Lack of power on light accel. at cruising speeds

[Squisher]

I recently bought a '98 F150 4X4 OFF ROAD with a 4.6 V8. pic
After I first bought it I drove it at cruising speed and gave it a little gas and the truck misfired and threw a code for "misfire #4 cylinder" The guy at Autozone suggested some engine cleaner which made it a lot better, no more misfires, but it still seems to have some serious hesitation under light accel. even more than the torque-less 4.6 is known for.

My first inclination is to change plugs and maybe wires, but I thought I'd throw it out here to see if someone has a different opinion.

 

[Zenmervolt]

Plugs and wires. That should have been the first thing you did when you got a misfire code. Engine cleaner is not the right "cure" for a misfire.

ZV

 

[Squisher]

Originally posted by: Zenmervolt
Plugs and wires. That should have been the first thing you did when you got a misfire code. Engine cleaner is not the right "cure" for a misfire.

ZV

Thanks, that's what I thought. I even said that to guy that at Autozone that pulled the code, but he said engine cleaner. I figured I'd give it a shot, hey, I'm as lazy as the next guy.

It did make a difference so that is why I was a little reluctant jump into a tune up. I thought someone here would think this was a clue for some other problem.

Thanks again.

 

[Iron Woode]

Originally posted by: Squisher

Originally posted by: Zenmervolt
Plugs and wires. That should have been the first thing you did when you got a misfire code. Engine cleaner is not the right "cure" for a misfire.

ZV

Thanks, that's what I thought. I even said that to guy that at Autozone that pulled the code, but he said engine cleaner. I figured I'd give it a shot, hey, I'm as lazy as the next guy.

It did make a difference so that is why I was a little reluctant jump into a tune up. I thought someone here would think this was a clue for some other problem.

Thanks again.

gummed up injectors do happen.

similar issue on my Crown Vic's 302. One cylinder was misfiring and a plug change didn't help. Took it to the dealership for testing and they found a blocked injector. Ran the cleaner through it and has been working fine ever since.

Personally I would give your engine a thorough going over.

 

[Pacfanweb]

#4 cylinder, you say?

Check the heater core lines, which are directly above the #4 cylinder. Make sure the aren't leaking on the plug/wire. That was a VERY common problem.

Then go ahead with the plugs and wires as ZV recommended.

 

[Scouzer]

good lord, those are $750k properties, nice

 

[exdeath]

SOHC or DOHC? I know the DOHC 4.6 engines are notorious for accumulating water and condensation under the coil pack covers, where it pools around the spark plugs which are deep down in the head where it's hard for moisture to evaporate.

Pull the coil pack cover and all the coils and blow out each plug recess with compressed air and take care to make sure the rubber gasket on the cover, and the grommet where the plug signal wires come in, are properly seated.

I get this all the time on my Cobra, and sure enough I always get misted with water from the #3 and #4 cylinders.

You can also check the insulator boot of the coil pack for burn marks or holes, etc.

 

[Pacfanweb]

Originally posted by: exdeath
SOHC or DOHC? I know the DOHC 4.6 engines are notorious for accumulating water and condensation under the coil pack covers, where it pools around the spark plugs which are deep down in the head where it's hard for moisture to evaporate..

No DOHC's in trucks. That's an SOHC, and they had a problem with the heater core hoses leaking on the rear two plugs. It's worse with the 5.4's, because they had a coil on each cylinder....the coolant leaks takes the coil out on those.