o4 f-350 engine drops to idle on acc

lraffe1 · December 16, 2008

I have a 04 with 163000 and on acc it cuts to idle. When I firsted started working on it there was no codes. I then found out it had a be reprogramed. I then removed program and retested. I then got inj codes and p0611. I replaced ficm and test drove tuck stills cuts out, on test drive I did get a pid recorded. When I got back to shop I checked recording and found pcm was flat lined during concern. I then inspected wiring harness and could not find any problems. I called hotline and suggested checking baro, map, and ebp. They also stated ebp was must likely cause. I test drove 5 times for 50-60 miles did not cut out. I gave back to customer acted up next day. I ran eec test no codes, pcm still flat lining. Still can not identfy any problems from recording an suggestions.

snw blue by you · December 16, 2008

What PIDs are you looking at? What is VREF when concern is present?

What is ICPV when concern is present?

I do not know if it is listed here but on PTS under Power Stroke Central tab there is a list of suggested PIDs that should be monitored.

I suggest you use them. I suggest the aforementioned PIDs because an issue with VREF can cause your concern, and a biased ICP sensor can cause your concern, there were also issues with the injector wire harness on these trucks that for no apparent reason would cause them to stall or do nothing more than idle.

That being said I am not telling you that is the problem so don't just go off half cocked an throw parts at it.

Perform a proper PID monitor and recording session as well as a harness wiggle test and you should find your issue

lraffe1 · December 16, 2008

I monitored map, baro, ebp, icp, maf, vref, sync, ficm sync, app and many others. when concern is present all pids are flat lines or angle to where pid voltage is when eng picks back up and runs fine.

Diesel Systems · June 10, 2009

I just got an '03 F-250 in that is going to idle under acceleration. No codes, latest program. Truck runs great then cuts to idle, glow plug light comes on, coolant temp gauges drops. When I let out of the pedal and get back on it the truck takes off. I cant get any good readings though due to the PDS losing communication while it happens. Any further info would be great.

Jon

Tony302600 · June 11, 2009

ive had this exact same problem before.....damnit what was the fix..... Posted Image

Bruce Amacker · June 11, 2009

It sounds like a basic electrical problem to me. Either you're losing power or ground to the PCM or a sensor could be shorting Vref to ground causing the PCM to lose communications. A rubbed harness is a strong possibility.

How would I go about diagnosing this?

Unhook the batteries and load test each one individually. A shorted battery will cause this complaint.

Do a charging system test to make sure there is not an excess amount of AC voltage present (.02vac at the batteries idling is a normal reading)

Do an intense wiggle test to see if you can get the engine to burp or lose data while idling in the shop.

Monitor PCM voltage during a test drive using a breakout box or backprobing the power and ground terminals to the PCM. There are several powers- pins 34, 46 and 40 are powers in, pins 11 and 23 are ground on the rear PCM connector, IIRC.

Monitor VREF while driving, too, at pins 45 and 29 on the rear PCM connector and pin 36 on the center connector. If VREF pulls to ground it could cause this.

If NPF, disconnect the alternator and take it for a road test.

Good Luck!

Posted Image

Tony302600 · June 11, 2009

ive had this exact same problem before.....damnit what was the fix.....

I remember now....mine happened very int. and also the glow plug light came on never had codes. I traced it to the wiring harness over the left hand valve cover by the FICM. It was on the ICP/IPR CKT's were chafed together causing that exact same thing.

i found it by having someone sit in the drivers seat hitting the accel pedal, and i yanked on the harness around the engine bay til i isolated it to that area when the engine would idle/die. Im 99% sure ure harness is f'd up.