Rough Idle after cruising with cruise control?

[TrqMnstr]

It happened for the first time today. I'm cruising at a constant 70 MPH no problems, when I exit the freeway though different story. My Supe feels and sounds like it's bogging, but a soon as I get on it it'll go away.

Normally it idles @ 1000 rpm no lower no higher
During Symptoms@ 500 rpm

What should I be looking for??

 

[bwest]

1. check codes
2. check o2 sensor

when using the cruise, the ecu reads o2 feedback for mixture adjustment (open loop).

btw- has your mileage changed at all since this started happening? I had the exact same prob a while back, pulled codes, did a diag test on the o2 sensor (it failed) replaced it, solved the issue...

 

[Figit090]

your car idles at 1000rpm's normal??

stock should be 650 or 700 (650 i think).

so...maybe your normal is actually screwed up.

maybe this has nothing to do with it but... today i was turning off my car and turned the key really slow...my gauges and electronics cut off but my engine stayed running and i still had throttle control of course ...but my idle went goofy and was probably around 800-1000 in my best guess. it dropped back down to 650 when i turned the key in the other direction though. so maybe....its electronic. that's all i have. just sparked a memory

i forgot to mention the COLD idle is up there...but not once heated.... it should sink back down

 

[TrqMnstr]

Thanks for the replies. I'll probably check the codes first.

 

[tookwik4u89]

Sticking EGR valve.

 

[johnathan1]

Check all of the throttle linkage as well.

 

[cwapface]

vacuum leak?

 

[TrqMnstr]

1. check codes
2. check o2 sensor

when using the cruise, the ecu reads o2 feedback for mixture adjustment (open loop).

btw- has your mileage changed at all since this started happening? I had the exact same prob a while back, pulled codes, did a diag test on the o2 sensor (it failed) replaced it, solved the issue...

I was backprobing O2 sensor and got no voltage readings in any of the three wires. Maybe I found it?? Also this might solidify my findings, On cold mornings when I start the car check engine light is off but, when I give it some gas, It comes on.

 

[johnathan1]

Ok, so you HAVEN'T checked codes yet?

 

[TrqMnstr]

Ok, so you HAVEN'T checked codes yet?

Not yet. I'll be doing that shortley.