1989 a4ld to FM146 swap - need help!

[Zachalanche]

I just completed my FM146 swap as far as all the mechanical components are concerned. I have been able to start my truck by just leaving the neutral safety switch plugged in and pressing it into the correct position while turning the key. the ruck ran fine with no check engine light for two days until I had time to hook up the clutch position switch and jump the wires for the neutral safety switch. At this time I also unplugged the battery. when I hooked up the battery again I found that my truck was able to start as it should with the clutch depressed, but the engine won't maintain idle and runs very rough when gas is applied. The check engine light is also on all the time. I have read that I need to get the different computer to match the manual trans but I need to know if something else is wrong since everything worked fine until I hooked up the clutch switch. any info would be much appreciated.
Thanks.

 

[engdept]

Did you swap the PCM (replace the auto PCM with a manual PCM)? If you didn't, that could be your problem.

 

[Zachalanche]

I tried the PCM out of a working 87 ranger with manual and exact same engine. Couldn't even get the starter to crank when I did that. apparently I need the EEC-IV form 1989? also why did everything work prior?
Thanks

 

[engdept]

You need a manual transmission PCM out of a '89-'92 Ranger with a 2.9 and all the same options. The older Rangers had a different pin out on their PCM.

The reason it worked before with the auto transmission is because the PCM was for an auto transmission.

Also, did you hook up the CPP (Clutch Pedal Position) switch or did you jump it?

 

[Zachalanche]

the part about the PCM year makes sense.

when I mentioned it working before I was refering to after the manual swap before I hooked up the pedal psition switch. I was essentially jumping it via the netral safety switch removed from the auto trans.

 

[engdept]

You shouldnt' have jumped it via the neutral safety switch. The CPP came from the factory with a jumper wire in it if it was an auto transmission. You could have left the jumper in it without a problem.

The neutral safety switch has 2 wires in the automatic transmission wiring harness that MUST be either tied together or tied into the neutral safety switch wires.

 

[Zachalanche]

the 2 wires you speak of were the ones I jumped/tied together. sorry I've been mixing up my terminology.

 

[engdept]

You probably fried your auto PCM.

 

[Zachalanche]

Great! I love fried PCM. not sure how I did that, but. I'm picking up a manual PCM today so we'll see how that works.

Thanks for the help.

 

[engdept]

Not a problem. Post up how it goes. More than likely if you have the neutral safety switch wires wired correctly it will work.

 

[Zachalanche]

Well, I think the junk yard sold me the wrong computer. They swear its for an 89 with manual, but it the Code # on it is C9B which according to www.fordfuelinjection.com is for a 2.8 L. when plugged in however i am able to read the error codes, which my original computer will not let me do. tis this another sign that the original computer is fried?

 

[engdept]

Yea that is a good sign your old PCM is shot. If it was a 2.8 PCM, I don't think it would allow you to read codes; I don't think the '84 had that feature.

 

[MAKG]

EVERY RBV computer had that feature. Back to 1983. Every EEC-IV computer contains a self test.

And the neutral SENSING switch must be connected on a manual transmission computer, or the idle will not work. And -- get this -- the KOER self test will refuse to run. Is that your issue?

The neutral SAFETY switch does become the clutch switch. There is no neutral safety switch on a manual transmission. It's perfectly legit to start a manual transmission in any gear or in neutral.

 

[Hahnsb2]

.

And the neutral SENSING switch must be connected on a manual transmission computer, or the idle will not work. And -- get this -- the KOER self test will refuse to run. Is that your issue?

Thanks MAKG, that explains why I can't get any KOER tests to work, haven't hooked up either of the tranny wires yet.

 

[Zachalanche]

alright I verified the part number of my computer with the dealership. they mentioned that I may need to have it re flashed. any thoughts? right now when I plug this computer in the truck won't even crank. At least with the auto computer it starts and runs, it just won't stay running without giving it gas. currently I have the clutch switch plugged in and the neutral on the auto trans harness wired together. so I don't think I should have any issues, but for some reason I am getting a MAP out of range code with the manual computer and I don't think that is actually the case.