Hello, I have a 5.4L with a misfire on #8. Yea I know, I've read a few threads about it so far but none seem to fully apply to my situation. So far I have pulled the connectors off one at a time (the ones going to the coils as well as the injectors). Nothing changes when i pull the connectors until I reach the cop connector on #8, lining up with code p0358 (the only code so far). I switched the cop and plug from a good cylinder ,#8 still missfires. I have continuity from connector c119 to connector at the coil. I don't know what the ohm reading should be so checked for continuity.I' m going all the way to the PCM in the morning to look for breaks.Good steady voltage on the other line. In my case the red/w green stripe. If this has already been covered in a thread(s)apologies. If anyone would point me in the right direction I'd be greatful.
Need help/direction with missfire issue
- Thread starter Sajohnson
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
docraymund
Full Access Members
First of all you dont pull the connector on the coil, you pull the one for the injector. And there should be a drop in engine speed if that cylinder is normal. If the #8 is really misfiring, check injector and coil terminals for resistance. Values can be found online. Also pull the boot and spring on coil #8 and clean the terminal (the one where the spring attaches to). If it still misfires ypu need to do a compression check.
I installed a new cop and did a compression check while I was there. Compression looks good. I even tried a HEI test on the #8 and # 5 cop. Test plug fires off on #5, nothing on #8. I pulled the injector connectors on at a time, all result in a rougher idle except # 8. I hesitate to say this but is it time to look at the PCM. I noticed previous work has been done . Connectors to the cop # 3,4 have been spliced and some of the injectors connector have exposed wires where some one has nicked the jackets
I also went through my OBD2 reader and came across "vapor generation Max absolute pressure ris" fail . I jave no clue as to what this is refering to. "Engine misfire ratio " fail not sure if this is telling me more than the obviius. And test $2A Data fail. Thos is from a cen tech obd2/eobd+ABS reader. Can anyone shed some light on this front. Thanks in advance.
Bedrck47
Full Access Members
I have attached prints
If you have a steady voltage at the R/LG wire on the coil connector that should be good
and you have continuity on the W/R wire from the coil connector to C119 That is also good You need to check for continuity from C119 to the PCM. Also check the pins in C119 for corrosion or if they have been pushed out etc.
If you have a steady voltage at the R/LG wire on the coil connector that should be good
and you have continuity on the W/R wire from the coil connector to C119 That is also good You need to check for continuity from C119 to the PCM. Also check the pins in C119 for corrosion or if they have been pushed out etc.
Last edited:
docraymund
Full Access Members
You can now check the signal on #8 cop connector I if it is present with a "noid light". If there is none, check the wiring from pcm to #8 for continuity.
docraymund
Full Access Members
That code was for the evap monitor leak check. It is not related to your current problem.
I have coninuity from c174 (the PCM) all the way to the cop connector. I inspected the pins on C174 they look good,clean, straight there was also some white paste present, ai call it nolox. Tomorrow Iwill see if I can pick up a noid light set from the local auto parts store. Why Am I checking the injector connector? Would it cause the cop to not fire if it is faulty? Im trying to under stand how this Expy works.
1955moose
Full Access Members
- Joined
- Nov 23, 2014
- Posts
- 6,004
- Reaction score
- 1,351
The fuel injector and coil firing are connected. The computer tells the injector to spray fuel, then the coil/ sparkplug makes it explode, then boom out the Exaust. Rember it's suck, squeeze, bang, then blow. The four strokes of a internal combustion engine.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
docraymund
Full Access Members
You check both the cop and fuel injector connector with the noid light. If it flashes, the circuit is ok. If it doesn't, and there is continuity from pcm to connector, the pcm may be faulty. You may also have bought a defective cop. You didn't forget to connect the spring on the cop when you reinstalled it, right?
1955moose
Full Access Members
- Joined
- Nov 23, 2014
- Posts
- 6,004
- Reaction score
- 1,351
The other thing that our members don't realize their doing, is when you remove the plastic cap from the coil on plug, they break, and most members just push them back. What happens is the connection gets wonky, and you get a misfire. Same thing goes for fuel injection connectors. They make replacement plastic connecters. At the very least, our members should use a zip tie, to pull it back tight, to make a good connection. Otherwise your chasing your tail, wondering why do I still have miss after changing cop and plug, or noid test on injector.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Yea I caught on to the connector thing. I found that not all connectors are the same either. When I first started Ifound a few of these loose connectors so I picked up some while I was at a salvage yard. Returned to replace the outer housing to find that not all of them could receive the two leads. Turnes out not all wiring harness are not the same,some leads are longer than others. That to say the silver fitting on the end that slides in the housing, on the cop. I ll focus on the injectors next.
1955moose
Full Access Members
- Joined
- Nov 23, 2014
- Posts
- 6,004
- Reaction score
- 1,351
Their are vendors online that sell new connectors, as well as the Ford dealer in a lot of cases. The heat from the engine makes the old plugs brittle. I've used automotive zip ties myself with good results. The other thing I do on old pins is to clean with some emery cloth, or small round wire brush, spray with electrical cleaner, then squirt a little dielectric grease across pins. You always want to disconnect battery of course, when working around electrical. Seems to work for me.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Put a noid light on #8 injector and it pulses. Tried the cop connector nothing. Put the light on #5 for confirmation,the light worked on both connectors. Any thoughts or ideas? Anyone. My brother suggested spraying non flamable brake cleaner around the intake to see if there is a leak. Might try that on the next round.
docraymund
Full Access Members
If that is the case, check for voltage on the #8 cop. Use a multimeter on 12v dc scale, negative probe on negative battery terminal, switch ignition to on position and test both cop terminals with the positive probe tell us if you get a voltage reading.
When I started on this,yes I had 12v. No pulse though. I just now cleared the codes took it for a spin ,10 miles went to 60 mph coasted to 30 back to 60,twice . Came back pulled the code p0354, p0354 and pending is p0355. At lest something has changed.
docraymund
Full Access Members
edit: that code was for the coil driver. looks like your pcm got fried.
Last edited:
Thats what I ve been thinking. I just want to be sure. I would like to know what caused the failure so I can make any needed repairs. Is there any other steps to confirm the pcm condition, other than what has been mentioned?
Similar threads
