Long High Idle After EVOIII Intake Manifold

[marcman804]

I recently installed an EVOIII intake manifold and a 1g throttle body on my 2g. When I first start my car it revs up to about 3k and stays there for a while and then it slowly comes down. It takes around 8-10 min for the idle to get to the target rpm which is around 800-900 rpm's. I have a keydiver chip with the rpm's set for that range and I also have compcam 101200's. Before the intake manifold and TB swap the car would start up and would idle around 2k and quickly idle itself down within a minute or so. Does anyone have any suggestions on what I can do to fix this or is this just how its going to be?

 

[007jimmy]

Was the TB used or freshly rebuilt? Either way do a boost leak test to make sure everything sealed up fine. Also check the tension on your throttle cable, it might be too tight.

 

[marcman804]

It was a used throttle body. I have yet to do a boost leak test yet but plan on doing it this evening when I get off from work. I checked the throttle cable and it has slack in it. I do notice that the throttle is like an on and off switch while driving and its very annoying, its like either Im accelerating or Im not. Could this possibly be the TPS?

Was the TB used or freshly rebuilt? Either way do a boost leak test to make sure everything sealed up fine. Also check the tension on your throttle cable, it might be too tight.

 

[007jimmy]

I bought a used 1g TB and the damn thing leaked so bad outta the shaft seals, I could barely drive the car. Did you use your 2g TPS and are you running emissions?

 

[marcman804]

Well Im definitely going to do the test this evening hopefully. But yeah I used the TPS from my 2g. Should I use the one from the 1g? I have yet to adjust the tps because Im not too familiar with doing so. Could a poorly adjusted TPS cause the jerky, on/off action from the throttle? Going through a parking lot is complete hell, I bet it looked like I was just starting to drive a manual the way the car was bucking .

 

[007jimmy]

No the 2g TPS is fine. If you have DSMlink you could run a 1g TPS. A TPS thats out of adjustment will cause issues. http://www.dsmtuners.com/forums/newbie-forum/324431-how-adjust-throttle-position-sensor-tps.html
Are you using the vacuum ports on the TB?

 

[marcman804]

I don't have dsmlink but I do have the evoscan/ecuflash setup but Im not currently running it on my car, I plan on getting a professional tune later in the summer. Im using one of the vacuum ports on the throttle body, I believe its the "A" port but Im not 100% positive, I can check when I get home from work. And the adjustment method of the TPS seems a little complicated? Is it possible to get evoscan to read the TPS position on the eprom ECU? I may have to swap out the ECU's to adjust the TPS via evoscan.

 

[marcman804]

I boost leak tested the car and had a small leak by the bov flange and I have a new flange on the way. I have also found another problem, I think it may relate to the tps but Im not positive. For some reason the car will not rev pass 5500rpm, when it gets up that high its like the rev limiter kicks in even when Im not going into boost. I drove the car and got it up to about 5500rpm in 1st gear and its like the rev limiter kicks in, I did it slow to keep the boost from building so I know its not a boost leak, I also tried it in 2nd gear as well but I have yet to try it in 3rd because Im pretty sure its going to do the same thing. Could the TPS cause this problem if its not adjusted correctly? I don't have a voltmeter yet so Im not able to set it by vfaq.

 

[marcman804]

Ok, I fixed the problem with the car not revving past 5500... The wire that activates the studder box had disconnected from the park/netral switch wire on the ecu. I fixed that but I still can not for the life of me figure out why the car takes so long to idle down at startup. Could it be the EvoIII intake manifold and 1g throttle body?

 

[007jimmy]

Have you fixed the idle problem?

 

[rebuild4g63]

you might have to drive the car for a certain amount of miles for your computer to learn what's going on. might also be your air idle control valve/motor. $95 or so. It is on your throttle body.

 

[marcman804]

I have yet to fix the high idle at startup. Th car will start up fine, it just takes longer than usual for it to idle down. It starts out at 3k and then slowly comes down to 750-900 RPMs. It drives great and pulls hard but its just annoying that it takes so long to idle down.

 

[marcman804]

So I did another boost leak test and I had one leak by the throttle body gasket so I fixed that. The car still takes a long time to idle itself down, it usually takes almost 10 minutes before it will reach the target idle rpm's. Does anyone know what could be causing this? Its driving me insane.

 

[pneumo]

There's a good chance the FIAV is stuck open and it's letting in more air past the throttle plate. I've seen this happen on several old throttle bodies. You'll have to remove the lower portion of the throttle body and fill one of the passages with JB weld, or get a FIAV blockoff plate from FFwdconnection.com
FFWD Connection - Race Injuns That Will Freeze Your Brain

 

[007jimmy]

So I did another boost leak test and I had one leak by the throttle body gasket so I fixed that. The car still takes a long time to idle itself down, it usually takes almost 10 minutes before it will reach the target idle rpm's. Does anyone know what could be causing this? Its driving me insane.

Its your FIAV. Its out of adjustment or worn down to bad. On your TB there is a freeze plug, when you remove that plug there will be an adjustment screw in there.
http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

Now if you want to keep the FIAV functional just dont bottom out the screw mentioned in that article. Just tighten it up a few turns..

 

[marcman804]

Ok thanks for all the info. Im about to go outside and try it now. If I was to turn it all the way in like it says in the article, what drawbacks would I get?

 

[007jimmy]

If you closed it all the way you would be blocking the FIAV off completely and your idle would stay around normal ( barring any leaks). That method is the free way to block the FIAV instaed of buying a block off plate. There are a ton of FIAV threads on here to read up on. I live in the northeast so i am keeping mine.