1999 GMC Jimmy Problems - Please help

[lester_26]

I am experiencing hesitation with my 1999 GMC Jimmy.

The vehicle starts and idles fine, however, when I start and initially hit the gas, the vehicle starts to accelerate (say 1 second), then there is a 3-5 second hesitation period before it resumes acceleration.

After this initial period, the vehicle runs fine until 1-2 hours into a highway excursion. At this point, the vehicle seems to be starving for power. I get real high rpm's and can't maintain a speed of 60 mph without the vehicle clicking in and out of overdrive. If I stop for gas and resume my trip, the vehicle seems to run fine for a while, then this problem returns. Ocassionally I notice a rough shift from first to second or second to third.

I have had a tuneup, new plugs, new air filter, new fuel filter, new battery and new alternator (old alternator died) and there was a minimal (if any) improvement.

Any suggestions? Any insight greatfully appreciated.

NOTE: thought I'd add, on one excursion, I did experience some "gurgling" sound of fluid coming from the motor (sounded like inbetween the passenger and driver seats).

[lester_26]

No smells associated either (i.e. no smoke or rotten egg smells).

[lester_26]

Anyone????

[clariveros]

I suggest reseting the computer (just disconect the negative on your battery overnight) it sounds like something similar that i had and i drive a manual, so so problem i first tought that it was my driving, but it would do the same thing out of nowhere the car would begin to either accelerate or decrease in rpm while driving and if sitting at a red light the car would drop rpms and sometimes just shut off.

[lester_26]

Well, looks like I made some significant progress.

I tried resetting the computer and the improvement was marginally. I then realized that ~ 1 month before all my probs, I had purchased an aftermarket gas cap. I lost it then replaced with a similar. So, on a recent trip to the USA, it looks like the new gas cap helped, however, I was still getting the continual check engine light on, but the sluggish greatly improved. I then bought a cap from the GM dealer in the usa and drove back the 1100 miles with no problems what so ever!

The only minor problem I have no is just after starting, my initial acceleration period is very sluggish. I take my foot off of the gas and re-apply and all is well for the rest of the trip. This happens even if I let the vehicle warm up. Any suggestions?

[BlazerLT]

Clean your MAF sensor by removing it and sprayin brake cleaner through it to remove dirt off of the MAF sensor filaments.

[smonaldo]

4WD Low. Mine thinks it is in 4WD lo, and computer is trying to limit the overrev, etc, when it shouldn't be.

[lester_26]

Originally Posted by BlazerLT

Clean your MAF sensor by removing it and sprayin brake cleaner through it to remove dirt off of the MAF sensor filaments.

BTW: Never read this til after. I replaced the MAF and all probs went away. Perhaps I should have tired this, but a new one was reasonable....$100. Thanks again...

LESTER

[BlazerLT]

Nice, I knew it had to be the problem.

[s1193919]

Originally Posted by smonaldo

4WD Low. Mine thinks it is in 4WD lo, and computer is trying to limit the overrev, etc, when it shouldn't be.

Mine has the same trouble. What did you do to fix it?

[ChrisGood]

Originally Posted by s1193919

Mine has the same trouble. What did you do to fix it?

He replaced the MAF...

Originally Posted by lester_26

BTW: Never read this til after. I replaced the MAF and all probs went away. Perhaps I should have tired this, but a new one was reasonable....$100. Thanks again...

LESTER