Loopey idle after 02 sensor install...

[Porkchop]

Loopy idle after 02 sensor install...

I ended up replacing the upstream 02's on my 98 today and after re-assembing the intake, and re-connecting the battery and starting the car it was acting very different.

Car would go into its normal cold startup mode and eventually go down to its normal idle... then go lower .. 500-400 rpm and start to have a really lopey idle, much like an old cammer car would. Yet driving it down the road/highway was normal?? It actually felt like it had a bit more power???

Anyway, came back and cleaned both the IAC and the EGR in hopes of it going away. The EGR cleaning did more than the IAC, yet it still went back to its lopey idle.

Anyone have ANY ideas.

And before you ask - yes the car is welded......



:::update:::

I swapped the new o2's out for the old ones and that seemed to ALMOST fix the problem, but the idle is still rough. It's no where near as smooth as it was before the swap...

I'm going to try to reset the computer again and see if for some reason that works. If not .....

 

[wuzzzer]

Possibly the computer trying to re-learn it's idle and timing, etc?

Here's the formal idle resetting procedure:

Idle Speed Program Reset Procedure
-----------------------------------------
1) Disconnect the negative battery terminal.
....Optionally, disconnect the keep alive memory connector in the small wire also landed to the
....negative battery terminal. You can then wait the 10 minute minimum, reconnect the plug
....and go to step 6. I have found this option to not be as effective as disconnecting the battery.
2) Turn on the headlight switch.
3) Wait at least 10 minutes.
4) Turn off headlight switch.
5) Reconnect the negative battery terminal.
6) Start engine normally (never press the gas pedal).
7) Allow the idle speed to settle for at least 30 seconds.
8) Within 70 seconds of starting the engine, concurrently apply all accessory loads.
....a) Climate control to MAX A/C.
....b) Headlight switch ON, brights ON.
....c) Turn steering wheel slowly ~1/4 turn side to side.
....d) Press brake pedal.
....e) ATX SHOs only: shifter to DRIVE.
9) Do not turn off engine for at least 5 minutes.

 

[Mels]

Anyone have ANY ideas.

Perhaps your new SHO is upset, what with you referring to it as a *Grn96Taurus* in your sig?

Hey, you asked (for ANY ideas)!

 

[Porkchop]

Possibly the computer trying to re-learn it's idle and timing, etc?

Here's the formal idle resetting procedure:

Idle Speed Program Reset Procedure
-----------------------------------------
1) Disconnect the negative battery terminal.
....Optionally, disconnect the keep alive memory connector in the small wire also landed to the
....negative battery terminal. You can then wait the 10 minute minimum, reconnect the plug
....and go to step 6. I have found this option to not be as effective as disconnecting the battery.
2) Turn on the headlight switch.
3) Wait at least 10 minutes.
4) Turn off headlight switch.
5) Reconnect the negative battery terminal.
6) Start engine normally (never press the gas pedal).
7) Allow the idle speed to settle for at least 30 seconds.
8) Within 70 seconds of starting the engine, concurrently apply all accessory loads.
....a) Climate control to MAX A/C.
....b) Headlight switch ON, brights ON.
....c) Turn steering wheel slowly ~1/4 turn side to side.
....d) Press brake pedal.
....e) ATX SHOs only: shifter to DRIVE.
9) Do not turn off engine for at least 5 minutes.

Mark, I have tried that. It almost sounds like a cigarette boat once the idle goes funky - I swapped the old o2's back in and it still does it but its much better, something is still a flutter... I think im going to take the intake off again and see if I forgot something (took it off for easier access to the rear plug.)

 

[Bizzy]

LOL I paid $650 for my lopey idle on my 94 Opal Frost. Count it as a blessing, it prolly sounds good.

Hook a vac gauge up to it a vac port and see what she is pulling at idle. there are very specific numbers the car should be making as per the book.

 

[V6&V8SHO]

Ive got a low idle rpm problem as well. Car runs perfect other than my low idle. It sits slightly above 500rpm at idle. 97 Ebony Satin SHO welded

 

[SHO#7]

I ended up replacing the upstream 02's on my 98 today and after re-assembing the intake, and re-connecting the battery and starting the car it was acting very different.

Car would go into its normal cold startup mode and eventually go down to its normal idle... then go lower .. 500-400 rpm and start to have a really lopey idle, much like an old cammer car would. Yet driving it down the road/highway was normal?? It actually felt like it had a bit more power???

Anyway, came back and cleaned both the IAC and the EGR in hopes of it going away. The EGR cleaning did more than the IAC, yet it still went back to its lopey idle.

Anyone have ANY ideas.

And before you ask - yes the car is welded......



:::update:::

I swapped the new o2's out for the old ones and that seemed to ALMOST fix the problem, but the idle is still rough. It's no where near as smooth as it was before the swap...

I'm going to try to reset the computer again and see if for some reason that works. If not .....

Have her codes checked. Eventhough the SES may not be on. There is a chance that she set a code. Is there a chance that the two pre-cat o2 sensor wires got mixed up. Like bank one on bank two's. I am not sure if it can be done on our car or not, but IIRC they are right across from each other.

 

[SHOZ123]

Sounds like a vacuum leak. See if pulling the IAC connector off while idling kills the motor. If it doesn't then there is a leak.

 

[Porkchop]

Thanks for the replies. I'll head back outside and see what the deal is.

I found out a few more things today after re-setting the computer.

1. Takes 2 turns of the key to start. First turn she cranks no fire, second she fires right up.

2. RPM's go from roughly 1500 rpm - 400/500 and back up agian.


I might just have to take the intake off and re-assemble it to fix the issue.

 

[Bizzy]

Sounds like a vacuum leak. See if pulling the IAC connector off while idling kills the motor. If it doesn't then there is a leak.

Hey brian this is prolly the easiest thing you can doto see if it is a vacuum leak.

 

[Porkchop]

Problem Solved.

Yeah me and my infinite wisdom forgot to tighten down the middle set of runners. I guess in my haste to get the project done (late evening project) I forgot.

Eh it happens, thanks for the replies. Running like a charm with 2 new o2's.

On a side note, im getting pretty freaking good at changing out the front bank o2's. I think my record thus far is 20 minutes

 

[Mels]

Well done 'Chop

 

[Porkchop]

Well done 'Chop

Loopy idle and a loopy mechanic...