Ford 5.4L HELP...got bigger issues now HELP

John Fuller

John Fuller

XJ Fanatic!!
Banned
Joined
Jan 3, 2015
Location
Boone NC
99 F150 5.4L auto 3:55 ratio
what mods have you ford guys done that actually give some gains in pulling power/gas mileage/overall driveability?? cat deletes? H-Pipe? Single or Duals (does duals actually gain anything for the extra money) and are chips/programmers worth fooling with on these.
Also, will dropping 265s down to 245s be good enough difference in mileage/power for the swap hassle/money or not. I know on jeeps (me being jeep guru) going from 31s to 33s noticeable difference so i would assume for any vehicle this would apply? on the cat deletes, i notice it has 4 cats and they sell the lower 2 cat deletes but was wondering if anyone had experience with actual gaining anything from that. Thanks in advance for input...(maybe i can return the favor in XJ input LOL)
 
and don't tell me buy a chevy LOL...i didn't buy this, i traded my volvo for it and it's in real good shape. had i bought a truck, yes would've been a chevy since i've owned 3 tahoes but couldn't pass this up for trade plus some cash in my pocket.
 
ok ford guys HELP!!! PLEASE. stupid missfire came back. several new coils new plugs, cleaned tb and egr passages/iac motor runs good but at idle you can def tell its missing. NO CEL THOUGH...went to unplugging coils and injectors one at a time...#7 no change when i unplug the coil or the injector and sometimes the #4 no change either and that has the new coil (twice now). PLEASE anyone got some ford advise (beside set it on fire lol) runs good but on take off at first you notice it and gas mileage is pretty shitty compared to before otherwise runs fine. It used to have the CEL on for #4 and #7 misfire, then went away but now few days ago came back. I've heard of ECU update flash???? anyone have had luck with this $100 update or is there something else there. thank you much for any help advise on this. bugs the crap out of me at idle and oh...it kinda comes and goes. most of the time it's there but sometimes it goes away. when it fires right up its gone...when lags in startup i know it will miss.
 
I know ford had a problem with the 5.4's plug blowing out because of the threads not being deep enough in the head but you should hear the compression leaking also with the motor running at temp you can take a bottle of water and drop some water on the exhaust runners and if it doesn't boil off that cylinder is not firing
 
ok. little truck history: had #4 helicoiled about month ago and ran perfect for few weeks then missed the weekend of the 24th when i was down at event and went away now it's been back for few days. while down there, was referred to local shop...put it on his big scanner spent hour or so switching coils, plugs, but #4 and #7 was showing up as almost dead but he could never figure it out except offered to do a $130 ECU software update but i held back spending that since it was just a 50/50 chance to fix it so now it has come back but no CEL for 3 days now but you can tell its missing at idle through sound of exhaust and the shaking of the motor a little when idleing. i thought maybe #4 was culprit but #7 is missing too and when i unplugged the coil and injector on 7, no change in motor but all the others made some change including 4??WTF...
 
Mine has a repair on cylinder #6, and every now and then will burn that plug up. I think the spark is arcing back to the thread repair and eventually just burns it and the end of the plug up.

They don't just leak compression around the plug, they blow the plug the F out and it sounds like a giant air-compressor running inside a cement mixer. When mine blew out, I honesty thought a front tire had fell off it was shaking so bad.
 
pulled plug on 7 and all is good too. i'm starting to guess electrical crap which is my weakness so anyone can point me in direction to start with the electrical stuff would be great
 
strange1 said:
Mine has a repair on cylinder #6, and every now and then will burn that plug up. I think the spark is arcing back to the thread repair and eventually just burns it and the end of the plug up.

They don't just leak compression around the plug, they blow the plug the F out and it sounds like a giant air-compressor running inside a cement mixer. When mine blew out, I honesty thought a front tire had fell off it was shaking so bad.
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that's what this one was exactly like that but what's the deal with 7 though...it seems more dead than 4. oh, at that shop down there we checked #4 and all was good as far as gap and plug went...should i pull it out again? i hate to pull the plug on helicoils out so many times lol
 
the second one i just got is oem..first one was Accell but now is back to oem. no matter how i swap coils or anything the miss stays on 7 and 4 but seems to be mostly 7. only with plugged up to software scanner can u see 4 and 7 being dead. i'm gonna go get it scanned from local guy who has same snap on software and see if it's still 4 and 7 but i'm pretty positive cause no change in 7 and mostly none in 4 either.
 
Replace all 8 coils as well as the plugs at the same time with OEM ones.
You want more torque? As a "Jeep guru", what would you tell a "customer" if they wanted more torque? Cat deletes, gas tuners and the like won't make a significant difference.
All that bolt on stuff won't compare to a gear change to 3.73 or 4.10.
Want torque? Multiply it and put to the ground efficiently
 
I do a lot of work myself, I even swapped out the blown 5.4 in my f250 myself, but I will not touch cylinder #6. If it is missing, I have a couple of coil packs to try, if that doesn't work it goes to the shop.
 
