strange idle, rpm and staling problems

[forcedpowerdsm]

I have been having some issues with my car lately.

1. When the car reaches normal operation temp it will begin to surge while idling anywhere between (1200-2300 rmps), this is sometimes worse when the weather is hot.

2. Today it began to drop rpms every now and then wot sometimes only for a split second and never more than 500rpms and others it will drop and rise and drop again very quickly still never more than 500 rpms.

3. Today it also began stalling every now and then with rpms dropping low then rising again then almost staling this all happened while at a slow roll when I had the clutch pressed in.

any ideas what this could be?

 

[xaosgst]

its more then likely a faulty ISC = Idle speed control motor. These tend to die on the 2g cars anywhere from 80-over a hundred thousand miles.

You can try cleaning the intake and checking for boost leaks but i'd say its your ISC.

You can do a search online for rebuilt units for just over a hundred bucks. 2 screws and a cable and its replaced.

 

[nuggets]

Theres a site dedicated to rebuilding these little contraptions, guaranteeing that it works. If i remember correctly they were only around 80 bucks, maybe 90.

 

[forcedpowerdsm]

do you remember the site name, i would rather rebuild it than buy a new one.

 

[mostapasta]

I have the exact same problem... still dont know what it is, I tested the ISC several times and it was always within the specs. You can go here for the test: http://www.geocities.com/MotorCity/Downs/7678/dsmtests.html

 

[DSM_One]

Check your BISS if its still there or it's o-ring may need replacing. Check this first it's a cheap fix. Other than that check this site http://dsm.org/how-tos/tttt/tttt3.html. If all else fails, check your ECU if it's going. It was on mine.

 

[forcedpowerdsm]

thanks for all the help guys i looked over the how to on DSM.ORG and im gonna try that tomarrow.

 

[forcedpowerdsm]

Well i unlpluged the isc and it was alright for about a day and this morning it does the same thing with the iac pluged as it does with it unpluged. my afc is now reading 0 rpms, 0 cor and 0 throttle even while i press on the gas. im now idleing at 500 rpms and not matter what i the car will not idle any higher even when messing with the biss. when i look under the hood to see if anything is disconected i smell tons of fuel and the engine is shaking like crazy. i tested the isc and all the coils tested fine at around 30 ohms. i checked the connections on the afc and all is good no disonected wires or anything. now that the car is idling like this it feels like there is no power at all even when you rev the engine. any ideas what this could be?

 

[Thomas91169]

i am also in the same boat. car will idle fine before i drive it down the street. as soon as i come to a stop and put it in neutral the car will either try to idle at 200rpm or will die completely. sometimes it will idle at 200rpm then bump itself back up to 6-700. but as soon as i come to the next stop same dilemma. the car has all its power except for when the AC is on, then it feels like it has half the power, i need to hit full boost to get to freeway speeds instead of usually giving it 1/4 throttle.

its happened about once a month the battery will die(i think one of my interior dome lights are staying on intermittently) so the ecu will reset, and when it does it has a hard time finding its idle. sometimes when it does this it will take a few stops then be fine. but i said its finally time to track down the problem and eliminate it.

i bought one of the remanufactured IAC's from CREBOtech, so ill see how that goes.

and forcedpowerdsm with no throttle or rpm signal is it a possibility your TPS is dead? just a hunch.

 

[xaosgst]

crebotech is where I got my used ISC from. They can be a bit slow depending on if they have any used ones in stock to even remanufacture.

forcedpowerdsm: it sounds like you have a more serious issue if you are smelling gas. You need to find out whats leaking before you go any furthur. Check your fuel rail and return lines for leaks.

 

[forcedpowerdsm]

i have checked the lines and could not find any leaks but the wierd part is that you dont smell any gas when the car idles proberly just when it is doing this stuff (refer to previous post) so i am at a loss. i will check the tps maybe mess with a few wires see how that does.

 

[gypsysdad]

i have the same problem with my 93 tsi. my isc is good. my tb is good. my tb sensor is good. i read some where last night that it could be a faulty egr. try blocking that off and see what happens. i'm gonna do that myself as soon as i fab a block off plate. for temporary you can use a coke can or something of that nature to fab a piece and see if that helps your idle surge.

 

[blue92laser]

Yo guys...

I was reading some of the posts. I dont know if anyone touched on it yet, but about the idling surging and jumping problem everyone is having....

Has anyone of you taken the ECU out and opened it up or even just sniffed around.
if not, I would more than likely do so now.

The caps on these ecu's tend to go and the more you beat on these cars, the faster they tend to go.

I know i had a stumbling problem/idle surgeing for almost a year and i finally, stubborn enough, took the ECU out and noticed the caps were bad and were marking the board up from the liquid they leak.

Look for burn marks around the caps(capictors), they are round and small, and pretty much grouped together towards the center of the board, take a sniff and if they smell like phish, get rid of them, have them replaced...

you can send them to me and ill replace them for fairly cheap.

Also, if you dont know if they have ever been replaced, replace them now or you are going to have future problems if you dont stay onto of them.

remember, you can run withouth a spark on a cylinder or a bad fuel injector, but without the ECU, the engine components cant even recognize what they do...IT IS IMPORTANT!

email me or PM me for questions...lata

 

[DSM_One]

Has anyone of you taken the ECU out and opened it up or even just sniffed around.
if not, I would more than likely do so now.

Follow his advice. I too had an idle surge problem, went thru the motions of what's in the vfaq and everything checked out fine. I finally got frustrated, pulled out the ECU and it was going bad. Replaced it with a rebuilt and fixed my idle surge.

 

[nuggets]

The website i was talking about earlier in my post WAS crebotech.


http://www.crebotech.com/




Im looking in to getting one from these guys rather than rebuilding or buying a broken one.


thnx for sparking my memory xaosgst