Dyno trouble - won't rev above 4500! (updated)

[zlexiss]

Went to the club dyno day today. Wasn't expecting any problems, car was basically the same as when I ran it back in April.

Except the car wasn't happy. On the dyno, in any gear, the car wouldn't rev over 4500 rpm. I was acting like it was getting the fuel cut off.

We checked the parking brake, still nothing.

Car is fine on the street - right off the rollers it pulled nicely up to 6k in both first and second gears. Just like it's always done.

Air filter is clean, fuel filter is new, and it's fine on the street, so what caused this?

(Update: see post at bottom with HP Tuners VCM comparison and ABS light..)

(Updated again 11/27 - ABS INOP solved and possible solution)

[ November 27, 2005, 12:51 PM: Message edited by: zlexiss ]

[foff667]

so you ran it on a dyno before with no problems?

[Rowdy Burns]

that's weird as ****.

if it was only happening in 4th i'd say it was the speed limiter, but having it happen in all gears kind of messes up that hypothesis.

[run3]

try to put your car on other dyno system, i mean different brands or models~

[zlexiss]

Yah, no one could figure anything.

My dyno run back in April was at the same place.

[foff667]

im thinkin possibly knock retard...ive seen this in several cars now where at 5000 rpms in any gear a ton(ie 15*) of kr will just appear with no explanation...i know on the street with a specific tune i had 0 kr on my gtp...throw it on the dyno, bam 8* for no apparent reason...just my theory and im stickin to it until you get a scan while your on the dyno ;)

[Turbo V6 Camaro]

Originally posted by foff667:
im thinkin possibly knock retard...ive seen this in several cars now where at 5000 rpms in any gear a ton(ie 15*) of kr will just appear with no explanation...i know on the street with a specific tune i had 0 kr on my gtp...throw it on the dyno, bam 8* for no apparent reason...just my theory and im stickin to it until you get a scan while your on the dyno ;)

yup mine sees KR on the dyno to

[mrbako]

did u disable the speed sensor? =top speed limiter

[zlexiss]

Would knock retard show up at the same point in every gear plus neutral, but not at all on the road?

I will have HP Tuners here this week. Time to do some scanning!

Bako: It's not top speed limiter, since it hit in all the gears.

I have a suspicion that the HPP3 left some junk in the PCM. Back in April I dynoed with all the HPP3 power settings, even back to stock, and got the same hp/tq numbers every time. Even after I pulled the HPP3 and sold it, stuff that should have gone back to stock, like the top speed limiter, is still at the HPP3 settings.

I think I'm going to see if I can get the dealer to burn the PCM back to total factory stock. Then I can compare that to what the HPP3 left behind and see if that gives me any clues.

"ABS Inop" light is still on from the dyno pull btw. I did a search and checked all the usual stuff like the wires from the wheel sensors and brake lights. Pushing the pedal trick didn't clear it either. Any ideas, I have an autocross in a couple weekends and would like my ABS back!

[foff667]

well in neutral the rev limiter is probably set to like 3500ish but ive seen it where cars would fall flat on their face at a given rpm because if it...ask kristen or little g

[AZ3.8Camaro]

I doubt its KR keeping it from revving.
Thats very wierd man. I will ponder it for a while.

[zlexiss]

Yah, I'm doubting KR too right now. The engine is pulling really strong, making full torque right to 4500, then it just cuts out like you've hit the rev limiter. Smooth curve with no bumps or anything up till that point.

Since I dynoed in April, I've:
- Removed HPP3. Still biggest suspicion, though I did do a pull with it uninstalled in April for comparison and it ran jsut fine
- Installed Alum flywheel, lightweight Spec II, and B&M Ripper. I'm going to pull the console this weekend and see if any wiring got buggered, but the parking brake light on the dish is acting ok, and we know the car is fine on the street.

[FunkZ]

Isn't there a neutral rev limiter? or is that only on the automatics?

[Red]

Originally posted by FunkZ:
Isn't there a neutral rev limiter? or is that only on the automatics?

"well in neutral the rev limiter is probably set to like 3500ish but ive seen it where cars would fall flat on their face at a given rpm because if it...ask kristen or little g"

[FunkZ]

Doh, sorry missed that post.