1992 Jimmy (W) Fuel/Air Problems

[rottonrattt]

get you some of that good old throtle body cleaner and go spray happy.that could be your problem.it usaly causes it to shut of at a idile but it will stay on if you give a little gas.try it its a cheap fix like 3 bucks a can it cant hurt thats for sure.

[rottonrattt]

also get you some wd40 and spay the hell out the egr valve its located behind the throtle body

[z3r0]

GM has a special way of cleaning their intake and poppet valves. It is a little more complex than your average vehicle. These vortec intakes are kinda silly and very hard to understand. I don't feel it would be ideal to clean an egr with a lubricant such as WD40. Maybe some seafoam...
Also, the egr on this vehicle is located on the bottom front of the intake not too far under the IAC valve.
Such suggestions could end up ruining someone else's vehicle.

I am changing the ECM tomorrow. I'll let you know how it goes.

Proper diagnosis is key and has been done thus far.

Saved money, is beer money. That $3.00 will buy me a 6 pack.:sarcasm1:

[z3r0]

Still stuck here. It was on page 1 at the end. Maybe overlooked...

Question: There is another small computer box mounted to the same bracket on the ECM it's white/semi transparent. There is a 4 pin connector (male) and a 9 pin connector (male) both side by side. What is this little box?

[z3r0]

Replaced ecm. Back to step 1. Same symptoms as when it broke down. I've gotten no where. What now?

[z3r0]

Finally got something accomplished. I got the truck to stay running long enough to let it warm up a little bit. Then I smelled some antifreeze burning off. I've gotten a real sign. I tore down the intake to the top of the engine and found there were 2 large spots in the gasket that were blown out. I am waiting for the permatex on the lower intake manifold gasket to cure. The upper plenum needs to be resurfaced and taken to a machine shop on monday. I'll let you know how it goes.

[z3r0]

Typed this up badly as i was in a rush.

Tore intake down to top of engine. Placed some old t-shirts over cam guard and inside the engine to prevent from having pieces of old intake gasket from entering. Place paper towel inside the different ports as well. I scraped the gasket clean from top bottom of intake and top of engine then removed the shirts and towels.

I used a shopvac to ensure cleanliness of engine and exhaust components. I placed a small amount of lube on top of engine to hold the gaskets in place while I carefully place the intake back on. Then tightened all bolts to torque specifications in the order of the bolt pattern. Replace the new spider and re-attached fuel lines and distributor cap. I am getting the upper plenum cleaned and machined in the morning.

Once together I am running a compression test to make sure I dont also need a head job. I am also going to get my exhaust fixed as there is a hole in the muffler and the catalytic converter looks like the original so I will replace that with a new O2 sensor. I'm sure I'll be happy witht he results when done. I just really hope I don't need a head job. Other than that... I'll rest good tonight. Broke but content.

[z3r0]

That's what I get for buying a vehicle on craigslist. But you win some you lose some.

[Leeann94astro]

Just think - after you get this done, you'll have a reliable vehicle that you know won't need any of that stuff for a long time.

[metallica21156]

id still say something is wrong with the tps. if its getting 5 volts supply from ecm and your seeing it drop as you press the gas then the ecm has nothing to do with it. make sure they gave you correct tps. i've heard of people getting the one for the full size blazer/jimmy not the mid size. you can just tell them you want a tps for a 94 s10 and that should ensure the correct sensor. also might be a map sensor issue.

[Schrade]

Maybe something else is causing the tps to fail.

READ THIS VERY CAREFULLY AND THOROUGHLY!!! I'LL cut through this horsewaste in short order. GUARANTEED.

Why do you say the TPS fails? The trouble code is Low Voltage. Go to a local mechanic, and get him to print out the PROPER diagnostic procedure from his computer for this code. Then do EXACTLY as the procedure says. You might have to pay him a few bucks.

You will need the harness pinout schematic for the TPS feed. NOT HARD TO FIGURE OUT by the picture.

When I put in the new TPS, I did not do the computer relearn steps.

The computer will relearn by itself after half a dozen OPEN LOOP (warmed-up) drive cycles. You'll know, because the transmission won't wind out each gear before shifting anymore. BUT, if there's a LOW Voltage problem, it will have a problem re-learning.

Mitchell says this can cause: Rough or unstable idle.Not likely Hesitation or stumble. Not likely Rich or lean running. Not likely Poor fuel mileage.Right Harsh or poor transmission shift quality. Partly right - see above.

Most are not likely in your case.


Does this vehicle lope idle at all when warm? Surge at stoplights?

Would there be another way to reset the TPS?

It will re-learn itself - see above.

My FPR was definitely bad as I did have what appeared to be gasoline in the plenum and in my oil.

COULD be. The vacuum supply to the FPR can draw gas into the intake, IF the FPR diaphragm is ruptured. BUT, you said fuel pressure HELD. So this cannot be.

The only way for fuel to flood into the intake/oil crankcase is leaking injectors, or ruptured FPR bladder/diaphragm. Double check your fuel pressure bleed-down time, and write it down til it goes to 0psi.

Also pull the vacuum line to the FPR, this way: COLD ENGINE, turn on the key, let the fuel rails prime, and then turn it off. Pull the hose and smell the line. STRONG gas???


There some GREAT pics of me backprobing a PCM connector in vette forums here post #68:
Automotive diagnostics at its BEST.

Basically the ECM is telling injector to dump more fuel into the system. Creating flood. Currently diagnosing ECM now...

You CANNOT know this unless you see a data log that shows the injector pulsewidth (in miliiseconds), like so:

Notice the normal is 128. This is not just for vette, but for ANY car.

I did fail to mention that my heads up display was giving me incorrect cooling temps and oil pressure.

This could be EVERYTHING. A faulty temp sensor COULD make the computer think the motor is cold, and LENGTHEN the injector pulsewidth (MORE FUEL).

The wire from TPS to ECM was good. Fault lies in ECM. Other problems lie in ECM also.

Why do you think THIS??? What was the voltage reading for the ECM pin for TPS signal supply???

get you some of that good old throtle body cleaner and go spray happy.that could be your problem.it usaly causes it to shut of at a idile but it will stay on if you give a little gas.try it its a cheap fix like 3 bucks a can it cant hurt thats for sure.

also get you some wd40 and spay the hell out the egr valve its located behind the throtle body

NO NO NO

Question: There is another small computer box mounted to the same bracket on the ECM it's white/semi transparent. There is a 4 pin connector (male) and a 9 pin connector (male) both side by side. What is this little box?

Need to see a pic. Could be ABS module?


Take back the ECM FIRST, since that was not the problem.

Let's start from square 1 - where are you now on it?


More good info; another post to bookmark uh HUH