Well here is one that I am just now learning. I was reading that the TFI IV ignition system is none adjustable and if you check timing and its not at 10 degrees Btdc that you need to replace the ignition module? Now granted I read this in the Chiltons but I dont imagine they got it wrong. So is it true? or are there other ways to skin this cat?? Is there a better may be not so expensive or difficult way to convert to a better system? well thanks in advance for the input
Joe

 

The 10 Degree base ignition timing is adjustable by turning the distributor.

stractor

 

Your Chiltons should have a detailed set of instructions for setting base timing, mine does. The procedure for setting EEC-IV TFI base timing has been posted several timings in this forum as well. First thing to remember is that the SPOUT needs to be disconnected prior to checking.

 

Found it, thanks for the prompt, the timing checks out good. 10 Degrees BTDC with the spout un plugged, after plugging the spout back in it does as the book calls for, so I have eliminated some things as to the rough running issue. There still is some pinging when stepping on the go fast pedal and top speed levels out at 72 MPH and doesnt idle right in gear when stopped. Idles good in Park or neutral, the intermittent miss at highway speed has gone away but there are still some issues, so its back to the books and scratching the head, any Ideas??? Thanks again
Joe

 

Just the everpresent question....have you pulled the codes? Your Chiltons will have the procedure for jumping the test plugs and reading your CEL.

 

Not Yet, I have the jumpers made and I got the procedure. I will get to them here soon, however, I recently bought the truck from the original owner 71 year old retired Army guy, he had it shut down for 2 months prior to me buying it, The carb. Accel pump was messed up and was dumping fuel so bad when I checked the plugs there was no gap on 3 of the 6, they were clogged soild with a carbon/fuel paste, the other three were real wet. So, I rebuild the carb do the tune up, plugs, wires, rotor, cap, find the engine with no air filter. Get it running clean the intake with a 1/3rd can of sea foam and run the rest in the tank, now I am starting to lean torwards a possible plugged Cat converter, I figure the old guy was running it so rich for at least 2-3 months prior to him parking it that there is a good chance a 21 year old cat might be part of the problem, So I think I might break a flange loose and take off screaming down the road to see if the power will return, if so, problem solved. If not then its time to look at the codes. By the way are you prior Air force by chance? I am retired Navy. Well thanks again

Joe

 

Sounds like a plan.

Air Force??? No, I'm Retired Army Aviation. Crew'd Huey's for 12 years then transissioned into Chinooks.

 

One very likely cause for this problem is the EGR valve, It leaks when it gets and can cause the engine to idle badly. Remove the egr valve and use the gasket as template to make a blank. install the blank and the gasket and try it. Before i tried this I replaced the Intake manifold gasket twice and rebuilt the carb.

1984 F150 TFI IV 4.9L

 

If the issue is the EGR it may be an easy fix. Pull the EGR and clean it with carb/throttlebody cleaner. With a vacuum tester make sure that it has full range of operation. If it does then clean the position sensor and harness plug with contact cleaner and reinstall with a new gasket.

If cleaning doesn't restore full range of operation it needs to be replaced. Or you can go to block off route. Either should solve the extra air if the source is a faulty EGR.

 

Well, the cats are not plugged. Took off the exhaust pipe and drove it. Still ran the same. I did a lot of thread reading on the EGR, mostly the EFI guys talking about putting in a restricor plate to correct there problem. I checked at Idle and there is no vacuum to the egr which is the way it is supposed to be, and its plumbed correctly as per the Vac. diagram under the hood. Would it idle rough if there was an EGR problem? I thought EGR problems were at higher RPM under load. Again the engine was run for a long time dumping gas, I did ponder the thought of the EGR being all carboned up. I am slowly with the help of this forum eliminating possible problems, I am now moving on to the EGR then onto checking cylinders by pulling the wires one at a time while running to see if there is a dead one?? I read in another thread to check the egr by pulling the green hose and taping it or capping it off then ignore the dash light and take it for a test run to see if things clear up. Well eventually I will find the problem, just wish it would be sooner then later. I just got it and I am chomping at the bit to take it for a long drive. Tanks again

Joe

 

If the EGR is not closing completely due too carbon buildup maybe.

A new gasket is only a couple of bucks. So you'd be a little ahead anyway to pull it, clean and op check it. If its bad make a temp block plate and reinstall.

Something else to consider. The exhaust ports in the head and/or the exhaust manifold could be partially fowled restricting airflow. I only point this out since you said that some of the plugs were fowled from overfueling.

 

Seems to be the next step. I wish I had a borescope then I could snake it all around to check things out, however, I believe when I pull the EGR that will tell some sort of story. either way clogged or not I am sure it is in need of a cleaning. Well I hope we hit it on the head this time. I know we are getting closer. Well, i will let you know how it goes.
Joe