90-91 Turbo Idle Surge, and yes the year does matter! Anyone ever fix it?

[n0va91TSI]

First off, I have read all the threads and read all the write-ups.



IF YOU HAVE A SURGING 90-91 TURBO DSM PLEASE READ THIS!



The problem with DSMs and idle surge is that there are like 20 different types of idle surge and different causes and solutions for each. The type of surge i have only happens in 90-91 turbo cars.

When the car starts it revs to about 2000rpms and quickly drops to about 1500rpms as it warms up the base idle will eventually go down to 1000rpms (my biss is all the way down)

Until the car is all the way warmed up if I coast out of gear for even a few feet it will idle surge between 1000-1500 rpms until the car comes to a complete stop where it then surges a few more times and then stops surging.

Even if your sitting on a hill and you let it coast a few feet just by letting off the brake it will start surging.

Once the temp needle is standing straight up it wont do it anymore.

I have bought 2 throttlebodys with ALL the sensors, and a few extra ISC motors that all work perfectly and still nothing. My idle has been properly adjusted to get it as low as posible which is 1000rpms. I just bought another FIAV because I may have to block it off to stop the surge but i live in a place with cold weather and really dont wanna have to resort to that. Plus its insanely hard to get it off the throttlebody without stripping the screws as I found out the hard way on a $115 waste of money.

I know other people have this problem, Im sick of wasting money and I really wanna know...

HAS ANYONE FIXED THIS??? AND HOW???

 

[mbenson]

Same year same car same problem Help ???

 

[n0va91TSI]

what stuff have you tried so far?

 

[spidy3]

what mods do you have? mine did it because it was running a little rich. I have the GM maf and maf-t. I turned idle adjustment on the maf-t one notch back from 0 and played with my BISS until i had a good idle, but i didnt mess with the BISS until i drove around for a while and car went thru open and closed loop (if you dont understand that then just drive around town and on highway for about 20 mins) then i set my idle at about 800rpm and no idle surge since. but i also had the intake manifold off my car not too long ago and cleaned every port that carbon could be plugging or sitting in until manifold was like new. you could try and spray about half a can of carberator cleaner in your TB, then start your car and let it run til you stop having smoke come out of your exhaust. if you do that make sure you rev your car once in a while so it pushes some of the crap out. Hope this helped a little.

Dom

oh and my BISS isnt all the way in incase you were wondering, but you should also make sure your idle switch is adjusted properly too before messing with BISS screw. its on the back side of your TB.

 

[n0va91TSI]

what mods do you have? mine did it because it was running a little rich. I have the GM maf and maf-t. I turned idle adjustment on the maf-t one notch back from 0 and played with my BISS until i had a good idle, but i didnt mess with the BISS until i drove around for a while and car went thru open and closed loop (if you dont understand that then just drive around town and on highway for about 20 mins) then i set my idle at about 800rpm and no idle surge since. but i also had the intake manifold off my car not too long ago and cleaned every port that carbon could be plugging or sitting in until manifold was like new. you could try and spray about half a can of carberator cleaner in your TB, then start your car and let it run til you stop having smoke come out of your exhaust. if you do that make sure you rev your car once in a while so it pushes some of the crap out. Hope this helped a little.

Dom

oh and my BISS isnt all the way in incase you were wondering, but you should also make sure your idle switch is adjusted properly too before messing with BISS screw. its on the back side of your TB.

yeah thats a different kind of idle surge Ive tired with a totally different and very clean throttle body and had the same prob. thanks anyway tho

 

[project_tsi]

Same year same car same problem Help ???

91 turbo laser. same thing here.

 

[funniegus]

Ditto.

 

[n0va91TSI]

tommorow im going to try to block off my FIAV and see if that fixes it. ive gotten pissed off enough by wasting so much time and money that ill deal with cold starts next winter. ill let you guys know if it works.

 

[steve]

Check and make sure the IPS adjustment hasn't been played with. It also serves as the throttle stop and sets how far the throttle butterfly is opened at idle.

Check your speed sensor to make sure the ECU can tell the car is moving.

Pressure testing the intake will identify if you have any other potential air leaks that act like additional bypasses like old hard injector insulators and EGR gaskets

My car used to be very sensitive to BISS adjustment until I replaced the BOV gasket and the thermo valve. Both were leaking.

Steve

 

[n0va91TSI]

Check and make sure the IPS adjustment hasn't been played with. It also serves as the throttle stop and sets how far the throttle butterfly is opened at idle.

Check your speed sensor to make sure the ECU can tell the car is moving.

