wierd idle surge

[badas93tsi]

My car just started doing this wierd idle surge b.s. The first time it did it, the engine was cold and i drove it like 7 miles and when I got to where I was going, it was idiling fine. Now its doing it even when its warmed completely up. I did a few searches and decided to unplug the isc while the car is surging to see if it stops, it didnt. Just for sh*ts and giggles I unplugged the mas, it idled fine. I had a friend loan me his mas and it surged with it too. I'm not sure what to do, I tested my isc with an ohm meter and got some irratic readings, but from what I read if it doesnt stop surging when you unplug it, its not bad. Please someone help, its annoying as hell.

 

[cb3016]

probably a bad O2 sensor, take a volt meter to it and make sure its within range.

 

[BOBS90TURBO]

Check the Biss(idle screw o-ring gasket).... I was getting idle surge a year ago and replaced the o-ring with a bigger one from hardwear store(I had to squeeze it in), and it fix it instantly.

 

[1fast97gsx]

Check the Biss(idle screw o-ring gasket).... I was getting idle surge a year ago and replaced the o-ring with a bigger one from hardwear store(I had to squeeze it in), and it fix it instantly.

Just a stupid question ... how did you actually remove the biss screw completely? I have it unscrewed to where I think the threads aren't contacting each other anymore, but it's not enough to let the head stick out to grab it and pull the whole thing out. I don't wanna take the tb off, but is that the only way? What about an easy out in the screw and pulling it that way? Kinda ghetto, but should make it easier in the future then too.

 

[badas93tsi]

What would be the normal range for the o2 sensor? I just replaced my biss and o-ring, so thats not the culprit, and dont use an easy out, it will break the plastic screw and then you will have to take the tb off. TRUST ME, I did the same thing because mine was stripped out on top.

 

[BOBS90TURBO]

I can not remember for sure, maybee a magnet or just a tiny pick type tool.

 

[badas93tsi]

A magnet wont do you any good, the biss is plastic.

 

[spoolinNpullin]

I had just recently bought my 1st gen, and it idled rough. I replaced my base idle speed screw and and gasket, also put a little Vaseline on the oring and rubber cap. Now it runs and idles great hope this gives u some help

 

[Forced4]

NOT Hijacking the thread...

My car is also idle surging. I have checked all kinds of things. I have a leak at the TB shaft and will get that repaired and let you know if that works. I also had leaks at all 4 injector seals, the BOV (gasket was still good but would not seal on POS UICP). Also my BISS oring leaked. That was all I could find so far. It still won't hold more than 3psi. My car was idling fine but at 1100rpm sometimes, then at 750rpm sometimes. That eventually became a surge that was 1100-1500rpm, someitmes fast fluctuation and somtimes a slower fluctuation. Another poss is the FAIV may be bad. Once I get all my leaks sealed and verify that is not it, I will be blocking that off and I will let you know how that goes as well.

As, always... Do a boost leak test. Find out what is leaking. Fix that and move on to the next thing. It is a time consuming process but in the end, it's all you got.

Rich
Forced 4

 

[Mike Marnik]

Cleaning you throttlebody also helps. use the vfaq on cleaning the throttle body its pretty easy.

 

[badas93tsi]

Yeah, I guess I should tell you guys the things I've done to try and fix it. The injectors are brand new with new o-rings, the biss is new with new o-ring, all new gaskets on tb, bov, uicp. Just came to mind that it didnt start doing it until I used the vfaq procedure to set my idle. Is there a possibility that grounding those two plugs out caused a short in my isc? Just a thought. In the process of making a boost leak tester. I'll let you guys know about the outcome. Thanks for all the help.

 

[BOBS90TURBO]

Your Logger will tell you if your ISC motor is working.

 

[badas93tsi]

I dont have a logger. I unplugged the isc while its surging and it keeps doing it so.....

 

[badas93tsi]

Ive tried testing the isc a couple of times and keep getting erratic readings. What ohm range should I have my meter set on? Just trying to cover all my bases. Somebody please help. Maybe someone fairly close to me has a logger for a 1g so I could see if the isc is malfunctioning. I need to get this fixed. Thanks in advance

 

[badas93tsi]

o.k guys, i took my tb off and cleaned it out, i took the isc apart and cleaned some corrosion off of the terminals. Now it wants to idle at like 3k. if i drive a while it will go back to normal, or if unplug the mas it idles fine. im sooo confused with this thing. somebody please help.

 

[badas93tsi]

Hey guys, I took my lower tb off and had a block-off plate cut at a local fab shop. Installed it a few mins ago, and it idles PERFECT. Of course I had to hold the throttle open until it warmed up, but after it reached the first mark on the gauge it was fine. It idles at 750 now with no surging at all. I have some more of the plates if anybody is interested. I'll include screws and a gasket for 15 shipped anywhere. PM me if interested.

