Engine wont rev above 3000rpm in gear or neutral

[goodoleboy]

vehicle:
1999 suburban,5. 7,4x4



Driving today Engine will not allow me to get above 3000rpm casuing the truck to slow down. . I placed it in neutral and it still would not allow me to get above 3000rpm. . It sputters when I floor it.I dont think its a tranny problem since it happens in neutral.

Note when I turn off the ignition and restart it goes back to normal driving, but will act up again a 5-10 miles down the road nd allows me to ge the rpm up to 5500-6000rpm like it should be doing.

Also truck has newer plugs, wires, and fuel pump and filter. . . Unsure if it has a new distibutor cap or not.



Could this be a oxygen sensor or catalytic converter, or a egr valve, or____________?



Note: I reset the Check Engine light a few days ago light by disconnecting the battery for 20 minutes, and no new codes have popped up today. .

Any help would be great. .

 

[JHZR2]

what was the CEL for???

 

[punisher]

So, what was the code you got before you reset the ck eng light?

Most newer vehicles have a rev limiter that kicks in while in neutral or park so revving it out of gear might not mean a whole lot.

EDIT: I have had a bad lever position/trans range sensor cause similar problems on another vehicle. The PCM thought it was in neutral/park all the time.

 

[goodoleboy]

cel was for a oxygen sensor bank 1 & 2
Yes i cleared the code after this occured the first time..

Interesting though on the rev limiter..But it allows me to rev to 6000rpm when its running like normal...So I dont think thats the problem..But im unsure really.

 

[mikered30]

This sounds like a dead MAF if you cant go above 3K RPM, but the code is for an O2 sensor. I would check and clean your MAF.

 

[punisher]

If you have lean codes for both banks, with those symptoms, I would start looking at fuel pressure and the MAF sensor as a starting point. A quick way to ck the MAF is to unplug it when the car acts up, and drive it to see if drivability improves.

If you have a scan tool it will be easy to read fuel trims. A bad MAF will also tend to read rich at idle while going lean under load/increased RPM.

 

[Bob The Builder]

I bet it's the cat. Those things are notorious for spitting to much oil through the combustion chamber and fouling the cat...eventually. It could also have been your o2 sensors going out. That would cause a rich or overly lean condition...either of which is hard on the cat. Go to a muffler shop. They should be able to test it for free to see if it's clogged up or burnt out. When the cat goes....it really...really limits the exhaust volume.

Oh by the way...the fact that it comes and goes like you mentioned...means that when it is getting hot enough to function properly, it is at it's high point of expansion. Yep.


I'll bet 5 dollars on that.

 

[goodoleboy]

thanks for the replies I will be going to a mufler shop in the am for a free testing of the cat and I will mention the maf and other suggestions also..

 

[goodoleboy]

Also note I hear a whistling when the truck was running fine from the underside of the truck..another site said its probaly the cat making the noise..

 

[Gary Allan]

That would be my guess ..the cat. A vacuum gauge should tell for sure.

 

[Shaman]

Sounds like when the fuse to my MAf sensor blew.

 

[mikered30]

I am going to go with the cat instead of the MAF, sounds more likely with you symptoms.

 

[MrCritical]

Cat Scratch Fever.

 

[goodoleboy]

Well guys it aint the catalytic converter, had both tested and they are ok..

Took it to a shop and he ran diagnostics and said it was the timing on the distibutor cap, and the cap and rotor look worn..Ill keep you updated if this fixes it..

 

[Bob The Builder]

Well, at least the test was free......I hope.

 

[goodoleboy]

Originally Posted By: Bob The Builder
Well, at least the test was free......I hope.


yeah it was free, diagnostics are $65 an hour though from the mechanic he refered me to..

 

[chrome]

I wonder why no one mentioned a clogged fuel filter as yet?

 

[goodoleboy]

Originally Posted By: chrome
I wonder why no one mentioned a clogged fuel filter as yet?



Thats what the tech first said, It was replaced last week along with a fuel pump though..

 

[punisher]

Originally Posted By: chrome
I wonder why no one mentioned a clogged fuel filter as yet?


It is just one of those things that is rare to come upon in the real world. I can remember 2 clogged fuel filters causing drivability concerns in the 10+ years I was at the "evil dealership". I have heard horror stories from techs in smaller towns that deal with a lot of farm trucks however.

Not to say you shouldn't check it as hooking up a fuel pressure gauge is one of the first steps for a concern like this.

 

[wantin150]

Originally Posted By: mikered30
This sounds like a dead MAF if you cant go above 3K RPM, but the code is for an O2 sensor. I would check and clean your MAF.


FWIW, cleaning won't do anything if the MAF is fried. Many have toasted theirs when installing CAI's in Toyota's by not disconnecting the battery terminal. At least in those cars, "limp" mode is set at 3k and is only fixed by replacing the MAF.