5800 RPM stumble
06-26-2008, 03:43 PM
#1
5800 RPM stumble 01 Trans Am with 6 spd manual.
Runs perfect in all conditions, except has a stumble at 5800 rpm. Conditions when problem occurs:
No misfire recorded.
All 4 O2's showing 950Mv.
Fuel pressure 46 lbs.
Pulse width on both banks 16Ms.
Problem is always repeatable.
Any advice would be appreciated!
Runs perfect in all conditions, except has a stumble at 5800 rpm. Conditions when problem occurs:
No misfire recorded.
All 4 O2's showing 950Mv.
Fuel pressure 46 lbs.
Pulse width on both banks 16Ms.
Problem is always repeatable.
Any advice would be appreciated!
06-26-2008, 03:55 PM
#2
Mods? Tuned? Recent work? Tried anything simple yet dealing with plugs/wires/maf? More info on the setup etc along with anything you have tried would be very helpful
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06-26-2008, 06:26 PM
#6
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What exactly do you mean by "stumbling?" I had a problem a while ago, and it may be the same thing you are experiencing. My rev limiter was kicking it at an indicated 5800 rpm. I was unaware at the time how inaccurate the factory tachometer is. I was actually at 6200 (rev limit), but just didn't know it.
You can figure out if this is the problem by rowing the gears. If the problem happens in 1st and 2nd, it is the same thing that was happening to me. The problem did not pursist in the higher gears because the car wasn't revving as quickly as it did in the lower gears and the factory tach could keep up.
This may not be your problem, but I figured it was worth a shot....good luck.
You can figure out if this is the problem by rowing the gears. If the problem happens in 1st and 2nd, it is the same thing that was happening to me. The problem did not pursist in the higher gears because the car wasn't revving as quickly as it did in the lower gears and the factory tach could keep up.
This may not be your problem, but I figured it was worth a shot....good luck.
06-26-2008, 10:44 PM
#7
What exactly do you mean by "stumbling?" I had a problem a while ago, and it may be the same thing you are experiencing. My rev limiter was kicking it at an indicated 5800 rpm. I was unaware at the time how inaccurate the factory tachometer is. I was actually at 6200 (rev limit), but just didn't know it.
You can figure out if this is the problem by rowing the gears. If the problem happens in 1st and 2nd, it is the same thing that was happening to me. The problem did not pursist in the higher gears because the car wasn't revving as quickly as it did in the lower gears and the factory tach could keep up.
This may not be your problem, but I figured it was worth a shot....good luck.
You can figure out if this is the problem by rowing the gears. If the problem happens in 1st and 2nd, it is the same thing that was happening to me. The problem did not pursist in the higher gears because the car wasn't revving as quickly as it did in the lower gears and the factory tach could keep up.
This may not be your problem, but I figured it was worth a shot....good luck.
I will take it up to 6000 in 3rd and check results.
Thanks for your input.
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06-27-2008, 10:58 AM
#10
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This makes perfect logical sense - RPM in 1st gear builds quickly and the tach can't keep up. Indicated 5800 could actually be hitting the rev limiter at 6200. I checked everything on the scan tool except RPM. I assumed the dash tach was correct.
I will take it up to 6000 in 3rd and check results.
Thanks for your input.
I will take it up to 6000 in 3rd and check results.
Thanks for your input.
06-27-2008, 03:46 PM
#11
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Pig rich is what the factory tune commands. But you
would be pig rich at lower RPM too. I favor the rev
limiter idea but that is not a "stumble", that is more
like whup-whup-whup until you shift. Another possible
cause of weirdness in a narrow RPM range is valvetrain
resonances. The weaker the spring, the lower that
will be seen.
would be pig rich at lower RPM too. I favor the rev
limiter idea but that is not a "stumble", that is more
like whup-whup-whup until you shift. Another possible
cause of weirdness in a narrow RPM range is valvetrain
resonances. The weaker the spring, the lower that
will be seen.
06-27-2008, 08:19 PM
#13
I'm having the same problem and mine does it in 1st 2nd 3rd & 4th gear once it hits 5800. I can't even use my nitrous period. I think it's something dealing with fuel but what's the possibility that it's timing or A/F ratio. Fuel pump & filter has been changed. Same results.
99 Camaro SS M6
Lid, LT Headers, Borla Ex, Skip Shift, 125wet
99 Camaro SS M6
Lid, LT Headers, Borla Ex, Skip Shift, 125wet
Last edited by bamaballa205; 06-27-2008 at 08:52 PM.