2002 Lincoln Town Car misfiring

The old man

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Started out having a misfire on #8 plug misfire on this vechicle with "coil on Plugs". Look at plugs and did not look too bad but decided to replace all of them anyway because of not knowing just how many miles were on them. It did not fix the problem. Plugs look like there had been no problem in the cylinder #8 and the rest of them for that matter. Normal wear . I switch out coil over #8 plug to #5 cylinder and #5 to #8 in case a cylinder misfire code comes, and see if it changes position. It still had intermittent misses. Anyway the MAF sensor reads from 1# per Min to 25# per minute or so going down the road. Switches back and forth according to pedal position. Cleaned the MAF sensor with MAF sensor cleaner just to make sure it was clean and not causing the problem from being dirty. The car goes down the road and misses on accelleration, cruising. intermittent. Runs even, then multiple misfires, then even etc. Sometime it feels unresponsive to gas pedal. Maybe like a throttle position sensor. Somtimes it runs good. Will not throw a code. Told her to drive it while I think about it and hope it throws a code so I can get a area to start in. Her and my wife went up to Frischs to eat and come back and said it was running smooth after it missed just one time. Go figure. Engine idles like there is no problem at all. Put some seafoam in gas tank before they went to Frischs. Don't know it that helped or not. Any ideas on these Lincolns 4.6?

Update: My sister in law drove the car home unhills, downhill, slow, past, and all and she called me and said the car drove flawlessly and better than it has been in a long time. I know that when I cleaned the MAF sensor, it did not make any difference to any great degree. I cleaned throttle body and made no difference. Plugs made no difference. Switching coil made no difference. The only thing that I can figure is that #8 injector may have got partially fouled by #8 spark plug not firing regular and when I put the seafoam in and it opened it up. Don't know why it is running good now. Tomorrow may be different through.
 

kev2

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With a scanner we can go to freeze frame and then the mode 6 info will let us see misfire counters for each cylinder... everyone has that available...
dont get mad at the stupid ideas - got to start somewhere
The code you have is P0308? - No other codes? ...I got to dbl check.. basically a missfire on #8 cylinder. Ford 4.6L #8 is the rear cylinder PASSENGER side... This can be - as you stated IGNITION, or fuel or mechinical...
The seafoam is a good move... the spark plugs also, I would suggest a fuel pressure test and an injector leak down... a easy vac leak check at manifold area #8...

...MAF, TB would affect ALL cylinders...

I think you are right with the inj issue- is vehicle driven? parked alot, not driven beyond the idle RPM band? fuel in tank for long periods? light throttle - like I drive :) an old fart
 

The old man

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PO308 is correct. No other codes at all. Not even a PO308 is showing up now. No such things as stupid ideas when there are no codes present and you have to check out everything that may be associated with the problem and don't know where to start. When it was missing I did not know if it was one cylinder or a number of them. The only reason that I cleaned the MAF sensor was that someone who put a new air filter in at one time or another did not get the top of the air box on correctly connected on the back side of the lid for the air box was left open and not clamped down and some of the air was coming in from the engine compartment and not through the filter. According to them it has been that way since they had it. Maybe 2 years. Of course I don't believe that. The filter was not all that bad. I thought at first it was recently replaced. Of course nobody knows who did that. It sure was not me. When I settled down and rested my mind(what is left of it), I realized that unfiltered air coming into the air intake may have affected all those injectors and it just showed up on number 8 and starting to get worse. Proabably cause of #8 misfire all along. Speculation of course. If it starts to miss again I will check out the things that you suggest. The car is driven everyday and not really babied but driven normally short and long distances. #8 cylinder show up on my program at drivers side rear. Seafoam probably was the final fix. Plugs did not hurt either and not that expensive when you are in there.
 

kev2

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yes yes you are right DRIVERS side rear.....

I fell into The conventional thought trap I was trying to advise you of... |8
 

NickD

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Found an erratic MAP sensor in a Lincoln, car would start and idle fine, but only on acceleration, no error codes for that. This was after thoroughly checking everything else out including a compression test.

Shop manual was worthless, learned this thing was outputting a 95-155 Hz change in frequency with an input change of 0-20"/Hg change in input vacuum, worked fine when cold, but when I put it in my temperature chamber, that output frequency went crazy. I opened it up with not know how, found the frequency output terminal was never soldered to the PCB. But I wrecked it in the process of taking it apart, so had to buy a new one. But did learn how to open it without wrecking it.

Symptoms sure sound similar to yours.
 

The old man

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This lincoln does not have a MAP sensor, but instead a MAF sensor. The day I gave it back to her, it run perfect. The next day when she came over to pick my wife up and go to the beauty shop, it missed about three times going by the school when she had to slow down. After that it run perfect to the beauty shop and back to her house without a flaw, uphills and all. Hard to pinpoint something like that when there are no codes thrown. I guess my next step is to get a copy of a freeze frame when it running good, and compare it to a freeze frame when it misses. Of course it probably won't miss at all the times I take it out to do this. And I will have to be the passenger, because when I try to look at the specs when driving, I am all over the road. That is no good at all. Whatever it was before she brought it over , with no check engine light on, but a code p0308 in history, she now tells me the check engine light was flashing at one time, when means something was critically wrong. But now. not nothing and car runs like a new one most of the time. I don't know if it is my scanner, but when I was going down the road trying to check specs, the scanner would say that there was no communication with the car and then it would come back on and everthing on the scanner was working fine. I suspected a ignition problem, but the only thing I could think of, besides the erractic scanner, in my confused state of mind was the crankshaft sensor. But you would think if it was that that is would throw a crankshaft sensor code. No signs of that on the scanner ever. Oh well lets hope that the seafoam will clean up the problem somehow or it will eventually throw a code.
 

NickD

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Good point, can't find a MAP for this car. Newest problem we are having is water in the gas, with all this rain, raining right now. Several airports in my region had to switch to above ground tanks. Seem to get plenty of problems for free, in this case, have to pay dearly for water in the gas problems. In more ways than one.
 

The old man

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By the way kev2, I am in process of studying mode 6 and how to get to it and what exactly does it mean when I get in there with all those numbers etc. I do have it on my scanner but as of yet, I do not know exactly how to access it and understand it. I down loaded 7 pages by "Mater Technician" on the "Practical uses of Mode $06". It deals in this section with Ford. It is really a great reading on rounding out your diagnostic skills. Once I understand what I am doing in Mode $06 , I think I can narrow down that occasional miss, and not throw a code, like you said through misfire counts and if that is not the problem may show up on items in mode 6. Will keep informed. I know this is not the last time I will see this Lincoln.

To me this is an interesting article. Thought others might want to read it.

http://resources.aeswave.com/old/Articles/ProductArticles/MasterTech200611mode6.pdf
 
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