SD problems with modifications, who has them?

[Ryan@FRP]

Hi guys, new to the site. was referred here by Southern_Pride.

I am a Mopar guy at heart, but I am learning my way around Fords.

My understanding is most if not all enthusiasts eventually swap out their SD ECU's for MAF ECU's and go that route, or go carb.

I do EFI tuning on the side, mainly on Mopars, which are ALL SD, and think that I can help those that could use some assistance in making their SD setups work for them both in terms of drivability and power.

So who has SD, what mods do you have, what problems do you have (surging? poor part-throttle performance?), and if you could make the SD ECU work, would you want to re-tune it?

[gadget73]

Mine ran badly lean according to the dyno A/F results. Lots of pinging and such too. I'd have left it SD if the standard response to the idea of tuning speed-density wasn't "MAF conversion". Annoying my MAF setup could stand some tuning anyway so its not like I totally fixed it's ills. It runs a little fat now instead of lean though, so I'm just wasting fuel instead of the motor. Mods in sig if its relevant. Most of my MAF issue is probably the MAF itself. Its not exactly the one that the ECM expects, so the transfer curve is a bit wonky.

[Ryan@FRP]

Mine ran badly lean according to the dyno A/F results. Lots of pinging and such too. I'd have left it SD if the standard response to the idea of tuning speed-density wasn't "MAF conversion". Annoying my MAF setup could stand some tuning anyway so its not like I totally fixed it's ills. It runs a little fat now instead of lean though, so I'm just wasting fuel instead of the motor. Mods in sig if its relevant. Most of my MAF issue is probably the MAF itself. Its not exactly the one that the ECM expects, so the transfer curve is a bit wonky.

How much of a PITA is it to swap between SD/MAF? Is it simply a matter of switching boxes and removing the MAF/adding the MAP sensor? Your setup is not all that extreme, a little VE tuning probably would have cleared it up. I am betting your SD leanout issue was at high rpms?

[gadget73]

It actually ran lean from idle mostly on up, but it did finally get below 15:1 around 4000 rpm or so. It was horribly lean from about 2500-4000 though, in the 17:1 range. I know the mods aren't that extreme, and I have yet to have someone explain why it ran as bad as it did, yet it did. World + dog said that it should have run just fine without tuning, yet it did not. I have the dyno graph around somewhere and I can scan it if you want. I haven't had it re-checked since I swapped things over but it feels significantly better driving and the fuel economy went up at least 1 mpg.

The MAF thing is about 5 wires. I think its move one wire in the ECM connector, tie in a hot, a ground, and add 2 pins for the MAF signal. MAP just gets its vacuum line unhooked and it becomes a BAP sensor. ECM itself gets replaced as well. I expect thats a bigger part of why everyone does this, its just so easy to do. The stock air intake plumbing is also sort of crappy, or at least its very much in the way, so a lot of people don't mind the fact that something else needs to be fitted.

[Lincolnmania]

my town car runs super with sd.
mods: thumper ported e7 heads, 1.7 roller rockers, ported intakes, 65mm throttle body, headers and duals

[Ryan@FRP]

It actually ran lean from idle mostly on up, but it did finally get below 15:1 around 4000 rpm or so. It was horribly lean from about 2500-4000 though, in the 17:1 range. I know the mods aren't that extreme, and I have yet to have someone explain why it ran as bad as it did, yet it did. World + dog said that it should have run just fine without tuning, yet it did not. I have the dyno graph around somewhere and I can scan it if you want. I haven't had it re-checked since I swapped things over but it feels significantly better driving and the fuel economy went up at least 1 mpg.

The MAF thing is about 5 wires. I think its move one wire in the ECM connector, tie in a hot, a ground, and add 2 pins for the MAF signal. MAP just gets its vacuum line unhooked and it becomes a BAP sensor. ECM itself gets replaced as well. I expect thats a bigger part of why everyone does this, its just so easy to do. The stock air intake plumbing is also sort of crappy, or at least its very much in the way, so a lot of people don't mind the fact that something else needs to be fitted.

It's not too too hard to figure out, forget everything you know about MAF.

It's a little different than the DCX stuff I'm used to , but Ford's SD ECU's reference part throttle fueling in accordance to the Volumetric Efficiency tables, that are laid out according to Load (DCX does it by KPA/Torr/Pratio depending on the ECU), and RPM. I suspect that the mods you have done have increased VE to a certain extent at all RPMs in comparison to a LOPO 302 from '86 (not too dififcult to do). This would in effect lower the load percentage, in effect using a section of the VE map that is normally programmed for less fuel in the stock tune. O2s can correct to a certain degree assuming they are functioning properly and in the exhaust stream.

