1992 GMC Jimmy Runs BAD intermitently

Hello all,

Man...I really hope someone here can point me in the right directions. I am NOT a mechanic. I only play one on the weekends. (hahaha)

So here is the story. Most of the time my jimmy and me get along just fine. It runs well and have had few problems. When I went to get the IM done this year they said the emmission were so bad it plugged the machine.

So I tunned it up (plugs, cap, rotor, wires, oil change etc..) I also changed the O2 Sensor and the CAT. (They told me last year that the CAT would need to be changed "pobably" next year so I just did it and got it over with) On my way to the IM place my electronic dash went out. So I got a permit and am waiting for my cluster to be rebuilt.

Mean while I am driving it with out the dash in. all of a sudden with no warning. I went to start it and it just barely stays running. I mean if you put it in gear or even turn the wheel it will die. So I limp it home feathering the gas to keep it running. While I was driving it home it ran fine unless I came to a stop when I had to feather the throttle to keep it going.

I get my dash back and pull the codes I get 24 and 34. Since I don't know if the the 24 code hit while I was actually moving I decided to ignore it. 34 is the MAP sensor. I changed it no change.

Then I go out the next morning and BANG! it works fine. runs great! Ran great for three days! then out of no where its doing it again.

I have checked everything I can think of. Even done somethings I am sure had nothing to do with my problem just to make sure. But during my troubleshooting I was looking at the EGR valve. I got it started (running bad) and I pulled the vaccum line on the EGR valve....Nothing happend just kept running bad. so I hooked it back up and stuck my finger in and moved the diaphram as far as I could....Still no change engine just continued to just barely sputter along.

I have heard of people having problems with carbon build up and it clogging the EGR. Could this be my problem? What are the symtoms of a bad EGR?

OR...If this is totally off base....What should I check next? I am totally lost!

Any help is always appreciated beyond your knowledge.

One of these days I will right an article on how to repair the bad window motors that are notorious in these babies. Saved me a ton of cash cause when I bought my jimmy NONE of the windows worked! haha

Thanks to all!

Bill12780

You should get a code 32 if the EGR valve had trouble.
You might check your fuel pressure,
http://i131.photobucket.com/albums/p288/Clunk_/Image033.jpg

You might also see if the knock sensor, just in front of the rear/drivers side spark plug, is still connected. Be careful, the plastic connector is extremely fragile.

Thanks for the reply!

I will check the knock sensor....

I did get another 24 code today and right after that it started runnin like crap! Could the speed sensor cause the computer to tell it to run bad like this?

I have no "easy" way (read don't want to go and buy a presure gauge) to check the fuel presure. Is there any kind of trick or other way?

I don't think its a fuel delivery problem cause when it runs like crap I can smell PLENTY of gas. I am starting to wonder if I don't have a air mixture kind of problem.

At one time I owned a lebaron. And it started to run like crap. I guess its a re common problem for the Idle Air Flow Motor to go bad in them. Basically its a little stepper motor with a spring loaded plunger that moves back and forth to allow/stop air movement.

I Wonder if there is anything like this on the Jimmy?

I will check the knock sensor and post back...

Thanks again for the advise and help!

Bill12780

Oh one other thing that might help clue you in. I noticed today that when its running bad and I start it the idle dose not go up and then settle down like it normally does. It just drops to next to nothing. (idel air mix? I don't know?)

Ok here is an update....

(should mention that my jimmy is the TBI NOT the CBI...)

I looked for the knock sensor. But could find nothing that looked like a sensor. I did find on the passenger side a sensor the the connector was nearly totally distroyed! I cut it off and soldered it back on. and coated the outside with silicone. But made no differnece.

Today I tore out the EGR valve. I had heard they like to get all clogged. IT WAS BAD! I thought "oh I got this sucker!" I cleaned it and the intake side and changed my oil preasure sending unit while I was there (its been leaking for a long time).

Start the car...Same problem!

So I am at a loss unless the VSS can make the car run bad. I have not found a straight answer on that yet.

Just to go over the problem again. The car just BARELY idles...It use to come and go (about three times) but now its all the time. If I just barely give some throttle it seems fine.

When I start the car normally it idles fast and then slowly comes down to normal. It does not do that at all. I give it a little gas and it revs up and right down to almost dead. The dash lights flicker and the engine just kinda sputters along.

I did notice today that when I do rev the engine it sounds really "throaty" for lack of a better word.

Does ANYONE have ANY ideas for me to try? At this point I have no clue other then like I said it does through the 24 vss code while driving.

PLEASE HELP ME! (or shoot me! one of the two)

bill12780

PS please no "BANG!" replies...hahaha

Hey Bill,

Ya gotta get the fuel pressure checked. If you can't beg, borrow or steal a pressure gauge drive, push or pull it to someone who can do it for you, shouldn't cost to much. A lot of the symptoms you are posting could be related to low pressure and high mileage GM's are notorious for pumps with low pressure. You want to measure engine off prime pressure (turn key off to on a few times), and leak down time, engine idling and engine running at 2000 RPM pressures and if you can pinch off the return line measure peak pump pressure. Post back results.

Sparky

Check your TPS sensor voltage. Pull on the wire, give the sensor a tap with the end of a screwdriver. A VSS problem will not give you a engine problem, but a bad ECM(computer) will give you all sorts of issues including false codes, poor overall operation, so thats something to think about. How are your grounds, especially your battery ground.

And as Sparky mentioned, check the basics, good fuel pressure, good spark, good vaccuum, no gasket leaks(throttle body gasket leaks).