What is a good spark advance to run at idle with no throttle input? I see 13.5 on my autotap and am having some idle surge. Engine is a 1998 5.4L.

 

Does anybody know the specs for timing at idle? I appreciate it.

 

I don't think it HAS specs - the timing is all under PCM control and is dependent on inputs from all the various sensors. It's not like the old school systems where there was a base timing spec. If you are getting idle surge without a CEL in a vehicle with no or minimum mods and a stock tune, you may have a sticky IAC or a sensor starting to go flaky - or a vacuum leak. You could also have a dirty throttle body - the EGR ports in it have a tendency to clog up. Your EGR valve may also be sticking open a hair. Have you tried clearing out the PCM with a battery disconnect and letting it relearn?

Bottom line - I highly doubt that ignition timing would be causing this, unless something is flaky in the PCM or with the various sensors.

 

I have cleaned the TB and replaced the IAC. I am noticing when I tap the throttle a little and this happens timing is going down to 2 degrees then back to 13-16. I thought of a vacuum leak possibility, but can not find one and the truck is pulling 20 on the vac gauge. When the surge is happening, the truck is in gear, it does not do it in park or neutral. Vacuum is a bit lower when surging at 15 on the vac gauge?

 

you have a dirty MAF

 

Which wouldn't surprise me if you have an oiled air filter.

 

Hmm - you think this might have something to do with it?

https://www.f150online.com/forums/v8...over-tube.html

 

Tube is fixed now with JB weld. Cleaned MAF after replacement and no change. Put suction to egr and engine stalled. No codes. Thinking this is transmission related as it only does it in gear.