FernyGT

i have aquestion, i just midified the air flow system and installed a Trick Flow® High-Flow Upper Plenums for Ford 4.6L 2V and the "service engine soon" light turned onn, but aparently all of the sensors are in good shape

i want to know if this is a common error or there is something wrong with the engine???

cliffyk

You need to have the codes read (any FLAPS [Favourite Local Auto Parts Store] will do this)--let us know what they are, and look them up here, then the problem can be resolved...

FernyGT

well i checked with the flaps and the following code showed P1506

cliffyk

That's an IAC problem--most likely something didn't get back together properly...

FernyGT

ill have to check the system again. Do u thing it might be the ecu??? maybe is not with the right calibration???

cliffyk

It is most likely, since you recently changed out the upper plenum, that something did not get back together properly.

The shop manual lists the possible causes in descending order of probability; with the PCM being last on the list:

• IAC circuit short to GND
• Damaged IAC valve
• IAC valve stuck open
• Vacuum leaks
• Failed EVAP system
• Damaged PCM

That the "calibration" (tune) is causing the problem is a very remote possibility.

Double check all of the connections (electrical and others) that you disturbed when you swapped out the plenum. Pay close attention to the EGR valve/plenum gasket--they often crack and leak if reused...

MU71L4710N

question. did you disconnect the battery terminal for 5 minutes to clear the ECU when you installed the new plenum? you need to do that when you put new boltons on.

swarthyfellow

It wouldn't make that much of a difference the computer would be able to adjust like it is supposed. You most likely didn't put it back together right. Did u connect the hose on the back of the plenum? Will it run fine at engine speed? Mine did that for like a day and then i realized i was dumb and missed the connection.

cliffyk

This is correct, disconnecting the battery to clear the KAM will force the PCM learn new idle air trim values, but it will learn eventually anyway.

Not clearing the KAM would not cause it to throw the IAC malfunction code; something got damaged or put back together incorrectly...

FernyGT

well i disconnected the battery cable for around 4 to 5 minutes and then it cleared off, but again in a while the light turns back on.

this is getting me preocupied since i dont want the engine to be damaged or the ecu.

All of the comments u guys are posting, are really helping me allot, Thnks...