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Discussion Starter #1
I had trouble a couple weeks ago and thought I had fixed it. It ran fine for the about 300 miles, but started acting up again yesterday. Here's the symptoms:
  • Bucking, missing at all speeds, but might run smooth for a few blocks, then starts bucking again
  • Intermittently idles fast - about 2500 rpm, but might idle fine for a while.
  • Strong sulfur smell. I assume it's the cat converter and might indicate rich condition?
  • No codes
I cleaned and tested the EGR - vacuum actuator works and pintle seats tightly. I also cleaned and tested the IAC - pintle seats tightly and motor seems to work.

Any ideas would be really appreciated.
-Stu
 

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O2 sensor or Coolant temp sensor can both run out of spec and not set a code . I would suspect the O2 sensor , the rotten eggs are definately a sign of the fuel mixture running way off ( which the O2 sensor should correct OR set a fuel mix rich or lean code ).
 

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Discussion Starter #3
Thanks for the suggestions. I hate to just throw parts at it, but that's probably what I'll end up doing. Worst part is, it's somewhat intermittent, so I won't really know if it's fixed.

I'm thinking that I can eliminate the IAC as a possibility. I figure it would only affect the idle, not cause problems under power. Do you agree with my logic?

Thanks again.
-Stu
 

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Wire Splicin Fool :-)
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Check for exh manifold cracks.

Check for dry rotted orings on injectors.

I would still wonder about the EGR, ESPECIALLY if it is NOT OEM.........
 

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i saw what you did there!
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too much fuel

ecm probably thinks engine is way colder than it actually is

so increasing fuel to it

try a new CTS

set timing to zero base with EST module unplugged


distrib could be worn and failing

is a common issue on the late '80s and newer v-6 and v-8 engines causes all kinds of odd things to occur
 

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Wire Splicin Fool :-)
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Dont replace CTS unless bad, test with ohmmeter and compare to link in my signature.....
 

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Cool, Tight, & STRONG....
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Well, the fast idle part is more than likely a vacuum leak.

They can be VERY hard to find. My own S-10 had a bad leak UNDER the big vacuum hose fitting that heads off to operate the heater flap/door valves. Just from looking down on it, the split in the hose was invisible. Drove me nuts, until I found it.

There was another leak in one of those little bitty hard, plastic vacuum lines, caused by the throttle linkage wearing into the line itself..that one would open up and leak more, as the engine warmed up..:rant:..

Another thing, you cannot simply replace these hard lines with an ordinary, rubber, vacuum hose (as sold by the Auto Parts store), because the hose has too much internal volume and vacuum and it tips over the delicate balance of the sensors that need a metered amount of vacuum fed to them. AND, there are two different sizes of these tiny hard lines. If you look closely at the "vacuum block" at the TBI you will see these two sizes. I just taped over my worn line with black electrical tape, and it worked out OK..

If you get to the point of confidence in all of your vacuum lines, move on to the EGR valve....
 

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Been there Done it
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Would be better if you started your own new thread in the 2.5L - 1st gen 4-banging section of the forum. Reviving an 8 year old thread isn't the recommended way to ask a question about a current problem.
Please tell us in that thread what you've done so far to diagnose your problem.
 
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