??? Oxygen Sensor bad symptoms

[GIBEYERSON]

Someone told me mine might be bad. Problems started when I replaced a head pipe and muffler. The car started running rougher and rougher. Idle is high so it runs but not smooth. On the highway it hums along until I lift slightly off the throttle. Then it stumbles which is pretty annoying. If I lift my foot off the accelerator it isn't as noticeable. The new parts on the exhaust system have black soot showing at the seams where the pipes join and at the exhaust tip. The head pipe seems to have a void at the transition from head pipe to flex section and the is black soot there as well. I have already cleaned the plugs which had a buildup on them.

I was thinking the catalitic converter was going bad but I've been told to check the choke (which is fine) and the O2 sensor.

Thanks in advance for your opinion.

[Frodo65]

Originally Posted by GIBEYERSON

Someone told me mine might be bad. Problems started when I replaced a head pipe and muffler. The car started running rougher and rougher. Idle is high so it runs but not smooth. On the highway it hums along until I lift slightly off the throttle. Then it stumbles which is pretty annoying. If I lift my foot off the accelerator it isn't as noticeable. The new parts on the exhaust system have black soot showing at the seams where the pipes join and at the exhaust tip. The head pipe seems to have a void at the transition from head pipe to flex section and the is black soot there as well. I have already cleaned the plugs which had a buildup on them.

I was thinking the catalitic converter was going bad but I've been told to check the choke (which is fine) and the O2 sensor.

Thanks in advance for your opinion.

Are you sure you don't have an exhaust leak that results in excess air getting in? Extra air would be misread as a lean condition, causing the ECU to enrich.

The main reason I suggest that is because of the exhaust work - which carries a risk of gasket compromise on an old car..

[GIBEYERSON]

Thanks for that suggestion. Since I posted that I had one good day to work on it and I lowered the float level. I seemed to get just a little bit better. The new flex pipe does have a void where the flex section starts and I'm going to have my bro-inlaw weld it when the weather improves. The car humms along great on the interstate but because of the stumble I find my speed constantly increasing. That is how it runs best. If I lift just a little it shudders slightly.

[CRASHDRIVE]

check also the EGR maybe needs cleaning or replacing

[fredricktflail]

My car was doing the same thing, It had to do with the wrong vac line being hooked to the egr valve.

[GIBEYERSON]

That sounds probable. there are so damn many of them. When the weather gets nice again I'll check that.
thanks

[MyCorolla]

Originally Posted by fredricktflail

My car was doing the same thing, It had to do with the wrong vac line being hooked to the egr valve.

I'm worried I may have that problem right now. Anybody have pictures of the proper EGR hose routing for a 1978 Toyota Corolla Wagon, 2TC, 5 speed?