At red lights, backing up small hills my truck can't seem to idle correctly. The idle will dip below 500 RPM and sometimes even stall out completely.

A few months ago it was doing the same thing, I did an idle relearn and the problem hasn't happened since (I haven't disconnected my battery since then either).

• I cleaned the MAF, with no improvement
• I checked a spark plug, looks in good shape (they're new)
• Fuel filter is new within 10 000km
• Checked for vacuum leaks with propane, found nothing (might have done this wrong)

This vehicle has no IAC (electronic throttle).

EGR? How do I test for this?

 

What year is your truck? What engine do you have? How many miles? Does your engine ever buck going up hills? Any codes logged? The more you can tell us the better.

 

2006 with the 4.6L V8. 140 000km. Engine does not buck going up hills. No codes. Idle is rock solid in park. Only hunts under load, stalls out rarely but drops below 500RPM regularly.

 

Did you clean the MAF with MAF cleaner?

I didn't see that you mentioned cleaning the throttle body? So if that hasn't been done it needs to also.

 

Electronics cleaner.

I'll pull the throttle body tomorrow and hit it with carb cleaner. I have a feeling it won't be all that dirty though, maybe I'll be surprised.

 

Have you checked your coil(s)? Perhaps you have a weak coil.

 

How do I check?

A Ford tech on another board suggested checking the resistance of all 8 injectors and voltage at the plug.

 

I'm not familiar with your engine, but if you have a traditional EGR valve, remove it and make sure the passages are clean (intake manifold passages too). Apply vacuum to the EGR valve with a vacuum pump and make sure it draws the piston up with the diaphram and that it holds vacuum. Also, get yourself a manual and look up the reference values for your DPFE valve (Differential Pressure Feedback EGR) and your injectors and do a pinpoint test to make sure your voltages are correct. Remove your DPFE and make sure it isn't clogged. You may be able to find these reference values on the Internet.

 

Thanks, I'll try that. Someone said crank position sensor, possible?

 

Cleaned throttle body, solved the problem.

CLEAN YOUR THROTTLE BODY IF YOU HAVE THIS ISSUE.