'06 F350 stalls when placed into neutral/park cold

deezul · December 12, 2011

I have a head scratcher here with a 2006 Ford F350 6.0L. A cold soak (overnight) truck will start (idles fine, NERU with no issues) and drives fine but when placed back into neutral or park will stall. Starts with no issue after stalling but will have this issue for three or four "gear to park or gear to reverse" events until unit is warmed up. When the truck is shut off (still cold) and then restarted it will start then stall, accelerator pedal has to be tipped in for truck to start and run. Truck has no starting issues when hot.

I performed KOEO, KOER self tests - No codes present. EGR test - Passed with no issues. Monitored PID list for concerns. When truck "starts-stalls" concern is present IPR pid ramps to 85% (causing ICP to ramp to 1400psi, 1.69v) on initial cranking and slowly ramps down, but as truck goes to stall IPR fluctuates from 55% to 14.8%, does this half a dozen times in a period of .5 seconds causing a saw tooth pattern on the PID graph. ICP stays steady at 1400psi (1.68v) and then when truck stalls IPR is ramped back to 77%. Attempted to start truck with ICP unplugged to check for bias ICP but issue was still very much present.

I was thinking perhaps it was an EGR issue or sticking IPR but have replaced those components with KNOWN GOOD parts and issue is still present. Any help or ideas would be great, thanks!

Bruce Amacker · December 12, 2011

Wow, this is a tough one and I've not heard of it before. Older trucks had a similar problem that would cause them to stall when put in reverse due to the tranny filter falling off and sucking air into the tranny. I doubt this would be your problem but it is relevant enough I thought I'd mention it.

I "think" your problem might be in the HPOP system. What's your IPR at a hot idle, 23% or so? Has the oil been changed lately? (If it's only stone cold, could the oil be tar?) I might check the low oil pressure and make sure it's good, and check the oil filter so see if it's OE and the standpipe isn't broken.

When truck "starts-stalls" concern is present IPR PID ramps to 85% (causing ICP to ramp to 1400psi, 1.69v) on initial cranking and slowly ramps down, but as truck goes to stall IPR fluctuates from 55% to 14.8%, does this half a dozen times in a period of .5 seconds causing a saw tooth pattern on the PID graph. ICP stays steady at 1400psi (1.68v) and then when truck stalls IPR is ramped back to 77%.

IPR should never go to 85% in my opinion, and if it does, ICP should be 4000+. IPR fluctuating wildly can mean oil starvation or aeration.

If ICP is staying at a steady 1.68 for any time while IPR is changing, the PCM is in FMEM or substitution mode and not showing the true value. If it were in my bay I'd be backprobing the ICP and seeing what it's really reading. I bet it's not 1.68v.

I'm just thinking out loud here to inspire thought. Keep us posted on what you find.

Good Luck!

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Fredsvt · December 13, 2011

I also ran into a similar problem on a gen1 7.3, wicked romping and stalling, with IPR and ICP jumping all over, with a stall.

Bad MLP sensor caused it. I plugged in another, with it in the N position, and it stopped doing it.

The PCM "thought" it was in gear when it wasn't.

Brad Clayton · December 13, 2011

I had an identical concern (as the cold start part of your problem). Truck wouldn't run long enough to get it hot. Anywho the block was rusted very badly and had pushed the cam sensor just a smidgen away from the timing peg to cause exactly the condition described.

deezul · December 13, 2011

By the looks of the block this may be the issue Brad. Unfortunately there isn't any flats left on the head of the bolt so once I get approval for re+re of p/s pump I will know if my issue has been fixed... Not sure though why once hot all issues disappear.

Low pressure oil system has been verified as operating properly..Base oil pressure is within spec. Filter is factory Ford and the standpipe is intact. Oil is not sludgy, it appears pretty fresh.

deezul · December 16, 2011

Well, the customer called in and said everything is working good! Thanks for all the help guys, I truly thought it was an issue on the oil side of things...