Engine Rough Idle

[MustangGT559]

Hello, how's it going. So I have an idle problem. So every time I start my car up (cold start) it idles fine. But when I drive it around, and park the car somewhere and start her up again it starts fine, but it drops RPMs like crazy! Its goes from 1000 to 300ish really quick. But then it goes to 500-600. It sounds likes it going go die and shut down but it doesnt. It runs really good. I recently changed the plugs, spark plugs and cap. And I cleaned out the MAF sensors and it still the same.

 

[stykthyn]

Dump the codes. A hot surging idle is an issue.

 

[MustangGT559]

Dump the codes. A hot surging idle is an issue.

It gave me code 34 and 10

 

[MustangGT559]

Dump the codes. A hot surging idle is an issue.

And 91

 

[stykthyn]

34 egr not opening, egr insufficient flow
91 o2 sensor voltage low, system alwayslean

 

[MustangGT559]

34 egr not opening, egr insufficient flow
91 o2 sensor voltage low, system alwayslean

Thank you! You know any fixes for those? I don't have any o2 sensors

 

[stykthyn]

Was your car tuned to remove them? Odds are you do have them down there.

 

[MustangGT559]

Was your car tuned to remove them? Odds are you do have them down there.

I don't think so. Not that I know of

 

[stykthyn]

Crawl under the car in the morning and take a look. They should.be in your h pipe.

 

[MustangGT559]

Crawl under the car in the morning and take a look. They should.be in your h pipe.

I know my car, and it doesn't have the o2 sensors.

 

[stykthyn]

Then you need to check your ecm and look for a chip otherwise you're never leaving limp mode.

 

[jrichker]

Then you need to check your ecm and look for a chip otherwise you're never leaving limp mode.

Good Advice, take it. Without O2 sensors, the computer has no way to tell is the air/fuel mixture is rich or lean. That's a big invitation for trouble.