Please Help Idle Problem - Accufab

[smoore2199]

Just installed the Accufab Plenum and I having a couple of new problems and some older problems are worse.

After completion i got in the car and the gas pedal was in the wrong damn place...my only guess is that i pulled on some throttle cables while i was moving the throttle body out of the way. So i was able to step on the gas and get it back into place so fixed that myself.

Next problem is my old idle problem is still sticking around. The car idles poorly (too high mostly) and when i drive it the rpm hangs up over 2000 most of the time. Its worse now that I put the new plenum in. I just replaced the IAC last week and the idle problem hasn't gone away.

Also the check engine light is back on now, I added the Mil Eliminators a month or so ago and thought i fixed that.

Any ideas, i reset the computer (i'm trying that again now too)...The idle was really bad when i got in the car (when the gas pedal was out of place) the car idled at 2500 and the pedal was about an inch closer to me utill i pushed it back. Now it idles up over a 1000 and hangs almost every time i touch the gas. In fact i was driving and the car was accelerating a little while i wasnt touching the gas...Sounds like a throttle cable problem or something...not sure any help would be great.

The relevant setup is...
1997 GT
Mac 70mm TB
Accufab Plenum
New IAC
Mac Cold Air Intake

 

[JonJon]

After I reset my computer my car does that for a while. I let it idle for 5 minutes or so, then go drive her hard. Then everything smooths out.


Oh, take the intake spacer out now that you have the plenum.

 

[smoore2199]

I took the intake spacer out during the install...after the last reset the check engine light is off but the idle problem remains.

The car now wants to idle around 1500-2000 all the time. And if i step on the gas either while driving or idle and rev it up past 4 it hangs at 4k for a bit then slowly (extremely) slowly works its way back to 1500-2000 rpm.

I know the car needs a tune up (oil, plugs, etc) could any of these things lead to an idle problem this severe?

 

[neoclasiccl]

Sounds like the TPS isn't giving the right voltage. Hopefully someone will chime in about setting it since I haven't personally done it.

 

[smoore2199]

uh whats TPS?

I got the engine code reader, i'm getting
P1506
Idle Air Control Overspeed Error

 

[JonJon]

uh whats TPS?

I got the engine code reader, i'm getting
P1506
Idle Air Control Overspeed Error

Maybe the idle screw on the Mac tb got turned too far?

I wish I had a pic... but it's a screw/nut that controls how far the butterfly is open at rest.

 

[Dan_Soprano]

I had the same exact problem a month ago on my F-150. Your Throttle Position Sensor (TPS) is bad. Try unplugging it and I bet the idle goes right down to normal. Thats what I did. Your check engine light will come on once you unplug it, thats normal. It will go out once you plug it back in. Don't drive the car with the TPS unplugged. Just unplug it for troubleshooting. The new TPS will run you about $35.

**EDIT** You can pick up the sensor at any local parts store.

 

[smoore2199]

I unplugged the TPS (I think so atleast...the plug right next to the IAC valve right, plug is on left side of IAC if your facing the IAC from front)

your right it idles perfect now...how do i replace though, it looks like the TPS is wrapped in a bunch of other cables...guess i have to fish it all out.


Thanks for everyones help.

 

[smoore2199]

Good news, I called Pep Boys and they have a TPS in stock for $25, sounds like a good idea.

Anything special I should know before installing it, I should have a voltage tester around somewhere so I can check that.

Thanks again to everyone for the help.

 

[JonJon]

I replaced my TPS when I installed my TB since I couldn't get the old one off
It was really easy to put on and I didn't have to do anything special.

Make sure you get a new gasket, or reuse the old one.