Need some help with hanging idle issue....kinda long

[x182dan]

Ok guys I've been chasing this for about a year now. Heres what I've done and what has happened. I originally had a professional products 75mm tb on there. I went to get the car tuned and the tuner found a problem with it. The iac didn't sit right and the throttle blade wasn't sitting correctly either. Also the car didn't have any hanging idle issues with the pp tb, but it did surge like hell because it wasn't tuned yet. I got a bbk and had the tuner install it while he had the car. So I never had the bbk tb installed without a tune. I got the car back and it had a minor hanging idle very minor he said it had something to do with these ECMs. Then over time it gradually got worse. It hangs around 2k for 1-2seconds before it drops to idle and it when I shift the car from gear to gear. I replaced the IAC twice. TPS voltage is good. No CEL has ever come on. I replaced the intake gaskets with zero change in the idle. This car also doesn't surge at all except when its real cold and I first start it but only for 10-20seconds then its fine. Any ideas? Should I assume its the throttle body? I was thinking about doing a foxbody tb swap but I don't really think thats gonna fix it. I unhooked the battery to reset the idle and it still does the same thing. If I unhook the IAC with the car running it dies right away.
Any ideas?
Thanks Dan

 

[birel21y]

Hi Dan,

I just went through the exact same deal. Its very frustrating. With my new engine setup (see sig) i had a LOT of idle surge issues with my 75mm BBK TB. I switched out the IAC, TPS, and nothing. tuned the TPS dead on to .98V. Nothing. Sealed all sensors, thinking it was a vacuum leak.. nothing. Finally i gave up and put my stock TB on, and BAM. It ran flawlessly. My idle surge was so bad, it would die after 10 sec. of surging. Now its gone. Im not sure if this had to do with my car not being tuned yet, but its possible. Ive always wondered how bigger throttle bodies are compattible with our cars. If you think about it...

Imagine opening your throttle 1/8 way open. Your TPS is measuring the same 1/8 throttle measurement as stock, yet with a bigger opening (75mm) there is more air coming in. Food for thought.


Hope this helps.

-Alex

 

[x182dan]

Hi Dan,

I just went through the exact same deal. Its very frustrating. With my new engine setup (see sig) i had a LOT of idle surge issues with my 75mm BBK TB. I switched out the IAC, TPS, and nothing. tuned the TPS dead on to .98V. Nothing. Sealed all sensors, thinking it was a vacuum leak.. nothing. Finally i gave up and put my stock TB on, and BAM. It ran flawlessly. My idle surge was so bad, it would die after 10 sec. of surging. Now its gone. Im not sure if this had to do with my car not being tuned yet, but its possible. Ive always wondered how bigger throttle bodies are compattible with our cars. If you think about it...

Imagine opening your throttle 1/8 way open. Your TPS is measuring the same 1/8 throttle measurement as stock, yet with a bigger opening (75mm) there is more air coming in. Food for thought.


Hope this helps.

-Alex

Thanks for the advice but I don't have a surge issue its a hanging issue and my car is tuned

 

[x182dan]

anyone?

 

[95cvgt]

i have the EXACT same problem. and its annoying as heck! and im sure were not the only two people with it. when i shift gears the idle just stays the same and then drops when i let the clutch out into the next gear. i never understood what caused it. so if there is anyone who has had this problem and fixed it please speak up!

 

[GDawg]

Might be your throttle cable binding up. I had that problem with my 75mm Accufab and I replaced everything and it would usually only get bad during cold weather. We fabbed a bracket to straighten it out more and that fixed it.

 

[x182dan]

I dont think its the cable because the cable is only 1 year old and is new ford and the same problem was there before the cable. I'm going to try a few adjustments this weekend and see if that fixes anything. Supposed to be nice weather so I'm gonna drive the car either way.
Dan

 

[CC'S95GT]

I'm having a similar issue. but I have a stock motor.
After the engine warmed up the idle will hang about 1000rpm or a little higher.
Then if I shut it off and refire it the idle is perfect and will remain.
It does occure more often with warm weather and less with cold.
I believe my prob is the IAC but I'm to lazy to deal with it right now.