1996 Jimmy rough idle - still trying

wildcatsua · #1 07-17-2005, 07:07 PM

I continue to try and solve the rough idle on my 96. It's definitely running rich. I recently replaced the #2 and 6 fuel injector and then started getting P0102 and P0175 now I got a P0122 and a P0300. You can smell the fuel when it idles in the garage. It takes extended crank time to start. Someone suggested the O2 sensor. I took all 4 of them out and they all have a heavy black soot build up indicative of rich burn.

I'm at the end of my rope. Something is telling this thing to run rich. It's killing me. PLEASE HELP!

wildcatsua · #2 07-17-2005, 09:05 PM

One other tidbit - it starts right up if you crank it right after turning it off. No hesitation at all. Turn the key off then turn it back over and it cranks right up just like the good old days.

Not sure what this means.

1993 Jimmy · #3 07-18-2005, 08:14 PM

Try cleaning the EGR Valve

wildcatsua · #4 07-18-2005, 08:50 PM

I replaced the EGR valve when I did the intake manifold gasket. Could I have missed something? Is there some connection between the rough idle and hard starting? thx

1993 Jimmy · #5 07-19-2005, 10:42 AM

What I did is read alot of the other post that have been posted in the past, and I tried alot of diffrent things. It all came down to changing the CPI, cleaning the EGR valve, and trying to clean all the carbon that I could get to.

drdd · #6 07-19-2005, 11:37 PM

try cleaning that EGR again. It's too easy not to. A new EGR could still clog with a chunk of carbon. Pull the EGR and check it. Ever changed your PCV? Do you overfill or "top off" your tank when filling up with gas? Report back.

Quote:

Originally Posted by wildcatsua

I continue to try and solve the rough idle on my 96. It's definitely running rich. I recently replaced the #2 and 6 fuel injector and then started getting P0102 and P0175 now I got a P0122 and a P0300. You can smell the fuel when it idles in the garage. It takes extended crank time to start. Someone suggested the O2 sensor. I took all 4 of them out and they all have a heavy black soot build up indicative of rich burn.

I'm at the end of my rope. Something is telling this thing to run rich. It's killing me. PLEASE HELP!

demotim00 · #7 07-20-2005, 07:15 AM

Quote:

Originally Posted by drdd

try cleaning that EGR again. It's too easy not to. A new EGR could still clog with a chunk of carbon. Pull the EGR and check it. Ever changed your PCV? Do you overfill or "top off" your tank when filling up with gas? Report back.

I have a question concerning "topping off" your tank when filling up. Would topping off your tank cause carbon problems with the EGR valve, or any other problems. I have a 94 Jimmy with excessive problems of the EGR clogging up w/ carbon. I'm talking about it clogs up like about once a week. I do "top off" to the nearest dollar when filling up, could that cause the excessive build up of carbon?

1993 Jimmy · #8 07-20-2005, 11:00 AM

I've never had a problem with toping off the tank. I have the same problem but I am in the process of pulling the lower intake and cleaning all the carbon out of all the ports. I think that might be the prablem. I will let you know what I find.

wildcatsua · #9 07-20-2005, 02:54 PM

Quote:

Originally Posted by drdd

try cleaning that EGR again. It's too easy not to. A new EGR could still clog with a chunk of carbon. Pull the EGR and check it. Ever changed your PCV? Do you overfill or "top off" your tank when filling up with gas? Report back.

PCV changed last month while chasing this problem. Tank not normally topped off. Will check EGR again and report back. Can you explain how clogged EGR can cause rough idle, rich burning, and hard starting? thx

drdd · #10 07-20-2005, 03:29 PM

You are ruining your EVAP system and canister. The tank must vent at the top. Stop topping it off.

Quote:

Originally Posted by wildcatsua

PCV changed last month while chasing this problem. Tank not normally topped off. Will check EGR again and report back. Can you explain how clogged EGR can cause rough idle, rich burning, and hard starting? thx

1993 Jimmy · #11 07-20-2005, 03:36 PM

Ok, I did a search on the web and found a good web site that might be able to explane it better than me.
http://www.misterfixit.com/egrvalve.htm

wildcatsua · #12 07-21-2005, 01:30 PM

Thanks for that info on the EGR.

I checked and cleaned the EGR again. No obvious problems and no change in performance - still idling rough.

I took the Jimmy to a garage out of desperation and had them analyze it on their scanner. They told me they believe there's a fuel leak in the plenum. I guess I'll be pulling that apart again to take a look.

Is this possible? Could it be the fuel pressure regulator? Any ideas what to look for? Any tests I can do?

thx

1993 Jimmy · #13 07-21-2005, 11:51 PM

If your Jimmy has the cpi you can pull the plastic cover off the top of the plenum and there will be a round part held on by 2 bolts. Pull that off and look in there if there are clean or brown spots(mine was covered with black gummy stuff all but where it was leaking and it was brown there). If you do plan on pulling it apart get plenty of carb cleaner and a small wire brush you will find out when you split it apart. I have some pics of what mine looked like, and I will try to post them in the next reply.

wildcatsua · #14 07-22-2005, 07:40 AM

No, mine is the CSEFI. I've had it apart before replacing fuel injectors. I talked more to the mechanic. He described exactly what I saw with the plenum removed - the area near the fuel pressure regulator is very clean. He said it's a sure sign that the diaphram in the regulator has a pinhole and is leaking. I asked him how he knew - he said he's seen it about 150 times. I will be replacing on Sunday. Will update.

Has anyone else seen this condition?

I have a picture of the plenum if someone can tell me how to post.

thx

1993 Jimmy · #15 07-22-2005, 04:10 PM

I could not get my pics to upload (they are to big) if you want to see them just e-mail me.

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