Hello All,
I've got a 1989 Ford F350 with 460V8. EEC is in limp mode, so it doesn't advance timing. I am wondering if I can put a vacuum advance distributor on it and retain the factory EEC to control the fuel injection.

 

No that will not work. The EFI distributor sends the PIP pulses from the sensor inside for several purposes besides triggering the coil.

What makes you think the truck is in "limp mode"?

 

Why not just ask the computer what is wrong and fix that so the system works the way it's supposed to? I'm not trying to be a smartass either, pulling the codes can be done without any special tools and those codes should at least point you in the right direction. With a truck this old it's just as likely there are issues with the wiring and connectors as there is with with the sensors themselves but this action helps narrow down the possibilities. There are lots of very knowledgeable people here that can help guide you through this and sort through the results you get.. if you're not savvy in that way.

 

Good Post Paul,
I have never figured out why people first thing want to pull parts & go backwards with fixes.
Craig

 

I've gotten the computer tested. First off it's neither retarding nor advancing timing, it's running the tranny in limp mode shifting pattern, and it doesn't retain any CM codes most of the time, and the only code I can get is 67, internal processor failure. I can't get the ECU to run KOER test either, it always kills the engine, and it can't maintain idle either. Once or twice, it won't kill the engine while running KOER, but then the CEL comes on and stays lit without leaving a code either (computer hangs). Oh, and it starts really hard when hot (not retarding timing when starting), and amazingly easy when cold.

I've checked with several other people who work on these computers, and they all agree the ECU is in limp mode.

I know your not trying to be smart . I've got a OBD1 tool, and have also borrowed a friends more expensive tool, with the same results.

Cause the computer won't tell me what is wrong other than itself LOL! The only code it ever gives me is 67, which for my computer variant means Internal Processor Failure. I'm planning to replace it with a aftermarket ECU, but right now I was hoping I could put a vacuum advance on it to help with performance a little til I can afford the ECU.

The CEL comes on when we are driving and the engine warms up all the way, it always turns off when the key is turned off and almost NEVER leaves a code. If it does, it's 67. Sometimes while driving, the CEL will turn off and the truck feels like a whole different vehicle (it went out of limp mode).

I'm not trying to go backwards LOL! I'm trying to get a little better performance while I am waiting to get the actual fix.

So if I HAVE missed something, let me know. But if I am right, I will have to get either the ECU fixed, or a new ECU, which I am looking to go with the latter to allow me to program a "highway mode" for better fuel economy when in O/D.

Another quick question. I am familiar with the Dodge engine control systems, but not as familiar with the Ford systems, so hence this question. Do these engines have either a crankshaft position sensor or a camshaft position sensor or is it just the distributor sensor that sends timing info to the ECU? I ask cause I didn't see those parts listed for my truck anywhere.

Thanks!

 

There is no direct crankshaft or camshaft position sensor like the later model vehicles use. The PIP sensor inside the distributor is a rudimentary trigger that sends rotation information to the computer. The stator does have a signature vane that signifies where cylinder #1 is at.

For reference: Fuel Injection Technical Library » Stator (RPM)


As far as getting a "new" PCM is concerned you are not going to get it tuned to provide what you desire. These devices are not directly programmable like a full-blown OBD-II PCM. A new one or rebuilt for that matter will have factory programming for the engine/transmission/emissions/gearing you already have based on the part number and code of the box. In order to alter that you will need to verify your PCM supports a chip or programmer on the J3 Diagnostic port, then if it does you will need a custom chip or tuner such as a Tweecer or Moates.


Give these folks a call to see if you can get a quote to repair your PCM: http://www.ecurepairnow.com/

 

Yeah you need a new PCM sounds like yours is toast, but that should sort out your problems since both the engine and trans is controlled by the one black box. I don't know what luck you would have with tuning for highway fuel milage even if you found a PCM that is compatible with a tuner, the stock calibrations will run the motor lean enough to be on the edge of detonation at light throttle tip-in so there's not a lot left to play with, from what I gather the biggest gains with the 460 come from gearing it to keep rpms down but of course towing/hauling capacity goes down along with those reduced gear ratios.

 

I'll call them, I did get a quote at the place I usually use for PCM repairs, they said $175.

I'm not planning on tuning a Ford EEC though, I'm planning on assembling a MegaSquirt ECU, and getting a standalone TCU.

Yeah I know the 460 is just plain a fuel hog. I have 4.56 gears, which doesn't help with fuel economy, but with those gears when the ECU decides to work it will out pull alot of diesels (no joke, I've had normal diesel drivers say they wish they had that power).

The stock tune from Ford is designed for emissions controls, so they won't (or rather can't) lean it out as far as it can go, mainly because of timing control and vapour recycling (EVAP, PCV). I know a guy who leaned his out to a 16:1 A/F ratio and was happy with it when he had made the needed modifications. He did that just with a tuning chip on his factory ECU, but he never used it for towing either.

Basically with the MS I can program a "highway mode", it automatically enters highway mode when it detects a high-vacuum low RPM condition (you enter the vacuum and RPM ranges), that way it only enables it when in whatever gear is desired, in my case O/D.

Well thanks guys! I'll let you all know how the later mods go