Ward

iTrader: (1)

Lets say I took a single plane open manifold, drilled it for injectors, put fuel rails, and a throttle body on it. Would it be possible to use a stock ECM to run it? Not necessarily the stock PROM, but a custom one. What about the ECM and harness from a multiport OBD-1 car, like an older V8 caddilac?

Also, if it is possible to use a TPI ECM, would there be any way to make a Ford TPS work with it? I ask because I have seen an adapter which is meant to bolt to a standard holley carb flange on an intake, then it curves 90* and allows you to bolt a standard ford 5.0L throttle body, which are a dime a dozen at the junk yard.

377Z

iTrader: (1)

Yes, this is possible. The computer does not know or care what engine it is running. To give one illustration, one of the computers GM used in F-body TPI cars was also used on some 2.8/3.1 cars (like the Berretta & such). Not only is the intake different, its a completely different motor with less cylinders! This was allowed since it was a batch fire injected system with a different PROM. The computer just aquires data from the various semsors and uses this information to control fuel and spark. The PROM contains the information that the computer "looks" at to determine target values for the fuel and spark it is controlling. Essentially you can tune the computer to match your combo by changing the information on the PROM.

Example: Lets say you go through with the dual plane, and you use a manifold that flows much better at 5500 RPM than the TPI. At this RPM the computer is still doing the same thing regardless of manifold; however you'd be running leaned out with the stock PROM values because the information on the STOCK PROM is programmed for the TPI's flow. TO remedy this, you would adjust values on the PROM to allow for the appropriate injector pulse time for the condidtions.

Unfortunately it takes some skill. The computer determines how much air is being injested into the motor with A LOT of data. Most people I've seen mod speed density (like the 90-92 systems) systems where air being used by the engine is calculated based mainly on engine load (vacuum & throttle position) and RPM, but accounts for temperature to estimate the air's density. Mixture is further trimmed by oxygen sensor output. Since the computer is estimating, not directly measuring airflow the system is less tolerant to changes than a mass air system (like the 85-89 systems) which does measure airflow directly. I know the theory, I sure wish I could put it into practice.

Hope this helps.

Grumpy

In order to reprogram the prom you need to know the information that's in it. I doubt you'll find much info like that on a Caddie ecm. It would make ALOT more sense to use a fairly common ecm that is well known, so you can spend your time tuning instead of reverse engineering the code.

Ward

iTrader: (1)

Do you guys think it would be practical to use a TPI computer to run a custom EFI setup? I would like to just run TPI, but in order to make TPI feed my 400 I would have to spend alot of money on a stealth ram or superram, and it still probably wouldnt flow great. I'm positive I could setup a custom EFI system, but programming the PROM is what I'm afraid of. Also, the easiest thing to do seems to be using a single plane carb intake with a throttle body adapter on it. The only problem is, there is only one such adapter I have seen,which is meant to take a Ford throttle body. Do you think there would be any way to make the TPI ECM read the Ford TPS? Would it just be something simple to program in the PROM? I have never programmed a PROM before, but I have much experience with computers, programming in VB, HTML, etc, so I doubt it would take me long to learn.

Grumpy

No problemo, just as you get more radical the effort goes up.

True

No need to be. Just takes some time and learning. Browse around for tuning help. Might read the Final Answers in the DIY-Prom burning area.

TPS is fine, but you have to work out a using the GM IAC, which is different then the Ford set up.

Hooter

You must pay for advertising.

377Z

iTrader: (1)

Do you guys use GM ecm's because they're inexpensive, because they have extensive capabilities, or both? I bought a Haltech E6GM for my '91 Z28 before I realized how many resources are out there for reprogramming GM ecm's. I did notice the Haltech seems to be a bit more primative. I think I'll be putting it on my '76 Cad 500--It was going to be carburated but since I already have the computer... oh... I can't wait... a fuel injected torque monster...