When the ECU understands it has to add fuel to achieve stoich AFR at part throttle, during Open Loop (WOT or heavy throttle) driving the ECU will PULL fuel under these conditions by referencing the LTFTs. Likewise, when the ECU is rich, pulling fuel in closed loop, it will add fuel in OLs. Many dyno tunes and their tuners lack emphasis in this regard, focusing on WOT and that's about it. I tend to spend 90% of my time on VE tuning/spark, 5% on setting OL target AFR, and 5 % on the "other" stuff.

I would think if there was a viable tuner specializing in SD that wasn't priced in the stratosphere, most people would forego the MAF swap. If I could find someone with an SD ECU, and had the ability to send a datalog from either a wideband AFR that logged MAP/RPM or a datalog from a Quarterhorse or equivalent unit showing Load/RPM/Long Term Fuel Trims, I'd gladly put together a retune.

[zoomie]

It's not too too hard to figure out, forget everything you know about MAF.

It's a little different than the DCX stuff I'm used to , but Ford's SD ECU's reference part throttle fueling in accordance to the Volumetric Efficiency tables, that are laid out according to Load (DCX does it by KPA/Torr/Pratio depending on the ECU), and RPM. I suspect that the mods you have done have increased VE to a certain extent at all RPMs in comparison to a LOPO 302 from '86 (not too dififcult to do). This would in effect lower the load percentage, in effect using a section of the VE map that is normally programmed for less fuel in the stock tune. O2s can correct to a certain degree assuming they are functioning properly and in the exhaust stream.

When the ECU understands it has to add fuel to achieve stoich AFR at part throttle, during Open Loop (WOT or heavy throttle) driving the ECU will PULL fuel under these conditions by referencing the LTFTs. Likewise, when the ECU is rich, pulling fuel in closed loop, it will add fuel in OLs. Many dyno tunes and their tuners lack emphasis in this regard, focusing on WOT and that's about it. I tend to spend 90% of my time on VE tuning/spark, 5% on setting OL target AFR, and 5 % on the "other" stuff.

I would think if there was a viable tuner specializing in SD that wasn't priced in the stratosphere, most people would forego the MAF swap. If I could find someone with an SD ECU, and had the ability to send a datalog from either a wideband AFR that logged MAP/RPM or a datalog from a Quarterhorse or equivalent unit showing Load/RPM/Long Term Fuel Trims, I'd gladly put together a retune.

i have a quaterhorse at the shop i work for, but i will be using a d9s computer from a mark vii. i am planning on tuning for 24 lb injectors, but have no idea where i would get a strategy for it, from what i understand the d9s is almost or very close to a da1 mustang computer. the build i am doing is a HO block with gt40p stuff on it, eventually i plan on getting a cam, but right now just getting the new motor in is priority. i would like to tune it afterward though

[Ryan@FRP]

i have a quaterhorse at the shop i work for, but i will be using a d9s computer from a mark vii. i am planning on tuning for 24 lb injectors, but have no idea where i would get a strategy for it, from what i understand the d9s is almost or very close to a da1 mustang computer. the build i am doing is a HO block with gt40p stuff on it, eventually i plan on getting a cam, but right now just getting the new motor in is priority. i would like to tune it afterward though

I think I can get a definition for a D9S, I have a LUXO (for a DA1) here on my laptop. If you can get a datalog for me, do you want help?

[gadget73]

It's not too too hard to figure out, forget everything you know about MAF. I suspect that the mods you have done have increased VE to a certain extent at all RPMs in comparison to a LOPO 302 from '86 (not too dififcult to do).

I had an ECM in there for an HO engine, not the lopo. That would have been really horribly off. I wouldn't figure that my motor has that much higher VE than a stock HO but apparently it disagrees. Could be the cam profile not being the same as the HO, though with a little less lift and duration if anything it should be the opposite problem.

Some of the SD ECMs are supposed to be compatible with various tuners but I dont know how well they actually work. The usual candidate is the Mark VII ECM because its far more available, but its very possible that the Mustang one would behave itself more better-like. I really wouldn't have been opposed to keeping the stock metering system if it wouldn't have been such a problem finding someone that would make it run right. Its outside the norm, so for most people its automatically bad and horrible and wrong and all that other crap that people say when they really just don't know how to work with it. I'm usually the guy messing with all that crap that everyone says is horrible, and frequently its not horrible at all, its simply that nobody knows how its supposed to work. SD is probably the same way. I'd like to learn how to do the engine tuning so it actually behaves and I think I'd understand it given the proper tools, time, and someone to 'splain it to me.

[86VickyLX]

I had hesitation issues with speed density. turned out to be the O2 sensor harness was backwards. I suppose if I were to ever go back to SD it would run just fine. Mods below in signature.

[1990LTD]

I'll find out soon enough, once my car is back together. I'll be running an SD computer (DX3) with an HO intake and a 95 cobra camshaft and 19lb injectors. I think it should run fine since I'm not running a much bigger intake system than stock, and my heads are still stock....but I could be wrong.

