Directed mainly to Zonker but any resonable answer accepted

In your MPG thread I asked if you tuned for the 19 pounders and you said no, and in the same thread you said that the ZX2 runs 17s stock. I have some questions that I wanted to ask, but didn’t want to thread jack, hence the new thread.

Got the background - now to my puzzlement.

I’ve hooked up 4 EECs to my TwEECer and grabbed a snap of the stock parameters.

The 4 EECs are: LXQ1, EMA0, MTA4, and PPD5. (2) four wire mafs EECs and (2) 6 wires.

The LXQ1 and EMA0 show an injector slope high of 17.46 lbs / hr, and Injector slope low as 21.05 lbs / hr. I’m okay with this as it supports the 17 lbs / hr that you stated and is what I’m use to seeing in Mustang land.

What’s causing me the headache is on the MTA4 and the PPD5 is that the injector slope high is 21.24 lbs / hr and injector slope low 22.5 lbs / hr.

My questions are:
Are the 4 wire EEC cars running 17#?
If they are, why in the _____ is would Ford be doing this?
On the MPG car, was it running a 4 or 6 wire EEC?

Depending on answers, more questions may follow.

Thanks in advance

the 4 wire eec’s run 17# as well afaik. they do have the early steel body injector and have a grey cap on the top (grey = 17lb)

the later models run the plastic body injectors and they are all grey in color.

as for the mpg car, it was a '98 using a stock 4 wire pcm and maf sensor. it was a california spec pcm (did not write the code down, sorry).

I don’t think the PCM code would matter - I think it’s more of a 4 vs. 6 wire EEC code thing.

The 4 wires I have looked at, and admittedly that’s only 2, have the same injector slopes, just as the 6 wires had the same, but my question ‘why did Ford do this?’ still remains.

The only thing I can think of is that Ford raised the slopes in the 4 wire EECs as a way of producing a leaner injector pulse, if you will, there by getting the mileage / emissions they were going for. In the 6 wires, the coding was revised / added to, so the slopes were able to return to a more normal setting and still retain the mileage / emissions.

I don’t know if this theory is correct, but it’s the only thing that makes sense to me at this time. As I under stand it you raise the High slope if you have a rich condition through out the curve - effectively leaning it. If you’re trying to get the most efficient fuel delivery, this might be one way of doing it when combined with other parameters.

What I do see, is that the 4 wires appear to have some fudge room in their injector size, 17 -21# - with the 19# being in the middle, that shouldn’t require any tuning as demonstrated by the MPG Car, and might allow you to pick up a few ponies in the process. Where as I would believe if you tried this with a 6 wire, you’d run rich if you didn’t tune.

Hmmmm… Guess I’ll have to find some 19# 4 holes.


If you do the MPG on the 2000 ATX as you mentioned possibly doing in the MPG thread, are you going to try the 19# on it? I would be very curious to see the reaction the 2000 would have.

And thanks for the feed back.

i plan on playing with my atx parts donor car (its a 6 wire, 2000 my) so we’ll see if it does get too fat from 19’s.

as for why ford did it, it might have something to do with the injector design… im going to guess the later model plastic body injectors have a improved spray pattern for better atomization.

that would be my theory anyways…


I look forward to seeing the results with the donor car.

Your theory on the better atomization could be correct, and if so, could easily play a part, or even a key role in in the theory I proposed.

Lack of information can be frustrating at times, but I’m at least getting ideas

Again thanks