ok... i originally had the problem about 3 weeks ago, i assumed it was my o2 sensor, so i bought a new one and replaced it. i also had a CEL and that went away after i changed it. i drove it around town real quick and it ran fine, didn't chug. i took across town a couple days ago and it dhugged a little but after that it was fine. today i drove it to my GF's house which was about an hour away and didnt have problems with it until i got to her house. we went into flint for lunch and when we were leaving olive garden it had a really weird whining noise, almost like a power steering pump has when it's empty. BUT, i dont have PS on my car. so that's ruled out. coolant is also at a good level. still no CEL through all this. on my way back just a little while ago, it started chugging again. and eventually it started losing speed, but maintained RPM's. it started chugging a little while later after i got it to gain speed again. i ended up stopping to get gas. after i got gas it ran fine up until i got into bay city and it started chugging again. and it has a new hesitation like it has a head gasket problem...(yay....) when i was in flint, it had a problem with idling really low as well. almost like it wanted to stall, but didn't... it didn't do that much, maybe twice.

out of all this mess. can anybody figure out whats going on? why would it chug after changing the o2 sensor. ? why would it lose speed, but maintain rpm's? what would cause it to idle low?

 

try unhooking the battery for 15-20 min if you havnt already after the new o2 sensor. It will reset the ecm.... if im not mistaken, the computer need to "learn" the new o2 sensor.

 

ok ill try it tomorrow. it needs to relearn the o2 even thought i had a CEL? i cant say 100% the CEL was for the o2 sensor, but....only assuming it was if it went out the instant i ran the car after install.

i will try the battery though. never hurts to try.

 

I don't think the OBD1 requires a calibration phase. A bad O2 sensor won't cause what you describe. Whenever the CEL comes on you should pull the code to find the reason rather than just replace stuff blindly. "Chugging" or misfiring when trying to accelerate at low rpm is usually an ignition problem such as bad plugs, wires, or cap / rotor. While it idles badly, disconnect the fuel injectors one at a time to see if there's a dead cylinder. Disconnecting a good cylinder will make it slow down. Disconnecting a bad one won't change anything.

"Loses speed but maintains rpms" I'm not sure what you're saying. If you're saying the engine revs up but the car doesn't go proportionally faster, that's a problem with the clutch if manual, or slippage in an automatic transmission.

 

guess next step is to change plugs and wires. they're the cheapest. if not, ill step to the cap.

car is a manual. the RPM's don't change, but i lose MPH. i'm not sure how old the clutch is...

ok, so if i don't have a CEL, it will still read a code out if i jump it?

 

If the CEL has been on but then went out since the last time you reset the ECU (disconnect battery), the code should still be stored.