[Ryan@FRP]

I had an ECM in there for an HO engine, not the lopo. That would have been really horribly off. I wouldn't figure that my motor has that much higher VE than a stock HO but apparently it disagrees. Could be the cam profile not being the same as the HO, though with a little less lift and duration if anything it should be the opposite problem.

Some of the SD ECMs are supposed to be compatible with various tuners but I dont know how well they actually work. The usual candidate is the Mark VII ECM because its far more available, but its very possible that the Mustang one would behave itself more better-like. I really wouldn't have been opposed to keeping the stock metering system if it wouldn't have been such a problem finding someone that would make it run right. Its outside the norm, so for most people its automatically bad and horrible and wrong and all that other crap that people say when they really just don't know how to work with it. I'm usually the guy messing with all that crap that everyone says is horrible, and frequently its not horrible at all, its simply that nobody knows how its supposed to work. SD is probably the same way. I'd like to learn how to do the engine tuning so it actually behaves and I think I'd understand it given the proper tools, time, and someone to 'splain it to me.

The smaller cam compared with the heads and other mods you've done would explain it. It's not so much the change in VE, but the change in VE which changes load which leaves the ECU referencing a different cluster of cells than expected. It's all about the fuel trims, not the VE.

I am using Tunerpro, and the DA1 boxcode with LUX0 strategy is mostly there. It's not perfect, but good enough for me.

I looked up about 10-20 threads about SD tuning (Ford-specific, mind you) and nobody really had a solid answer as to why SD is so bad, just "my tuner told me I need MAF" or "You can't mod SD bro". The few guys that were playing with SD were just modifying fuel pressure!

If you understand basic tuning concepts (advance, AFR, etc), I could probably have you making changes to your own VE map in 1 hour.

[86VickyLX]

I looked up about 10-20 threads about SD tuning (Ford-specific, mind you) and nobody really had a solid answer as to why SD is so bad, just "my tuner told me I need MAF" or "You can't mod SD bro". The few guys that were playing with SD were just modifying fuel pressure!

It's not really tuner friendly because, it's relying on a sensor that measures vacuum or lackthereof to determine engine load. The engine is pulling 19 inches of vacuum (just a number I picked) in stock configuration. Now you port the heads, put a different intake on, bore the motor out some. Now it still pulls about 19 inches of vacuum, but the computer still thinks that it's a stock configuration. There is not really a decent adaptive memory on OBD-I cars (except mid 90s when they were getting ready for the OBD-II crossover). The problem with tuning Speed density is, you really don't know how much air is entering the engine, without a mass air sensor, and potentially a wideband O2. so if you were to go to all the trouble to fit your car with a MAF sensor for tuning purposes, it would be a lot less annoying to make it a Mass Air system. It's more straight forward to tune a MAF configuration than to tune a Speed Density one.

I'd love to see what you come up with though. I for one would love to see a SD tuned panther. I have the quarterhorse software and I'm running an A9P (Mass air auto) in my vic, with a quarterhorse. Though my next panther, whenever I get it, I'd like to keep Speed Density for the convenience of plug and play and not having to mess with any wiring.

[GM_Guy]

I would think if there was a viable tuner specializing in SD that wasn't priced in the stratosphere, most people would forego the MAF swap. If I could find someone with an SD ECU, and had the ability to send a datalog from either a wideband AFR that logged MAP/RPM or a datalog from a Quarterhorse or equivalent unit showing Load/RPM/Long Term Fuel Trims, I'd gladly put together a retune.

Affordable is the key. More often than not, junkyard MAF swaps are cheaper. In case you are not aware, the Ford eec-iv SD is not directly programable, which plays into Mustang MAF swaps being the norm for high performance guys. Mustang material is common. Aftermarket Lo-po SD support is nothing.

For SD mods you got things like the SCT 6600 http://www.sctflash.com/products.php?PID=31 it is a piggy back chip for SPECIFIC SD computers. So even if you wanted to do this with your cv/gm, you would still need to swap to a compatable (usually Mustang) SD computer to pull it off. Back in the "old" days, SD mods where mostly single tune piggy back chips. If your going to swap beyond a basic HO conversion, most opt to do a MAF swap, since you can usually source all the bits 'n pieces for realtively cheap.

Alex.

[84merc951]

i would like to have someone figure out sd as ive been fighting the hesitation and surges for 3 years now with the ecu showing no codes. my other cfi car runs better than my sd wagon. the sd is so iregular as it will run like a top for hours then with the flip of the switch it runs poor at idle, part throttle issues, and idle surges. i thought for sure it was my egr system but the egr eliminator didnt fix all of the issue. every day i get closer and closer to thinking of a carb swap. i wish i didnt live so far away from most of you guys because people out here dont no much about anything.