I installed a C&L Plenum and Accufab 75mm TB about two weeks ago...well, I haven't had any issues at all until today when I decided that I was going to make sure everything was bolted on tight....well, I started going around the plenum making sure each bolt was tight, NOT touching the TPS at all....later I hopped in the car and took off, but noticed the RPM's were sticking at about 1,100rpms for about 5 seconds and then dropping back down....anyone have any suggestions on how to fix it???

 

after you rev it, it stays up for a bit then goes down right? its fine they do that. no big deal.

 

mine does the same thing, but it doesnt hang for 5 seconds....maybe 2 seconds....and I have a 70mm Throttle body..

I think its cause u have the larger throttle body it hangs a lil longer??....

SO i wouldnt worry about it hangin for ah bit....

 

Yeah, that's what it does. I'm just mad cause if I would have never messed with it things would have been perfect. Is the rpm hang at 1,100rpm a TPS voltage issue?

 

yea....

U should get the voltage reading..and adjust if nessesary.

 

Exactly, our tps sensors are very touchy. Id say since you messed with the tb, check it to be safe. Might as well, only takes 5 mins.

 

When you unplug the IAC wire harness, at what rpm does the car idle? This is a critically important issue to getting this setup correctly.

Your car should idle around 700 and the rpms should not hang. So, we need to get it to do this for you.

By running the car with the IAC unplugged this will allow us to see if the base idle is set correctly. If the base idle is set too high, the car will simply idle high and the rpms will hang. If the base idle is set too low, the idle will hunt. That is, the idle will be all over the place.

The second thing that can cause a high idle, is a malfunction with the TB itself. Some of these do not close properly from the factory.

Thirdly, the TPS could be miffed. But, from what I have seen, a hosed TPS will tend to idle higher than what you are seeing. When mine when bad, either the car idle like complete crap, or at about 3,000 rpms.

Getting back to the IAC: Start the car. Unplug the IAC harness. The idle should drop to about 400 - 500 and the car should almost die, but not. If it idles high, then either the TB needs to be replaced or the idle set screw needs to be adjusted.

Then, adjust the idle set screw so the the TB begins to close slowly until the rpms drop and the car seems like it is gonna die. If adjusting the set screw does not seem to help, then remove the TB completely. Hold it up to the sun light and look for air leaks under the blade. You should not see any air gap. If you do, the TB needs to be replaced. This means the car is getting air when it is not supposed to causing a high idle.

Most likely your problem is related to the idle set screw setting.

BTW, running the car with the IAC harness unplugged will cause an SES.

Also, be sure to mark carefully the postion of the set screw before making any changes at all. This way if you need to adjust back to where it came from the factory, you can easily do that.

 

when i installed my 75mm and plenum my idle rpms stuck at 2500... it ended up being the computer didnt reset when i unplugged the battery, the rpms dropped after a drive cycle so it might just fix itself like mine did.

 

That is actually a good point. I assumed he reset the computer, but perhpaps did not.

 

Thanks for all the info guys. I checked the TPS voltage this morning and it was .95v, which is too low. After adjusting it a bit the voltage jumped up to .98v and the idle hang vanished!

 

how did you adjust it?

 

I put my Accufab 75mm TB and plenum on the day before my tune and drove it 175 miles, did a run on the dyno, and then my TPS broke! But the night before the RPMs would stick at 1500 and when I put the clutch in they would raise about 1000 rpms instead of falling. After one TPS later and the dyno tune the RPMs are perfect... we never touched the TPS and Accufab said not too, so I dunno what happened, all I know is the new one fixed it (the spring broke on the old one)

 

I adjusted it by using my predator to get a constant TPS voltage reading and then unscrewing the two screws and adjusting the angle of the TPS until the voltage was between .97-.99.