Ok my Dad is going to put a stock TPI setup on his Street Rod very soon. Right now it's a stock LG4 with a Comp Cams 260 duration camshaft. With the TPI swap, he's gonna take off the '416's and put on some World Products S/R heads too. My question is, which system will perform the best under these conditions with no PROM burning? I know MAF systems can take these mods easier than MAP systems, but I need some input on this.

 

MAF will run better with no prom burning.

nick

 

What kind of street rod? I'd go with an SD on a street rod just for the sole reason that you don't have to plumb in a MAF sensor. My '27 Ford will have no room for a MAF sensor much less an intake duct for it, so I'll be running an SD setup so I can have a TB mounted air filter.

But even if that weren't a concern, SD is easier to tune if you can burn chips (and anyone can burn chips; the resources are right here on and linked from TGO).

Just with those heads and a mild cam, the SD won't perform badly without tuning though.

 

It's a 34 Ford. That's a really good point about ducting the MAF sensor. I doubt it will fit anywhere, since he has a huge electric fan in the engine bay already too and A/C. I guess I could help him burn a chip if the SD system goes wacko with the cam.

 

MAF cars run like crap if you change your injector size until you change the eprom. Also, if you max the MAF, you MUST fix the problem inside the eprom or you could risk toasting your motor by running too lean and detonating.

If you want to modify an EFI car and have it perform as it is meant to perform, you need to modify the eprom PERIOD! I don't care if it's MAF or SD.

The big advantage of going SD is it's much cheaper than MAF. In fact, most guys I personally know that have MAF are converting to SD when their MAF sensor goes. I can find SD 7730 ECMs, connectors and MAP sensors for next to nothing where I live. I find the early 1990s Cavalier V6 wiring harness is VERY CLOSE to a SD TPI F-body wiring harness. Swap a few pins and VOILA, you have a SD TPI F-body wiring harness.

Lastly, I have not been able to find many MAF ECMS in wrecking yards these days. Definitely not as plentiful as SD ECMs. SD ECMs are cheap, but when you can find a MAF ECM, they are now asking more (due to it's rareity). The SD ECM came on a lot more different types of cars than the MAF ECM.

So from a cost point of view, SD is definitely the route to go.

PS: When you get into eprom burning, you will find SD much easier to work with.

 

They are both fine. I wished I had an opportunity to try SD on my setup, but I don't have a harness and ECM at my disposal to give it a whirl.

Glenn, how does the SD setups react to a Supercharger? My maf has been so-so. I'd like to play with the timing a bit more, though.. Front two cyls run leaner than the back ones, of course.

-- Joe

 

That's just an issue all intakes with front mounted throttle bodies face. That's why those ugly *** Ford 5.0 intakes run so nice.

 

My car runs great with 24 # Svo injectors, a lot better than it did with the stock injectors. And I have done no work in the prom.

And I did not see anywhere in is post where he mentioned that he was going to change injector size. And with the combo he mentioned he would be no where near maxing out the flow capabilities of the stock MAF.

nick

 

I won't get into this MAF vs SD fight. If you are interested, go to the DIY Prom Board and read up on some of the discussions related to MAF vs SD.

But, you will notice on the DIY Prom site, that people switch from MAF to SD not SD to MAF - hmmmm, wonder why? Maybe it's because you can convert to SD cheaper than buying a new MAF sensor. But, on a cost basis, MAF looses hands down.

You can read Johnny Hunkins correction on the HP difference due to the "MAF Restriction" in the intake. No, it isn't 95 HP as he originally thought, but 31 HP. But this is on a 350 HP engine. As your HP rises the difference will increase.

My personal reason for preferring SD is that you can tune SD more effectively for temperature and elevation than MAF. The MAF is the sole means for the ECM to detect elevation and temperature change via the heated wire. That heated wire does not calibrate perfectly to elevation or temperature unfortunately. Remember, that MAT/IAT sensor on a MAF car is strictly for the EGR, it does NOTHING for temperature correction to the ECM - that is ALL done by the MAF (and in error).

PS: With your 24# SVO injectors, you are running rich and not performing optimally until you tune your eprom. Guys with SD can make a number of modifcations too and their car appears to run just fine also - until they get their assess whooped and they wonder how a guy with less mods beat them.

 

Joe, to convert to SD, you only have to repin the harness. The instructions are available on the DIY Prom Board from Mike Davis. In fact, I'm going to help a friend with the conversion this weekend. It takes less than 1 hour to repin the harness to the 7730 style of connectors. Then you just plug in the 7730 and the MAP sensor (you can even reuse the wire leads that go to the MAF). I figure 1 1/2 - 2 hours to complete the conversion (and that is with beer breaks).

