Question about the X3Z ECU

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GTJay99
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Question about the X3Z ECU

Post by GTJay99 »

So I have an extra X3Z in the garage and gave it to my bro to use in his GT. He's runnin a cobra intake and added 24lb injectors. Does the X3Z require a specific MAF Sensor. Reason I ask is when the X3Z was installed car will not start. Just sputters and dies. He's using a factory ford GT Maf. When A9L installed car ran just with wrong injector pulse. Any help be great. I know the X3Z has correct signal output for 24's. Not sure if it's wanting a specific curve signal frol MAF. Or if my spare X3Z is a bad one. Never changed it on my 93 so never had the issue.
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1986Browns
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Re: Question about the X3Z ECU

Post by 1986Browns »

The factory MAF for a GT (standard 5.0 HO) is set up for 19lbs injectors. The Cobra EEC is looking for the 70mm Cobra specific MAF set up for 24lbs injectors. Without a custom tune the Cobra computer and Cobra 70mm MAF are kind of a "matched pair" so to speak.

Change out the factory GT MAF for one from a '93 Cobra and that should take care of the issue.
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Re: Question about the X3Z ECU

Post by 1993cobra »

It should start , even if you unplug the maf sensor
GTJay99
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Re: Question about the X3Z ECU

Post by GTJay99 »

Ya the car tries to start but wont run. With a9p it starts fine. Just trying to determine if the X3Z is toast
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Re: Question about the X3Z ECU

Post by Two Coupes »

This thread is aging, but I thought I would chime in.

Our 93 Cobra's MAF are for 19 lbs. The X3Z does the conversion to the 24 lbs that came on the cars.

http://forums.corral.net/forums/eec-tec ... a-ecu.html

I came across this link not too long ago. It was news to me... Soon after, my car developed a pronounced flat spot in mid range rpm under moderate acceleration. I threw in my old stock MAF sensor from a 19 pounder 89 coupe and it runs as good as ever.
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93Cobra#2771
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Re: Question about the X3Z ECU

Post by 93Cobra#2771 »

The thread you linked to is full of inaccuracies.

The MAF between the cobra and standard 5.0 are indeed different. However, that difference is accounted for in the EEC itself with a table called "Mass Air Transfer Curve". It is a table that says "when voltage on MAF is X volts, the MAF is flowing Y cfm of air".

The injectors have their own programming within the EEC. Injector size is as simple as it sounds. The number represents the size of the injectors. In ford EECs of that time period, MAFs ARE NOT calibrated to a specific injector size.

The reason why you can swap a Cobra MAF for a GT with little problems is that the transfer curves are fairly close to each other until you get in higher flow rates (WOT operation on a modded car). Then you can run into problems if you aren't careful.

As far as your flat spot - if you disconnect the battery (clearing the "Keep Alive Memory") short and long term fuel trims, does the flat spot go away? Does it come back after a certain amount of driving?

And, as you said, could be the MAF starting to have issues. But sounds more like a throttle position sensor having issues. Hard to say without doing some true diagnostics on things.

CLIFF NOTES: Ford MAFs ARE NOT related to any specific injector size.
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Re: Question about the X3Z ECU

Post by Two Coupes »

GTJay99, The X3Z, 24s and a standard HO MAF not only starts, but is drivable. Mine is...

93Cobra#2771, I Don't want to hijack this thread. I will post another thread or hit you up by PM and walk through the drivability of my car. Thanks for your help.
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