Now what?? Cylinder misfire....

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jpslim

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I know you guys have talked about this before, but I get a little lost when the talk goes beyond spark plugs and ignition coils. I have an 01 LS8 and am having a cylinder misfire issue. The service engine light is on and it runs very rough and makes a knocking sound when idling although it seems to run fine when driving down the road. I took it to AutoZone to have them read the code and it was reporting a cylinder 4 misfire and that the gas mixture was to lean (he said this was prob related) so I replaced ALL the spark plugs and the #4 ignition coil (passenger side rear). I just started it up and it is no different. I've seen in previous threads talk about leaking injectors causing misfires. Could this be my problem? and how hard is that to fix? Please don't make me take it to the mechanic!!!
 
Thanks for reposting the thread #s El Es. I missed the one with the broken connectors. I broke all the ones I touched too, and I am careful.

I was told on Flatratetech that certain 3.9s had valve issues too. Doing a running compression test is a good thing to do. So...injector, or head replacement is what I have been hearing. I think my car is running even worse now that I swapped the injectors around. I probably just need to break down and buy an injector and throw it in. Will do more testing Saturday.

I guess I am not alone. But then...who is when their LS is broken? :)
 
lsbit said:
Thanks for reposting the thread #s El Es. I missed the one with the broken connectors. I broke all the ones I touched too, and I am careful.

I was told on Flatratetech that certain 3.9s had valve issues too. Doing a running compression test is a good thing to do. So...injector, or head replacement is what I have been hearing. I think my car is running even worse now that I swapped the injectors around. I probably just need to break down and buy an injector and throw it in. Will do more testing Saturday.

I guess I am not alone. But then...who is when their LS is broken? :)
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No worries. I have read some TSB regarding valve issues and the heads not being cut right or something of that nature. I will see if I can find the TSB again.

You know the only reason I do not sell my LS at this point and buy a new car is due to the level and quality of support of fellow, both male and female, owners. I rue the day that I have to buy a new car and the LS is no longer RWD; I might have to buy a used one just so I can stick with what I know.

At any rate I sure appreciate you all being out there willing to help a fellow out.
 
You might try some BG44K in the tank, but I've found on these new style injectors that once they go, they're gone for good.

If you're getting a misfire AND a lean condition, I would suspect a plugged injector...or perhaps one that is burned out. A miss will show up at idle and low engine speeds, high loads, much more than at cruise speeds. You can take a stethescope and listen to the injectors individually and see if #4 sounds any different. I have an OTC electric stethescope that is fantastic, but a long screwdriver held to your ear will also work. If it sounds different, you may have isolated your problem. You can also pull the fuel rail and test the pattern of the injectors, but man, that is scary. You would need to lift it up slightly so you can see the bottom of the injectors while still connected to the wiring and fuel lines. Then have someone crank the engine over and watch the pattern out of the injectors and see what happens. I would suspect that #4 will be bad. That is the only way I know to test fuel spray patterns and flow without some expensive equipment, but it sure is scary. I would ensure there is no way that fuel or vapor could get near a spark. I would put rags down under the injectors and I would make damn good and sure I had a fire extinguisher handy!!
 
2001LS8Sport said:
Then have someone crank the engine over and watch the pattern out of the injectors and see what happens. I would suspect that #4 will be bad. That is the only way I know to test fuel spray patterns and flow without some expensive equipment, but it sure is scary. I would ensure there is no way that fuel or vapor could get near a spark. I would put rags down under the injectors and I would make damn good and sure I had a fire extinguisher handy!!
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Like 2001LS8Sport says, sounds like playing with a big pack of matches. There is no shame in taking it to the dealer to have it diaged and tehn doing teh repair yourself. It might set you back 100 bux to let them find the problem but it would save you a lot of time and reduce your exposure to a hazardous situation.
 
I replaced the #4 injector yesterday (pricey little bastard) and it seems I have just made things worse-#4 and #3 are misfiring now. I made an appointment with Ford to look at it and I'll see if it is something I can fix or if I'll just have to break down and have them do it. I'll keep you posted.
 
sorry to hear the problem continues jpslim. I do not recall whether you replaced teh coils or not, have you? also, are you using a K&N type air filter?
 
I just the replaced the #4 coil because originally that was the only cylinder misfiring so it has a new plug, coil, and injector. Am I missing something? I thought about using a voltage tester to see if I had current going to the injector and the coil, but didn't get that far.

Also, negative on the K&N filter, I put in a new Puralator last week.
 
Originally it only misfired while idling but now I can feel it while idling and while driving under normal circumstances. I haven't really put any load on it yet. Oh yeah, after I replaced the coil and the injector, I pulled the plug out and it was still wet with fuel.
 
I am not sure where I read, it was a forum post, but I read that there was some chaffing of the wiring harness for either the coils or the injectors. If you can do a visual inspection of the wiring maybe wrap them in tape or flexi conduit.
 
