Idle goes down when stopping.

[ricktherebel]

Really going bananas on this problem. No codes. Changed every sensor, fuel filter, etc. When driving runs beautifully, great acceleration. But not all the time it may try to stall but computer brings idle back up. acceleration ok, no bogging down someone told me to change fuel pump next. Dont want to do this, big job if it wont fix problem.

 

[imp]

Really going bananas on this problem. No codes. Changed every sensor, fuel filter, etc. When driving runs beautifully, great acceleration. But not all the time it may try to stall but computer brings idle back up. acceleration ok, no bogging down someone told me to change fuel pump next. Dont want to do this, big job if it wont fix problem.

Have you cleaned the Idle Air Control? Attached to the Throttle Body, they tend to get "sticky" inside due to carbon build-up. If you haven't looked into that one, try it. Easy enough to replace, if need be. imp

 

[ricktherebel]

Brand new one. really at a loss.

 

[lincolnshibuya]

is it a motorcraft idle air controller? otherwise it's a hit and miss. IMO aftermarket idle air controller doesn't work properly//

 

[decipha]

verify you have no vac leaks and if not then do a simple base idle reset, should fix that right up given the mechanics are in order

with the engine warm at a stable idle go unplug the iac valve, if it stalls open the throttle stop screw a turn to give it more air, plug the iac back in turn the ignition off and fire it back up. Give it a good 10 min of idling to bring the idle back down and unplug the iac again. If it stalls again you need to crank the throttle stop open more. If it stays running your issues should be resolved. Plug the iac connector back in and enjoy.

 

[ricktherebel]

is it a motorcraft idle air controller? otherwise it's a hit and miss. IMO aftermarket idle air controller doesn't work properly//

yes motorcraft

 

[ricktherebel]

yes.

 

[ricktherebel]

verify you have no vac leaks and if not then do a simple base idle reset, should fix that right up given the mechanics are in order

with the engine warm at a stable idle go unplug the iac valve, if it stalls open the throttle stop screw a turn to give it more air, plug the iac back in turn the ignition off and fire it back up. Give it a good 10 min of idling to bring the idle back down and unplug the iac again. If it stalls again you need to crank the throttle stop open more. If it stays running your issues should be resolved. Plug the iac connector back in and enjoy.

Thanks will give it a try.....

 

[ricktherebel]

Did not stall when I tried this. But now while coming stop it stalled 3 times. I am really at a loss. can the fuel pump do this?

 

[swshawaii]

WHICH engine? 4.0L SOHC V6 and the 4.6L V8 can both have stalling issues for very different reasons. "No codes" meaning you physically scanned for trouble codes, or because there is no check engine on? It IS possible to have stored DTC's in memory regardless if the CEL is on or off.

IF you have a two-door Sport, check the PCV elbow. Similar symptoms and does NOT always throw lean codes.
P0171 & P0174 4.0L SOHC's Sport/Sport Trac

IF you have the 4.6L V8. Please list your 2002 engine in your signature below "level". Thanks!
Rough idle and "Check Engine Soon" light - FIXED

 

[ricktherebel]

4.0. No engine light. I also used a code scanner and nothing shows up. Can the fuel pump give me this problem?

 

[drdoom]

Any vacuum leaks?

What kind of diagnostic tool do you have access to?

 

[TechGuru]

Lock up converter not disengaging?