I'm having a problem with my truck. I have a 1988 F150 with 135,000 miles on it, 4X4, 5.0L V8, 5 speed. I'm having a shuddering problem when I get up into 3rd gear and above. It sounds like a missfire. I usually shift between 2200 and 2500 RPM, but anything below 3000 causes the truck to shake. Once my RPMs approach and pass 3000, the shaking slowly decreases.

I have replaced the spark plugs(twice in the past 6 months) although they were fine. I had the fuel injection cleaned. New plug wires, boots, distributor cap, rotor, coil, air filter, oil change, all new u-joints and a new clutch, slave cylinder, and master cylinder that I now have 400 miles on. This problem was happening before all of the work I did to it, but it seems to slowly be getting worse.

I have NO check engine light, and everything else seems to be fine. I'm thinking about just replacing the whole iginition system with MSD, but I want to try and figure out the problem for sure before spending the money.

Any help would be great, thank you for reading,
Jamie

 

Do you still have the air pump and associated plumbing? There is a steel tub connecting the 2 cylinder heads at the back that rusts out and can cause this problem. The solution is to either remove this tube and plug the holes or install a new tube.

 

Thank you, I'll give it a check

 

I checked the tube, and besides a little dirt, it's in great condition, I did notice looking through my repair manual, I have the TFI IV ignition system, yet the rotor and cap Murrays gave me looks like the parts off the Duraspark III system, I'm going to replace those parts and see what happens.

 

What do your plugs look like when you removed them. All should be tan/brown.
What about the air pump and plumbing?
Have you pulled the codes?

 

I don't have the plugs anymore, but i remember thinking that they looked fine, they all looked the same. I'm not really familiar with the air pump system other than that cross tube. And I haven't pulled the codes. I thought the Check Engine light would be on if there were any codes.
I did replace the Intake Air Temperature sensor, and it did seem to help a little bit, next I'm replacing the coolant temperature sensor, and the Oxygen Sensor when I can get it off, it's rusted on pretty bad.

and thanks for your help again, I'll give the plugs a check and check all the air pump stuff.

 

Even if the check engine light is not lit, it may still give you codes to point you in the right direction.

 

I'll give the codes a check then, Thank you

 

Alright, I made a trip to Autozone for some knowledge. I replaced the Ignigiton Control Module, and It fixed 95% of the problem. Now it just seems I have a timing issue. I've tried rotating the distributor to get the best result possible(I heard you couldn't do this on Fords, only Chevys; but it worked on mine). No more shuddering, but a little shaking now and then. I'm still going to replace the O2 sensor, I just need to get it. Hopefully that fixes the rest of the problem.

 

Check firing order ?

 

i never knew autozone gave out knowledge.

get a timing light and disconnect the spout and properly time your engine.

 

I checked the firing order, next is the whole timing light deal. And Autozone hands out way more knowledge than Murrays. Half the time you can give a guy at Murrays an exact part number, and they will still give you a wrong part. Plus the woman I talked to at Autozone knew exactly what she was talking about.

 

quote from autozone employee today, "we do not have obd-1 testers anymore because most people have 96 or newer vehicles."

first time i was in an autozone for a year and probably the last time for awhile.

i am glad the autozone woman parts person helped you out.

 

I see, touche