Hey guys, im having an idle issue, when I start the car cold and drive and come to a stop I have a really jumpy idle. From around 1000 to 2000rpm, but once the car warms up and I do a WOT pull the idle seems to go back to normal right around 900rpm. Could it be bad iac motor?

 

do u let your car warm up before u drive? i wouldnt recommend starting up and taking off... give the car a chance to warm up before ripping it down the street

 

Here is how I fixed my problem. I had the same issue:

- Check for boost leaks: fix any leaks
- Remove and clean the throttle body
- EGR Valve : remove and clean. (use degreaser & carb cleaner)
- Make sure all of your vacuum hoses are tight and connected
- Adjust your idle screw on the top of the throttle body
Worst case, you will need to buy air fuel servo ($425)

 

Whoa, easy with the $425 cost, lots of people sell them for 50-75 used. Check the for sale forums. There's also a part that fits the Evo off a Chrystler Sebring or something like that, it's only around $200 new.

You need to pull it to make sure it's functioning correctly. Unscrew it, check for the o-ring, and have someone turn the car to on (don't start it) to make sure the motor works, it will click and move the center piece in and out as it searches for the idle. When this happened on my car somehow that o-ring magically disappeared and it isn't an o-ring just any shop sells, not even sure if you can get it from the dealer...

And like white said, running your car at WOT cold is a very very bad idea. The car has a built in mechanism to protect damage and if you've never logged it then do so. When I start up my car and I try to rip it I hit fuel cut and it knocks hard basically to tell you to WAIT DUMBASS. The code is in the ECU already for this and it can be adjusted.

 

Im saying, ill wait for it to get to operating temp then take a good run, sorry for confusion. Ok ill check the valve itself and o ring. Thanks for the help ill post back when I do all that

 

There was no confusion, some people just cant read/comprehend.


Sometimes the BISS and ICS get a little carbon buildup around it.
My suggestion; remove, check, clean, reinstall, adjust per the FSM.

 

Can you pm me how to remove the ics and biss and whats fsm?

 

Remove the IAC with the 3 Phillips screws attaching it to the throttle body.

Clean any carbon buildup.

Worst case is you will get a new one from amazon or a Chrysler dealer. (G series 2.4 engine in Sebring/Stratus)

 

Factory Service Manual. I'd. Only pull the ISC and clean it. Leave the BISS alone (it might already be set properly)
Whatever you do, don't clean the grey film from around where the throttle plate seals against bore. That helps the plate seal.

To test the ISC

From the manual:

Measure the resistance between idle air control motor
connector terminal No. 2 and either terminal No. 1 or
terminal No. 3.
Standard value: 28 − 33 ohms [at 20°C (68°F)]
(3) Measure the resistance between idle air control motor
connector terminal No. 5 and either terminal No. 4 or
terminal No. 6.
Standard value: 28 − 33 ohms [at 20°C (68°F)]
Q: Is the measured resistance between 28 and 33 ohms [at
20°C (68°F)]


Looking at the connector with the clip facing up the pins are as follows:

1 2 3
4 5 6
_____

 

Thanks for all the help guys, takin out the iac after work to check it

 

I have the same problem. If I don't let my car at idle for at least 5 minutes upon cold start up once I drive off then coast to a stop the idle sits at 1500 then slowly drops.

In my situation, I've replaced the tb seals, gasket, replaced the biss, I've replaced the iac, reset the biss and idle. Have no boost leaks, deleted the egr. No change.

These cars like to be warmed up before driven off, otherwise they're laggy and feel like your dragging a semi.

 

They all should high idle when engine temp is cold. Also, you really don't have to let them warm up before driving.

 

I feel more comfortable letting it warm up before driving, also its not the high idle, its the bouncing. From 1000rpm to 2000rpm and then once I get a couple pulls in it stops for a bit and restarts.

 

If you get an IAC get it off Amazon its like 118 bucks rather than 400 some from the dealer.

 

Yep, sounds like good old fashion idle surge.

1. Idle (foot off the gas)
2. Too much air is getting through the throttle body (ISC stuck open)
3. O2 sensor registers lean cond. (too much air)
4. ECU adds fuel to achieve correct mix
5. RPMs increase due to increased fuel/air supply
6. At 1500 RPM the ECU goes into decel mode and cuts fuel (*)
7. With only air coming into the engine, the RPMs drop rapidly
8. At 1200 RPM the ECU turns the fuel back on
9. Goto 2.