UPDATE: whew whew whew. i got a friend to get me the PCM diagrams and entire ignition curcuit diagrams and WOW..spent 6hrs today probing wires and more wires and testing coils and more testing...double checked my work 3 TIMES and ended up with same result and also compared my results with the GOOD known working cylinders and coils and conclusion was...PCM has to be bad or it needs a reflash. every wire tested fine, every coil tested fine, all withing the Ford OEM specs for resitance/ohm/voltage so anyone have any luck with ever getting this Software Update/reflash they call it. apparently there is a "update Software" for the PCMs of the older Fords ignition system but i wanted to make sure wires were all good before spending the $100.
 
my brain is smoking right now with all this wiring crap...i hate electricals!!:kaioken:
 
There is a company in Florida that does ECM repairs. I used them on my 98 xj and it's working like a charm. I will use them again if I need another computer repair. This is who I used. http://stores.ebay.com/ecuexchange/
 
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ghost said:
There is a company in Florida that does ECM repairs. I used them on my 98 xj and it's working like a charm. I will use them again if I need another computer repair. This is who I used. http://stores.ebay.com/ecuexchange/
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thanks for the link. i'm waiting for the "drive cycles to finish" after all the wiring testing and the reset, since it reset while unplugged, and gonna have my friend scan it one more time before he sends it to Ford for me to have the ECU reflashed and updated. His shop will do it for 100. Right now it's driving fine and shifts smoother than before but from what i've been reading, that's normal when you unplug and reset the computer like I did for several hours. It would be nice if it stays fixed but we'll see. thanks again.
 
ok to any "master techs" who can maybe help, here's one for ya: today replaced all plugs, compression at 140-148 on all, coils all tested good, injectors are tested and good, coils AND injectors are all firing (tested with noid lights, laptop software watching live data and some other fancy shmancy thigy lol), New TPS (shifts smoother!!), cleaned TB, cleaned EGR and ports, ran 2 fuel injection flushes through it before plugs change, NO VACUUM LEAKS-sprayed almost 2 cans of carb cleaner everywhere and nothing, pcv valves are good: last but not least>>>ECU according to both techs working on it appears to be working just fine and no issues. Also tested all wires to coils and injectors and ohms/resistance checked out good. The miss is noticeable at idle and you can smell the funky chemical smell and hear the exhaust but once you get going, all power is there and no miss???
SO anyone chime in on this: the only outcome the techs came up with was when they were watching the live data, fuel trim at idle was 15% and then goes to pretty much normal once you get moving but they didn't/weren't able to figure out why. they said it's dumping too much fuel for some reason at idle (or the other way around if i mixed it up, lots of diagnosing info today) and that is the cuase of the miss condition at idle. truck has 200k looks to have original cats BUT before recommending to replace those expensive things, any way to check and also does anyone think one or more O2 sensors is causing this even though no codes or data to "prove" they are the culprit?? sorry for long post and much thanks to anyone with some good tech advise. i'm out of ideas. thank you for any help!!
 
oh sorry lol DUHH!! it's got a slight "dead miss?" is what the other techs called it but you can hear and feel slight miss at idle (truck shakes a bit/and motor and you can hear it in exhaust and gas mileage has dropped pretty drastically so it seems). power is there once u get going but this miss at idle is just plain annoying and i'm one of those "tinker with it till it gets fixed rather than live with it..on my DD at least).
 
Have you put new plugs and coils on it? When they first start going, you get a skip at idle and under part throttle. Mash the gas and it goes away. I know you said you had swapped the coils around, but can't remeber what you had done about plugs.
 
Cats, O2 sensors and TP sensors don't cause misses.
Replace your coils. If by some magic stretch one isn't bad, they will fail soon. How did you "test" them before? How do you know one isn't arching in the head? No electrical test will tell you that.
Test for a burnt valve with a dollar bill. I've told you that trick before.
If nothing else, realize this is over your head and as Andy Griffith once said "Aunt Bea, just call the man."
 
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Do you have the ability to do a leak down test?
You could have a bad valve guide, you would notice it at idle but after that probably not. If you can do a leak down you can't have more the a 10% leak down. Good luck!!

BTW you could buy a toyota and solve all your problems! :flipoff2:
 
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What plugs did you use????
 
snappy said:
What plugs did you use????
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ok update...just installed ALL new Ford Dealer Motorcraft plugs yesterday and drove today quite a distance (about 25miles) and drove really good Except: only time i could notice the skip/miss is when in overdrive at that certain speed it shakes the truck when feathering the gas but otherwise it climbed back up the mountain at 55 effortlessly. i didn't test the coils..2 techs did at Clark Tire who i know to be very good certified techs and with 3 different types of computer/diagnostic tests, they said all the coils were reading out fine just like the 3 new ones. My miss on 4 and 7 is gone unlike before in the computer.
....my next step was going to be plugged cats??? 200k miles with original cats i figured and so has others that they would be clogged somewhat or more and to me the truck seems strong but to one guy who test drove, he didn't think the 5.4 was at the power band it should so he recommended cut in between the 2 cats on each side, inspect them and replace if need be or should be and also change muffler since it has pretty good leak at the rear of it. i know cats are expensive so i've been putting this off but it makes sense with so many miles that surely they ought to be some pluggage there.
 
Jody Treadway said:
Cats, O2 sensors and TP sensors don't cause misses.
Replace your coils. If by some magic stretch one isn't bad, they will fail soon. How did you "test" them before? How do you know one isn't arching in the head? No electrical test will tell you that.
Test for a burnt valve with a dollar bill. I've told you that trick before.
If nothing else, realize this is over your head and as Andy Griffith once said "Aunt Bea, just pay the man."
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hey man i'm sorry can you explain the dollar trick to me again and this time i'll copy and paste it on my computer. thank you very much. also you seem to have pretty darn good mechanical skills so from what you've read on here, replacing the remaining 5 coils would be your next step rather than mess with the exhaust/cats? also i've been reading up on a lot of "ford DPFE sensor issues where it causes this very similar issue" any thoughts on this? thank you
 
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