Restof150s

Basically bought my truck (1993 f150 extended cab 2wd) roughly 3 years ago. Drive it home it had a slight knock that I wasn't comfortable with. I ended up rebuilding the engine. (I was a mechanic for ford at the time, I work for john Deere now) we'll ever since the engine rebuild I have this buck/miss/jerk loss of power. Happens when cold and at high RPMs, about when it shifts. I CANNOT figure it out. Here's the list of parts I've installed, not all for this concern just mods I've done and parts that have failed over time.
Parts list:
TPS
IAC
transmission (made the truck 4wd so I opted to change out the whole unit. Brand new rebuild from monster)
New fuel pump (rear, the front needs a pimp now)
Ignition control module
I even put the spout/pip connector in (yeah I knew this wouldn't fix the concern I had a couple spares so I tried it)
Water temp sensor

Like I said, some of these parts were not installed to try to fix the problem just some that had failed over time. I just installed the TPS and IAC because they failed. I put a known good (used) ignition control module on.

I have checked the timing and adjusted it several times, plugs and wires have been checked and double checked. Routing wise, I haven't switched out plugs for new ones. I stuck new ones in when I rebuilt the engine. I have NOT put a distributer in.

Here's a more thorough description of what the truck does. Under any kind of acceleration when cold the engine will buck/jerk BAD it has a loss of power and if I'm rolling down the road while it's doing this and I put it in neutral. When I rev it I can make it back fire through the exhaust. Hot drives fine for the most part. Unless under a real bad load then it'll buck/jerk a couple times and then clear out. I let a friend borrow the truck and he towed a fox body mustang roughly 125 miles round trip. He said truck did fine even up a steep grade on a tall bridge.

Restof150s

Sorry 5.8 engine.


Edit: forgot to mention, key on engine running codes I have EGR insufficent flow and cylinder contribution not performed due to throttle movement during test or what ever. No other codes.

Rusty but trusty

Is the TPS adjusted properly and working? My 5.8 / auto shifted about as smooth as a sledge hammer when the TPS was bad. Most people will say motorcraft only, i can't really say as I followed the advice and all is well, so no clue on other brands. Other things that come to mind is a possible clogged up exhaust system? How are your cats? have you checked the timing?

Restof150s

Trucks been doing this a couple years now, it's not a daily so it can go months without being driven. I sometimes forget it has a problem lol. It's had two different exhaust systems on it, the first set up brand new everything. Second set up, straight pipe. As far as timing yeah checked it multiple times. I haven't fine tune adjusted the TPS. I installed the TPS because it failed but thought it MIGHT help the problem, but no change even the slightest. I'll have to adjust it soon to be able to say it's set in.

Restof150s

Well me and a buddy got together and got to thinking about it, looking further into anything I could have missed or anything. We ended up putting a distributer on it. Stabbed it timed it by ear (my friend did). Test drove it and it seemed to clear up. Been driving it off and on for couple hours now. I put a timing light on it at my buddies house, dead on timing. He did it by ear at that, I mean dead on 0. So we'll see in the next couple days if that will fix it completely. So far so good.

Chris_1

iTrader: (1)

Timing should be dead on 10 to 12 degrees Before TDC with the spout out (I believe).
Probably what you meant, but I thought I'd mention it anyway.

And if it isn't solved, try putting a fuel pressure gauge on it.

Restof150s

It's at 0 with the pip/spout connector out.

I've put the fuel pressure gauge on it. But that was a couple years ago when it first started doing it. So I can't really remember what it was. Lol


Edit: it was in spec back then, plus I had put a new fuel pump in since then. Within the last 6 months actually.

Chris_1

iTrader: (1)

Pretty sure it's supposed to be at 10 degrees before TDC. If it runs better at 0, could it be possible that the timing chain is off a tooth ?
Just a guess.
Maybe try it at 10 degrees and see if it's better or worse.

Toplait

yep 10 degrees. My Speed Density 5.0L liked 13 and my 5.8L likes 12...

Are you getting any codes? First I would check that... -or- you will most likely be buying parts randomly.....

You could have a number of problems that could cause this issue. EGR, MAP, TPS, Ignition components, such as the Coil, Fuel issue.


Other then that measure fuel pressure at rail to eliminate a fuel pressure issue.

Make sure plug wires are not damaged and are routed correctly. Check cap and rotor to see if in good condition. . Check spark plug gap to make sure they are gaped correctly and are tight.

justintendo

yes, 10 btdc with spout out is spec, so you have a boost in power and mileage waiting. your buddy was "dead on" wrong. funny when people say they "set it by ear"....on a fuel injected vehicle with computer controlled idle...