Hey guys I took my 88 F150 for another long distance drive at 65mph and I saw an issue that I overlooked last few times I was doing 65 it has always done it also.


For some reason it does not want to rev over 3500 rpms unless going down hill going over 70.


The truck did great otherwise but everytime I hit a hill it would slow down because when I gave it more gas it wouldn't rev up otherwise it would have done great.


The truck currently turns between 3K-3200rpm at 65. It acts as if it has a rev limiter on the truck and won't let it rev. If I could just get the truck to see 4K rpms everyonce in a while I know it would do the hilly 65MPH trips I drive without a hiccup and keep up if not do better then our newer vehicles.


Truck is a 88 F150 4x4 302 C6 RCLB 4.10s with 31s. The 302 has HO pistons (higher compression pistons hypereutetic,aluminum), comp 31-255-5 cam, and is completely rebuilt all the way. The trans has a shift kit in it also and was rebuilt in 95. The exhaust is fairly new with a custom y-pipe and no cats still stock manifolds for now.
Thanks for any help
Trav

 

Does it act like this in every gear or just 3rd at highway speed? I'd start easy and put a new fuel filter on it. Also had a faulty coil do something similar once. Would run like a bat out of hell to about 3500-4k and just fall flat like a limiter.

 

Check fuel psi.

It could be weak and your flooring it won't bring the psi any higher.

Another thing, in my '92, 302, bored 0.040 over, 31-255-5 Comp Cam, 1.7 Crane R. rockers, 3.55, 4wd, MAF conversion, I'm pushing it all the way to the floor depending on the grade of hills in DRIVE, not OD. For that extra Umphh! , I drop it into 2nd, and get up and by!

 

Fuel pressure is the first thing you should check.

Also, no codes present?

And damn, 3500 rpm cruise is not comfortable. Ever think of an auxiliary od?

 

Does it in every single gear yes. Might have to put a new coil on it was in the plans anyways (want an MSD) even though mine is brand new along with all the ignition system (timing is at 12* BTDC).

Yep floored it she still turned 3500rpms only would not go farther. I didn't feel comfortable droping it into second when I am already turning 3500 rpms in 3rd.
Everything in the Fuel system is new (and working) minus injectors which I cleaned up. Fuel PSI is good I checked it after I put a new pump in again.
Every sensor minus ACT is brand new and working. Only code is for the TAD and TAB which is because I have the smog system deleted.


No I don't want any OD on this truck it rarely goes long distance my chevy or new to me 91 Bronco 4x4 351W E4OD will do most of the long distance. This truck only does long distance once in a while it mostly just drives me to and from work 50mph being speed limit most of the way however I would like the truck back to where it should be.


Only thing I have is the rear anti lock light which I haven't figured out what that is maybe a VSS? could that cause my issue?
Also my downshift cable can be stubborn at times and it takes a while to down shift after driving 65MPH for more then a couple miles. Could this be an issue?
Want to replace the cable but don't know where to get one for a 302 C6 4x4 EFI.
Trav

 

I know very little about transmissions, but I have spoken to a reputable transmission guy that is as solid as they come.

I got tired of the "creeping" above 65 and I had been been contemplating having my AOD completely rebuilt or a different valve body being installed, so that I could have that extra ummmphh! So I talked to him about the problem and a solution. I asked him about dropping into 1st as that is all I have on the column shifter after (D) and would it cause any damage. He said that with the AOD, the internal governor won't let it shift that low at a given speed to prevent damage, that it will drop to 2nd, and that it would be ok as long as I didn't keep it there for an extended amount of time. Granted, you have a C6, but perhaps you have reached the max for the internal governor at that speed.

I just wanted to share my experience with the same problem.

Also, stay away from MSD junk! It's just red colored expensive plastic.

 

You got a bullnose bronco now too! Where do I see pictures of that!?

 

I will have to try it or ask the trans shop in the town that I was driving to. LOL


No I got a bricknose bronco. I will be uploading pics soon in my 88s build thread.
Trav

 

Wow I feel stupid. I meant brick nose haha special moment.

 

Ok so I tried droping it in 2nd at 50 and it seemed to rev a little higher then 3500 now. I couldn't do 65 as I wasn't taking that road and to many sheriffs out right now. Usually at 50 I am turning 2500 rpms so it raised it 1000 rpms.


Also it seems to me like it is going into 3rd to soon. I am wondering if I can somehow make it drag out 2nd a bit longer. I can't seem to remember what part you have to change out to make it take longer to go into 3rd. I need to find out either way as I have a C6 I am going to be rebuilding to put in this truck (stage II trans as I want the truck to be bulletproof more or less).
Trav

 

What does it do if you put it to the floor from a stop? It should wind out to about 4200-4500 RPM before shifting into 2nd.

 

Nope if you floor it from a stop goes up to 3500-3700 rpm then shifts (if I haven't done it in a while it shift hard).
Trav

 

That sounds too low to me for wide open (you kept your foot planted to the floor, right?). The AOD, E4OD and 4R70W trucks typically shift around 4200-4400 RPM wide open.

There's a little screw inside the vacuum modulator you can turn in to raise the shift points.

 

The detent lever on the side controls wot upshift point try adjusting the detent cable

 

My modulator valve doesn't have a screw.


I was able to get up to 65 and drop it into 2nd and it roared to 4500 rpms today since everybody was stuck in church.


Almost floored yes but I believe if you floor these trucks it cuts off the fuel or at least I know it does when trying to start it.


mudsport what is the detent cable? I only have a downshift cable and it isn't adjustable.
Trav