2000rpm on its own. I plugged the iac back in and it didnt change.
Also, i started the car with the iac unplugged and it acted the same as when plugged in. While unplugged, after 30 seconds or so of running the car started reving up to 2000rpm on its own. I plugged the iac back in and it didnt change.
06-16-2016, 08:41 PM
#3
I installed a new TPS and that didn't affect anything. I pulled the IAC to clean it and discovered the oring for it was missing. It must have been stuck inside the old the throttle body when I swapped the electronics over to the new throttle body. I reset the pcm and let the car idle for a while with the ac off then on and took it for a drive. The car still dies when you first start it but the 2000rpm idle issue seems to be gone. It idles fine during driving. Any idea if the car will be able to learn a startup idle or do I need to take it back to the tuner now that I fixed the leak at the iac?