As for SD with a Supercharger. The problem with the 7730 is that it is a 1 bar MAP sensor. But, guys have found that they can repin the 7730 to work like the 749 ECM and then run the $58 code from the Syclone/Typhoon using a 2 bar MAP sensor. That works just fine.

 

I am not trying to say that MAF is better then SD, I am going to switch my car to SD in the near future.

He asked what would be better with no prom burning and I think hands down MAF would run better with the mods he is going to perform.


And the 31 HP they gained was by running no duct work, just an open TB, so I doubt on the street with some intake plumbing and a filter. That they are going to see those kinds of gains, but that is whole other discussion.

nick

 

OK So you repin it to a 7730, then repin it to a 449? Is there a writeup on this? I'm sure its been asked a billion times.

Is the 449 the GN ecm or something?

-- Joe

 

The GN's use a 148 ECM,
the 749 came in Turbo Sunbirds and of course the SyTy's.

In order to run a 749 in place of a 7730 is repin a couple wires. One injector ground is moved as well as the TCC. Must use the SyTy wiring diagrams when using TPI, the Sunbird wiring diagrams (the injectors are different than TPI) are different. Need to run a 7730 V8 memcal in the ECM using the $58 SyTy, Sunbird code. Have done it, just need to change the knumcyl to 0 (8 cyl) and adjust the injectors size to match. The $58 code will run a 2 Bar MAP and there is software that will allow a 3 Bar MAP if you run that much boost. Mine fired up first time using a reworked 165 harness. Do a search for Bobalos or myself on the DIY Prom board for more info. cheers, Bob

 

SD > MAF

 

Interesting.. How much boost can the 730 take before you truely need a 749?? Or is it just a bad idea to run boost on the 730?

-- Joe

 

Well theres no factory code written directly to control boost with a 730, $58 code has/can been used in a 730. See 749 inna 730 in the diy-efi archives. I have not done this route myself, was recommened that going with a 749 was the best route. There is still much tuning needed, have not got any road time as of yet with mine, but she does run, fires everytime, bit of a studder at idle and she pops thru the intake occasionally. But I have not made any changes other than to V8, injectors and invoked manual code. Have not had any road time as of yet just bolted in a nine inch and still finishing fabricating mounts for the disc brakes. cheers, Bob

 

Interesting.. I'm still debating..

Are the proms (chips) on the 165 and 730 the same?
I'm thinking of burning my own proms, rather than going with Accel DFI like I origininally planned.

I've been reading some posts on here about changing the source code. Sounds kinda appealing.

Though assembly is icky, I think my Motorolla 6502 (Commodore 64) programming days will come back to me.. heh

-- Joe

 

Most that burn there own proms will tell you once you get over the inital shock eg, informatioin overload, that there isn't much the factory ECM can't do other than run low impedance injectors, which really all that DFI, and maybe simpler software offers. If you start digging into the code then, well it up to you how far you go. hth, Bob

 

iroc22, I'm almost done my MAF -> SD swap, so if your dad wants to check out my setup, I wouldn't might dropping by your place. Takes me about 1 minute to switch between the two systems.

 

Alex, do you switch that easily?

 

Hmm that might not be a bad idea. My Dad doesn't have his TPI setup yet, but he will be getting it soon.

 

I went to the local electrical parts store and got some crimp on quick disconnect connectors.

Originally I wanted to have them all on one connector, but the wires were too short, so I had to use two.

I removed my EGR solenoid and used the EGR signal wire for the MAP signal wire. I also spliced into the TPS 5V and ground wires for the MAP sensor. To switch, I just unplug the quick disconnect, plug in the MAP sensor, and unplug the MAF sensor. Then I switch the PROM.

Tomcat on the PROM board did all this stuff, I just copied him.

Oh yeah, this is with the Holden Commodore 808 code. The hardest part was switching the steering to right-hand drive to be like the Aussies.

I've got some issues with trying to hook up the scan tool though... I'll make a post on the PROM board when I get it all figured out.

iroc22, let me know when he gets the setup. I've got a 165 wiring harness if he needs it.

 

Man that'd be great. We should maybe setup a time.

 

i have recently purchased a MAF tpi to replace my tbi... you guys are saying to switch i need to do some simple stuff (time consuming) and get the sd computer???
Shawn

 

Actually you're in a good position for the swap because you probably still have the MAP sensor and the connector, with nice long wires on it.

If the swap that I'm doing works out, you can keep the 165 computer, but you'd need PROM burning equipment, and probably lots of tuning.