Late model question.....surging...EFI

[badbronco]

Hey guys and gals..my bronco is still at home with a blown motor. (saving $ for a 408!!!) But i still have to have something to work on. So my friend has a 5.0 and it surges while idling. I"ve heard this in mustangs too. What makes it do this? TPS sensor?? I have no clue. Thanks all I"ll keep you posted on the 351w.

 

[jasondemitri]

my uncle has a lincoln with an ho motor (92 i think). anyways, his does the same thing and i have no clue. the reason im curiouse (sp) is i have the same motor from an 88 gt in my garage waiting for some down time and time to study the efi's before i start. anyways, let me know what you come up with because i dont have a clue<br>jason

 

[rulebreaker]

This is a very very very common problem with 5.0L Fords. You can go to corral.net and do a search on a hunting idle and read for hours! No lie! Most common problem is the TPS adjustment or lack there of! From what I understand it maybe in the programing of the EEC and in some cares cannot be fixed! Mustangs tend to be the worst, because of programing that holds the rpm's up during a shift to keep the camaro's in the rear view mirror. Good luck! ;D ;D ;D

 

[howiebilt]

I can honestly say ... been ther done that ! It is a pain in the a$$ and I have done the searches and adjusted the TPS and fought with everything and everyone over this . In the end , I figured out that I had a bad PCV and put a new one on it and it's been happy trails ever since . Vacuum is a touchy thing ;D

 

[Weelow]

Look in the corral.net tech section they did a writeup on the surging and it was the tps but for full details<br>(from the sight)<br>It seems that many people have trouble with the way their 5.0 Mustang idles. Symptoms are usually a stumbling or rough idle which may be the result of modifications, or any number of other factors that may contribute to the problem. Clogged Emissions Gas Recirculation (EGR) Valves or Idle Air Bypass (IAB) solenoids are often to blame. A bad Throttle Position Sensor (TPS) will cause the engine to "hunt" for a proper idle setting. <br><br>If you are experiencing idle problems first check the IAB. If it has large amounts of carbon deposits in it you may need to clean it using regular carburetor cleaner. You will have to remove it to do this, DO NOT clean it while it is on the car! If you have checked to make sure that your EGR, IAB, and TPS are clean and properly set and you are still experiencing problems try the following: <br><br>Clear the EEC-IV's idle memory by disconnecting the battery for 20+ minutes. <br>Disconnect the Idle air bypass solonoid <br>Reconnect battery <br>Start engine and set idle speed to desired RPM with stop screw on throttle body (900 rpm works great with E303 or larger cam) <br>Turn off engine and reconnect the air bypass solenoid<br>*Optional -- set TPS to 0.90 - 0.95 volts (Do not exceed 1.0 volts MAKE SURE!) Use a digital volt meter! <br>Start engine and let it idle for 2 minutes with no accessories on. <br>Turn off engine for two minutes <br>Start engine again and run for 2 minutes with every accessory turned on. <br>Turn engine off again. <br><br>Your computer should have now re-learned the new idle settings. This procedure assumes that you have a clean IAB valve. If it is carboned up then you may need to remove it and clean it with carburetor cleaner. <br> <br><br>