i have a chevy blazer ...year 95.

In the past i was experiencing rough running and shudders and then an engine light coming on. we were told it was the EGR valve getting plugged with carbon.

but now i was experiencing kind of a diff problem...the car would be fine until usually i would back up then put in drive and step down on gas. the gauge would jump as well as the car while trying to accelerate. then on pops the engine light.

we took it in and the only codes to register with a diagnostic was a bad map sensor. said mechanics replaced it. i learned soon after that it was doing the same thing. they said could be a bad part that they put in. so they replaced it again. a little while later it started doing it again. they had the car over night and no codes would register and also the engine light would never come on for them.


so i took the car and it ran fine all this week until last night when the engine light popped on again. over night it went away and later saturday it came on again.

its coming on with that acceleration jumping. i dont know what the problem could be but if ANYONE could help that would be so great! i just drove it and light was still on but it seems to be running fine. thanks.

 

I'm trying to figure this out. Your truck had been diagnosed with having a clogged EGR valve. Was this problem fixed? Did they clean the EGR valve or just replace it?

Next problem... When you back up then put it in drive and hit the gas, what gauge jumps? - the tachometer? How did they come to find that the MAP sensor was bad? Did they get a code for it or did they scan the sensor data to actually find that it was bad? MAP sensors either work or they don't, they don't typically flip-flop back and forth unless there is a wiring fault.

What is happening when you say 'acceleration jumping'? Is the engine stuttering? What is jumping...? Does it do this more when it is damp/wet outside?

Please give me some more details because I really don't know what it is that is actually going on. To the best of your ability, please try to answer all of the questions I have listed above. Thanks.

 

the egr problem was an old issue and im thinking that this isnt the egr. cuz it isnt doing what it did when the egr was clogged. and back then they just cleaned it out.

this time around they did a diagnostic for codes and the map sensor popped up as bad. so they replaced it. but obviously that wasnt the thing causing this issue.

the speedometer is what jumps. the car is "missing" when i accelerate...thats what i meant by jumping. so once that occurs...the engine light comes on. and then it might do it for a bit. but then it runs fine and light stays on. tonight now the light is off when i ran the blazer and took it for a spin. it seems to be coming and going.

my father seems to think it could be the fuel injector needs cleaning. and as far as weather conditions. im in minnesota so its wet from snow lately.

anyhow i appreciate the help....please give me any ideas.

>...i see to remember hearing the blazer from 95 having a problem with the engine light just acting up. but i take the engine jumps as ruling that out as a possibility.

 

Run a bottle ot Seafoam through your gas tank as well, that will clean out your injectors.

Does the engien rev up and not go as fast as normal?
Does this happen after longer then normal idleing. Like waiting for someone?

 

It could be a clogged injector. but it could also be a number of other things. you say the service engine soon light comes on sometimes. you need to take it somewhere to get the codes read when the light decides to come on. you say the map sensor was replaced so it might be throwing a different code now. also dont rule out the egr valve as the source of the problem. getting them cleaned is really only a temporary fix. sometimes if the egr valve is only slightly clogged they will seemingly run fine. I had an s-10 that would do the same thing. It would be running fine and the ses light would come on. then sometimes when it came on it would miss a little bit. turned out to be the egr valve. it might not be your problem but it would be worth the time to check it i think.

 

also, if you happen to have the CPI engine you could be a victim of a leaky CPI unit. It is a very common problem with those motors. Under the plenum is a spyder injector system. It has a fuel regulator on it which over times begins to fail and starts to leak gas. There are also two fuel lines coming from it commonly called a "nut kit". Over time these lines can become brittle and start leaking gas also. If you have the CPI engine this would also be a good place to look