Fox What To Do To Get My Mild SEFI 5.0L To Run The Best. Tune?

ZephyrEFI

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Mar 9, 2019
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Hi

So, I'm looking for opinions. Here's what I've got going. I've built my Zephyr around swapping in a 1990 SEFI drivetrain/harness/dash. The parts car was a LX 5.0 with an automatic. You might as well just think of it as a 1990 Mustang. Over time, I've upgraded or replaced just about everything except for two things, the shortblock and main wire harness and engine electronics. The A9P is still in place. Among the replaced parts are a T-5, GT40P heads and intake, 24# injectors, 190lph fuel pump, C&L 73mm MAF, and Ford Racing GT40P shorties, and better flowing exhaust. The 5.0L is tired and has never run that well for whatever reason. I modded the engine over the years pretty much out of boredom and to put off deciding what to do to make the thing run nicer. I know I've made things more complicated on myself in the process though.

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Well, the time has finally come to do something about it. I'm about to replace the stock shortblock with a new one from TRE Performance. I will take the opportunity to swap in a mild Flowtech cam, and upgrade the rockers to pedestal mount rollers. Not looking for crazy horsepower here, just a nice street cruiser. Anyway, once that is in, it's time to address the electronics. I want this thing to run like new. I want it to start right up, have no problems idling, and not start pinging when I get on it.

I've heard that “calibrated” aftermarket MAFs have their limitations, so I grabbed myself a '93 Cobra 70mm unit to swap in. It's close to the C&L in size, and matches well with what I've got downstream of it. I've also heard that if your MAF and ECU don't understand each other, the thing will never run right. I have been looking at the possibility of adding a chip/programmer to my A9P, but the mismatch with the MAF has me rethinking that. I'm considering getting myself an X3Z Cobra computer. I understand that you CAN modify the MAF curve with a programmer, but that just looks like a nightmare to deal with. I'd really like to avoid that, hence the Cobra computer. Most of my parts on the engine are Cobra spec anyway, except for the rockers. I do also like the fact that the X3Z is a manual transmission ECU, unlike my A9P. I've heard that can cause idle and cruise problems not having the ECU match up with the trans. But I still might be looking at a dyno tune with a programmer because of the cam and it would be nice if the ECU didn't go looking for the AIR system that's no longer there. All the other emissions stuff is in place though.

So, I'm leaning towards going to an X3Z with programmer, but if we go that far + dyno tune, we're pretty much looking at the cost of a PnP Megasquirt. So, that's on the table too. People really seem to like them, and it bypasses the MAF issue entirely.

I'm curious to hear some people's experiences with this sort of thing. Do you think the X3Z will even need to be tuned? What would you do in my shoes?
 
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a91what

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I'm biased, my car is running on megasquirt... I got bored with speed density tuning and tuned it MAF. Just cuz I could, now there is a learning curve but with some guidance the Ms is easy.

All that said the stock ECU will easily do what you want it to.

Btw i have a set of pedestal mount svo 1.72rr
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Have you scanned the computer for codes? Also there is a thing with the 02's between the auto computer and the stick one, they are pinned different.
What I'm saying is work out any problems you have with the setup as is first then it makes the block swap go smoother.
 

Dan02gt

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Mar 2, 2003
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I've seen nothing but issues with C&L meters. I would recommend swapping it with a ProM calibrated for your 24s. I bet it would make a big difference.

The idle issues you have heard about with the miss matched computer/transmission is probably due to the NSS that used for load calculations based on if the car is in gear (auto or manual) or has the clutch pushed in on the manual. We did manual swap on a 91 GT my dad had and left the auto computer in place. We just properly connected the NSS and his car ran perfectly. With a E cam never the less.
 

aztecgwynn

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Apr 3, 2015
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I personally with the experiences I have had with my 93 fox and I have used 2 tuners is find one that is familiar with or for your application! And what I mean by that is go to someone who knows that Fox Ford electronics, please stay away from shops who tune newer vehicles and have not tuned your type of car for YEARS!
We have OBDI so not many have the adapters or software anymore too do our type of cars, you can always as well go to mega squirt that is also an option but not many are familiar with that let alone guys who drive their foxes like me who drive daily and don’t have another vehicle to drive to work while you tune your car yourself and it sits at home.
I never had a C&L meter but I have a Pro M now but when I bought mine from LMR.com and received but never checked till tuner plugged into car bad! Dyno computer could not recognize any meter. Until my tuner disconnected and thoroughly checked meter he saw what was wrong. One of the plug connectors was pushed out all the way so meter was not making contact
I would have returned meter to LMR.com but now I was 1 hour away from home and my cold air intake had just been cut because it was too long with ProM meter so we had to push forward.
Moral of story was this when you order any parts from somewhere check all connections to make sure all good. And most important go to a tuner who knows your car and your electronics.
 

