I posted this in the TBI forum back in December but didnt get a reply.

I've got a 78 Ford F150 rockcrawler with a 351M and a 4 speed. I've been running TBI on it for a few years with the 7747 ecm. The 7747 is dialed in pretty good for the stock rebuilt engine but I'm wanting to switch to the 7427 pcm and run the $0d MAF bin that Demented24x7 posted up on this board cause I'm planning a head and cam swap soon.

IF anyone has done this swap I've got a few questions. First on TunerPro it shows a high and low speed fan output in the scalars but I've only found mention of the fan control going to pin E1. Is that the only fan output or have I missed the other one?

The other question is about the VSS moving to pins F2 and F3. I've only got one VSS wire with the 7747 coming from a 8000 pulse per mile ford VSS through a 4 out buffer with a divide by two circuit piggybacked so It sends out 2000 ppm to the ecm. The MAF signal goes to F12 so the VSS was moved to F2 and F3 from what Ive read. To which pin do I hook my VSS signal? From what I can tell F12 was the 40 pulse transmission output signal and F13 was a 2000 pulse per mile from the DRAC so I'm confused.

Do I just hook my vss directly to F2 and F3 and which is the high signal and leave F13 disconnected or do I hook the 2k pulse to F13 and leave F2 and F3 disconnected? Both? Neither?

 

Im actually the author of the code

I will put some stuff together and post it here, to give you the basics.

 

Thanks dimented! That would help a bunch. I've been googling and reading until my eyes hurt, LOL.

 

Actually saw you have a 7727. Hardware is slightly different. I went thru setting up a 7727 with another user here. Its slightly different than the instructions for the 8625, just have to dig up the old threads where we did the conversion. The 7727 is missing some hardware that the 8625 has.

 

Thanks. Any help is appreciated. Not sure if its a typo on your post but my computer is a 7427 not a 7727.

 

Can I bump this as I need this info too?

Edit: ugh...I think I just wasted my first post on here...

 

Welcome aboard!

What do you need help with? How to hook it up?

 

No, I've done a good bit of research and got the MAF hooked up. But I don't know if I am using the latest code and I saw the fan controls in the XDF but never saw which pins it used in any of the post. I also need to get it tuned but...I have a stock GM 290hp crate engine (iron heads) and th350 trans, no wideband, and no oxygen sensor. I also couldn't find what all I could edit with a different XDF, like VSS input and flags for a manual transmission. I also have a hydroboost brake system would it help to enable "Power Steering Spark Compensation"? I'm starting to get that lost and overwhelmed feeling, sorry for the long post. Thanks.

Edit:Well i burned my first chip, if i'm not mistaken..it seems to run better than my stock computer, but that might have been in limp mode. I've posted my bin and a short xdl below. Thanks for any help/pointers.

 

Your 2000ppm VSS signal goes to pin F13, and you need to select the option "speed not from Drac"

 

Ok, so i installed an O2 sensor today, and recorded a little. I still haven't figured out the pins for the high and low fan control. I also couldn't get my speed to show connecting my VSS to pin F13 or my P/N to work by connecting it to pin "E5"

 

To get the VSS to work with the 2k PPM, the that flag should be unchecked AFAIK. The 2 kppm signal comes from the DRAC. With that unchecked, the vehicle speed is taken from the magnetic differential input which is designed to directly read the speed from the VSS magnetic pickup. Try it and see if the speed works.

 

First for the fans, only one speed is supported at the moment. Seems to be lots of requests to add a second speed, so I may go ahead and see if I can use the CPP to act as a secondary fan speed.

As for the P/N, is the manual trans flag set in the PROM? If that is, it will be perpetually stuck in drive, regardless of the P/N status.

 

Is the SES on? If its off, then its running off of the MAF. You can tell by doing the paper clip thing and pulling codes. Also, the datalog will show no MAF frequency, in which case it will be running in standard speed density mode.