So my car doesn't seem to be running quite right. It generally runs kind of rough, but when I'm accelerating very slowly, around 45 mph, the car will sometimes start sputtering and jerking. If I give it more gas I can acclerate out of it. Also, once in awhile there is a loud pop out of the exhaust. I originally thought I might be running rich because of the smell (no cat) and the fact that eventually black stuff builds up on the ground effects where the exhaust is, although it takes a long time. I put the car in field service mode, and the light was flashing slow, which means the car is running lean I think. Engine is a 350 tpi, the previous owner blocked off the EGR with a plate from TPIS - not sure if that matters or not. Do you guys have any suggestions? Thanks!

Chris

 

Check your wires for cracks and splits. Pop the hood at night and check them out. Look for blue sparks jumping around between them and the block. Bad wires can cause jerking and backfiring. I had this problem a few months back. Replaced the wires and she ran like new....nice and smooth. I recall, like what you said, that it seemed like I could accelerate and it would go away for a bit.

 

Thanks for the reply, but I just replaced all the wires a couple of weeks ago, so I'm pretty sure that's not it. Is there a good way to check whether I'm running rich or lean?

 

Anybody? Whats the first thing I should check? Thanks!

 

Thinking about getting an air/fuel ratio gauge, but I've also heard that the O2 sensors in this car won't tell you much? Good idea, or is there somethin else I should do?

 

Pull your plugs and see what color they are. I'd start checking for vacuum leaks around everything, plenum, runners, throttle body, canister, vacuum reservoir etc and check your fuel pressure. If it set a code for a lean condition and is the same as my 89 camaro l98 it should be a code 44. By field service do you mean you shorted out the A&B pins with a paper clip on the ALDL to check code? There is a sticky that tells you what all of the codes mean. If that is what you did there will be a code 12 set which is normal (one flash followed by two flashes repeating). If other codes are set they will appear afterward code 12 flashes three times. Then the process will repeat. Slow flashing doesn't mean anything.
Jerry

 

No, there are no codes being thrown. Field service mode is when you jumper the A and B terminals while the car is running. If the light is flashing faster than once per second, the computer is leaning out the mixture, and if it is flashing slower than once per second, it is enriching the mixture.

 

hmm never heard of that before...interesting.

 

I've never ever heard of that or read about it here. Far as I can tell it's not in my GM service manual either. I can't see how a light that flashes every couple of seconds can keep up with the rapid changes to fueling an ECM makes? Well I'm not what I consider an expert but I can share with you what I think is the case.
Check your plugs to verify your condition. A black exhaust is rich sign.
If your not setting a lean 44 code my GM manual states to.
1)Make sure your O2 sensor wires are not contacting the exhaust or have shorted through to ground.
2)Disconnect the MAF sensor start the car and see if your BLM goes rich. If it does you have a bad MAF
3)Water in your tank or dirty fuel filter.
4)Exhaust leaks.
5)Verify fuel pressure at idle and driving through the problem. Vacuum to regulator removed and plugged you should be in the 40 to 47 lbs range.
6)injector balance test (requires fuel pressure gauge and a switch to activate the injector).
7) Air injection system-squeeze the left side air hose into the exhaust header while in closed loop. If the BLM goes low there is a problem with the air injection.
8) None of the above consider replacing the 02 sensor. Pull it out if its white colored it's contaminated. Usually goes rich when this happens though.

I'm currently fighting the same sort of problem (lean condition with occasional bucking and stumble surge when idling) so these are steps I'm taking. Including resistance checking my wires, checking grounds, vacuum leaks (found one but it didn't help). Checking canister purge and flow testing the fuel pump. I might consider a new distributer pickup as they are cheap.
Jerry

 

Thank you for the advice - I will try that. As far as the field service mode goes, try doing a search here, I think it was Vader that was posting the information about it. I just found out about it also - not sure how reliable it is, but it's interesting.

 

I had the same problem, so I had my fuel lines cleaned and I changed my fuel filter/pump. No problem after that. However, I didn't have the popping sound. Hope it helps.

 

yeah i have the same problem as well. i buck when the rpm is over 1000. and the needle jumps to about 2000 and back and forth. when i give it gas it goes away but if i maintain my speed it still does it and i havent let go of the gas. i thought for a sec that maybe i broke a the needle on the rpm guage bc i dont here the difference in engine like u d figure u d here the engine more at 2000 rpm and then drop when it went down. So far i changed the o2 sensor twice once before my flowmaster and once after, high flow cat, dist cap and rotor, new spark plugs, and wires, fuel filter, fuel pump, adj regulator, fuel line from fuel pump to filter, mass air flow sensor, and i run 93 octane i dunno if maybe i should take that down a notch. code 44 running lean and it said o2 sensor and i changed it and it s still doin it. could it be bc i cant clear the code and how can i without a computer is possible

 

try changing the TPS. That is what I did and now my car runs like a queen. also consider throwing in a new O2 sensor.