evening all have a question. i have a 03 f350 v10 auto 4x4 has 185k on it, a couple weeks ago i started it after it had been setting for a week started normally as always but when it come down off high idle it sputtered a few times then sounded like it was running on 5 cylinders, i stepped on gas pedal and it at first it just slowly started raising rpms then just like nothing was wrong it jumped up in rpm and ran normal. i originally just thought maybe some water in gas and or setting, didnt act up for 2 days then did it again, this time i just left it alone and listened to exhaust and it is missing on several cylinders, after about 10 to 15 seconds it will start firing on more and more until its hitting on all 10. it has done it a few times recently off and on but we went on a camping trip and it did it every morning it was started or has sat and not run for more than 6 or 8 hours, after it does its spell it runs fine towed my camper with no issues. it only has maybe 20k since it was tuned up by me motorcraft double platinum plugs fuel, air pc valve etc. while camping got bored and started checking a few things and noticed that when its taking its spell the entire drivers side of the engine is not firing, i swapped a few of the coils from one side to the other to try and narrow down but have same result. fuel pressure good and there is nothing unusual on scan tool while its acting up and has no codes logged nor has engine light ever come on. i have been searching internet for issues like this but getting nowhere, wondering if i have a pcm, wiring issue and or maybe something to do with the failsafe cooling strategy trying to kick in when not needed, im puzzled and looking for some insight before throwing parts at it or taking to a dealer. tia

 

First you need to check for any codes - you can have codes without the check engine light on.

Second, which would be important, datalog the computer and check what it thinks the temperature is - it could very well be going into failsafe.

On the other hand, it could be something in the wiring - the entire bank of injectors and coils have +12V running to them. I don't remember exactly, but I think the entire bank may be feed by one wire, while the other bank is fed by another.

Could you tell if it was just spark, or fuel, or both? Did the exhaust smell like rotten eggs? (running rich/raw gas would do that).

 

it has never had any codes in it, i monitored coolant temp at startup and it was right along with ambient temp after setting all day and rose accordingly as engine ran even when messing up. i have monitored several items while engine running normal and going thru its spell and nothing is out of sorts both running good and missing. as for the whether its spark or fuel issue not quite sure, it doesnt smell gassy or of rotten eggs when it is missing so thinking its fuel related. in process now of locating my noid light to back probe injectors and coils to see if i can find out what is happening there and hopefully get it figured out thanks for reply i will figure this out one way or another and let you know what i find

 

Sure sounds like electrical.
We have a 2002 6.8L and according to the wiring diagrams the fuel injectors are fed with (I think) 12v. The voltage splits at connector C110 and goes to each bank of injectors. The voltage goes thru the injectors and back to the PCM to be grounded by the PCM with individual relays to complete the circuit. Since the PCM supplies all the injectors with a single supply line and individually fires the injectors it may not be the PCM. With only one bank not firing I would start looking at connector C110 (or 2003 equivalent) and splices S136/S131 in the wiring harness. A worn spot in the harness or a wire with just a few strands left to conduct would explain an entire bank not firing.

 

well my noid light come up with no results, it showed that both injectors and coils were receiving power and being triggered even when it was messing up. i just let it do its thing and when it come out of its spell it continued to miss one one cylinder, i started disconnecting injectors and found #9 not firing. pulled that coil and there was moisture on the sides of the boot. i removed all 10 coils and also found moisture on #4 as well, blew all holes out and decided to check plugs. i tuned this up the day i bought it four years ago but it only has maybe 29k on complete tune up( i dont drive it alot) plugs look ok but #4, 9 and 10 plugs were slightly loose, not real loose just not as tight as they should be. the threads on plug and in head look fine, put them back in and cleaned coils and put them back in, no more miss. im going to see what happens after it sits again wondering if possible that if one coil shorts out if it can kill the rest on that bank, i work on over the road heavy duty diesels and some are designed this way with their injector circuits. regardless im going to change the plugs and get new coils and boots. whats the preference on coils i like oem but are there alternatives since there are 10 to buy and oem tends to be more expensive im not looking fr performance gains just reliability in that area

 

My 99 sort of does this. I alternate driving the truck and highlander. so it may sit for a week or two. But it may sputter for 2-3 seconds then smooth out as normal. never does it from day to day.

 

well the loose plugs and moisture i found in two the holes didnt remedy problem so the search continues

 

Decide to try and coolant temp sensor, got one from local parts store, just plugged it in and set it on the intake next to t stat, truck started and run good. i plugged old sensor back in and started and it went back to the missing game, plugged new sensor back in runs fine, now the new sensor is coolant immersion while the one on engine just threads into and boss in the cylinder head casting where there is no coolant. i put the new sensor in and hole that is in coolant crossover next to t stat and run it and no issues, im going to get the correct sensor but for now im going to see how it does after setting again and hopefully have found my issue, glad i keep my hair short because i would have pulled it out by now. will post final results if interested...

 

Excellent news, definitely keep us posted.

 

well truck run great for 3 days straight, went to leave yesterday and back to same issue so back to the drawing board with this one......

 

You need something like the Torque app for your phone or tablet (Android) and get a Bluetooth OBD-II reader off of eBay or Amazon. They're pretty cheap, like $20-30.

Use that to read what the PCM THINKS is the coolant temp or cylinder head temp. If you get the correct CHT sensor, and the wiring all looks good, and the computer still thinks that the engine is overheating, it's going into limp mode.

Years ago, there were at least a couple of people that had the same issue, and it turned out the PCM was bad.

 

i have a scanner that i have had hooked to it and the coolant temp always starts at ambient temp and gradually rises as engine runs, looks the same when running bad versus not, i still need to get correct cts/cht, i have had a sneaking suspension that it is the pcm. just trying to rule anything else out before getting the wallet opened too much at one time appreciate the input and will keep updated as this saga continues

 

Have you tried removing all the connectors to PCM, spraying some contact cleaner in them and reseating?

 

The mystery continues...

 

New pcm is on order, in the meantime been driving truck all week, same sos in the morning but runs great the rest of the day, did buy a new maf sensor and the next day it did not act up but acted like it wanted to. The new maf sensor seems to have made it run better as of driving power and smoothed out the idle a bit, time will tell ill figure it out one way or another, starting to feel like a diesel owner jk... will update when pcm arrives...