pesky problem
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From: clementsport canada
pesky problem
ok, i have a 79 f-100, with a 84' 302, and aod. at highway speeds, going up a slight grade, it turns about 1900 rpm, with this slight load on the engine, it will start to loose power and almost "skip" or "hitch" this is really starting to annoy me.
the motor has 60,000 km's on it, it's a rebuilt long block ( runs great most of the time) it has new wires, plugs, rebuilt carb, new fuel filter, new duraspark box, new air cleaner, fresh syn oil, a 180thermostat, and a new dissy today... still the same problem....
could there be something i'm missing,,, could my tranny be causing this.. it has 400,000 km's on it... seems to work great...
someone please give me an idea... im gonna try the big hammer fix next...
the motor has 60,000 km's on it, it's a rebuilt long block ( runs great most of the time) it has new wires, plugs, rebuilt carb, new fuel filter, new duraspark box, new air cleaner, fresh syn oil, a 180thermostat, and a new dissy today... still the same problem....
could there be something i'm missing,,, could my tranny be causing this.. it has 400,000 km's on it... seems to work great...
someone please give me an idea... im gonna try the big hammer fix next...
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pesky problem
Check your fuel delivery, it sounds like your engine is starving for fuel under load. Check the tank inlet, fuel suction lines for air leaks, restrictions, etc. You can get a tee fitting and put it in your fuel line at the carb and put a fuel pressure gage in the cab (check for leaks) and drive the truck while having a friend watch the gage.
A slipping transmission will let the engine speed up while the road speed drops.
A slipping transmission will let the engine speed up while the road speed drops.
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From: clementsport canada
pesky problem
ok, tried an eletric inline fuel pump in it, seemed to work worse after, took that out, pulled all the plugs (bosh platiums) and one seemed to have the electrode burnt way down in, but all were a nice light brown..... put in a spare plug, and tried it again still acting up, but not quite as bad... still hurts drivablity on the highway.. i'm gonna try the carb off our other truck after work.... i don't mind paying to fix this if i could find the problem.
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From: clementsport canada
pesky problem
humm egr,,, i'll check that, i think i know where it is.. behind the shop in the junk pile...
pulled the carb off, and found that the economizer/power valve was leaking... as usual... gonna try replacing that tomorrow.
pulled the carb off, and found that the economizer/power valve was leaking... as usual... gonna try replacing that tomorrow.
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From: clementsport canada
pesky problem
ok did a little more testing tonight, found that it makes a slight "poof" or partical skip at idle up to about 2000 rpm... after that it seems to dissapear... thanks to straight back duals, it sounds to be the drivers side, and after pulling one wire at a time and listening, i've narrowed it down to the front plug on the drivers side. i changed that plug(put a used spare in) and didn't seem to change... i also checked the timing 3 times, checked for a vacum leak, and tried a different coil, all with no change... this is gettin on my nerves.. i'm gonna change that wire in the morning.
i also tried misting the wires with a spray bottle of water and didnt' see any leaks ( it was dark out)
i also tried misting the wires with a spray bottle of water and didnt' see any leaks ( it was dark out)
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pesky problem
Even an engine with one dead or malfunctioning cylinder with everything else good will continue to pull under load. You put in a new distributor but is the advance working? Is your engine timed properly? Have you checked the position of the timing marks to make sure the balancer ring hasn't slipped? Is the distributor advance mechanism hooked up to the proper vacuum port? Check your fuel supply again. An electric pump won't help if it is pumping air or vacuum. Check in the Garage forum for a tip on how to test your fuel pump inlet side.
A melted plug electrode would indicate a lean mixture or preignition. Just one melted plug would indicate an extra lean problem with that cylinder. Check to see if there is an air leak or a vacuum port into the runner that feeds that cylinder.
A melted plug electrode would indicate a lean mixture or preignition. Just one melted plug would indicate an extra lean problem with that cylinder. Check to see if there is an air leak or a vacuum port into the runner that feeds that cylinder.
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Joined: Apr 2002
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From: Woodruff, SC
pesky problem
pulled all the plugs (bosh
>platiums) and one seemed to have the electrode burnt way
>down in, but all were a nice light brown.
Toss the Bosh plugs and put in some Autolites.I had those Bosh plugs in my truck and they were'nt worth diddly.
Wiz
[link:www.clubfte.com/users/thewiz427/index.html|"Wiz's Place"]
>platiums) and one seemed to have the electrode burnt way
>down in, but all were a nice light brown.
Toss the Bosh plugs and put in some Autolites.I had those Bosh plugs in my truck and they were'nt worth diddly.
Wiz
[link:www.clubfte.com/users/thewiz427/index.html|"Wiz's Place"]
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From: clementsport canada
pesky problem
[updated:LAST EDITED ON 03-Oct-02 AT 11:26 AM (EST)]i was talking to a guy this morning, who used to work for the local ford dealer, he said that symptoms like that were often caused by a high mile aod tranny, and a tranny flush would usually cure them. he said that the torque converter gets dirty, and kicks in and out of lock-up, causing the feeling of a skip, or rough running engine.
this would explain why it only does it in OD, not in 1st, 2nd, or 3rd...
i've got new autolite's comming in the morning... (gotta love that napa delivers)
i also did a quick compression test, and got 145 on the front 2 cyl (with only those 2 plugs removed, and the coil disconnected, so it wasn't spinning very fast) i've checked for vacum leaks, and i think the fuel system is fine, you can hold it to the floor till 150 km's and it never makes a hitch ( had a leak last summer, and it would die at about 90 )
this would explain why it only does it in OD, not in 1st, 2nd, or 3rd...
i've got new autolite's comming in the morning... (gotta love that napa delivers)
i also did a quick compression test, and got 145 on the front 2 cyl (with only those 2 plugs removed, and the coil disconnected, so it wasn't spinning very fast) i've checked for vacum leaks, and i think the fuel system is fine, you can hold it to the floor till 150 km's and it never makes a hitch ( had a leak last summer, and it would die at about 90 )
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From: Louisville,Ky.
pesky problem
Could be a tranny problem. The lock-up clutch packs in the AOD's are very weak. Eventually it will lose 3rd and OD. The design of this tranny is awful. The converter locks as soon as it shifts to 3rd, even under full power. In most other trannys, the converter is only locked while cruising. If you accelerate, they release the clutch until you back off of the gas after reaching a desired speed. This eliminates a lot of wear and tear on the clutches. Most trannys also have the lock up clutched in the converter, so if they do go bad, The tranny will still pull, but the AOD uses 2 input shafts and the lock-up clutches are in the tranny, so an overhaul is required once they are bad.
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pesky problem
It would have been nice to know that it had power if you gave it gas 
-that eliminates the fuel system.
You have eliminated most of the electrical problems except a broken wire in your harness.
That just leaves those
AOD's. Of course the AOD is probably less problematic than E4OD's or the 4R100. Check out the tranny forum and the problems with them.
-that eliminates the fuel system.You have eliminated most of the electrical problems except a broken wire in your harness.
That just leaves those
AOD's. Of course the AOD is probably less problematic than E4OD's or the 4R100. Check out the tranny forum and the problems with them.
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From: clementsport canada
pesky problem
sorry about that torque, i thought i had said that in my first post.. guess not... thanks for all your help guys, this was really getting on my nerves, i expected the tranny to start slipping long b4 it did anything else... i'm gonna try the flush, if that doesn't fix it, i've got a spare aod sittin in the shop, with only half the milage.i traded the c-4 that was in my 78 for it, figured i should have a spare, seening we have 3 of the aod's between my father and i.