'94 S10 Blazer 4.3L Sputtering, Stalling, Burned Carbon Smell, & CEL

[wavinwayne]

I'm currently driving a '94 Chevy S10 Blazer with 142k miles, on permanent "loan" to me from my father in law. I get to drive it whenever I want, with the understanding that I buy the gas & do the oil changes.

The Blazer had been running perfectly until last week. It has developed a nasty habit of sputtering, stalling when I come to a stop, & a bad burning carbon smell. These symptoms do not happen every time I drive it, only about 1 out of 4 trips. The service engine soon light also comes on after these symptoms have been present for a few minutes.

I'm thinking of the following possibilities:

1. Failing fuel pump (or a short somewhere in the wiring), causing it to run lean, thus the burned carbon smell from the catalytic converter.

2. Dirty fuel filter, not allowing enough fuel to reach the engine, which in turn causes the sputtering, stalling, running lean, etc.

3. Bad Spark plug, sending unburned fuel to the cat., which results in the cat. overheating & causing the burned carbon smell.

4. Bad spark plug wire

5. Clogged catalytic converter (not sure if this is even possible???)

Am I on the right track, or do the BITOGers have some more suggestions? Thanks in advance.

 

[Brett Miller]

Bad news my friend. You have a classic case of a bad CPI unit which is not a cheap repair. If I remember correctly the CPI is a central injector with poppet valves for each cylinder. It must be replaced as a unit and is several hundred dollars.

 

[blackbird]

my guess is carbon plugging up the egr valve. Have you checked the fault codes?

 

[wavinwayne]

quote:

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Originally posted by blackbird:
my guess is carbon plugging up the egr valve. Have you checked the fault codes?

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How do I check the fault codes on an OBD-1 equipped vehicle?

 

[wavinwayne]

quote:

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Originally posted by Brett Miller:
Bad news my friend. You have a classic case of a bad CPI unit which is not a cheap repair. If I remember correctly the CPI is a central injector with poppet valves for each cylinder. It must be replaced as a unit and is several hundred dollars.

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In that case, the Blazer goes back to my father in law, where it will sit & slowly die in his back yard.

 

[blackbird]

to check the fault code you can use a scanner, code reader or just a jumper wire. Under the drivers side dash is the "data link". If you have a repair manual it should be explained. My understanding of a bad CPI unit is the same symptoms, but with raw gas coming out the exhaust

 

[wavinwayne]

quote:

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Originally posted by blackbird:
to check the fault code you can use a scanner, code reader or just a jumper wire. Under the drivers side dash is the "data link". If you have a repair manual it should be explained. My understanding of a bad CPI unit is the same symptoms, but with raw gas coming out the exhaust

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Thanks. As far as the last part of your statement......there is no raw gas coming from the exhaust pipe. It's as dry as a bone; No smell of gas either. The smell is very similar to what a huge industrial carburizing furnace smells like.

 

[punisher]

http://www.troublecodes.net/GM/

Although I worked on Fords at the dealership, I seem to remember it was easy to R&R the EGR valve and knock the carbon out of the pintle on a 4.3 Chevy.

 

[wavinwayne]

punisher,

Thanks for the info. I'll try to read the codes today.

Are you the same "punisher" that was giving "Chumley" such a whipping over on the Bentley forum? If so, did the both of you's get banned? I have not seen any posts from either of you since the oil analysis thread got locked.

 

[punisher]

Not the same "punisher". I am a mod in another forum though.

 

[wavinwayne]

quote:

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Originally posted by punisher:
Not the same "punisher". I am a mod in another forum though.

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Thanks for clearing that up.

 

[wavinwayne]

I read the fault code. I'm getting fault code 32. According to the link that punisher provided, this points to an EGR problem. I will attempt to perform some diagnostic tests & report back.

 

[blackbird]

depending on how often the valve is getting plugged, just pull the vacuum hose off the brake booster, put a funnel in it, and SLOWLY pour some sea foam in it. this has always worked for me

 

[wavinwayne]

quote:

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Originally posted by blackbird:
depending on how often the valve is getting plugged, just pull the vacuum hose off the brake booster, put a funnel in it, and SLOWLY pour some sea foam in it. this has always worked for me

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Funny you should say that; I did that very thing about an hour ago. All is well at the moment.

On a related note; I never knew that the brake booster vacuum hose sucked so much air in. It was like a hoover vacuum cleaner. All I had to do was hold the Seafoam can at a slight angle near the vacuum hose & it just sucked the Seafoam right out of the can. It was cool.

 

[wavinwayne]

I drove 45 miles to work in the Blazer this morning. All is still well after the Seafoam treatment.

 

[blupupher]

I had the same vehicle, and similar problems with both the EGR and the CPI. Parts alone were almost $400. I did the work myself. The CPI started first and did not throw any codes, but when the EGR went bad (and the engine started running really bad), that is when I got the code.

 

[wavinwayne]

So far, 90 trouble free miles since the Seafoam treatment.......fwiw

 

[BlazerLT]

quote:

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Originally posted by wavinwayne:
So far, 90 trouble free miles since the Seafoam treatment.......fwiw

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Remove the EGR valve and clean it and install it back with a new EGR gasket.

You will have this happen again I can almost guarantee you.

The cause of the carbon in the EGR valve is indeed the CPI injector leaking.

This is my CPI repair.

http://www.s10forum.com/forum/showthread.php?t=113559