a91what

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If you want to read about the MS system you should look around in the digital tuning forum, almost everyone there is using MS.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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My opinion on dyno tuning.
you don't need it with bolt on stuff, unless that bolt on is a supercharger or turbo. Then you just plug in a ms system and tune it yourself.
 

ZephyrEFI

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Mar 9, 2019
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Steve, I actually just bought the 1.6 rockers recently. I chose them because my new shortblock has a bit more compression baked into it, and my P heads have been milled a bit more. I was concerned about piston to valve clearance, although the pistons do have reliefs.

I do have a scanner, and the computer has nothing for me except the KOER code of it looking for the TAB and TAD that aren't there. Check Engine light is not on.

Yeah, the C&L is going. I've heard that "calibrated" MAFs can cause air fuel ratio problems at some RPMs and limit your power. I imagine, even with a quality one, that can probably be eliminated with a long, drawn out MAF adjustment/tuning period, but I really don't want to have to spend months fiddling with this thing. I just want it set up, and be done. Those few mm you'd gain over the 70mm Cobra MAF aren't worth it to me. If it's a good enough match for the factory 65mm throttle body, GT40 intake and 24# injectors from the factory, it's good enough for me. The problem is FINDING an X3Z. They can be had on ebay, but they are going for 3 times what the McParts stores used to have them for. Do you find that to be true with the Pro-M?

Yeah, I know about the O2 harness thing. What a stupid mess with all the year to year differences and everything. I actually spent most of my time here on StangNet looking into it before I joined. Lot of helpful stuff here! Anyway, I think I know what I need to do. The thing with the NSS is a problem too, I'm sure. The A9P is confused when i come to a stop. Even if you wire it up, you still won't be in gear with a load when you come to a stop anyway. I actually cut the NSS circuit and wired it to my clutch switch when I did the tranny swap after careful research of the EVTM.

I have spent some time in the tuning forum too. Looks like there's a lot of knowledge! And it's certainly not lost on me how well-liked the Megasquirt is. I wasn't aware though you could tell it to use the MAF. That's kind of cool. Which one do you have, Steve? I was thinking of the PnP one. I don't want to have to rewire (not that I'm afraid of wiring), because I want whatever I do to be reversible and SIMPLE.

Good to know about dyno tunes. I was worried about having power over the full range of RPM. Right now, with the old engine, HO cam, GT40 intake and heads, A9P, and C&L MAF, I get some serious pinging when I get on it. I'm not that good at setting mechanical timing either, so that may be a thing too. I'm not used to that. I was trained on EDIS cars and OBDII. Speaking of OBDII, I was thinking if i go with the Cobra computer, I would use an SCT 6600. It appears to me that you can monitor your sensors on a laptop with the SCT just like OBDII can. I would love that.

I do think I've chosen a good tuner too. I actually know him from school.

Thanks for the opinions so far!
 

a91what

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My ECU is a heavily modified diypnp. I added a second ECU inside the case, it's called a tinyxio and it is basically an expansion card that talks over canbus with the diypnp.
I am using a Lightning MAF 90mm for it's amazing resolution. The car ran close to perfect on the first start with one of my basetunes loaded.

I am actually looking to upgrade my ECU for my next engine, if you are interested i can build mine to suit anything you want and then some... including a basetune and my remote tuning support.
 
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ZephyrEFI

Member
Mar 9, 2019
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Shakopee, MN
My ECU is a heavily modified diypnp. I added a second ECU inside the case, it's called a tinyxio and it is basically an expansion card that talks over canbus with the diypnp.
I am using a Lightning MAF 90mm for it's amazing resolution. The car ran close to perfect on the first start with one of my basetunes loaded.

I am actually looking to upgrade my ECU for my next engine, if you are interested i can build mine to suit anything you want and then some... including a basetune and my remote tuning support.
That's nice of you, thanks! We'll see what happens when I get things back together. I have a friend that's offered to lend me an X3Z to try also.

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