mystery miss
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Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
mystery miss
Ok, 94 4.0, developed a miss a couple weeks ago. I replaced coil pac, wires plugs (2 sets) , and crank sensor it persisted. I put truck into shop they analyzed everything, said they could not find cause, everything I had done was good. They checked fuel pressure said it was good, compression from around 175 - 200 (175 in 1 cyl only all others better). they did say that the injectors were satisfactory and rated them at 4-5 out of a 10. the miss will come and go, have run seafoam thru fuel, and today its not worse but at times it does feel like 2 not firing.
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
Last edited by Hank85713; Jun 8, 2012 at 11:11 PM. Reason: spelling
Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
Likes: 0
From: Boston, MA
Ok, 94 4.0, developed a miss a couple weeks ago. I replaced coil pac, wires plugs (2 sets) , and crank sensor it persisted. I put truck into shop they analyzed everything, said they could not find cause, everything I had done was good. They checked fuel pressure said it was good, compression from around 175 - 200 (175 in 1 cyl only all others better). they did say that the injectors were satisfactory and rated them at 4-5 out of a 10. the miss will come and go, have run seafoam thru fuel, and today its not worse but at times it does feel like 2 not firing.
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
The coilpack probably belongs on your suspect list. They're known to crack underneath & leak or arc to ground causing a weak spark that can blow out under load, or intermittent no spark.
SO, maybe try raising the coilpack & at night with the engine running, looking for an underhood light show when you spritz the coilpack with a spray bottle of water.
Let us knowwhat you find.
SO, maybe try raising the coilpack & at night with the engine running, looking for an underhood light show when you spritz the coilpack with a spray bottle of water.
Let us knowwhat you find.
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Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
I asked the garage about an icm, said the computer is good, its a new coil pac and there was no change from the old one I just replaced?
I am thinking it could be related to the timing chain as it has never been changed. Timing was off just a little but not enough to indicate per the garage. it looks like about $4K to get a reman engine with accessories and to also get a reman transmission. I went to look at newer trucks but none available and I dont want an F150. they had a 02 with almost 200000 on it for $10K (3.0 eng), $26K for a xl with 18000 on it! So I think with the upgrades I have that the 4-5K would be just as good.
I am thinking it could be related to the timing chain as it has never been changed. Timing was off just a little but not enough to indicate per the garage. it looks like about $4K to get a reman engine with accessories and to also get a reman transmission. I went to look at newer trucks but none available and I dont want an F150. they had a 02 with almost 200000 on it for $10K (3.0 eng), $26K for a xl with 18000 on it! So I think with the upgrades I have that the 4-5K would be just as good.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
Likes: 0
From: Boston, MA
I asked the garage about an icm, said the computer is good, its a new coil pac and there was no change from the old one I just replaced?
I am thinking it could be related to the timing chain as it has never been changed. Timing was off just a little but not enough to indicate per the garage. it looks like about $4K to get a reman engine with accessories and to also get a reman transmission. I went to look at newer trucks but none available and I dont want an F150. they had a 02 with almost 200000 on it for $10K (3.0 eng), $26K for a xl with 18000 on it! So I think with the upgrades I have that the 4-5K would be just as good.
I am thinking it could be related to the timing chain as it has never been changed. Timing was off just a little but not enough to indicate per the garage. it looks like about $4K to get a reman engine with accessories and to also get a reman transmission. I went to look at newer trucks but none available and I dont want an F150. they had a 02 with almost 200000 on it for $10K (3.0 eng), $26K for a xl with 18000 on it! So I think with the upgrades I have that the 4-5K would be just as good.
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Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
There were no codes when they scanned the truck of any kind. All sensors were checked and again none were found to be bad. so I dont know what to look for unless the ignition module is separte from every thing else and would not be spotted by a complete engine scan?
why do you think that the $$ spent would be so bad. age of the truck? that was taken into consideration, reman components? I have looked for newer and do not want to spend the $$ they want for a replacement. This will be the last vehicle for me as a daily driver as I am only a part time person and semi retired. I dont want payments and from the few examples I saw they were no better than what I currently have. The new trucks are rated no better on milage than my current one so there is nothing to consider there as an argument.
why do you think that the $$ spent would be so bad. age of the truck? that was taken into consideration, reman components? I have looked for newer and do not want to spend the $$ they want for a replacement. This will be the last vehicle for me as a daily driver as I am only a part time person and semi retired. I dont want payments and from the few examples I saw they were no better than what I currently have. The new trucks are rated no better on milage than my current one so there is nothing to consider there as an argument.
