So I get the PCM back today and plug it in, thinking the new injectors and spark plugs will fix the rough running problem I had before. NOPE! The thing misses so bad on cylinder 5 that I finally got a CEL out of it after a short trip and sure enough it came up P0305. I have new injectors, new plugs, I have swapped the COP from that cylinder to another one. I can pull the injector wire off with it running and it doesn't make any difference now, it's pretty much a dead miss. Being a mechanic myself, I know what I need to do next, although I don't have the equipment to fix what I think is wrong with it.......... I will bring my compression tester home tommorow and a bore scope and take a look at the cylinder walls. I don't understand what could have caused this......I have been running a safe tune, high octane gas, and I change the oil with mobil 1 every 5,000 miles and now this. I am absolutely sick right now........

 

check computer make sure no bent pins do you have a spark plug tester like this one
http://www.amazon.com/Professional-M.../dp/B000MHNDSM

 

Also I pulled my coils one time and cracked a plug ran like **** was a hair line crack to looks like a scratch

 

Like Bootleg sez, I'd look real close at the plugs to make sure you didn't crack an insulator when you installed them. I use a $35 $nap-on socket for those plugs and I still crack one every now and then. Also, you'll need a special adapter to check compression since the plugs have different threads than the usual 12mm or whatever it is.

 

Do you have a set of noid lights? Check if that injector is firing

 

What's the odd's of something internally damaged in that cylinder? It doesn't make any abonormal noise, it didn't just start all at once, I don't ever remember hearing anything blow up under the hood. I talked to a guy that used to work at the local ford dealer and he said that he couldn't imagine it being bottom end problems on that engine. I will grab a noid light and a test light and make sure im getting signal to the injector and the coilpack. Is it ok to back probe the connector on the coil pack and check for 12V with a test light, or with a meter....or does that circuit use something different? Is it ground controlled or power controlled?

 

The injectors are ground side switched, the PCM provides the ground to the injectors and they're powered off fuse 34 in the central junction box. I doubt you did any harm to the engine, I just haven't seen any bottom end failures from those aside from injector problems. Verify injector pulse (I'd use a noid light if you have one, just because I don't like test lights for this kinda work - no real reason, just my preference), and pull the #5 plug and check the insulator, be sure it isn't cracked. Also, check the pins on the injector and its connector, make sure the pins aren't bent or backed out, do the same for the coil and its connector.

 

I just went out and pulled that plug and the cylinder has a lot of oil in it. Oil on the end of the plug too. I cranked it over and let it run with that plug out and it blew some oil mist out and then it went away but there is a lot of airflow going on there. I wonder if the oil is there because of the misfire or if it is the cause of the misfire. I know on the old S-600 V-12's with cylinder shutoff on the left bank would foul out plugs and fill the cylinders with oil really bad just because they weren't firing. UGGHH this isn't lookin good either way. Quintin, have you ever had the heads off of one of these before, or replaced any rings/rods/pistons? Ever seen a cylinder wall scored up so bad it caused a complete misfire at idle?? This one has got me stumped and it's driving me crazy........I deal with this crap every day and I haven't ever seen anything quite like this.....

 

A guy that works across from me is replacing a head on a Mark LT, driver's side as a matter of fact. If a cylinder wall was scored bad enough to cause a miss at idle, I'd expect to see blue or black smoke from burning oil or fuel.

Let's backtrack a little though - did your #5 misfire occur before or after your PCM swap?

Can you verify injector pulse, either with a noid light, or just listening to the #5 injector with a stethoscope or a screwdriver handle to see if it's clicking?

How about spark - pull the #5 coil and stick an old plug in it to verify that you've got spark.

I haven't followed your whole story, but I'm thinking if your misfire showed itself after you got the PCM back from Roush, maybe a coil or injector driver in the PCM is damaged.

Edit - I'm on AIM right now and I have the '05 wiring diagram pulled up right now too, if you want to try flinging some more stuff at the wall to see if it'll stick.

 

Hi Matt;

I'm with Q on ths one.

I don't believe in coincidences myself - I think it's a driver in the PCM also.
You've pretty much ruled out plug, COP, & injector.
It IS your PCM, right? Not a swapperooni?

Quintin - How many PCM driver issues have you seen?

Occam's razor - running fine before the PCM was R&R'd.....? You had no codes prior to this, right?

Good luck, man. Between your good troubleshooting & Q's fine help, you'll get it figured out....

Cheers
Bubba

 

Sorry, I went to bed after that last post, lol..... I'll have to grab some of that stuff today at work and bring it home with me and see what I can come up with. Noid light, test light, volt meter, bore scope, and we have a compression gauge that doesn't actually screw in, but you just hold it over the hole and it has a rubber end so I think I can work with that. This problem started back before I got the PCM from Roush. A few weeks back, I just started noticing a rougher than normal idle, with no CEL, and it would go away as soon as I accelerated and got rolling, only noticeable at idle. I figured it was either another injector going out or a plug because that cylinder plug was fairly dark compared to the others (rich) so I went ahed and ordered the IC kit since it came with new injectors and plugs. After installing that and firing it up last night, is when this complete miss started on that same cylinder. It now doesn't go away at all, it misses 100% all the time, accelerating or not. That's a lil more backgroud for ya, but I'll report back with anything I find when I get back this evening!! Thanks for the help so far!

 

Okay, you had a miss a idle. Let her sit for awhile and swapped out some parts, now have a dead cylinder. Probably a fouled (oil) plug. But the plug won't foul that quickly, assuming that you changed them recently, because of a bad spark. And oil is getting in the cylinder. Oil can come in from the bottom, the side, or the top.

Top: Bad valve guides - Unlikely

Side: Cracke ring/scored cylinder - Super Charged, slight chance
Side: Blown Head Gasket - Super Charged, highly likely

Bottom: Cracked Piston - Super Charged, moderate chance

 

What is the rough running problem you had before? I don't want to highjack a thread, but have something that sounds silimlar. Both before and after my intercooler upgrade, but especially after, I have trhown a check engine light and Codes PO 351-357 (coil failure). It runs, but vibrates like hell at times under light throttle (usually in the 2400-2500 rpm range) at slow to highway speeds. Teh vibration is very hard and shakes the hood, teh wipers etc. I'm calling that a miss, but i'm no mechanic. The Ford guys tell me the coils are checking out fine, and they are trying to balme it on my 4.56 gears, which I don't think are related at all. No way that is causing the thing to throw codes for the coil. So I'm following yu situation with interest, and woul like to know teh rough running problem you experienced before. Any further thoughts form this knowledgeable group of mechanics 9of which I am not) would be greatly appreciated.

 

I looked in the cylinder with a bore scope and from what I can tell, the wall is pretty scored. I actually talked to mike at TP and he suggested that the top ring land on the piston could be broken which would make sense.....The problem I had before was this cylinder running on about half power before it completely went dead. Only did it at idle at part throttle, any more and it had enough cylinder pressure to overcome it. Take the oil cap off and see if there is any air rushing out. I pulled my oil cap and it has a nice puff puff puff comming out of it now.........

 

dam matt, sorry to hear about your trouble... i know youre anxious to get it fixed and see how she runs with the IC so i bet this is frustrating. hopefully it will be simple...

im having a rough idle too, but i think i have a different problem than you...

anyway good luck