Engine wont rev above 3000rpm in gear or neutral

[SuperEd73]

When the problem occurs, is the rev limit exactly 3,000 rpms or does it vary? If it varies then it could be any of the ideas mentioned previously but if it is exactly 3,000 rpms, then that does sound like some form of rev limiter kicking in when it's not needed. How is the engine power up to that 3,000 rpm range when you're driving. Does it feel weak or does it feel normal and then the engine cuts out at 3,000rpm?

FWIW, I had a '96 Olds Cutlass with the 3.4L Twin Cam engine. It had a neutral rev limiter at 4,000rpm. Engine would just cut out at that point. I guess to protect from accidental full throttle reving or high rev neutral drops into gear. The redline on that engine was in the 6,500 rpm range.

Ed B.

 

[goodoleboy]

Originally Posted By: SuperEd73
When the problem occurs, is the rev limit exactly 3,000 rpms or does it vary? If it varies then it could be any of the ideas mentioned previously but if it is exactly 3,000 rpms, then that does sound like some form of rev limiter kicking in when it's not needed. How is the engine power up to that 3,000 rpm range when you're driving. Does it feel weak or does it feel normal and then the engine cuts out at 3,000rpm?

FWIW, I had a '96 Olds Cutlass with the 3.4L Twin Cam engine. It had a neutral rev limiter at 4,000rpm. Engine would just cut out at that point. I guess to protect from accidental full throttle reving or high rev neutral drops into gear. The redline on that engine was in the 6,500 rpm range.

Ed B.


Hi, It not at exactly 3000rpm today when it acted up it was around 2500rpm..Does not seem to have any power when floored, but I can lightly press on the gas and get up to 80mph in about 2.5 minutes,LOL Really it takes that long...

 

[mechtech2]

I had a hard to diagnose running problem that was a piece of broken off cat material that would now and then plug the exit hole, then fall back..
Try to figure that one out!

 

[Shaman]

can you disconnect the exhaust and see how it runs?

 

[punisher]

Originally Posted By: mechtech2
I had a hard to diagnose running problem that was a piece of broken off cat material that would now and then plug the exit hole, then fall back..
Try to figure that one out!


Sometimes you get lucky and have an EGR code with a clogged cat due to the backpressure forcing the pressure sensor voltage out of spec. If there is any question, hook up a vac gauge (as suggested above) and that will make quick for a quick "clogged cat" diag.

 

[Bob The Builder]

I don't know...I still think it's the cat for some reason. How did that guy check it? From my understanding they have to drill a small hole on one end of it and look inside with a light.

Don't worry...I can take it when I'm wrong...it's just that I have had this type of problem before. No really.

 

[Drew99GT]

Just to rule out the MAF sensor, unplug the connection to it and drive it (it'll throw a code but will still run).

The MAF sensor took a dump on my moms car and would sputter and run like [censored] at certain times - unplugged the MAF sensor and it ran fine (with the CEL on). Trip to the junkyard for a new sensor, reset the ECU, and she ran great.

 

[Gary Allan]

Originally Posted By: Bob The Builder
I don't know...I still think it's the cat for some reason. How did that guy check it? From my understanding they have to drill a small hole on one end of it and look inside with a light.



You use a vacuum gauge. Your vacuum should remain fairly constant under no load at a stable rpm (you'll get some bouncing and a dip as you crack the throttle). The engine's just running out any air/fuel that you're supplying. There's no load to allow the throttle open at that speed. If you see vacuum dropping off as you bring up the rpms (stabilized) ..then it points to a restriction in the exhaust.