Mustang EFI / 347" - tuning options

[jbickhart]

I put all stock '93 Mustang EFI parts on my motor before I knew it was a 347" engine. I haven't touched the computer. I added an A/F meter in the dash and I've been driving it for several months. Is this close enough?

Cruise: 14.2-14.7
Idle: 15.5-16.5
WOT: 12.9-13.6
16mpg avg.
Excellent throttle response from 400rpm to 5k. I haven't rev'd beyond 3000 in months. I don't need max HP..... can't keep it between the lines above 70mph anyway.

Flat top pistons
Dart 190cc intake aluminum heads
mid-length headers
208 / 212 @ .050 H Roller cam

I don't want the 'project' of custom tuning. If I need to adjust.... what should I try?

 

[Mountain Ram]

Plenty of power and good gas mileage... What are you wanting to change and why?

Todd

 

[blazinchuck]

Plenty of power and good gas mileage... What are you wanting to change and why?

Todd

exactly lol

 

[73azbronco]

It looks like you need to be schooling us. Those numbers look fine. Curious how you didn't know before but now know its a 347?

 

[xcntrk]

Do you get any knock at WOT? 12.9-13.6 seems a little lean to me... Slightest bit of knock at WOT could result in damage and with a 347 stroker there's no fixing scored cylinder walls....

Just one persons opinion - I'm no expert but have done a lot of EFI tuning...

 

[jbickhart]

I just want to keep the motor healthy and wasn't sure what A/F ratios to look for. Im "far" from what most recommend for a 347" motor. Part of what makes it ok is my altitude.... I live at 6000 and haven't driven below 5000. The other part is a self imposed limiter around 5k.

I think ill leave it as-is. But, I don't imagine it will handle WOT at sea level. No knock at 5000- 12000 feet.

I bought the truck unseen with a carb'd "rebuilt 302". After delivery I noticed the heads and HO firing order. I didn't pull the pan until after buying stock 302 Efi stuff.


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[blazinchuck]

if ya skeerd, say ya skeerd...lol. ive hit 6500 no problem;D

 

[jbickhart]

Im scared. With rock crawler spring, coming off a WOT run through 2nd gear to grab 3rd put the truck on the front bumper and I have a little bump steer issue that moves me across the fog line towards the ditch. Id be happy with 300 lb ft and 150horse.
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[jbickhart]

Xcntrk,

I have a set of 24lb injectors. Would u try them with a recalibrate mass air (C&L)?

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[ilovemaui]

If it ain't broke don't screw it up. I don't think you see much out 24 lb injectors except lower milage. What diameter MAF are you running? Gears?

 

[jbickhart]

4.11 gears. NV3550 OD trans. 33" tire. 60mph....2000 rpm.

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[xcntrk]

Xcntrk,

I have a set of 24lb injectors. Would u try them with a recalibrate mass air (C&L)?

24lb injectors at a minimum. You have a motor built to produce 350-400HP and are running an injector designed to support 250hp. Also your MAF is too small at 55mm which is limited to around 275hp. As for how to trick the PCM running larger MAF & injectors; personally I'm a fan of direct tuning and sensor scaling within the PCM, but I know many have luck with those re-calibrated MAF's too.

But don't take my word for it; hear it directly from Ford Racing:
http://www.fordracingparts.com/download/tipsPDF/ProperlySelectingEFIComp.pdf

 

[JackHoleRacer]

I added an A/F meter in the dash and I've been driving it for several months. Is this close enough?

Cruise: 14.2-14.7
Idle: 15.5-16.5
WOT: 12.9-13.6

I dont want to hi-jack, but what is a A/F Meter? and is that what you used to get those numbers? How do you use this meter?
I apologize in advance......

 

[73azbronco]

AFR is air fuel ratio. Used to determine if the mixture is right

http://en.wikipedia.org/wiki/Air–fuel_ratio

I'm still lost, so how do you know it's a stroker? I ask because with 19lb and stock ecu, your afr numbers are right on, including
wot, might you really have a 302?

 

[xcntrk]

I'm still lost, so how do you know it's a stroker? I ask because with 19lb and stock ecu, your afr numbers are right on, including
wot, might you really have a 302?

What part of those numbers are "right on"?

Idle is too lean, cruise is too rich, and WOT is too lean.

Idle is less important as the motor is under zero load, but may run a little rough. Target idle should be 14.7.

Cruise AFR is important for gas mileage. It's okay to go leaner as the motor is only under minimal load. Average cruise can be around 15~16.

Wide open throttle is critical. Too rich is safer but at the cost of power and MPG's. Too lean is more dangerous (danger being detonation threshold). Ideally you want to be lean enough to produce peak power but still have a margin of cushion against knock threshold. You need that cushion for potential changes in fuel (aka summer vs winter blend), changes in altitude, and changes in temp, all of which can influence detonation threshold. There's also a point of diminished returns, or commonly known as minimum best timing (MBT), which also relates to AFR. This is that narrow point between making peak power and going over the edge towards detonation. Where 1 more degree of timing advance or 1 more gram of air (leaner), only gives you a return of minimal power gain at the cost of higher risk of det. That said, target WOT AFR ranges are generally between 11-12:1 for safe & powerful operation.

$.02c

 

[KyleQ]

You have an AF guage, if you want an easy fix you can pickup an adjustable FPR and bump your fuel pressure up a little bit to take care of your lean idle and WOT A/F's, but you will loose some MPG.

The correct was to address this is to have it professionaly tuned on a dyno and have a chip burned for it. There is nothing wrong with the EFI parts you have on it, but I would get at least a 70MM MAF and TB on there and get a tune.

Those 19lb injectors at 99% duty cycle will support 300HP - you want your duty cycle around 80%... You want at least some 32lb injectors to safely support 400hp.

 

[73azbronco]

I agree but, according to the article I linked:

maximum power is frequently reached at AFRs ranging from 12.5 to 13.3:1

so the OP's WOT numbers of 12.9-13.6 are pretty close for initial settings.

Cruise at 14.7 is perfectly stochiometric.

Idle at 15-16 is lean, but he says no issues, he is at altitude so unless he feels or hears detonation at idle.... Thats why I'm asking, how does he know he's got a stroker? It sounds with those numbers like he doesn't. I would expect WOT to be lean if he had an untuned undersized EFI system.

 

[KyleQ]

expect WOT to be lean if he had an untuned undersized EFI system.

It still has a MAF and O2 sesnors - the computer can still read and account for how much air is going through the system. You can run a 408W with a stock Mustang PCM just fine - you won't get maximum power out of it, but ti will run fine.

If he doesn't have detonation and runs mid grade he should be fine - at least he has an A/F gauge, watch that and enjoy it.

 

[73azbronco]

exactly, but my question remains, how does he know its a stroker?

 

[ilovemaui]

AFR is air fuel ratio. Used to determine if the mixture is right

http://en.wikipedia.org/wiki/Air–fuel_ratio

I'm still lost, so how do you know it's a stroker? I ask because with 19lb and stock ecu, your afr numbers are right on, including
wot, might you really have a 302?

I am currently running a 76 mm maf and 19lb injectors in my 408. I have a wideband O2 with gauge and I'm running pretty much exactly the same AFR. So, I'm not surprised by his numbers.

I'm planning to run a 90 mm MAF and 42 lb injectors. Waiting for a replacement Quarterhorse tuner (my first one was defective).