For the last month I have been reading page after page of postings and am happy to say my truck has been repaired.

A few months ago I noticed as I cruised my truck down the street around 22 - 28 mph the truck would gently start bucking/jerking but would come out of it when I would accelerate. When I would lift my foot off the accelerator to decerate the bucking would return.

A few weeks after the bucking symptom started I noticed my truck wouldn't idle down after it warmed up. It would hover on the tach around 1200 - 1400 RPM. When I would put it in gear and I held the brake it would drop to 1000 RPM.

I ran the KOEO and KOER and came up with the 13 code.

I have 67,000 on my 89 f 150 302 5.0 and I hadn't did a tune up in quite awhile so I changed Motorcraft cap and rotor, wires and plugs. I hooked up a Echlin Injector Flushing tool and ran a can through the injectors. Fuel Pressure was excellent.

The Module that sits just under the lower distributor cap by the Distributor hold down clamp and bolt, had a prong that just didn't look weather worthy so i replaced the module and cleaned the connector.

Started the truck up and it ran no different than when I first began tuning it up. Nothing had changed.

I went back to the engine and cleaned the IAC and EGR and did a vacum test and multimeter test on the EGR. I also cleaned the Throttle body. Dirty but with in spec.

Since it had been sometime since my last tune up everything from the distributor cap, plugs, IAC, EGR and throttle body had carbon build up or some sort of heavy wear.

I started up my truck and ran it, had cleared codes and disconnected the negative battery cable and rehooked it. My truck still ran terrible. Nothing I had done had changed anything.

The truck still bucked and jerked and had a high idle. I didn't want to just start throwing parts to get somthing to change.

So I went back to the postings and did some more research. One thing I didn't want to do is start second guessing myself. The postings helped me keep that confidence and trudge onward.

I next planned a stragety and removed the throttle body looking for a vacum leak and looked at the gasket and did find a hairline tear in it. A cheap part so I replaced it. I had also shot some propane around the intake and had no RPM increase, before and after installation.

During that process I checked the TPS with multimeter. It was out of spec so I replaced it with a Napa part. Re- ran KOEO an KOER and got an 11 code, which I had read that was a ghost or common code and no big deal. Used a old MT style Snap-On scanner.

After clearing the 11 code I restarted the truck and the high Idle problem was gone. The Bucking and Jerking remained so I went back to the posts and read some more.

I came across the spark plug routing of the 7 and 8 cylinder earlier on and thought I had routed correctly when I put on my new wires.

I felt I should give my handy work a recheck because I had my hands all over the engine and felt I should recheck bolts and secure any over looked harness areas etc.

When I checked the 7 and 8 plugs I had them set in the clips as 5, 6, 7, and 8. so I rerouted 8 to clear the valve cover better and went as far as putting plastic wrap around it.

I then set the wires up as 5, 7, 6, 8 in the wire loom clips to seperate the 7 nad 8 wire per the post.

I had been pulling the battery negative cable in between repairs so I could start with a clean computer to learn the changes. I went out and drove the truck and the bucking and jerking had gone away.

At next tune up I'll replace the EGR and gaskets and look at the distributor closer.

The EGR was so full of crud and when I cleaned it I thought the pintle seat had that okay look to it, but it also had a ring around it so wear was present on the pintle and seat.

I did notice my upper distributor cap clipped on okay but if I grabbed it with both hands I could move it, like it wasn't lining up or seating exactly like it should. I never replaced the bottom half of the the distributor cap and am thinking maybe I should have, I am leary of getting a moisture problem now. Not sure of how good of a fit I should really expect to have there.

I would like to add that without the helpful posts I would have had to take my truck to the Ford Dealership.

Fortunately after spending some quality time under the hood with my wrenches and my 3 year old son, we saw this repair from start to finish and great sense of accomplishment which I could not have done without everyone posting and helping.

My exhaust tailpipe is starting to look rough so I will tackle it next.

 

If someone said, high idle with bucking and jerking to me, I would have said a vacuum leak is causing the high idle and the resulting lean condition is causing the surging. The symptoms go together so well I would have just beat my head against a wall looking for it. Cool.