Hooter

Yes both reasons, cheap and the factory software runs rings around the aftermarket.
What manifold are you using on Caddy 500?
Have you seen www.500cid.com
Theres some great info there
Brad, seeing that you have edited my posting, how do I go about advertising. I thought my posting may be a big help to all you F body fans.
Regards
Hooter

377Z

iTrader: (1)

Actually, I live in a near Chicago, Illinois and Maximum Torque Specialties is in Delavan, Wisconson; less than 100 miles away. I went out there and got all my parts from Al Betker (the guy who owns the business you gave the link to)--nice guy. Only non-stock style parts are the camshaft (slightly hotter than stock) and the rocker shaft conversion kit--otherwise stock, compression and all. I have a built TH2004R that I could use with I believe the Spohn crossmember in a Thirdgen. Unfortunately I've heard it requires a hood with more clearance--I have a very clean 1991 Z28 automatic and I love the stock hood (the only aftermarket hood I like is like the one on Brads car, and it doesn't look like it adds too much room), and a 1991 Trans Am convertible that is now a 5 spd. I could probably use a ram air hood but the 500 isn't drilled for a pilot bearing and I don't want to have to get a $$$stronger$$$ trans yet(its a T5 now). Such a dilemma. The motor hasn't ran yet since its been redone, intake is stock and I'd really like to run the performer but then it'll be even taller.

Hooter I don't remember your post before it was edited; do you have a 500 in a thirdgen? So far I've only found one person (caddytransam) thats actually done it.

Hooter

My Caddy is a stock Black 68 472 de ville 4 door hardtop. I just love it, Its got real attitude, and last one with vertical head lights.
Al (MTS) reckons leave TH 400 with high diff gears as they are such torque monsters, and will just spin everywhere with lower gears.
This was the same with my TPI 400. I found it best with 2.75 gears and TH 350. It was very mild an ran 12.94 and 1.92 60ft time on street tyres. I used Kalmaker on that too.
Lower diff gears resulted in no traction.
Hooter

Grumpy

Assuming, can lead to troubles.
In your first paragraph your assuming that the calibration will be too lean. To start tuning without actually seeing what you have can lead off onto tangents.

Speed Density, is Speed Density, that means the ecm just looks at engine speed, and manifold air density to estiablish load, Throttle Position doesn't figure into the Load calculation.
And your statement about the MAF being more forgiving is in error. It only SEEMS more forgiving since there are so many fewer data points for the calculation, not to mention that the sampling is so much more filtered. And the ecm is doing calculations to determine the fuel needed so the MAF is no more accurate in figuring out the load, or fuel requirements then the MAP systems. Well, until you get to the oem level and have to deal with the EPA, and worry about CAFE numbers, but that is a level removed from what the average guy is going to see/ do.

Both are just a different means to the same end. A CORRECT calibration in either will be within the limits of error for testing, in most all your street applications.

Grumpy

You should try the Romulator.
Much more cost effective, and not locked to just using it with one ecm.

377Z

iTrader: (1)

Assuming can lead to troubles, you just proved it with your incorrect interpretation of my post.

First, I mentioned nothing about tuning without seeing what you have, I'm not sure where you got that. I mentioned a particular part, a dual plane intake that flows much better than TPI at 5500 RPM. The point I was illustraiting is if you take a TPI system and modify so that the intake flows more air at a given load and RPM, you will be lean because at that given load and RPM, the computer is receiving more air than the value it is programmed to see at that load and RPM. Since it is not "aware" of the extra air before it is reprogrammed, the required extra fuel will not be provided. How lean will you be? Don't know, don't claim to know, never claimed to know. However, it can only help to deduce the trend to expect when you actually will approach it--sometimes it may even save your motor. Thats the key, its a deduction, not an assumption. I swapped the 305 TPI with a 377 and based on the parts I selected, I deduced it would be rich at idle due to much lower vacuum signal, and leaner with more load and RPM due to much greater capacity. Did I tune it before I knew what I had? Of course not, I knew what I had because I selected the parts!! Did I try to tune it before I saw exactly how lean it was? No. Did it help that I knew what trends to expect? Yes. Sure, you can come up with situations where other parts are changed that bottleneck the system so that it won't run lean, but then why change anything.


