1995 S10 Blazer 4.3L Check Engine Light

I recently took my 95 Blazer to Minneapolis (about 1,000 miles round trip). It currently has 143,000 miles on it. Ran like a top mostly.

A few things though:

Ever since I've had this truck (96) if I get it over 65 on the interstate for a sustained period of time, the Check Engine Soon light comes on. It eventually goes out and stays out for the rest of the trip. The truck runs fine, it just seems wierd to me. Happens after I run it for about 10 mins or more at constant speed above 65.

This time on the way back, it ran like a top on the interstate but when I got into city driving it idled like crap. Cut out, rattling the pipes it was shaking so hard. I figured bad gas (bp in Des Moines looked run down), or water in the tank. After I ran it down to under a 1/2 tank I put in some other gas. Ran like crap for a while and then all of a sudden was fine.

Has anyone encountered this? Should I be concerned about the Check Engine Soon light? I tried to buy a puller but the mechanic said it's a hybrid (OBC?II connectors hooked to an OBCI box). Does that sound right?

Any help is appreciated.

Art

Reply to
Art Wakefield
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Classic symptoms of having a piece of carbon get stuck in the EGR pintle. The sure cure fix is to install a "Klean Screen"(tm) EGR gasket from Tomco;

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Yes. The light is trying to draw your attention to a problem. it may be EGR related, it may be something entirely different.

Sounds right because it is right, except that it's OBD not OBC. Yours is a bastard system, (not OBD1 and not OBD2), it will take a professional grade scan tool to extract codes.

Get someone to pull the trouble codes before things get worse.

Reply to
Neil Nelson

Art if the diagnostic plug under the steering wheel has a 16 pin connector and the under-hood label shows obd-1 then it's a hybird system. Another clue is the distributor cap has the wires plugged in horizontally rather than vertically. This system is sometimes referred to as obd-1.5. I bought this:

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and use it with my laptop. I found most of the engine data can be read even though the system is listed as an obd-1. I'd agree with the other poster on the egr symptoms. There was a prom update on the

4.3 to cycle the egr valve to clean out carbon. However pulling the DTC is the best approach to see what's setting the code.
Reply to
DonW

I'd put $50 on it being the EGR valve.

Doc

Reply to
"Doc"

Me too. GM has a published fix, and it's not a screen between the valve and intake. GM can re-program your engine computer to prevent this from happening again. The EGR on my old truck, a 94 Jimmy, clogged at 60,000 miles. I had a dealer do the published fix, was free at the time, and it didn't happen again in the next 55,000 miles.

Reply to
Mike Levy

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Yep, they have the EGR hang open for longer on deceleration and it blows the carbon out of the system.

Doc

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Reply to
"Doc"

Nope, it's an aftermarket fix, thought I had made that clear.

You were lucky, in many cases the re-program doesn't cure the problem although it may help with how frequent it occurs. At $10, two bolts and ten minutes time, the EGR screen is cheaper, faster to implement and can be done by the average DIYer.

Reply to
Neil Nelson

Until a bigger chunk gets caught.

Reply to
Neil Nelson

Thanks to everyone who replied. The level of expertise on this group amazes me! It sounds like the consensus is EGR and I will look into all methods described and let everyone know the result! Thanks again!

Art

Reply to
Art Wakefield

DIYer.==================

What happens to the carbon chunks behind the screen? Wouldnt they just build up behind it till it completely cloggs up? Doesnt seem like a good solution to me.

Reply to
Scott M

They can only do that during the time that there is EGR flow, as soon as the EGR shuts off or the engine is shut off, they'll fall off of the screen. Haven't had one yet that posed a problem but it would be simple enough if it did to un-bolt the EGR and blow the chunks out with compressed air, then drive it another 50-60K miles.

You're absolutely correct. The "good" solution would be for GM to fix their screw up 100%. Since that isn't going to happen, this one is the best alternative to date.

Reply to
Neil Nelson

Nope on my wifes 94 the chunks just drop to the bottom of the screen and stay there, The way it is designed it really cannot clog since the screen isn't flat, it inserts inside the port on the intake and forms a sort of inverted cone. Take a look at

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and you will see what it does.Oh and the GM fix may work unless your engine has large chunks of carbonblowing out, the ones in the wifes average about 1/8" square and are bigenough that they will not pass through the valve even if it is fullyopen, they just stick the pintle open and Presto crappy idle and thelight is on.

Steve W.

Reply to
Steve W.

================== ya, Ive seen a few electronic EGRs on S-10s with 4.3Ls get stuck open now and then. I have a 94 Sonoma and mine has plugged only once that I can remember(in about 60K miles). It idled rough at a stop , lit the CEL, then it cleared up on its own by the time I got to the next light. If mine did it alot, I guess I would stick that screen on it too :) When I first got it, it surged while cruising. It turned out there was an updated prom for the problem that involved the EGR. Is this the same update for the sticking problem that someone mentioned earlier I wonder?

Reply to
Scott M

Probably. You may have just had your PROM updated after GM released the EGR update, so your update incorporated yur cruise fix and the EGR fix...

Reply to
Mike Levy

pull the fuse out to disable the light

Reply to
Brad Rollins

And kill the PCM and dash cluster as well?? GREAT idea! Then he really wouldn't have any problems as the damn thing wouldn't even start.

Doc

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Reply to
"Doc"

Pull ECM out.

:-)~

~KJ~ /knows doc will come back with a serious flame

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Reply to
KJ

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