Swaping from Speed Density to Mass Air.
 

I posted this in the LT1 Tech section a few days ago, and after moving it to the top a couple of times, I got no replys.. Any help would be appreciated guys..

I have a 93 Z28, and have access to a 94 Z28 Wiring harness..
For the setup Im currently building , the Mass Air setup would work much better than speed density for part throttle driving, and for the fact that I can use a Scanmaster to monitor knock retard. Something I cant do with the Speed Density.

Anyone done this swap? What all is involved and which harness actually needs to be swapped.

Im thinking only the harness that has the wiring for the Mass Air needs to be swapped out, then the 94 Computer swapped for the 93..

Anyhow, any help would be appreciated..

James

I am trying to do the exact thing that you are.. i just posted 5 min before you.. If you find any information on this please let me know and i will do else wise.. my e-mail is lt1camaroman93@aol.com


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87 iroc 350, t-tops. 15.2@90 stock for now.
93z a3 with a trans break and 3500 stall, nitrous works 100shot, ported heads, lunati 232/242 duation 510/525 lift 110lsa, groty long tubes, true dual 3" with H-pipe, magnum rockers, !cat, !egr, !air !A/C 13.96@100 first time at track with no mods. Comming soon, adj torque arm and tubular lca's

You will find more differences than just the mass air meter. That's the obvious one. But the 93 has batch fire injectors, one wire from the 93 ECM to four injectors in each bank. The 94 is sequential fire, requiring an individual wire from the 94 PCM to each injector. Then there is the tranny. If you have a 4L60, the 94 PCM will be looking for the "E" signals/inputs to the 4L60E, which you don't have. With an M6, the PCM will be looking for the skip shift solenoid, which the 93 does not have... that's an easy one to correct.

These are the obvious differences that I can think of, but there are probably more.

What specific features/requirements of your current setup cause you to feel that mass-air will provide you with improved operation over speed-density? Big cam? The aftermarket computers are almost all run speed-density, and they can handle anything you can throw at them.

If you are really into monitoring the knock retard, I would think the Auto Xray would work... not sure, but you need to check.

I personally don't see the benefit in the conversions... maybe you could explain your thoughts a little more, so we could help.

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Fred
94 Formula A3+1: 381/TH400+OD/N2O

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11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year

The setup Im building is a ~8.5:1 383, AFR 220 Heads, approx 18-20psi through a D1 or D1R, and Nitrous.

The car is a 93 6 speed Z28.

I was under the impression that the MAF really helped out with part throttle driving on a blower car, I also was under the impression that the 94-95 OBD1 computers could handle a bigger injector than the 93's Speed density OBD1 computer. I need the biggest injector I can run. I dont like the fact that if I want to program the car I have to pull a chip out of the computer, flash it and reburn it, which requires extra hardware to do over the 94-95 cars. I also like the Scanmaster, it can be mounted in dash, is on all the time, and allows you to glance over and see what the car is doing, not like having a bulky Laptop flying all over the car. The car will have a Wideband O2 on it with real time display, but Id like to monitor other things as well besides AF..

Those are really the only reasons I wanted to swap. If Im wrong, let me know!!

As far as the swap is concerned though, I have the entire harness with the injector connections, MAP, MAF, Ignition, all that on it. Im know I can turn the Skip shift off with programming software, That wouldnt be a problem.

James

My reason was mainly for tunning.. I dont like that fact of having to have chips burned if i do any major mods.

James
With a setup like you are building you should be looking more at a aftermarket DFI system. 20 psi on a stock computer then adding in juice is just plain screaming for problems. NOT that it maybe cant be done but it is just opening alot of worms.

If all you are wanting is to have something smaller to look over at to see reading etc. there is lots of egt gauges and wide band setups. You can go from 50-2k for one.
Steven

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383 Inches of stroked turbocharged fun.
If one is good shouldnt 2 be great????? :D:D:D
TURBO=TORQUE
TORQUE=FUN

My Car

damn james your really goin all out arent you. With that kind of setup your lookinto the low 10's and maybee 9's with slicks. Good luck to you and the mouth is sealed

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94 A4 BURGANDY Z
MODS: SLP CAI,FLOW MASTER 80 SERIES MUFFLER,!CAT, SS WHEELS, NITTO DR, MSD 8.5MM WIRES, MSD DIGITAL 6 IGNITION, SLP MANUAL FAN SWITCH,ATI procharger(8psi), HOOKER LONG TUBES

A quick check on airflow indicates you are going to be looking at 800-900gps w/ 20# boost and an aftercooled inlet air temp of 120degF and 7000rpm. I don't think the stock MAF sensor will handle that kind of flow. I could be wrong here, I know I'm not knowledgable on blower motors, so correct me if I'm wrong.

If you are serious about that level of boost, I think it would not be a very good idea to switch to mass-air, or even to use the stock PCM. You need an aftermarket computer that can live with the signal from a 3bar MAP sensor. Then you will have a speed-density system that you can tune dead-nuts on.

Spending the amount of money that it takes to build a 20# blower 383, then poor-boying it with the stock PCM seems counterproductive.

This is also a new experience to me.. I do have some frineds making 650 rwhp on stock computers, I didnt see why the computers couldnt handle another hundred rwhp or two...

Im still doing research on the tuning issue, a FAST system wasnt in the budget, I fear I may have to push the project back some more to make room for it though http://web.camaross.com/bb/frown.gif

I can't comment specifically on the "how-to" aspect except to say that if you have the right wiring harness and the diagrams (or another car to look at side by side) it should be just a matter of time and patience.

The concept makes sense. I like the MAF, though it has somewhat of a bad name as a potential inlet restriction. With 20lbs of boost I would also want some way to tune directly for boost. Even for my paltry 14lbs I opted for the Superfueler for that reason. The reason I have do not want an aftermarket ECU is that I want to keep the MAF. The concept of using a 2-bar MAP sensor and retuning the PCM to match has been discussed. It's probably possible, but I think it would be very tedious at best.

Rich Krause

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'95 Z-28 383 with Vortech, nitrous, etc.
"1FASTZ28"