94 x losing power while driving

[TMW]

its a 94 4.0 5 spd 4x4. sometimes it runs great sometimes it skips and loses power as i am driving...so much so that i have to start down shifting to try to keep up speed. most of the time it just continues to slow down. sometimes it will spit and sputter and start going again for a few miles then do it all over again. when it starts to lose power at idle it is turning very low rpm like 500 or less.at first i thought it needed a tune up but sometimes it clears up and runs fantastic and has lots of power. only does this after it warms up. any ideas on what could be happening here?

 

[natenkiki2004]

Another forum member had almost the exact symptoms and after diagnosing, it turned out to be faulty wiring to the ignition coil. Look at the plug and coil pack, and if you have a multimeter, test the coil out following these instructions:

Note: The original source for this image has disappeared but I was able to hunt down another copy, clean it up in Photoshop and have saved it for my records, I suggest you do the same. For anyone that wants the original, click here.

 

[TMW]

cool thanks i will go try that

 

[TMW]

ok did that and got nothing. the meter stayed at 1.0 ohms. would the truck even run like this...mine does great sometimes and sometimes it has no power and skips. i am ordering a new coil and putting it on and going from there i guess

 

[TMW]

across the connector its 1.3 on all. the plug terms are all 1.0...i would say its bad

 

[TMW]

ok this is what i got testing the ohms the right way

 

[TMW]

just in case its not this does anybody think that it could be a clogged cat

 

[larrydd999]

TMW, I'm going to disappoint you by saying that looking at your test results I don't think it's the coil, although it could be... There are numerous threads regarding engine issues that include loss of power, and the causes range from fuel pump and other fuel system issues to an intake manifold gasket failure causing a lean condition. Have you checked the computer for any codes? I would start there.

 

[Alanslinky]

I had a similar problem with another car of mine. After tearing apart the upper half of the engine trying to find anything it could possibly be all it turned out to be was an old battery cable running to the computer was frayed and coming apart. The engine would cut out when the cable lost contact and then turn back on by itself when it regained contact.

 

[TMW]

ok well i drove it today but it does not have new coil on yet but does have a replacement fuel pump assembly( fuel gauge was not working so got a jy unit and replaced fuel gauge works now). when cold it runs great and will til i shut it off. when i crank it back up it skips has not lost power at all since but it still skips some times. like today i shut it off came back 20 minutes later and was skipping drove about 5 miles shut it off came back out about 10 minutes later and no skipping. got about 1 mile down road and it had a miss til i got back home...about 6 miles.

 

[TMW]

oh and the check eng light only came on three times but stayed on about 2 minutes and when back off...once today and two times the day i got it driving it home.. and the light would go off while driving it

 

[Gadget X]

How long has it been since you put plugs and wires on it? Could be an old wire.

 

[TMW]

just bought it and they do need replacement, the wire have a brown discolor at the boot at the coil. autolite coppers and a decent plug wire coming soon.

 

[TMW]

new coil pack on...not a big change.. just a slight improvement

 

[Gadget X]

I'm thinking that the new plugs and wires are going to have a bigger impact on your problem. Good luck with it!

 

[TMW]

new wires, plugs looked good but are 765's and calls for 605's so i will be putting them in soon. still has slight skip but nowhere near as bad as before. before i put the 605 autolites in i will be doing a seafoam. getting there...thing does have 242k miles so the seafoam might help alot.....we shall see.

 

[TMW]

ok drove it some more. when the motor is cold it starts and runs great no skipping but after you drive for a little bit and it sits for about 20 minutes when you start it back it skips but shut it back off and the skip is gone....any ideas

 

[Roadrunner777]

If I only read your last post, and noting your location and time of year, I would say it is another issue of vapor lock. The thing that really brings it home is that if it sits warm, it has problems starting back up. The easiest and cheapest way to prove this out is to add a bottle of Techron to a half full or less tank and see if it fixes it. If so, then the real issue is a bad check valve in your fuel pump. I think I have seen 3 of these just so far in July.

 

[Eddie9195]

I had similar symptoms on my Isuzu Rodeo, my problem turned out to be the crank position sensor. I chased my tail and put a bunch of new parts on it before I figured it out.

Good luck, as you can tell, it could be several different things.

 

[TMW]

it has no problem starting....it runs rough only after it warms up and you shut it back off and it sits for about 20-3- mins then it skips....but before that it runs really good.
has a new fuel pump,new coil napa belden wires,autolite 765 plugs...changing to 605 like it calls for.

today after i shut it off and start in back it skipped bad and never stopped, this thing has a mind of its own