Slow Iroc

Well, I'm going to do it guys, I'm going to take the plunge and get a single plane intake, setup for EFI use, a big throttle body, and get ready for high RPM power...

Downside, computer control. DFI is too expensive, and a carb...well...just isn't cool, lol. So, I have an 86 Iroc, that is a MAF car (obviously!), but I will no longer be able to use the MAF, and I won't be able to replace it with a MAP sensor either. That leaves me with the "Alpha - N" or fuel and ignition advance based upon TPS voltage...

Now this is where I will need some real help. I've read most of the articles I could find on prom buring, and it seems pretty simple, especially once you get used to it. You copy the prom as a binary file, and edit the tables to your liking...then reuse the old prom with the new charts. Sounds easy enough. However, in this case, I won't simply be able to edit existing fuel and advance maps...this will require a complete reworking of the program, as far as I can see. Somehow I have to eliminate the MAF information, the MAT information, the EGR information, and run the car solely on the O2 sensor at part throttle and the TPS at 3/4 thorttle and higher.

Now here comes the question part of this whole thing. First, IS THIS EVEN POSSIBLE with my existing ECM? Second, how dificult do you think it will be to accurately make a binary file for this application? Is there anyone out there with personal experience that I can go to in case I run into problems (like the car not starting, lol). Also, will I be able to keep my fuel pump relay?

Thanks,
Slow Iroc

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86 IROC-Z, Retired for winter, weird oil leak (drains out in about 3 minutes), new 355 other than that, TPI, 700R4, edelbrock headers, removed AC/Air pump, heater plate conversion - no heater (loL). 14.8@90MPH

Next project (think I'm going to scrap the IROC)- mid 80's monte carlo, 383, edelbrock performer RPM intake, cam, holley double pumper carb, sportsman 2 heads, NOS. Hoping mid/high 12's on motor, mid 11's on spray.

TRAXION

SlowIroc,

What you have described is a major undertaking. By major I mean HUGE, ENORMOUS. If you have years of experience at disassembling machine code (assembly language), modifying it, and then reassembling it then yea - you could do it. But, even then it would be a fairly large task. To be honest - even I would not consider such a project. Basically, what you want to attempt is 'assembly language programming'. This is completely different than modifying the tables, flags, and constants in a PROM image.

As I see it, you have 2 choices.
1) Convert to a 730 so you don't have to use the MAF
2) Go with an aftermarket DFI system.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

Slow Iroc

Okay, by 730, I assume you are refering to the 90-92 MAP computer? That would be great...except for one thing, I can't use a map sensor either...the intake is just not designed for one... so what I'm curious to know is why the 730 would be better than my current setup?

Thanks,
Slow Iroc

Grim Reaper

For the MAP sensor, you just need to plug it into any place you can get vacuum from the manifold.

TRAXION

Why do you think that your setup can't use a MAP sensor. Of course you can. Just get a billet 4 barrel EFI TB that has vacuum ports. Another option is to plug a fitting into the 4 barrel intake manifold or into a spacer between the manifold and TB.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

Slow Iroc

Okay, so basicly your saying a stock Bosch MAP sensor will work in this setup, as long as I have the required vac. ports (I'll have 3 to play with)? I didn't realize I could use a MAP sensor and a hose to a vac port, so that is some great news! Now, the bad news...Do I have to change my wiring harness or have a custom one made? The reason I ask this is because I would like to make the installation as simple as possible (don't we all strive for this?) and that harness is a PITA in my car to do anything with.

If I have to use a stock MAP harness...what about the accesories? I'm running V-belts, not Serpentine, and since every 88 and later car was Serpentine...well I don't see how it could be made to work with my Vbelt accesory positions. Of course, I could be mistaken here as well.

Lastly, do you think that by use a MAP sensor, that it will become MUCH easier for me to burn a prom for my application, or will it still be Mission Impossible...?

Thanks guys,
Slow Iroc

CanadianBeast

It seems to me that with the 730 and a map sensor it's mission very possible especially with the knowledge on the 730 avaivalable on this board, (Glenn and Trax). I assume you've read traxion's and Glen articles, search for p730, I think. If you search a little more around here somewhere there are links to a site which outlines converting a maf harness to a map harness.
You are plannig to plumb the injecters into the runners on the single plane, correct? If so I think you'll have pretty good sucess with the 730.

87IROC350

http://www.eecis.udel.edu/~davis/z28/

Check out this link for all the information you need on the conversion. I am currently making the conversion on my car.

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87 Iroc 5.7, AFR190, SLP Cam(218/224), SLP 1 5/8 headers & cat back, Random CAT, SLP Runners, 48mm TB, custom chip(by me), Vigilante & Probuilt trans.

Slow Iroc

Well that dosen't look like it would be too tough...or that easy for that matter. So the 90-92 cars use two knock sensors, or just a different knock sensor? How do you run the lead for the new (second) KS using a MAF harness? Lastly, are the clips for the MAP and MAF sensor even remotely the same physically (Number of leads going to each at least)?

Seems like MAP is a real PITA, but hey, it's the only way to do this, whatever works I suppose...

Funny though, I was going to go with the single plane for it's price compared to a MR, (along with it's much better air distribution -cylanders 5-8 are starved in the MR, especially 7 and 8, but we won't even go there in this post), however after the cost of going to a MAP setup is included, the MR is actually cheaper...and some might argue that the MAF is a better way to meter air because it does it directly, as oppossed to estimates based on vac. Also a blower can be used with a MR...god, so many things to think about! Either way, I will be burning my own proms, so expect to see a lot of stupid questions from me, that I may overlook in articles...

Slow Iroc