Pressure testing the intake will identify if you have any other potential air leaks that act like additional bypasses like old hard injector insulators and EGR gaskets

My car used to be very sensitive to BISS adjustment until I replaced the BOV gasket and the thermo valve. Both were leaking.

Steve

im good on all that but thanks

 

[BaddAssGst]

91 Eclipse, same problem. I've just learned to live with it. I've done everything I could find on idle surge to fix the problem and haven't figured it out yet.

 

[steve]

im good on all that but thanks

Lets not play guess what I've done or checked.
Tell us everything you have tried and what you've found in enough detail that we can be sure you didn't overlook something.

BTW- there are enough difference between 90 and 91 cars that there is no possible way your problem is specific to only those two years. 91 and early 92 cars with 6 bolts are 99% identical in the engine bay so if it was specific to some year it would be more likely shared with these years than 90 and 91.

The fact that your engine does the FIAV cold idle up and then drops as the coolant heats up would suggest the FIAV is functioning and something else is causing the fact that you can't bring the idle down below 1k with the BISS adjustment.

Steve

 

[n0va91TSI]

Well i blocked the FIAV after a few hours of toil and more money and guess what....still has the surge.
YES THE YEAR MATTERS just trust me on this one. its a specific group of symptoms that only us 90-91 (mostly 91s) turbo have. any other surge acts differently.


Here is what i have done so far:

cleaned the throttlebody
replaced the entire throttle body
put in new gaskets
replaced the FIAV
blocked the FIAV
replaced the TPS
replaced the sensor that pushes in when the throttle plate is closed
checked that the plate closes all the way
replaced the ISC 4 times
checked everywhere i could reach for vaccum leaks
checked my vaccum pressure which is 20 mili/merc
sealed the biss hole with silicone

all the parts i got were used parts i got on ebay and such so who knows

i havent tried a new 02 sensor but i have a numeric A/F gauge so i can see how its reading if that would help. I havent taken off the intake manifold and checked for cracks. And i have not replaced the ECU.

my mods are:
no cat or muffler (sounds mean! deep rumble)
MBC @ 15psi
boost gauge
A/F gauge
K&N filter
"Home Depot Intake"
grounding kit
Valve cover vented and filtered so as not to shoot oil into the intake

but the car did this crap when it was totally stock when i first bought it last year

 

[n0va91TSI]

it seems to surge less severly with the FIAV blocked but it still does

 

[LaN-]

i'm a newb but i know i had idle issues with my 91 and i replaced the injector O rings and the TB shaft seals and it seems to be good now

 

[n0va91TSI]

i'm a newb but i know i had idle issues with my 91 and i replaced the injector O rings and the TB shaft seals and it seems to be good now

never thought of the o-rings ill keep that in mind thanks

 

[I_eat_DSM's]

Do you guys depress the throttle when you do a boost leak test? We couldn't figure out why my friends 1991 did this until opened the TB and the injector o rings hissed like leaking air was going out of style.

 

[Tsi_User]

Sorry to bring this thread back from the dead, but I too have the EXACT same idle problems in my 91 (at least i'm not alone here)

Anyone have the same symptoms and fixed the problem yet?

 

[I_eat_DSM's]

If any of your guys get a CEL, you DEFINITELY need to check you engine temp sensor. I had a similar problem to this with my 1990, saw the CEL, pulled the code, replaced the connectors on the wire to the engine temp sensor, and was then greeted with a PERFECT idle.

 

[Spoolin4Ever]

Have you INSEPCETED the ECU? You said it was not replaced, but never mentioned whether or not you inspected it.

 

[Spoolin4Ever]

Sorry to bring this thread back from the dead, but I too have the EXACT same idle problems in my 91 (at least i'm not alone here)

Well it was not dead, it's only 2 weeks old.

hehe but around here it's always good to apologize for reviving a dead thread, cause people around here always have to say somethin

 

[titogs95]

I had it. ( knocking on wood.)
Mine actually was the ISC by itself at first. I changed and got fix.
I installed a Fuel pump and came again for a long time. I fixed the ISC again and didn't work. After a while I installed a FPR and put a cap on th BISS and my problem got fix. (I was running really rich!!!!!!!!!!!! at idle)

Hope that help.
Tito

 

[Tsi_User]

i've replaced the ISC, plugs/wires and the CAS. I guess next is vaccum test and injector 0-rings

 

[steve]

I guess next is vaccum test and injector 0-rings

You told me back on the 4th that you were "good on all that".

Steve

Sorry, Nevermind

 

[just_passed_you]

NovaTsi said that.