 

[Terrorize]

are you low on coolant? if so that would be a prob---the coolant btemp sensor is a variable in how a care idles, it could be screwing with the idle

 

[pitbullowner_2]

where is the biss screw located at i looked all over i have a 91 awd talon tsi please help

 

[pitbullowner_2]

Please someone help me find my biss screw i have a bad idle surge and i can't find the the biss screw anywhere. I have a 1991 all wheel drive eagle talon tsi, please help me.

 

[badas93tsi]

its on the throttle body. it may have a black plastic cap over it

 

[Dragon Talon]

Hey guys, I took my lower tb off and had a block-off plate cut at a local fab shop. Installed it a few mins ago, and it idles PERFECT. Of course I had to hold the throttle open until it warmed up, but after it reached the first mark on the gauge it was fine. It idles at 750 now with no surging at all. I have some more of the plates if anybody is interested. I'll include screws and a gasket for 15 shipped anywhere. PM me if interested.

Was wondering what you blocked off... Did you take your throttle body off and block something in there...??? I have the same wierd idle surge, idle at about 1100 to 1250rpm.I have started to do several checks. Only two things I have come across that is strange..# 1 a ticking noise comes from my isc when the ignition is just turned on..But the resistance,(tested in ohms) was in good range.... #2 I checked the resistance of TPS when in working back and forth the TB, which was reading (550-4870) Meaning lower# with TB closed and higher# WOT.. But spec in manual is (1100-5600ohms) But I can not check the voltage reading...All these test are being performed by manual procedure.. These are just a couple of things I have tracked down...Any1 got input if my TPS is bad?

 

[BudmannG]

Was wondering what you blocked off... Did you take your throttle body off and block something in there...??? I have the same wierd idle surge, idle at about 1100 to 1250rpm.I have started to do several checks. Only two things I have come across that is strange..# 1 a ticking noise comes from my isc when the ignition is just turned on..But the resistance,(tested in ohms) was in good range.... #2 I checked the resistance of TPS when in working back and forth the TB, which was reading (550-4870) Meaning lower# with TB closed and higher# WOT.. But spec in manual is (1100-5600ohms) But I can not check the voltage reading...All these test are being performed by manual procedure.. These are just a couple of things I have tracked down...Any1 got input if my TPS is bad?

I would set your TPS at .90 or a flat 1.0, That is where mine ran the best.

I went threw the same problems as everyone here. I did the throttle shaft seals. I did the BISS, TB gaskets, TPS. Anything I could clean I cleaned. Then I found a FIAV for a real good price. Put it on and it ran smooth and idled great. But as soon as you started to roll it would surge. So the answer to everyones question is? These throttle bodies are OLD and probably wore in real good. So some of these TB will have to be replaced completely.

Now my question for the thread starter. How did this plate help you in fixing your car? Yes it may have stopped your idle surge but........ Now you have to hold your foot to the floor or the throttle open just to get it to start. Could you be taking a chance of flooding the car out?

 

[Dragon Talon]

Everyone is talking about this (FIAV)... Can someone please explain this....??? What it is???

 

[jesspr1997]

I figured I would throw this out there. I have a N/T 2nd gen. The thing was giving me a lot of trouble, it had a very sporadic idle between 1500-3000 rpm. I replaced the IAC and the TPS with no luck of lowering the idle. Turns out where the IAC motor met with the TB is metal to metal, not a good idea. the TB itself was worn away not allowing the IAC to fully seal, thus causing a sporadic idle. I found myself at the local parts store finding out about a TB which all they had were salvaged ones or something. I figured I could wind up with the same problem if I used that route. I found the best solution was to somehow block part of the airway the IAC was supposed to be taking care of and to adjust my idle with the screw on the throttle body. Hope this is relevant and possibly helpful to someone with a 2nd gen.

Jesse

 

[Turbo Talon 111]

The FIAV is the lower part of the TB where the coolant runs through it.

Read this guys: http://www.dsm.org/how-tos/tttt/tttt3.html

basically a bad IAC, leaks anywhere (shaft, sensors, biss, etc), blocked passageways (FIAV, IAC, BISS, etc) could all cause it. Mine ended up being the shaft seals.

Needless to say I spent a lot of time with this problem and learned alot about it in the process. You can also buy replacement seals for the shaft but i'd have to look for where since i can't remember. something i read suggests using orings instead of the seals. i tried but its a bad idea. it makes it stick and just don't work as well. i eventually ended up just buying a different used TB. good luck guys. this really is a PITA problem.