iroc-ice

My car has trouble idling. When I'm sitting my car idles around 700-1000rpm, but sometimes it drops to 300-500 and starts to turn of then it jumps back up to 700 or so. My car worked fine before I took my exhaust off. Right now its running through the manifolds-ypipe-cat. I think the lack of back pressure is the cause. I can't put my Dynomax exhaust on until I get a new cat. The old one's flange is to small for the flange on the exhaust pipe. Do you think the exhaust being off is cause my car to idle weird? Thanx

Ray D.

grafx

dude my car is having the same problem. My post is right below yours!!

onebinky

iTrader: (1)

Could be all kinds of good stuff, but open exhaust wouldn't be one of them

How is charging voltage? Maybe you knocked some wires loose on the back of the alt or starter and it's not charging right.

Any vacuum leaks?

Any wires up againsed your manifolds or exhaust? Grounded out ECM wires can do some wierd things, as well as secondary ignition wires.

All plug wires are seated all the way on the plugs and cap?

You want to start looking at anything you could have possibly messed up while playing with the exhaust.

If that fails, start with the more in depth stuff.

Typical intermittent drivability causes could be:

Bad/loose engine ground
shorted wires
water in the fuel tank
crap floating in the fuel tank temporarily clogging the pickup
dead spot on the TPS in the idle area

Check out this stuff and see where it leaves you. This is far from a complete list, but it'll get you started in the right direction.

onebinky

iTrader: (1)

Oh, did you bump or hit the o2 sensor, or tug on the wire to where you could have damaged it?

That *should* throw a trouble code if the computer doesn't see it. If it is still trying to reference a dead sensor though, that could cause all kinds of trouble. It would constantly be trying to correct a rich/lean condition that doesn't exist.

iroc-ice

My SES light is on, but thats cause I need a new Air Temp sensor. Thats probably not the right name, but its the sensor that plugs into the air filter of the TBI. Could that be it?

onebinky

iTrader: (1)

That could very well be it. If that fails, IIRC it usually defaults to -45 deg. F. That will make the car run pig rich, causing idle problems and make it smell real rich.

If the ECM knows that it's bad, it really has no clue what the air temp is, and is left to guess. Could explain the hunting idle as well.

iroc-ice

Better go buy one. Don't like running rich. Hope they don't cost to much.