Second, MAF is more tolerant of mods, I know because when I had an '89 5.0 Mustang, the MAF cars would run properly on more radical cams than the SD ones--and it doesn't matter whether its Ford, Chevy, or whatever--MAF takes a direct measurement of air entering the engine, whereas SD has lookup tables that deduce air flow into the motor based on load, speed, and barometric conditions. MAF doesn't need to figure out load because it has the direct measurement of volume of air which needs a corresponding amount of fuel.

Don't mean to be a jerk, I just think you misunderstood my post.

Hooter

The romulator still isnt real time tho', and gives no feed back of what is happening, nor the breakdown of the diagnostics.
the factory diagnostics only give the final equations, whereas the "k" word gives complete breakdown of total fuel equation, all transients, all outputs, all inputs.
It takes a bit of convincing at first, but once you've used it, you'll be converted for ever.
Also, there are provisions to run 65, 76, & 85ml Air Frequency Meter (MAF), same type as on GEN 3, combined with MAP which still does transients.
These work really great on either multi throttle body setup or just large 1000 cfm 4 barrel type throttle body, where you loose throttle resolution in situations where say at 50% TPS you are at 100kpa MAP whereby 100% TPS makes no difference.
The AFM's (MAF) have different calibrations to suit different size, and measures air digested. There is a 3D Injector Multiplier map (Inj Mul) which can fine tune similar to VE table to cater for different VE's of different engines, but once again, without real time feed back of what o2's are seeing, you have to rely on self learning.
Anyway, hope you can appreciate I am not trying to impress, but just adding possible interest.
Hooter

Grumpy

If you'd been more clear in what you were stating it wouldn't have been so open to misinterpretation.

MAP or MAF, they both figure out LOAD.

MAF uses a sensor, just as MAP does.
They are subject to math to make a calculation to what amount of air the engine is using, and then determine the fuel to satisfy that requirement.

Pure MAF makes one poor assumption.
Just for grins.
say we are using 100gm/sec at 3K rpm, and want 12.5 AFR. then at 100gm/sec at 6K want 13.5. How are you going to do that?.
In the GM ecms they use a correction known as LV8. What's LV8? a given afirflow at a given rpm. So MAF does in fact do a load calculation.

Being GM specific here, per board requirements.

Grumpy

There is no NEED for anything being real time.
That's why one uses data logging.
You data log what was going on, analyse it, then make your changes.

I can use Lockers, and a Romulator, and do anything you can.
With Lockers if I want to watch all 255 memory locations, I can.

I can log a WB to my Lockers (scan tool), and have as much or more info., then you do.

This on-the-fly, and real time serves no purpose other then being hype, in my world. All it does is add the temptation of trying to drive and make changes. Which I would hope we would agree is dangerous.

Doing things with data loging, and the romulator, forces one to stop, and think of what they're doing. Heck, they might even take notes so that they notice trends, that they would over look by being able to do instant changes.

And from having done some on the fly changes, ie fuel and timing changes, when in cruise, it takes a motor 10-15 minutes for the temps to restabilise anyway.

The AE stuff you want to go on about, is moot when using a WB anyway. With a WB you can see how far lean or rich your AE stuff is and that's a million times more important then knowing what the ecm calc is.

With Lockers, Romulator, a WB, and appropriate hac, I can spend less then K, and tune any number of cars, using different ecms.

Not trying to impress, just explain what's really needed, or in my opinion, what's important.

377Z

iTrader: (1)

Do any of you know if a 7730 ECM can run optispark? It still is a distributor after all isn't it? I guess it comes down what signals the optispark uses.

Reason I ask is I just bought a 1993 LT1 w/75K, I want to run it with the 7730 thats in the car already.

As another option, is there another distributorless system I can adapt?

Thanks guys

EDIT: I just realized (a bit too late) to start another thread on this.