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Intermittent Miss '95 Blazer 4.3 CPI

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Old 12-23-2003, 11:37 PM   #1
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Intermittent Miss '95 Blazer 4.3 CPI

Hello,

I have a 1995 Blazer 4X4 with the 4.3 CPI engine and 118,000miles on it and it is behaving very strangely. When the weather changes or is damp/cold the engine misfires at idle and is very audiable. This is not a problem once it is brought off idle.

It also will just cut out for a half a second or so going over hills at about 50-60 miles per hour and it will repeat it several times and then clear up. Sometimes it will not do it at all.

The service engine soon light comes on every once and a while but not usually.

Does anyone have any idea what the problem is? This is a good blazer and I have had it since 19,000 miles and this is frustrating.

Thanks a lot
Old 12-24-2003, 07:40 AM   #2
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I have a simular problem I've narrowed it down to a leaky(driping) CPI. (i think)

let you know as soon as I change it probably around 1/2/04
Old 12-29-2003, 07:32 PM   #3
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check local gm dealer for recall--read in diff post about this.
the first time they look at it they try to clean the injector assy, then if that doesnt do any good then they rep the assy.
call first --if there is no recall you will have to pay for checkout.
Old 12-29-2003, 09:50 PM   #4
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CPI unit, Nut kit, and egr valve.
Old 12-29-2003, 11:18 PM   #5
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Also how long has it been since you did a full tuneup(cap/rotor,wires,plugs,filter)?Worth a try,along with using Seafoam to clean fuel system,before diving into the CPI.
Old 12-30-2003, 01:43 AM   #6
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Quote:
Originally posted by coolram
Also how long has it been since you did a full tuneup(cap/rotor,wires,plugs,filter)?
Old 12-30-2003, 03:01 AM   #7
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My 95 4x4 blazer is doing the exact same thing, i sure hope its not the CPI. Let us know how the CPI change out goes Bigthreefan!!!
Old 12-30-2003, 10:56 AM   #8
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A new cap, rotor, plugs and wires were done at about 102,000 (16,000mi ago).

I dumped Fuel Injector cleaner into it yesterday and drove it about 45 miles with no improvement noticed.

My service engine soon light was blinking as I was coming home and the next time I went out, it stayed on solid. After getting in the throttle to merge into traffic, it shut off but the symptoms were still there.

When it is running bad, the exaust pipe smells like it is running very rich.
Old 12-30-2003, 12:47 PM   #9
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when your engine light is flashing it means there is a misfire detected--if it smells rich then its getting too much fuel causing the misfire--call the dealer and see if you have the recall.
Old 12-30-2003, 12:59 PM   #10
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More than likely it's the CPI or the nut kit going bad..This will cause those symptoms.
Old 12-30-2003, 01:27 PM   #11
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I would go to Autozone or the dealer and get your codes read.

Sounds like you have a sensor acting up. Everytime the engine light comes on, a code is stored in the computer.

It could be the CPI but the CPI doesn't kick on the service engine light.
Old 12-30-2003, 01:38 PM   #12
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it will if it causes a too rich condition and the 02 sensor to go nuts... I've seen that happen too many times with CPI...
Old 12-30-2003, 01:47 PM   #13
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True, he should get the codes read and I hope he doesn't clear his computer.

The codes will tell all.
Old 12-30-2003, 02:02 PM   #14
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man, not to sound all passimistic (sp?), but i was already there before and i know the symptoms. I replaced the car, rotor, spark plugs, spark plug wires, fuel filter, etc... Basically, a full tune up. heck, i even ran sea foam before all that. ran a tiny bit better. But after the next oil change, it was getting worse. so i pulled the upper plenum and saw washed gas on the manifold, thus the culprit being the CPI unit and nut kit.
Old 12-30-2003, 03:14 PM   #15
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Xtremejimmy, we are not solving your problem, we are solving the thread starters.

If he is getting check engine lights, the smartest course of action is to get the computer checked to narrow it down before the engine is torn apart.
Old 12-30-2003, 05:24 PM   #16
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The computers already been checked several times and not cleared. It has read anything from O2 sensor curcuit low (only the first time) to just the knock sensor curcuit being low. Otherwise it is not causing codes. I guess it must be the CPI unit.
Old 12-30-2003, 07:43 PM   #17
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Those are codes if you are getting something read by the scanner.

Sounds like a lean cylinder bank.

Which bank was the knock sensor acting up on?
Old 12-31-2003, 10:19 AM   #18
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i was getting a knock sensor low on bank 1
Old 01-01-2004, 02:50 AM   #19
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Re: Intermittent Miss '95 Blazer 4.3 CPI

Quote:
Originally posted by goldduster318
Hello,

I have a 1995 Blazer 4X4 with the 4.3 CPI engine and 118,000miles on it and it is behaving very strangely. When the weather changes or is damp/cold the engine misfires at idle and is very audiable. This is not a problem once it is brought off idle.

It also will just cut out for a half a second or so going over hills at about 50-60 miles per hour and it will repeat it several times and then clear up. Sometimes it will not do it at all.

The service engine soon light comes on every once and a while but not usually.

Does anyone have any idea what the problem is? This is a good blazer and I have had it since 19,000 miles and this is frustrating.

Thanks a lot
how many miles on those plug wires?

sounds like a burnt plug wire. which will cause it to miss under load (going up hill). when my 95 did this, it wouldnt do it all the time.
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