EFI, plugs 1,4,5,8, black, 2,3,6,7, white, detination included!

FASTERDAMITT · Sep 2, 2008

I getting some funky running issues when warm operation. It will detination under light throttle but also burble like it getting to much fuel at a little higher rpm. I understand the computor on this EFI fires 1458 plugs on one cycle and then 2367 on another. I found a little corrosion in the computer plug and cleaned it up, then put some diolectic grease on it. Still have the issue. I know the white plugs are running lean as I can hear the detination as soon as the engine gets near warm. No codes.
Anybody with an experience like this?

Viperwolf1 · Sep 3, 2008

If you use the HO firing order it's firing 5481 then 3726 in that order. Also interesting to note is that the inner cylinders are lean and outer ones are rich. Could have something to do with the intake manifold airflow. Fords EFI intakes all have nearly equal length runners if you count the upper manifold length. Does that system use a Ford ECM? I would think there would have to be some compensation programmed in for runner length differences.

FASTERDAMITT · Sep 3, 2008

Yes it uses a Ford ECM. What I don't understand is why one bank if firing lean and the other is rich. The computer must be sending injector signals incorrect. I checked power and ground to the ECM and I found 12.6 volts and good ground.

stevestang · Sep 3, 2008

I think the firing order on the Ford late model efi engines is 1,3,7,2,6,5,4,8
could it be possible the inside injectors are clogged or gummed up??
Are the inside injectors the same make and model as the outside???
I have heard that impedance matched injectors work better.

I would also check the wires going to the inside injectors.
You can always swap an inside injector with an out and see if the prob follows the injector

FASTERDAMITT · Sep 3, 2008

The injector firing is different than the plug firing. The computor sends signal to the four inner injectors at one time and the four outer at one time. So the plugs are firing at different times than the injectors. So I'm pretty sure it's a computer issue or similar.

70_Steve · Sep 3, 2008

I don't know $hit about EFI (yet), but I took a look at the Mass-Flo EFI system. Looks like it comes with its own harness but uses a Ford EEC.

What's happening to your plugs looks like what I've seen in other threads where the O2 sensor connections have been switched from one side to another. Only difference is that, normally, one whole side (1, 2, 3, 4) is lean and the other side is rich. You might want to take the time to ohm out from the EEC connector to each of the injector plugs, to make sure the EEC is firing the correct injector.

Socal Tom · Sep 3, 2008

What was the donor car for the ECM? My first thought would be to disconnect the o2 sensors. Also disconnect the battery for 10 minutes, then try it. If it still detonates, then you may have plugged injectors.
Tom

FASTERDAMITT · Sep 3, 2008

What would disconnecting the 02 sensors do? I'm not sure what car computer comes from, I would have to cross the part number.

70_Steve · Sep 3, 2008

FASTERDAMITT said:
What would disconnecting the 02 sensors do?

The EEC should go in to open-loop control, relying on lookup tables in memory for the amount of fuel, based on TPS.

FASTERDAMITT · Sep 3, 2008

If I disconnect the battery first it would clear the memory, should I do this before disconnecting the 02 sensors or just not disconnect the battery at all?

Viperwolf1 · Sep 3, 2008

Disconnect the battery to clear the memory, then disconnect the O2 sensors, then reconnect the battery. It's always a good idea to have the battery disconnected when messing with any sensors.

FASTERDAMITT · Sep 3, 2008

Ok. Does anyone know if the 02 sensors are linked to the way the injectors are fired or does the computer utilize signal for left and right sides only?

(Bank Firing Injectors · Bank fire means that the injectors are divided into 2 groups. On V8 engines cylinders 1 4 5 and 8 open together and cylinders 2 3 6 and 7 open together. · Bank Fire program is not dependant to the firing order of the engine.)

Broncobowsher · Sep 3, 2008

What computer are you running? If it is a truck computer (batch fire) it may not be running the drivers correctly.

Although I don't see how it would happen in this case, I rember stories about swapping left and right O2 sensor wires and the engine would get confused and go mixed rich and lean. The sensors don't swap sides, only the harness swaps sides. May be worth a shot.

rcmbronc · Sep 4, 2008

The Mass-flo system I installed in my brothers Trans Am uses a A9 Ford computer.

FASTERDAMITT · Sep 4, 2008

I'm not sure. I assume the number is on the case, I would have to look.

Socal Tom · Sep 4, 2008

Ok, I looked at the Mass FLO website. What they appear to do is use a ford computer to fire a GM throttle body. So it's probably a batch fire computer.

I think you have either got the o2 sensors installed on the wrong side or you have a plugged injector.

Tom

grant_71 · Sep 4, 2008

Isn't this what happens when you have a non-HO engine, then switch the injector plugs to "match" the old firing order?

rcmbronc · Sep 4, 2008

Socal Tom said:
Ok, I looked at the Mass FLO website. What they appear to do is use a ford computer to fire a GM throttle body. So it's probably a batch fire computer.

I think you have either got the o2 sensors installed on the wrong side or you have a plugged injector.

Tom

The Mass-Flo system uses a Ford Mass Flo type computer along with a custom designed throttle body. It has a GM style custom made Mass-Flo meter that is converted to talk with the Ford Mass flo computer and their custom chip. It also uses multi-port fuel injectors. The MAF is mounted on top of the throttle body.

I would recommend calling Mass Flo. They seemed real helpful when I was ordering the system I put on my brothers trans am.

rcmbronc · Sep 4, 2008

Is the intake a dual plane or single plane on the Ford version?

FASTERDAMITT · Sep 4, 2008

Single plane Victor JR.
I was leaning towards something with the 02 sensor. But what is confusing is only two plugs on each head are lean, but two are rich. I wonder if the 02 sensor is wired some way that could cause this.
I should call Mass Flo again, Chris said look for corrosion on eletrical contacts which i did find some and cleaned, I just like picking your brains though.

EFI, plugs 1,4,5,8, black, 2,3,6,7, white, detination included!

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