97 Jimmy acceleration woes- help?

[boilermaker68hd]

Hi, I have a '97 GMC Jimmy, 4.3L auto. A few days ago it just started to have acceleration problems. It idles fine, purrs like a cat, and in park, it revs fine, seems great, just as normal. It doesn't miss, stumble, or hesitate when I jump on the gas. But on the road, it's falling flat on acceleration. With the pedal mashed, it slowly builds up speed and I can tell it just seems like it wants to bog down. It will eventually get to about 4000 RPM but stops building at that point. It will eventually shift if I let off the pedal some. Terrible on hills. Loses speed and the valves clatter like mad once it hits about 3700 RPM when you're really pulling a hill or trying to pass. NO engine codes, though. Took it to autozone and had them run the scanner on it just in case the SES light was out, but NO codes. Changed plugs and fuel filter. The engine surges slighty at cruising speeds, too.
Talked to a mechanic and he said to check for a vacuum leak. Some of the hoses were rough looking so I changed all the ones that looked bad. The intake gaskets were replaced last year so I checked the bolts, still snug. Changed the PCV valve too. 114k miles and never a problem til this. What now? Thanks for any help.

 

[Molson02536]

Hi, I have a '97 GMC Jimmy, 4.3L auto. A few days ago it just started to have acceleration problems. It idles fine, purrs like a cat, and in park, it revs fine, seems great, just as normal. It doesn't miss, stumble, or hesitate when I jump on the gas. But on the road, it's falling flat on acceleration. With the pedal mashed, it slowly builds up speed and I can tell it just seems like it wants to bog down. It will eventually get to about 4000 RPM but stops building at that point. It will eventually shift if I let off the pedal some. Terrible on hills. Loses speed and the valves clatter like mad once it hits about 3700 RPM when you're really pulling a hill or trying to pass. NO engine codes, though. Took it to autozone and had them run the scanner on it just in case the SES light was out, but NO codes. Changed plugs and fuel filter. The engine surges slighty at cruising speeds, too.
Talked to a mechanic and he said to check for a vacuum leak. Some of the hoses were rough looking so I changed all the ones that looked bad. The intake gaskets were replaced last year so I checked the bolts, still snug. Changed the PCV valve too. 114k miles and never a problem til this. What now? Thanks for any help.

Could be a faulty fuel pressure regulator or a faulty TPS. Start with the simple and check your TPS and clean your MAF and replace your MAP sensors. I am leaning towards a back tps so check the sire leads to your TPS and replace the TPS if it's faulty.

Good luck and keep us posted and will not hurt for you to use http://www.seafoamsales.com/ to clean out any carbon deposits.

 

[happy 2011]

sounds like a pluged cat or low fuel preasure.