Mass Flo / Ford Mustang F.I. help needed

[philminotti]

Hopefully someone here can give me a direction to go...

My new 482FE build is using Mass-Flo injection, which is essentially the injection system from the '89-'95 5.0.

I'm having a major problem with timing ( I think). The distributor wiring harness has a "spout" connector, which enables the computer to handle ignition advance.
With the "spout" connector removed, my engine starts fine, idles fine, has rock solid base timing. Mass-Flo recommends a base timing of 14* without the spout, which should jump to about 22-24* with the spout. With my engine idling happily at about 950 rpm and 14* initial, I insert the spout connector, and the motor dies. The timing becomes erratic, the engine misfires. When I watch it with my timing light, it almost seems like the computer is dumping in loads of advance and causing misfiring.

Like I said, with the computer controlled advance disabled, the motor runs really well, revs well (albeit slowly), with very stable timing. I'm getting 8-9" of vacuum, which may be a little low, but shouldn't affect ignition advance, I don't think, as this F.I. system doesn't directly measure manifold vacuum anyway.

I've double checked the distributor installation. I have spoken to Mass-Flo. That's all I really want to say about that.

I may try posting at EECTuner.org as well, but I know we have some real geniuses here as well...

Any help would be appreciated.
phil

[wrench87]

the only thing i can think of is make sure you are 14 degrees before top dead center and not after?, i know on the 5.0 mustangs they have 2 scales so it is easy to overlook. iam not sure how the fe balancer is marked. you may also check and make sure you have a ground strap on the back of your cylinder head to the frame, i remember moving my distributor on my 342 with mass flo and hearing the fuel pump cycle due to the distributor looking for a ground through dis body.

[wrench87]

also this set up uses a bap sensor not a map sensor so make sure there is no vacuum line connected to it.

[Blittleton]

I'm having a major problem with timing ( I think). The distributor wiring harness has a "spout" connector, which enables the computer to handle ignition advance.
With the "spout" connector removed, my engine starts fine, idles fine, has rock solid base timing. Mass-Flo recommends a base timing of 14* without the spout, which should jump to about 22-24* with the spout. With my engine idling happily at about 950 rpm and 14* initial, I insert the spout connector, and the motor dies. The timing becomes erratic, the engine misfires. When I watch it with my timing light, it almost seems like the computer is dumping in loads of advance and causing misfiring.

Phil,


Of all the Mass Flo's I have done. this is never the case. With the spout disconnected, the engine is wanting to die, idle erratic. At least with my case. I think your timing is off or using the wrong set of timing marks. Typically the carb FE is wanting 18 base and 38 Total if I not mistaken.

Bill

[Ronbo]

I'd be chasing that vacuum level first...

Idle air bypass motor sounds like it's stuck open to me. (couple "love taps" might get it unstuck)

No trouble light codes coming up? www.fordfuelinjection.com has lots of valuable info on this system. Basiclly the Mass-flo is a stock '93 Mustang setup with a GM LS 6 air meter adapted to it.

Could be a bad TFI module, but it doesn't sound like it. Might try clamping off the PCV hose as well.

[philminotti]

Thanks for the replies. Perhaps I marked my balancer wrong. I have to pull the passenger side head anyway for a coolant leak, so I'll be able to check.

Ronbo, is there some link between manifold vacuum and timing that I'm not understanding? Mass-Flo is not a speed density system (as you know), and doesn't directly sense vacuum. I agree, my vacuum is disturbingly low, but I can't figure how low vacuum might create my timing problem.

phil

[Ronbo]

That's true. But you could end up with lean levels being detected by the O2 sensors or unusually high air flow levels reported by the mass-air meter (or high air flow not being reported in the case of a leak). I'll have to check, but i believe the SPOUT also diables most of the other logic loops besides timing adjustment. (basically the computer only uses the fuel map)

Vacuum leaks are one area that the computer's logic processes can't compensate for very well.

The Mass-flo system has a "bare bones" set of sensors, especiallly compaired to today's setups so it's not as forgiving as the sales fluff makes it sound like. For example no speed sensor or knock sensors like most modern production systems.

Actually your post threw up a flag, coolant leak? An intake gasket could be your air leak as well.