running rough

[Kyler-]

I just bought a Bronco II 5 spd 4x4. When I bought it, it ran rough, I was told it needed a new computer. upon purchasing I bought a used computer from the wrecking yard plugged it in and the truck ran the exact same way.

When started on a cold engine the truck generally dies right away. If you keep on the gas until it warms but a little bit then the truck won't think about dieing but it runs rough, sounding like its missing in a cylinder. When I first got it it idled around 500 Rpm and sounded like a piece of junk. the screw on the side of the throttle body was completely backed out. I've screwed it in (about 3 turns) so now it generally idles between 700 and 1000 rpm. I've run injector cleaner and air intake cleaner through and the truck is now sounding a little bit better.

Tomorrow I am changing the plugs, wires, dist cap and the rotor.

Anybody have any idea as to where I should be looking towards for the problem?

P.S Never blows out black smoke and exhaust does not smell like unburnt fuel

 

[countryboy]

have you checked the fuel pressure and changed the fuel filter i remeber a thread not long ago where a rby was doing the same thing or close to it and it turned out to the fuel pump on the frame rail if you didn't know it you have two fuel pumps

 

[Kyler-]

I've now changed the plugs wires distributor and the truck runs a little better but still misses at low rpm and idles rough.
The check engine light never comes on.
Where should I look next?

 

[IMenriched]

I've now changed the plugs wires distributor and the truck runs a little better but still misses at low rpm and idles rough.
The check engine light never comes on.
Where should I look next?

Has the AIC (air idle control) been cleaned? http://www.fordfuelinjection.com/?p=39 often this can be removed and cleaned relatively easily, & with good results

the screw on the side of the throttle body should be set with a VOM (volt Ohm Meter) http://www.fordfuelinjection.com/?p=30

How does it run other wise?? going down the road

 

[robertc1024]

+1 on IMenRiched suggestions. Clean the AIC - made a world of difference on my '88.

 

[Kyler-]

Now with new plugs etc. in the truck accelerates pretty good.
It still has a idle problem, sometimes it idles at 500 rpm other times at 1000.
I cleaned the iac and now a lot of the time it idles around 700rpm but it still feels like it has a miss. When at stop and the rpm is at 700rpm the truck runs greats. When at stop and the rpm is at 500 the truck hesitates and has slight problems accelerating. At idle it seems like it has a miss.

Where do you plug your voltmeter into to get the tps numbers?

 

[IMenriched]

Where do you plug your voltmeter into to get the tps numbers?

http://www.fordfuelinjection.com/?p=30

look at the bottom of page of the enclosed link and read last paragraph.

with throttle closed you may have to adjust the screw until you get the .91v this sets the tps to the correct starting point.

from there it should read smooth and easy as one moves the throttle. as the article states. meaning the needle on the VOM isn't jumping or hesitant.

 

[Kyler-]

So I've been trying to set my tps using the idle screw. that page says to line it up with .91 but for some reason mine has a 3 before it. I left the vehicle off with key in on position then tested the tps, I was at about 3.84 so I backed it out to 3.91 but now the truck barely even idles and does not run very good. Did I test the sensor wrong or is the sensor busted?
Also when I give it gas it doesn't run half bad it just idles really bad.

I Ran the self test and I believe I got code 23