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Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
OK, took the icm module in for testing, the garage had saidd they tested it BTW, and it was found to be ok. Just for GP's bought a new one anyhow and installed it. A little better but nothing all that significant. it was the orginal and so the age and heat and other exposure added to my decision to replace it.
So now the only other items that are age related to be changed are the injectors, as I said earlier they were rated 4-5 out of 10 by the garage and they are the OEMS, been taken out 1 time and cleaned about 100-150K back. new set will run around $300, anyone know of any significant differences between the orielly (BWD) or the autozone (GP Sorensons) other than the price? both have 1year warranty, Auto zone are about $30 more.
So now the only other items that are age related to be changed are the injectors, as I said earlier they were rated 4-5 out of 10 by the garage and they are the OEMS, been taken out 1 time and cleaned about 100-150K back. new set will run around $300, anyone know of any significant differences between the orielly (BWD) or the autozone (GP Sorensons) other than the price? both have 1year warranty, Auto zone are about $30 more.
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Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Ok, 94 4.0, developed a miss a couple weeks ago. I replaced coil pac, wires plugs (2 sets) , and crank sensor it persisted. I put truck into shop they analyzed everything, said they could not find cause, everything I had done was good. They checked fuel pressure said it was good, compression from around 175 - 200 (175 in 1 cyl only all others better). they did say that the injectors were satisfactory and rated them at 4-5 out of a 10. the miss will come and go, have run seafoam thru fuel, and today its not worse but at times it does feel like 2 not firing.
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
Its a good indy shop, said they have encountered this before with no explanation (on a chebby). truck has 300K on it no previous engine problems, injectors removed and cleaned at around 200K.
just lookin for ideas, as I am stumped. When I start it sometime will just run perfect. shut off and it runs like crap next time. As I said it has checked out on a scan good, no codes, computer is fine.
Thanks
SO, maybe because of the slightly lower compression on one cyl, CCDF belongs on your suspect list & maybe because of the mid grade score on the fuel injectors, they might be figuring in causing combustion chamber deposits????
In that case, why not consider a 20 oz dose of Chevron Techron Concentrate Plus at the pump (so you get good mixing) before filling up with Chevron, Texaco, CalTex, or now Shell, which have some PEA in their ad pack, so with the 20 oz dose of Techron it'll raise the treat rate 10X above that of pump gas alone & will usually get the tidy up job done in one tank.
Then do the daily 3600 rpm for 2-3 miles part of Fords 4.0L decarb TSB, run most of the treated tank out & see how it goes. If CCDF is causing a random valve seat sealing problem, the Techron & some blow it out runs might help. It'll tidy the injectors up too!!!!
One of the autoparts stores has the 20oz size on a bogo deal this month.
More thoughts for pondering, let us know how it goes.
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Cargo Master
Joined: Feb 2002
Posts: 2,414
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From: Tucson USA
pawpaw, I dumped in a can of seafoam on a 1/2 tank of fuel, ran it for 20+ and it still misses. Refueled it and it still misses. Bought some GP Sorensen injectors at autozone yesterday will install and go from there. Yes the shop said there could be a carbon issue, but I run techrone through the system regularly. It was on sale at costco last month so bought a couple of 6 packs. The truck gets reved to 3K fairly regularly to try and keep deposits down. Like I said the T chain has 300K on it, so it could be stretched a little (timing was off just a tad they said), and I do have a little oping in it so It just may be a weak injector also. time will tell.
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Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
Ok final update. I bought some autozone injectors (GP Sorensons) and got them installed this afternoon. Took care of the miss, truck runs great. Got up on the interstate and she will bury the needle in OD with AC on. One injector looked really dirty at the tip so I guess that was it. No need to change the engine or anything else. Just need to now get some of the other things that were going to also be done done.
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Ok final update. I bought some autozone injectors (GP Sorensons) and got them installed this afternoon. Took care of the miss, truck runs great. Got up on the interstate and she will bury the needle in OD with AC on. One injector looked really dirty at the tip so I guess that was it. No need to change the engine or anything else. Just need to now get some of the other things that were going to also be done done.
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