Can't find the problem

Tony302600 · January 18, 2007

I had a 04 6.0 99995 miles come in for a bucks/jerks when hot at highway speeds and runs rough on cold start up. Did the normal diag, in history had cam and crank codes. Thought that was cuz the hardstart/runs rough cold and the customer excessivly cranking it. Did the reprogram for it, egr failed, coked up, cleaned it. Test drove it for 20miles on the streets...ok....test drove on the highway from 50mph-90mph couldnt get it to act up. Monitored all my pids nothing strange, then before the exit light throttle it bucked jerked. I pulled codes, nothing, other tech said maybe some carbon got into the cylinders from the intake, customer wanted his truck back, ok for a week.

Came back today saying its doing it wanting to drive it with me, i was busy but the ex-diesel tech now service writer test drove with him, didn't act up at all and now he doesnt know if it did it when it was cold or hot. He's going to bring it back tom.

Just wanted to see if anyone has had this problem before, should i chase the turbo sticking, crank sensor, cam sensor? the cam sensor connector replaced and fuel filter were replaced 3,000 ago, i checked the connector ok, it was ok. The company has all their maintainence done with us so thats out. Any suggestions welcome.

Alex Bruene · January 18, 2007

Is it an early or late build 2004? Maybe an ICP leak or a wire chafe if I had to guess.

Jim Warman · January 18, 2007

Now is a good time to get familiar with recordings.... It can take a little bit to learn which PIDs you will want to monitor for a particular concern... gather too many and the scan rate slows down - possibly enough to miss an event. Too few, and we might need to repeat our road testing.

Getting used to these sorts of scan tool diagnostics will increase your worth as a tech and make a lot of customers happy - not to mention make life much easier....

There's a lot more to the PC/ED than lists of DTCs - each PPT has an introduction that gives some decebt insight into how a subsystem works. Also, if you are feeling a little overwhelmed, there are guided diagnostics on PowerStroke Central.

I vaguely recall a TSB for P2614 and P2617 but I have seen these codes on trucks that stall often in one drive cycle (can also be a sign of chaffing) - In OASIS, you can enter the DTCs retrieved in the symptom code areas...

For your case (not knowing anything about the truck or the concern), I would probably set up the scan tool to monitor EGR_DES, EGR_VP, EGR_DC#, VGT PIDs, may be V_REF, V_PWR... maybe the FICM input powers (FICM_LPWR and FICM_VPWR)...Any of these can be as much a matter of taste as a matter of need and my little list is, by no means written, in stone.

The real beauty of a recording (don't forget to set up your pre and post trigger times to suit your reaction time) is that you can take all the time you need viewing it looking for the anomallies...

Good luck.

Keith Browning · January 18, 2007

I'll second the data recording advice. From *my* experience, the highway tip-in concern sounds like a sticking EGR valve. If the valve failed before you cleaned it, what did it fail for? I have come to the conclusion that cleaning a sticking valve will not fix it. I now reserve cleaning EGR valves for those that are only clogged-up. Making recordings will help you catch a lazy valve.

Tony302600 · January 18, 2007

Jim, thanks for the advice. Now when i said i did my normal diag, e.g fuel pressure while driving ect. ect. ect. i meant test driving while monitoring 2 pid inputs at a time. the first time i test drove i monitored ficmpwr, ficmsync, rpm and pulse. to my understanding rpm is cam sensor, and pulse width is crank. I even went as far as doing those 2 single pids, enlarging them to see any dip in the sensors, ( I remeber that from engine diag class) then i went to monitor the turbo subsystem. I will keep u guys up to date today when i get to work.

G. Bedford · January 19, 2007

Hi Tony, did your normal diag. routine include a close inspection of the FICM harness chaffe points? Might be worth while to flex/tug the harness and check for a engine "skip" while doing so.

Tony302600 · January 20, 2007

G. Bedford, the FICM harness recall was done by another tech, i should have looked but the guy hasnt brought it back in yet, said he will if it acts up. It isn't one of those once a week, its a once/twice a month thing when it happens and only real quick.

snw blue by you · January 22, 2007

Jim,

Excellent post!

Without actually being the one repairing the vehicle, based on Tony's description and the fact that it is obviously intermittent, my money is on the harness and I don't mean the FICM harness, although that MAY be a concern.

Best of luck Tony.

Tony302600 · January 23, 2007

Ok guys the guy came back, (im working with ford doctor on how to get the recording up ) and i drove with the guy. Po488,, p0470, p0341, p0336 I monitored everything ( in groups of 4) and they only thing that was acting up was the EGRDC, EGRTP, and RPM. they would go from half straight down to what they are at idle ( EGRDC from 60% - 0%, EGRTP 45% - 2.45%, rpm from 2500 - 790 back and forth) in a saw tooth pattern rapidly and intermittant. Nothing with pulse width, nothing with all the FICM pids, nothing with vpwr they were all constant. I was told that the RPM is the result of the EGRTP sticking ( from hotline ) or I have a tone wheel issue.