I read the misfire test procedures and one of the things the shops has to test for is compression.

Also, did you get any lean code p0171 or P0174
 
I don't remember which lean code I received--I need to get a diagnostic reader so I can quit running across town to Auto Zone.
I do recall seeing some silicone around the wires leading to the cylinder coils that looked kind of rigged, wonder if it has something to do with that. Also, almost all of the clips to the injector harness are broken, but I read in previous threads that about everyone has the same problem, so I wasn't worried about that. Anyways, I'll look at the harnesses and wires tomorrow after I get off work.
 
jpslim said:
I just the replaced the #4 coil because originally that was the only cylinder misfiring so it has a new plug, coil, and injector. Am I missing something? I thought about using a voltage tester to see if I had current going to the injector and the coil, but didn't get that far.

Also, negative on the K&N filter, I put in a new Puralator last week.
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Be very very careful here. If you use the wrong type of volt meter, you can overload the circuit and burn out a driver in your ECM. Digital volt meters are usually ok. Analog are NEVER ok. A better way to go is to try and find a noid light that you can make work. What it will do is "flash" the pulses at you. An O scope would be the best, but is out of most people's price range or need. I think I would disconnect the harness from the injector and hook up a noid light and briefly start the vehicle and see what happens.
 
2001LS8Sport said:
Be very very careful here. If you use the wrong type of volt meter, you can overload the circuit and burn out a driver in your ECM. Digital volt meters are usually ok. Analog are NEVER ok. A better way to go is to try and find a noid light that you can make work. What it will do is "flash" the pulses at you. An O scope would be the best, but is out of most people's price range or need. I think I would disconnect the harness from the injector and hook up a noid light and briefly start the vehicle and see what happens.
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very good point.
 
LSBit:
Thanks for the pictures of coil replacement. I did a spark plug replacement, so they helped. do you know the OHM readings on the coils, good and bad? Would like to replace them all but $$$$$. Luckly the valve cover gaskets were replaced by warranty was up. Tough for big hands to get in some places.
Anybody know of a site that has a flat rate manual?
I have read alot of the Threads, and my service rep also said do not use Bosch plugs, the Motorcraft worked for 75K, and cost $4.00ea.
Pete
 
Gasman said:
LSBit:
Thanks for the pictures of coil replacement. I did a spark plug replacement, so they helped. do you know the OHM readings on the coils, good and bad?
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I am glad the pics helped.

As for ohm reading; hard to check the coils that way. If you had an "open" you could find it, but a shorted winding is hard to catch. I have a lot of test equipment from working on electronics over the years, but 98% of the time, I use low-tech methods and the "swapping around" method is what I used to find my bad coil. :)
 
2001LS8Sport said:
Be very very careful here. If you use the wrong type of volt meter, you can overload the circuit and burn out a driver in your ECM. Digital volt meters are usually ok. Analog are NEVER ok. A better way to go is to try and find a noid light that you can make work. What it will do is "flash" the pulses at you. An O scope would be the best, but is out of most people's price range or need. I think I would disconnect the harness from the injector and hook up a noid light and briefly start the vehicle and see what happens.
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Didn't ever get that far, I took it to the doctor today. After they read the codes they said that #4 had a "random" misfire and that cylinders 1, 2, and 3 were misfiring. He did mention something about possible chafing but said it could get expensive. Super. I guess I'll find out how expensive tomorrow.
But hey, at least I got a sweet Taurus to drive around until then....
 
Wow! The entire right side is suffering misfires? That should make it easier to diagnose though. I would have a very difficult time believing that you have 4 injectors, coils, or plugs all going out at the same time on the same side of the engine. I'll bet you have either wiring or ECM problems. Probably wiring.
 
jpslim said:
Didn't ever get that far, I took it to the doctor today. After they read the codes they said that #4 had a "random" misfire and that cylinders 1, 2, and 3 were misfiring. He did mention something about possible chafing but said it could get expensive. Super. I guess I'll find out how expensive tomorrow.
But hey, at least I got a sweet Taurus to drive around until then....
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If they read my codes, I'll bet it would show the same thing. It is from me disconnecting injectors to check for RPM drop. :)
 
Well, they are still not sure what it is, they told me that a Ford engineer happened to be in the shop the other day and he wasn't even sure. It's making kind of a bad sound from the front end of the motor and they think that there could be something wrong with the heads so they're goin in to check it out. My car is an '01 LS8 Sport with 50,500 miles..just out of warranty. I asked the service guy if Ford had some sort of assistance program for poor saps like me and he said that my car qualified for something like that. The first 500 bucks is out of my pocket and Ford would pay for up to $1500 in repairs and then the rest is back to me.

This is my first Ford and after two months I haven't been real impressed with the quality (I know, I know, but right now I'm a little biased) but the service, at least at this dealer, has been pretty good. I wasn't really expecting them to budge at all. We'll see how it all turns out in the end.
 
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