WTH Still idle problems, list of stuff I have replaced :(

[dmc67]

OK guys here's a list of stuff I have changed

ISC Motor
Throttle stop switch
Replaced Vaccuum lines
Rebuilt throttle body
Blocked off EGR

this is the only time it idle surges when your goin down the road shove in the clutch and it will idle surge. when ypour sitting still the car idles perfect, also I got the idling set at 1000 rpm's when ya start it, it idles at 1000 but when your goin down the road shove in the clutch to come to a complete stop and after it quits surging it may be idling at 1200 1000 or 800. Any help would be greatly appreciated.

Thanks

 

[weith1111]

TPS? Have you checked to make sure the ISC is working properly? www.plymouthlaser.com has a step by on a couple of these.

 

[T2Small]

If the car is idling well and warmed up, try unplugging the connector from the ISC. This will prevent the ISC from adjusting and could be an issue while cold, but this should prevent any more surge while the car is warm. This is NOT a good fix, but this can determine if the ISC is still the problem. If you still get a surging idle, obviously it is not the ISC.

Have you bypassed your FIAV, or have you blocked it off? I would definitely consider FIAV problems as you haven't listed the FIAV in the bin of parts that you have replaced.

Finally, how did you "set" your idle to 1000RPM? By simply adjusting the BISS, or by actually reprogramming the ECU to idle at 1000RPM?

 

[dmc67]

yes sorry when I rebuilt the TB I tested it and here are my results.

TB closed 1.1ohms
TB open 4.5ohms


and it is adjusted all the way.

 

[dmc67]

I set idle to idle with the BISS

It does it whether it is cold or hot it wont do it while it is idling only while the times are moving. goin down the road 55mph shove in the clutch it idle surges from 800-1200 rpm's for about 1 minute or until tires quit moving.

 

[T2Small]

Setting your RPM that way (BISS) with a somewhat functioning ISC will not work (or at least not correctly).

The ECU's target RPM is 750 RPM (if you had a 2G - I don't know what 1Gs target), and the ECU will instruct the ISC to close off as much as possible to hit that target idle. If you open the BISS enough, the idle won't be controllable.

When your car is in motion, and coasting the ECU will enable coasting idle fuel cut. Basically it will cut fuel above a set RPM limit (1200 RPM I think?), and won't re-enable fuel until the RPMs drop sufficiently (900-800 RPM?). So this surging is simply because your BISS is out of whack. Set the BISS properly as per the manual or VFAQ instructions, and see if your idle surge doesn't disappear.

 

[dmc67]

Ok I will try that but reason I had it at 1000 is b/c polyurethane motor mounts vibrate da heck out of ya with it idling at 750 rpm's

 

[T2Small]

Yeah, upping the idle is a good idea for your rear's peace of mind, but you really should do that with an ECU code change.

 

[weith1111]

yes sorry when I rebuilt the TB I tested it and here are my results.

TB closed 1.1ohms
TB open 4.5ohms


and it is adjusted all the way.

It's been recommended to set the TPS to 0.9 closed. I don't think this will solve the surge though, the BISS correction should. www.plymouthlaser.com/tps.htm

 

[dmc67]

well I set the BISS screw to idle at 750 rpm's warm I went down the road and back and itr never surged but when I returned it was idling at 1000 rpm's now what guys?

 

[92awddsm]

well I set the BISS screw to idle at 750 rpm's warm I went down the road and back and itr never surged but when I returned it was idling at 1000 rpm's now what guys?

Check the adjustment on the throttle cable. I had similar issues once and found that after the car was up to temp, the throttle cable would hold the throttle open just enought to cause idle issues. Also, check to make sure you have continuity between the closed throttle switch and ground when the throttle is closed. If not, readjust the switch. If you still get no continuity, chances are the ground strap is missing from the tb and needs to be replaced.

 

[dmc67]

ok awddsm I check the continuity between throttle stop switch and I used a bolt for ground and I continuity. i also tried adjusting the BISS I hooked the ground wire up like it said to the one right behind battery box to the battery and i got it set perfect to idle at 750 rpm's when I disconnected it idle went up to 850-900 rpm's. and went for a drive and it was idling at 1000 rpm's I messed with the throttle adjuster on the intake but that didn't seem to help any.


Thanks

 

[92awddsm]

Check your manual and it will also give directions for grounding at the diagnotic terminal used to reset isc values. Withut resetting the isc, you can not get an accurate idle adjustment. I would tell you which terminal to ground at the obd connector but I dont have my manual close by.

 

[dmc67]

well I grounded them both set the idling to 750 rpm's and then unhooked tthe jumper wires and same ol' stuff happened. jumpin from750-850 back down to 650 then to 750 after I drive the car it idles at 1000 till it sits for a few minutes then it starts idling down. and fluctuating again

 

[dmc67]

any1 else have any ideas?

 

[weith1111]

Quit bumping, that's the second time this thread.

I don't see your response the the FIAV nor if you eliminated the ISC as the problem? I think you need to go back through and eliminate things one by one. Find a buddy with a good "x" and try his out. If your car works fine with his, then you've found it!

 

[dmc67]

yes I have eliminated the ISC it does it whether it is hooked up or not. I cant block off the FIAV b/c I live in WV and in the winter time it gets pretty cold. Their are hardly any 1g's around here I am buying another 93 Talon N/T the Timing belt broke on and goin to go from their.

Sorry for bumping the thread but none of my parts stores around here know wth their talking about and the dealership wants to charge me $30 an hr just to look at it and see if they can figure it out, and chances are they wouldn't. So I am stuck to the net trying to figure it out myself.

Thanks

 

[weith1111]

No one is saying to block of your FIAV, but it could be faulty. It's such a small amount of air that's wreaking havoc on you, so I wouldn't look past this being worn or stuck or whatever may happen to it to not allow it to work properly.

I know how frustrating this can be, my idle surges too. Funny thing is, for me, if everything is all out of whack the idle is fine, set the TPS, BISS and make sure everything is how it should be and then it idles poorly. Go figure.