This is topic Idle surging after warm up in forum Tech Talk at Northern California Ford Owners  .


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Posted by B_stang89 (Member # 13695) on :
 
I gotta 89 Fox 5.0. I just installed f303 cam, Trickflow Street Burner intake, 24lb injectors, 76mm mass air meter, bbk cold air intake. I set my fuel pressure to 42lbs with vac disconnected, tps set at .98, New IAC valve, idle plate (cause car would idle high without it).

The problem is when car is warm and is been driven to the store etc. When I start it, it looks like trying to find idle (surging up and down) and eventually dies. I have to hold my foot on the pedal until it settles to a steady idle. I checked for vacuum leaks and cannot detect any. Any help would be appreciated, thanx😎
 
Posted by iSTUNT707 (Member # 11430) on :
 
Un plug ur mass air and see the difference otherwise adjust ur TPS should b at .096-.099 range

[ 2014-09-22, 12:22 PM: Message edited by: iSTUNT707 ]
 
Posted by 92_5.0 (Member # 7624) on :
 
some foxbodies are just un-curable. I've learned to deal with mine.
 
Posted by fordfiveoh (Member # 13107) on :
 
Could be an intake leak? Or the throttle butterfly valve isn't open enough for air to enter the intake? Are the 24lb injectors matched to a 24lb MAF sensor?
 
Posted by B_stang89 (Member # 13695) on :
 
Yea I unplugged it and it starts to run crazy. It runs worse when I have my fender well breather on so I just run filter on mass meter. But always surges on first start when warm, but after that it's fine? Is something very minor I know it, it always is.... smh
 
Posted by NK2186 (Member # 12319) on :
 
unplug the IAC, does it get better or worse?

Also when you did all of these changes to the TPS and whatnot did you reset your idle? If so was the IAC still connected when you moved the idle screw?

My 89 was being a cunt and doing this same shit with the e cam until I replaced the IAC and TPS then unplugged the IAC and reset the idle.

Once I got the idle smoothed out on a warmed up engine problem was gone!

Good luck [Whoo Whooooo!]
 
Posted by B_stang89 (Member # 13695) on :
 
Yep, I did the idle reset procedure. And it wasn't plugged when I got it to idle at the lowest 850-900rpm without it dying out. Once it idled, I turned car off plugged (Brand New) IAC and let run for 5 min with no accessories on and then again with everything on, etc. I have to use the idle plate for it to act right. And now I can unplug my IAC and that wouldn't have any effect. It's like it's not working anymore.
 




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