high idle /cold start

[1bad4g]

i want to start with,my car runs 100% the info that i want is how to adjust a cold start idle?
if i start it cold. the rpm's jump to about 3,000.till it warms up.(about one minute) then slows down. the motor has forged ross pistons in it. and you can hear some piston slap for about 4-8 seconds.
from what i have read, this is how pistons get worn out.

so. how can i lower the idle on a cold start? do i adjust the TPS, or set the idle when its cold?

any info would be great.

ps. its a 91 auto tsi

 

[xxNocturnalxx]

Check timing and set idle. Should be set when fully warm. I don't know about piston slap, it's probably the worn out lifters your hearing on start-up.

 

[Indian]

It's normal for it to be higher on start up, and fall back when its warm.That does seem a little too high though,When adjusting the idle, you need to have the engine at operating tempature, Ground the timing connector, and adjust the BISS. In return if your idle is set too high, it will also lower your cold start idle obviously.

 

[bombDSM]

+1 for biss adjustment. That biss screw can cause some really weird problems

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[spawn87]

thats not at all the poroblem guys he said at cold start up and then it goes down... meaning its the FIAV. it simply needs to be readjusted. i did it on my tb cause when i first finished my build it did the same thing and it took care of problem... the BISS screw will just mess up normal idle.

this write up will show you how to adjust it just ignore the block off plate parts. its more detail so you know how to take it off.

http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

this is the actual write up i used:
http://www.dsmtuners.com/forums/articles-intake-exhaust/320951-fiav-adjustment-disable.html

 

[92AWDHX40]

Lots of us overlook the simple things in that thread regarding idle. Not just surge.

 

[1bad4g]

thats not at all the poroblem guys he said at cold start up and then it goes down... meaning its the FIAV. it simply needs to be readjusted. i did it on my tb cause when i first finished my build it did the same thing and it took care of problem... the BISS screw will just mess up normal idle.

this write up will show you how to adjust it just ignore the block off plate parts. its more detail so you know how to take it off.

http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

this is the actual write up i used:
http://www.dsmtuners.com/forums/articles-intake-exhaust/320951-fiav-adjustment-disable.html

thanks for the link..and yes its WAY to high in cold start. then goes down to 850(were i set the idle at) when warm..i have also noticed it surges 3 times then stops.. these cars are strange beast

Check timing and set idle. Should be set when fully warm. I don't know about piston slap, it's probably the worn out lifters your hearing on start-up.

not when there brand new 3mm lifters. with cly head oil port mod

 

[GRace]

It is the FIAV, I had the same problem. While you are in there you might as well change the throttle body shaft seals if you haven't already.

 

[spawn87]

yeah like GRace said... i just send mine to throttlebodys.com and had them rebuild it. i tell you the price is great for the great quality he puts into his work and really fast return. mine only took 5 days flat (send, work, and return) and im far from him.

 

[Indian]

Check your coolant level as well, vacuum leaks, and clean your throttle body.

 

[icancruz]

I had this problem, along with bad surge, on my 1g. I resolved the surge first, and continued to try everything to fix the FIAV issue, but it wouldn't quit. In the long run I ended up replacing the TB with a rebuilt/overbored one, which fixed the problem. The passages in the TB that are related to the FIAV can get blocked, and even a thorough cleaning will sometimes not resolve the problem. You may save yourself alot of headache by replacing the TB

 

[DJ23GSX]

I had this same exact problem and like Spawn stated you need to adjust the FIAV just like his 2nd link shows. I didn't close mine all the way cause it is actually designed to idle high on cold start ups. I did about 1-2 full turns on the plunger screw and it brought my cold start idle from 2600rpm's down to about 1000rpm's and once its warmed up it idles rock solid at 800 While you have the tb out I would also suggest a good cleaning and doing the tb shaft seals too. They are notorious for leaking vacuum/boost.

 

[1bad4g]

are you running stock injectors or bigger?

stock 390's its an auto car

Check your coolant level as well, vacuum leaks, and clean your throttle body.

i have.. the car is gone over daily..it does have a boost leak at the front tb shaft seal behind the TPS it only leaks at 16+psi..its the only one..i just keep boost low. 12psi

 

[Street Faze]

i had the same problem with to high of an idle at cold start also, followed the links mentioned and fixed that(thanks tuners!) The one thing i cant get rid of is....when i come to a complete stop it will idle at 2000rpm(sometimes), Idle was set when warm aprox. 8-900rpm. I did pull the TB and clean it, replaced gaskets. I did not do shafts seals, could this be the reason?

I have ZERO idle surge

 

[DJ23GSX]

i had the same problem with to high of an idle at cold start also, followed the links mentioned and fixed that(thanks tuners!) The one thing i cant get rid of is....when i come to a complete stop it will idle at 2000rpm(sometimes), Idle was set when warm aprox. 8-900rpm. I did pull the TB and clean it, replaced gaskets. I did not do shafts seals, could this be the reason?

I have ZERO idle surge

Check to see if your throttle cable is adjusted too tight. I had a similar problem when mine was to tight and every time I would come out of a wot pull and throw it in neutral it would idle a little high till tapped the gas pedal a few times to fully close the tb plate.

 

[Street Faze]

I tried that also, next to no tension on the throttle cable. I've lubed the cable and all springs...

 

[DJ23GSX]

I tried that also, next to no tension on the throttle cable. I've lubed the cable and all springs...

Worn tb shaft seals can also cause the tb plate to not fully close as well. Do a boost leak test and see if yours are leaking.