5.4 missing

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Feb 28, 2003 | 09:39 AM

kwilliams

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5.4 missing

I have a 99 F-150 w/ 5.4 w/ a mis-fire problem. I have 75000 miles so I went ahead and changed the plugs. That helped a lot but did not solve the problem. I pulled all of the coils and ohm'd them out according to the manual. I got close to the stated 5.5 ohms across the primary. On the secondary the published ohms is 5500. I got 5700 ohms above the rubber isolator. But I got 9000 ohms on the flat that touches the plug (below the isolator). I got this on every one of them. Is this normal? I think I have a coil problem but am not sure??

Feb 28, 2003 | 11:59 AM

FortyFords

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5.4 missing

For the coil packs remember that heat will change resistance if their breaking down.
chk them after engine is hot, been running for awhile.

Or get the engine on a lab scope or a scanner capable of reading each cylinder misfire count!

Just my thoughts

Rich

Mar 10, 2003 | 02:26 PM

gsprague

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5.4 missing

I was having a similar problem of misfires. I certainly know a skip when one cylinder goes and it was nothing like that.
I decided to try something I have done with my fuel injected bike that worked. I ran it on an alcohol mixture. I poured approx 2 gallons of 99% isopropyl alcohol into 1/4 tank of gas and it cleared up the misfiring almost immediately. This is probably not a recommended repair but, it worked.

p.s. the performance has never been better, even after the alcohol was used up.

Mar 20, 2003 | 01:30 PM

BRONC72

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5.4 missing

i own a 99 f-150. 4x4 5.4v8

there has been a coolant leak by cyl number 4. several times. i have personaly replace coil #4 5 times. and at 135K i just repplaced coil number 1. work was just done to the engine. so ill bet that someone cracked something they werent sposed to while putting the coilpack back on . but who knows. coil 4 and 1 are the only ones that i have ever had to repalce

Mar 20, 2003 | 01:48 PM

kwilliams

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5.4 missing

Thanks for you comments.

I cleaned the fuel injectors early on thinking that could be part of the problem, but it wasn't. I have a code reader and the first code I got was a general misfire. After a few days the code went away (not the misfire). After a couple of weeks it started running really bad 1 day and I got another code. This code was a cylinder 8 misfire. The truck started running better (back to the usual misfireing) at the end of the day. After that I switched coil 8 w/coil 5 hoping to get a misfire on cylinder 5. I never did. Finally I took it to a shop to read the codes. They drove it and tried reading codes. They couldn't get it to read codes either and thought that I should be getting plenty of codes, by the way it was running. Anyway I finally changed coil #8 (now #5). The coil label on the new one was a little bit different again, so I guess it is a 3rd generation coil. Hopefully this one will last longer. It has been running great since then, although the last couple of days it seems sluggish again. I think the coils are breaking down (since I'm measuring higher resistance) and will probably have to replace all of them eventually.

Mar 20, 2003 | 02:18 PM

BRONC72

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5.4 missing

watch out. if anyone knows where one can buy coils at a cheaper price other than from ford. that would be great. cause the price went up . at least in the area that i live in . before they were about 80.00 . now they charge almost 200. and installation is extra. i need to get a code reader so i dont get raped taking the truck to ford. can anyone recomend one.
thanks.
brant

Mar 20, 2003 | 03:15 PM

kwilliams

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5.4 missing

I got my coils at O'reily (used to be HiLo), they were about $60.00. The code reader I got at Autozone for about $100.00. I forget the brand name, but it can read and clear codes.