Driving back from class this evening, stopped at a light and noticed the truck was missing. Felt sluggish taking off and when I got home I had P0275 - Cylinder 5 Contribution Fault. Used my AE to turn off #5 and verified its a dead miss, doesn't even occasionally fire.

I also had P0603 KAM Memory Error, but it has popped up in the past and only comes back occasionally. Cleared the codes, idled it for a bit, and P0275 Cyl 5 Contribution was the only code showing.

I know there are wire chaffing issues on the '03 engines, but I wouldn't think it should show up all of a sudden as a dead miss. Any ideas other than that? Also, which one is cylinder #5, is it 3rd back on the driver's side?

Thanks!

edit: More info, ran the injector buzz test and all 8 clicked every time, fired it up and #5 still missing.

 

3rd back on passenger side

 

Thanks Mark. More info, ran the injector buzz test and all 8 clicked every time, fired it up and #5 still missing.

 

Injector 5 (or cylinder 5) is not putting out as much as it should. I guess it could be a wiring issue (or connector), but often times it is a bad injector.

 

It doesn't seem to be putting out anything, when I turn it off there is no difference. So strange that it would just stop all of a sudden... I'd hate to tear into it and change the injector and have that not fix the problem.

 

Yeah I hear ya ........ just check the wiring real good - including the connector.

Not sure what else you can do - perhaps a Tech can give you more.

 

Wiring and plug looked fine. New symptom I just found today, it only misses when its warmed up, when cold it runs fine. I'm thinking its an o-ring on the high-pressure oil side of the injector. Does this sound likely or could it still be an internal o-ring or other injector failure?

 

Recently, I solved a similar issue for a guy on the #5 FI. It was a loose pin in the wire harness conector.

Suggest you remove the wire harness connector and check it carefully to ensure the sockets are fully seated. Also, with it plugged in, jiggle the connector to see if it fires.

Hope this helps.

DSMMH

 

Since it passes the injector buzz test, I don't think its a wiring/plug issue. I'll double check the plug though, thanks.

 

My only comment on the buzz test is it is a static test and not a dynamic test. When you add fuel pressure and HPOP pressure to the FI, it may require more current to operate and a bad connection may not allow the proper current to move the spool and fire the injector.

GOOD LUCK!

DSMMH

 

That's a good point, but it also doesn't miss when cold, only when warmed up. I will double check the connector tomorrow though just to be save. I'm thinking its the internal o-ring at the high-pressure oil rail.

 

Very well said. Since you get a good look at the wiring, connector, etc as you are going through the injector removal process, it is always worth looking it all over rather than immediately assuming it is the injector itself. From what I have been told though, it is more common for it to be the injector.

 

Well, its definitely a weak injector. Runs fine until warm when more HPOP pressure bleeds off and then it doesn't have enough to fire. Wednesday I took a chance that it was a bad o-ring and swapped #5 with #3 and put new o-rings on both, ended up just moving the miss to #3. Have an injector ordered and should get here today so I'll install it tomorrow.

 

Ok, I'm wondering if there is another problem now. Got the bad injector replaced, took it out for a test drive, felt a few random misses, figured it was air in the system. Today driving back from the golf course (where a ball hit the roof!!!) it was missing consistently after warming up. Checked the codes and its showing #6 bad now, also smokes pretty good under hard acceleration. ICP and everything looks good according to AE. Only think I can think is, 3k miles ago I switched to Valvoline 5w-40 and it must be a little thinner when hot than the Mobil 15w-40 so my HPOP pressure is bleeding off a little more. Any ideas?

 

I would try the oil switch. If that fixes it, then you may have a HPOP problem. Don't know your mileage and this is a PITA but have you checked or changed the HPOP oil filter screen under the oil cooler? They have a tendency to disentegrate.

DSMMH