1985 F-150 idle issues.

Hey everyone. Im new here with an 85 F-150 4x4 swb with a fuel injected 302 that im currently restoring. it has a re-manufactured jasper engine that i installed and i have replaced high and low pressure fuel pumps, distributor, throttle position sensor, coolant temperature sensor, heater core,  idle air control valve, and the air charge temperature sensor. When i purchased the truck it had a cracked block due to the previous owner having a leaky water pump and instead of him replacing it he continuously would just add water. well a hard freeze happened the January after hurricane Harvey and claimed the block. I have about got the drive train all lined out and am about ready to start doing paint and body work. (ill add pictures of the truck later) Ive been looking into possibly converting this engine from speed density to MAF and was wondering if anyone here has done this? my reasoning behind wanting to do this is because i want to add a cam to the engine and my research has shown that doing so to a speed density setup would cause a lousy idle due to it effecting the vacuum on the MAP sensor. Has anyone had any experience with this? Thanks in advance.

I can't comment on converting to maf system but I can say that putting a more aggressive cam makes the computer a little confused with speed density. I have an 86 f150 with a 302 efi. I rebuilt it and put bigger heads, and a performer camper cam along with quite a few other modifications. Anyway the camper cam isn't crazy aggressive but it does make the truck have a hard time with idle to some extent. If you were to blip the throttle and expect the engine to come to a nice idle then that will not happen. Mine will start idling up and down crazily until I manually bring the throttle up and let it down slowly. The truck also seems to have to relearn how to run every so often too. But right now im in the process of rebuilding the engine harness because it is in terrible shape so that couldve also been playing into some of the issues i was having. Sorry about rambling on and it gives you some insight into what it runs like with speed density. On a side note the truck runs down the road just fine.

Welcome to the forum!  

I don't know any more experience with SD vs MAF than you, but I have read that it doesn't take much of a cam change to get the SD outside of its map, and then it doesn't run well.

And, my understanding of going to MAF is that you have to change out the ECU to an EEC-V, which takes a different wiring harness, both for the ECU itself but also to the injectors and to accommodate the additional sensors.

Unfortunately, between the time of your truck being built and the advent of EEC-V systems in the mid-90's the power distribution wiring changed significantly, with a power distribution box being implemented on the driver's side, and the ECU wiring emanating from there.  So I don't think it is as straight forward as it might seem at first.

HOWEVER, I've not yet done the wiring, so I may be wrong.  Let's let those that know more about it chime in.

First, welcome to our group of craziness! The 1985.5-1986 EFI system is a bit of a bastard system, it was Ford's first foray into port injection and as such has a number of differences from the cars and 1987 up trucks. First thing I would recommend would be to look at the EEC pinouts (Gary, I can't remember where it is hidden) to see the differences.

The 302s got MAF/SAFI in 1994 for automatics, 351s in 1995, and a very few 460s in 1996. One more thing to consider, early 1985.5 EFI engines have a completely different fuel rail than later models. The fuel delivery system was used through the 1989 model year on all EFI engines, 6 cyl through the 460.

If you update to a later SD system, you will need to (a) repin the EEC connector and (b) add a speed sensor unless you have a speed control, then you can use the existing sensor. Even the EEC-V box will fit in your existing mount location and the power and fuel pump relays will work with the newer systems.

The pinouts are in Fuel Systems/Carburetors, Chokes, & EFI/EFI.  (Boy, I need someone to help me rationalize the layout thereof!)

It depends on the cam chosen. And for a truck, I think you should be fine. because unless you are going for a high RPM cam ( which most truck guys are not ) , you are looking for something without a lot of overlap, but as much lift as you can get. That won't be too much of a problem with SD.