hey guys i have a 95 f150 with the 302 in it. i just completed the 4r70w to zf 5 speed swap. so far everything went good. my only problem now is the truck seems to have an intermitent skip under acceleration. but i only notice the skip while accelerating in 2nd and 3rd gear, and it seems to be at a constant throtle pressure. i checked for codes and the only ones i have are a bunch of trany codes from doing the swap and having automatic trany plugs disconnected which i expected.does anyone have any ideas what would cause this???? its driving me crazy and i have to drive it to NC next week so i need this fixed!! the truck never skipped a beat when i had the automatic in it so thats what is really confusing me?

 

sounds like you have a miss in the ignition...I have the same miss in my 01...its a pain and I did a complete tune up it went away 99% but is now slowly coming back...havent messed with it much as my play toy has been taking to much of my time...

 

OH MY GOD...I just thought of something...speaking of my play toy... you would be a savior if you still have your original factory tranny wiring harness...I will buy it from you...pay for shipping and all... I ripped my 95's tranny wiring harness right in half on the trail and only have the front half left....I went to ford dealer...they stoped making the part in 03...they gave me a ford related junkyard....I called them...they said no...ive called every yard in town...no models new enough to have that tranny in it only old aod and c-6's n such...I even been on junkyarddog.com...still nothing...my 95 has a 302/4r70w combo in it...the exact harness you just pulled out with the tranny...you would be a saint if you sold it to me!!!

 

im not sure. everything on the ignition system is brand new. i just put a new set of plugs and a new tps sensor on it today and its still doing the same thing. i wondered should i have left the mlps switch pluged into the harness after doing the swap or am i way off on thinking that? either was its a miss under acceleration and its not constant it will come then go. maybe a map sensor?

 

actually after thinking let me rephrase this. under load its cutting out at a certain throtle pressure it seems. its not really a skip but it cuts out them right back on in a split seconds time. the more im thinking it could be like its running out of fuel but i put a pressure gauge on it and its reading fine. i also switched tanks and its doing the same thing on both.

 

Have you checked for vacuum leaks? I had an annoying skip/dead throttle then VROOM, sputtering idle. Never got a single code from the EEC. Look in my gallery at what I did find, though.

 

it cant be a vacumm leak because it idles fine the problem is during acceleration or under a load.

 

Oh, but it can be. If the gasket blows out between the runners where the plenum and intake meet, it'll drop vacuum between the runners, and cause some lean-miss at light throttle, and on occassion, mild back-fire, ESPECIALLY if it's a speed/density system. Even if it does idle fine. I was merely asking to clarify if you've checked. Apparently you have, because you say it can't be a leak.

But, if you're that convinced, when's the last time the screens were cleaned in the fuel injectors? I got an old 'Bird that's doing that (and then some) now. Idles perfect, runs like a raped ape at WOT, but SUCKS under light throttle. No codes from the EEC, new rotor/cap/wires, all Motorcraft purchased at Dealer. Guy in the 'Bird forum I visit suggested clogged filter screens in the injectors. Considering the throttle body on that thing has NEVER been apart .... I don't have much choice but to try it. Maybe reduced fuel flow under higher vacuum which reduces pressure (light/steady throttle) is being further impeded by debris in the screens. Dunno. Any surging when you hold the throttle steady?

I'm not trying to be a know-it-all. I'm trying to help you figure out your problem by asking questions.

 

You swap in a manual ECU ? With swap

 

I would guess you probably had this problem before the tranny swap but since the clutch doesnt fully lock up until 42-45 in our auto tranny's it dampened the effects. Now that you have a clutch and its completely locked together you can feel it...so I dont think it had anything to do with the swap...

I would spray carb cleaner or something along those lines around your intake and vacuum lines...if your idle changes at all you have a leak at the spot where you sprayed and the idle changed....also check your fuel pressure at the rail should be between 32-42. 32 At idle and 42 at WOT. Then let us know what happened and we can try to go from there...

 

I had exactly the same problem you are having, what fixed mine was replacing the plenum to lower intake gasket. I also did the same things as you trying to fix my issues, plugs and tps. I pulled the plenum off to check the injectors because my truck idled fine so in my mind it couldent be a vacuume leak. I even sprayed carb cleaner around the intake and didnt find anything. BUT I had a split in the plenum gasket on the passenger side under the plenum roll so my carb cleaner just wasnt getting to the right place.

 

Hey Camaro man, I have the EXACT same problem with my 95 f150. I recently swapped the AODE for a new 5-speed. I kept the AODE computer and it runs fine except it skips every once in awhile under load. I was wondering if you ever figured it out and if so, what did you do. I need help with mine, the hesitation is so annoying sometimes.

 

I just put a Zf in place of my e4od, and I started to notice little misfires more too - Im pretty sure that the truck always has them, it's just that much more noticable without the buffer in there. I figure i'll change my plugs (I havent seen them in a few years) and go from there.
<img src="http://www.rit.edu/~btm4554/mytruck_small.jpg">

 

just went through this same thing, my buddy spent a year chasing this down, has something to do with the speed density, mass air crap, he ended up using a 5.0 mustang computer and repinning it and it went away, had to change some the engine harness, as he needed a second o2 sensor, he got a rite up off the computer, do a google search for mass air conversion

 

This is EXACTLY what using an unlit propane torch is good for, not to mention, no liquids laying around on stuff to catch on fire if there's a leaky spark plug wire. You can stick the nozzle of the torch under the plenum along the right side, and you'll hear it idle up, even if only slightly when the gas finds a way into that intake. Disconnect the IAC and let it idle slow (450-500 RPM) for higher vacuum, and you'll really hear it when the gas finds a way in. Even if the propane ignites, it's a quick flash, and possibly a lit torch that you can pull away from the engine before something catches on fire. If the carb cleaner/tb cleaner/injector cleaner ignites, you have a pool of stuff that's going to get mighty hot before it burns away, and may do some serious damage to wiring harnesses. Under the plenum curl (right side) seems to be the most common place for failure. Dunno if it's because of the gasket shrinking with age and the plenum being propped up with the brace or what. The Torx bolt on mine was only finger tight when I removed it. I didn't even need a ratchet on the extension to back it out.

Of course, mind your ventilation if you do this in a garage, and wear your safety glasses. Your eyeballs will thank you if there is a flash.

This is really an EASY job if all you do is the plenum, TB, EGR, and IAC gaskets. All but the EGR gasket come in one kit for around $20 IIRC. The EGR gasket is usually a graphite/fiber gasket that can be re-used anyway, if you want to cut an $8 corner. Put some Permatex HyTak on the lower intake, the gasket, then some more HyTak, drop the plenum on, and it should be good to go for a LONG time. DO NOT USE RTV on an intake. The little beads that will most assuredly squeeze to the inside will eventually come loose. The air going through those runners has a pretty high velocity, and a pretty nasty pulse. You'll be real lucky if they don't stick to a valve and hold it open. I just don't like RTV near anything that goes INTO the engine. It took me all of 30 minutes to have the plenum laying in the floor with the TB separated and IAC off. It took a lot longer to scrub and clean parts than disassembly and assembly combined. And WOW, what a difference. Felt like a new truck again. I wouldn't hesitate to pull the plenum again if I get that annoying miss again. It's probably one of the easiest things I have done on my truck.