whats up guys
its a 94 blazer with 4.3 its got like 160,000 miles
the problem is that it is running really crappy, it has like no off the line acceleration and is running very very rich it kinda gets better as the car warms up, but still very much there. today i heard a loud pop, im guessing it was some kind of backfire that lit up the rich exhaust. it sounds like its misfiring or something when you rev it, not smooth at all. any ideas or suggestions are appreciated
i checked the engine codes, and i cant find where i put the paper
it was something with egr and O2 sensor rich

 

Well if the code is coming up about the O2 sensor most people say to replace it after 80K miles, I would say it it is original or replaced once I would replace it again, they are pretty cheap.

 

would the o2 sensor cause this much trouble on its own?
my brother cleaned it off the other day when he replaced the starter. and oh yeah, it takes a while to start.......hence burned up starter

 

I not sure if cleaning it off will help? but I am not sure.

hard starting - I would check for poor fuel flow and or poor spark.

The running rich could the O2 sensor as it may "see" a lean condition and be adjusting accordingly causing a rich condition.

hence the backfire.

I would also check to see if any vacuum lines came off or are cracked.

 

Maybe a clogged cat.

 

'94 262 V-6 = CPFI. Test the fuel pressure. If you don't have at least 61 PSIG, it isn't going to run worth crap. You may actually have more than one issue, but the hard starting is very typical of fuel delivery issues on the CPFI systems.

 

after you check the cpi injector assy., check the digital egr vavle. i bet the egr valve is jamed with coke... The valve opens and any coke or buildup gets sucked into the vavle and the pintle gets jamed open and it does exacly waht you describe. Runs rough, wants to stall when stopped. I fixed mine by cleaning the egr valve and re-seating the pintle. After that, i disconnected the valve so it wouldnt open and readmit more crap. Sets the ses light but it gets rid of the problem. You cant clean the egr vavle and reinstall it. It will simply get jamed open again. I figured this out after taking that sob valve off twice. Disconnected it and no more probs.

 

sorry to take so long. where do i find the egr valve on this car.
by the way, its running so rich that there is gas in the oil. i found out cus the oil pressure drops at a stop when warm, and i smelled the dipstick-smelled like gas. it seems to drive a lot better when it gets warmed up. im not trying to do anything but keep the p o s running. any quickfixes or ideas would be appreciated. ill check those engine codes again soon too. also, when it gets too much gas, sometimes it will just die out-im thinking its just really flooding out
any more ideas?

 

Start with the oxygen sensor. If it hasn't been replaced, it needs one. If the computer sees from the sensor's signal that the exhaust is lean, it will richen the mixture; if the sensor is bad and tells the ECM that it's lean even when it isn't, you get what you've got.

Cheap, easy, high probability of a fix, you need one anyway every 50k miles or so. Jist do it and go from there, see what it needs next.

Also make sure the vacuum line that goes to the fuel pressure regulator is hooked up and not broken (no leaks). That will richen it way up too especially at idle and cruise.

 

Check the EGR vavle like 24x7 said to see if its stuck open. I also agree with Vader on checking the fuel pressure. The CPI uses an injector assembly that kinda looks like a spider and uses poppet-sp? valves kinda like a desiel. These valves can stick open or closed, get clogged or crack.

 

yes... the cpi system is a very poor design. Prone to clogging and leaking. THe egr vavle will be beneath the upper plenum on the engine in the front. Its kinda a pain to get to so check the o2 sensor first like said above, then the cpi injector to makle sure it isnt filling the intake with gas, and you should also be able to easily get at the egr as well. Youll definatly want to pull the intake to make sure the cpi isnt leaking or cracked. One thing i hate about those cpi injector things is that their expensive. The one form gm ran me $380 the last time i had to switch it out.

 

yeah, ive noticed before that when i looked in through the throttle body that the inside of the intake (plenum, im not sure what to call it) anyway, it was filthy in there. it needs some serious carb cleaner squirted through there. could this also be the problem?

 

and where do i find this vacuum line to the fuel pressure regulator
like where under the hood is it. these newer cars are greek to me.
also, can i use the o2 sensor off my camaro in the blazer. dont worry, the camaro is tucked away in the garage awaiting its second rebuild. maybe itll get done right this time

 

<h1>____</h1>
(That's Red Line, for the rest of you...)

The '94 is likely to have a 3- or 4-wire heater O² sensor, so I doubt your ThirdGen sensor will work. The last 4-wire I bought was about $54, so it isn't a real bank-breaker.

 

There is no vacuum line to the fpr. On the CPI units, the fuel pressure regulator is part of the CPI injector assy. If the fpr is bad or leaking, the whole assy must be replaced. Its usually a good idea to replace the CPI injector anyhow if your working nearby it and you have things apart. My S-10 has been through three of them. Replacing it will probably make a noticable difference in performance.