92 S-10 4wd Blazer problem running

4.3 vortec, auto. It was running fine a couple of days ago. now????????? It might go down the road fine then slow to a crawl. 10 - 15 mph. lots of spitting and sputtering. Took it to a garage yesterday and they said the computer says too rich of a fuel mix. They also so said 1 of the causes could be the O2 sensor. Ah, that was not the problem.(45.99 @ o'rielly's). Now any ideas? Catalytic converter? vacuum line? 1 guy said that there were 2 bolts on the backside of the block and they had gotten oil on them and we needed to take it to a dealership and have them fix it?????? What? I need it running by in the morning. Any and all help would be greatly appreciated.

 

Hopefully someone else here can jump in and answer MY relevant question regarding the poster:

Can these computer testers 'know' that there indeed is a rich problem with the engine? (say like a malfunctioning fuel pressure regulator?), as opposed to say the engine running so lousy that the gas is not burning good and sending out raw or partially burned fuel, confusing the computer into thinking there is a rich-burn condition?

 

new O2 sensor, fixed the vacuum lines(with the right parts)new coil, and disconnected the catalytic converter and it still runs like crap. Moderate acceleration up to about 20-25 then any acceleration at all and it sputters and dies. New fuel pump in last 4 months also.

 

Since you're talking about a rich condition and you've changed the 02 jobbies, I would lean toward MAP sensor. It's the little gizmo clipped to the breather and a tube running to a vacuum source.

Hope this helps,

Bob

 

2 things to look for, 1. EGR, take it off and clean it, also clean out the 2 ports (usually will pull a code though). 2nd spider assy, look down into the upper plenum, if one side or the other is "clean" there is your problem....drivers side clean it is the "nut kit" passenger side clean it is the FPR.

 

In addition to Cabot's suggestion, I think I would also rescan for codes. It's DIY on OBD-I GM stuff:

http://www.troublecodes.net/GM/

Your data link connector should be under the dash above your left knee.

Fuel filter been replaced? Also, I would be inclined to check fuel pressure even though the pump was replaced (side note: was it doing this already before the R&R?). Ideally you would connect one that could be seen while driving to ensure there isn't a pressure drop happening when the power loss occurs.

As to ecman's question; I think the newer OBD-II stuff is more sophisticated in that manner. The older OBD-I systems were generally more of a guideline as to where to start looking. Hoping Mark (HotinOKC) will jump in here as well.

And a late thought, when you pulled the O2 sensor was it black and sooty like an actual rich condition would create.

 

an oxygen sensor is just that...it senses oxygen level in the exhaust stream and generates a voltage proportional the amount of O2. assuming a computer is operating, then you can generally trust a scan tool...if it says it's running rich and the )2 voltage is pinned at 900 mV, then it's really rich...not to mention that it's going to stink like rotten eggs and possibly emit black smoke from the tail pipe. one exception is this...during an ignition related misfire oxygen doesn't get consumed during compustion but rather just passes thru. this abundance of O2 is indicated (remember, it's an O2 sensor, not a fuel sensor) by the 02 sensor and interpreted as a lean condition by the controller, which in turn adds more fuel to compensate for the perceived lean condition. ok...that's it for 02 sensore 101

one very common thing on those vehicles is plugging of the vacuum port in the bottom of the throttle body where the vacuum hose for the MAP sensor attaches. remove the hose with the engine running and if it's plugged it won't change...if it's not plugged, you'll hear the sucking noise caused by the vacuum leak. you might be able to get by with a piece of wire or some carb spray into the hole while it's running to dislodge some crud. this would get you going for now...the real fix is to remove the throttle body, clean the crap that's packed in the bottom of it and replace the throttle body gasket (these are also a weak area).

fuel pressure and volume are also important, but this more time and some equipment the average person usually doean't have. EGR valve stuck open is also a possibility and likewise may require more time...check the throttle body first

 

Checked the codes(check engine soon light was on)It showed a code 43. Low voltage to ecm according to my book. I disconnected the battery to erase codes. Reconnected the battery after about an hour. Drove it and and drove it and drove it. Acting the same but no check engine lite, no codes. I checked and rechecked. Spiting and sputtering and I also noticed if while it was going through one of it's tantrums it would also backfire if I pushed harder on the throttle. No codes at all. I had bought a Map sensor yesterday after seeing online that all the symptoms matched the map sensor. After I got no codes today I put the new maps sensor on. It acted better. A lot better as long as I worked the throttle just right. But it is nowhere close to being normal. I am taking it tomorrow morning to a garage and let them check it out. I am at a loss as to what to next.
If anyone has any ideas please tell me but if no extra help is forthcoming tomorrow to the shop it goes. I don't have the money to do it but got to have the vehicle. Egr was taken off and cleaned, new O2 sensor, new coil, we unplugged the ecm and blew out the connections and reconnected it. Not to mention changed the oil and checked the gas cap(That was one of the suggestions)

Any new ideas. I do not have a volt meter and so some of the suggestions are null and void because that. I did not want to break anything like the little gizmo on top of the upper intake that needs a new o ring according to the instructions.

Thanks for everyones help.

 

i think a code 43 is a knock sensor/EST problem...doesn't fir what you are describing. check where the vac hose hooks on to the throttle body and see if you have strong vacuum. a vacuum guage helps if you have or can borrow one. good strong vacuum at idle (18-22 inches) with instant change when the throttle is opened. if not, then it's what i said in my previous post. it doesn't cost anything to check it...so far you have thrown alot of unnecessary parts at it.

 

Score one for carguy. Always nice to have a pro around to help us amateurs.

Here's what 43 should be, I think:

"The ECM did not detect a knock signal during near wide open throttle operation with coolant temperature above 194� F or the knock signal was present for 5 seconds or more during normal engine operation."

 

Took it to a shop. Told them what all we had done. He asked about fuel pressure. But when we told him how easy it started he said no way it was that. It has to have 60 lbs just to start and that would be plenty for it to run fine. But lets just test the pressure. Best we could get was 19 lbs! Aha! So even though it was new in July bad fuel pump. We pulled it(me and the boy) replaced it. And I saw there were no o-rings on the ends of the fuel lines that come out of the tank. On the new total assembly (we were just replacing the pump) there were o-rings. I got o-rings and put it all back together. On the drive around the yard when the boy(17 y/o)turned around and pulled on the paved drive he gave it to much throttle and lit up the tires. Thanks for everyones help!