Hey guys,

I'm experiencing bad idle when the car warms up and after I drive it on the frreway or something.....sometimes it'll run fine and sometimes it won't....i just put a 350 in a 86 transam and was wondering if it could be the O2 sensor....i don't think it's been changed in 9 or so years and at least for 50,000 miles.....

Or could it be the EGR...that's a little harder to change so i was wondering, what's an easy way to test it out?

thanks

 

I'd guess it's the O2 sensor, but I can tell you it's not the EGR. The reason for that is that the EGR is supposed to be open when the car is warm (and in cruise mode). The only time you have problems with the EGR is when it gets stuck open and the engine is cold. On a cold motor there isn't enough residual heat from the heads being warm to provide the extra heat input required for the high combustion temps of the exhaust gases. So if the problem is only when the engine is warm, there's no way it's the EGR.

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Black 88 GTA L98
DEAD
but a new crate engines on the way
E.T.F.A Member #11

 

Thanks for the info....

Is it possible to have a bad O2 even if it throws no codes out...cause that's the problem..i'm not getting any codes with the bad idle...

 

If you aren't getting any codes I bet that you've got a bad injector or two. Ohm them out.

 

The injectors are all brand new and have only 1500 miles on them...i doubt its the injectors....

and even the car runs really well when the car is cold and everything...and even sometimes when it's warm it runs ok...

would it be the o2

 

It happened to me once- my O2 sensor went bad and I never got a code from the ECM about it. Bad idle, too- as soon as I replaced it it ran fine. This was on a stock '84 305 carbed T/A setup, btw - I don't know if it might be different on a 350 or not.