Rough running 1995 Blazer

[djgriff]

I hope someone can give me some ideas on what the problem is with my 1995 Chevy Blazer. I’m not a mechanic but if these symptoms seem to not require taking it into the shop, then I’d like to do it myself. I just changed the spark plugs last week because it wasn’t running very smooth, but that hasn’t fixed the problem.

Here’s what the Blazer is doing:
1. The engine slightly surges when driving at a constant speed, but the rpm’s don’t change.
2. Sometimes takes several crankings to start.
3. Every so often it will cut out while driving. Doesn’t seem to matter the speed.
4. When pulling up to a stop sign, the brakes will get hard to push (indicating that it’s about to stall). I need to keep the brake on and give it a little gas to keep it from stalling.
5. Engine seems to still run rough.
6. The exhaust has an odd odor. Not like sulfur, but smells.

Thanks for any advice you can give me

[blazes9395]

Do a search for both EGR and CPI injector. Very common on these trucks. I would say EGR in your case, but could also have a CPI problem too. Theres so much written about this.

[rlith]

Sounds like you're running a bit rich and the cat is working overtime (hence the sulfer smell) More than likely a bad CPI and/or nutkit

[djgriff]

Thanks for the advise, I'll do a search and see what I can find.

[rlith]

Originally Posted by djgriff

Thanks for the advise, I'll do a search and see what I can find.

\
Pull the upper plenum and look for signs of washing (where one side is cleaner than the other) If the passenger side is washed, it's your CPI unit, if your driver's side is washed, you have a bad nut kit...Replace the nutkit anyway if you replace the CPI so you don'thave to pull it later... Some will tell you to pull the throttel vane and look down into the plenum, but that's not often accurate for the signs of washing...Do it right and pull the plenum.

[djgriff]

I guess I'm not doing the search correctly because when I search on "EGR" under the "Search this Forum" on the right side, it comes back with an AF Message "Sorry no matches,,,,,," It should have at least displayed your post since you told me to search for EGR. What does EGR stand for?

[blazes9395]

EGR is Exhaust Gas Recirculation. Its an emissions component. It reduces the amount of nitrous oxides in the exhaust by recirculating exhaust gases have already gone through the combustion process in the engine. The EGR valve limits the amount of gases that can pass through it, which is in turn controlled by the PCM(VCM) of the car. IF the EGR valve is broken, stuck, clogged,(which is very common for these CPI systems) then the valve cannot limit the amount of gas passing through, and causes a rough idle, weak combustion, stalling at idle, etc, etc.

The EGR valve on the CPI equipped truck is located about under the intake, its the cyindrical piece that has wires going to it at the top(the plug). Usually all it needs is to be taken off and cleaned very well and it works properly again. But if your getting carbon at the EGR valve for it to get stuck, its usually a result of a leaking CPI injector, leading to a rich combustion.

Rilth mentioned how to diagnose the CPI injector, which again, is very common for the CPI system.

Hope this helps.

[Cruize]

Search for "EGR valve." My search brought up 4 pages of threads.

By the way, my 95 is running rough / barely runs. Here's my thread.

http://www.automotiveforums.com/vbul...d.php?t=612276

Is this similar to what you are experiencing?

[sonnyyy]

Originally Posted by djgriff

I hope someone can give me some ideas on what the problem is with my 1995 Chevy Blazer. I’m not a mechanic but if these symptoms seem to not require taking it into the shop, then I’d like to do it myself. I just changed the spark plugs last week because it wasn’t running very smooth, but that hasn’t fixed the problem.

Here’s what the Blazer is doing:
1. The engine slightly surges when driving at a constant speed, but the rpm’s don’t change.
2. Sometimes takes several crankings to start.
3. Every so often it will cut out while driving. Doesn’t seem to matter the speed.
4. When pulling up to a stop sign, the brakes will get hard to push (indicating that it’s about to stall). I need to keep the brake on and give it a little gas to keep it from stalling.
5. Engine seems to still run rough.
6. The exhaust has an odd odor. Not like sulfur, but smells.

Thanks for any advice you can give me

You have described exactly the symptoms of my blazer ,, I have cleaned the egr , the check engine light went out but it's still running rough on the idle. Starting it first thing when its cold I didnt get the smell or smoke,

Let me know how you fixed yours so I can fix mine.

[linchas123]

The fic fast idle control on top of the inlet air port on the vortec v6 tends to melt internally if doing heavy traffic over time and will stick. remove and look at internal plunger. if melted replace with new about 70 bucks

[blazerbob91]

Another way to check for washing in the plemun is to pull the valve under the Vortec name plate on the top of the plemun. Use a flash light to look inside for fuel washing. This way you don't have to take everthing a part. If you see washing the get a new spider assembly and nut kit. There is a good how to on this on this board.

[sonnyyy]

When you say washing,, what is the meaning to that phrase ?
My son thought we'd try putting a rag on the exhuast to see if there was loss in back pressure from the muffler or catylitic convertor and it did smooth out somewhat,, but then it started blowing blue smoke out for almost 5 minutes of accelerating.
Started it a hour later ran smooth in neutral but wanted to stall in gear and the gas smell still there.

[wafrederick]

Another thing to check is the distribitor gear and it will do this.Pull the distribitor out and inspect the distribitor gear for shiney spots after cleaning it up wth brake clean.I seen one do this and ran great after replacing the distribitor gear.GM does have problems with distribitor gears wearing out.

[ZL1power69]

Originally Posted by sonnyyy

When you say washing,, what is the meaning to that phrase ?
My son thought we'd try putting a rag on the exhuast to see if there was loss in back pressure from the muffler or catylitic convertor and it did smooth out somewhat,, but then it started blowing blue smoke out for almost 5 minutes of accelerating.
Started it a hour later ran smooth in neutral but wanted to stall in gear and the gas smell still there.

Washing means clean areas insid ethe intake caused by a fuel leak. Usually it is dirty everywhere inside the intake. If the leak is on the left its usually the regulator thats leaking, if its the right side its the fuel lines/nut kit.

Also, this thread is also over 2 years old. If you have any additional problems, please post a new thread in the appropriate section.