Weird Rev limit.
Posted: Sun Aug 17, 2008 10:01 pm
Ive noticed recently a strange occurrence with my s300 unit, which is installed in a p28 ecu.
Sometimes randomly (at least it seems random) while trying to pull away from a light (or rev the car at all) the rev limiter kicks on at a measly 3500 rpm. It does this usually in each gear and it sometimes stops mid gear and lets me past 3500. Usually 3rd. But tonight I noticed that if I shut the car off while driving and then proceed. It runs fine. But if I stop the car, say at a light or something..I then cant pull away from the light, again. This is starting to aggrevate me. At first I thought it could be the vss signal and the car was stuck in launch control..but my launch control is set to 5k so its most certainly not that, also I finally managed to catch it on a datalog and watched what happened. Rev limit right on at 3500, no CEL's No warnings. Nothing.
I do notice thought that when it does this just before it hits the limiter there is a huge loss in power as if the timing is being drastically retarded, or there is a ton of fuel being dumped. While its running in this mode the exhaust will pop and crackle while in decel and the idle is a little rough and the car will die in a short time if I don't move.
Any time this isn't going on the car runs perfectly though. It seems as though something is kicking the ecu into a safety mode.
Any thoughts? Ive already checked every wire I could on my jumper harness, my gauge cluster, and under the hood. None of my solder connection are loose or change the way the car runs at all.
Sometimes randomly (at least it seems random) while trying to pull away from a light (or rev the car at all) the rev limiter kicks on at a measly 3500 rpm. It does this usually in each gear and it sometimes stops mid gear and lets me past 3500. Usually 3rd. But tonight I noticed that if I shut the car off while driving and then proceed. It runs fine. But if I stop the car, say at a light or something..I then cant pull away from the light, again. This is starting to aggrevate me. At first I thought it could be the vss signal and the car was stuck in launch control..but my launch control is set to 5k so its most certainly not that, also I finally managed to catch it on a datalog and watched what happened. Rev limit right on at 3500, no CEL's No warnings. Nothing.
I do notice thought that when it does this just before it hits the limiter there is a huge loss in power as if the timing is being drastically retarded, or there is a ton of fuel being dumped. While its running in this mode the exhaust will pop and crackle while in decel and the idle is a little rough and the car will die in a short time if I don't move.
Any time this isn't going on the car runs perfectly though. It seems as though something is kicking the ecu into a safety mode.
Any thoughts? Ive already checked every wire I could on my jumper harness, my gauge cluster, and under the hood. None of my solder connection are loose or change the way the car runs at all.