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Old 10-29-2007, 07:55 PM   #1
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Default Throwing out a PCM idea...

Those that have been keeping up with my experiments know that I have been tossing around the idea of having the SSEi controlled by something other than the factory PCM. There are those that say the factory PCM is good enough, and I should leave well enough alone, save for a MEMCAL change. I've been wanting something that I can make changes to, see data in real-time (well, easier than what I have now anyways), AND be able to control the transmission. MegaSquirt has been something I have heavily been looking at for a while, and now they have a daughterboard that is in beta testing that can be used as a trans controller.

However, CO$T is still a huge factor. Actually, for me...it'* the only factor. I even thought so far ahead as to utilize the connectors from a bad PCM (and the case for that matter) to house the MS gear, so it truly would be a plug-and-pray setup.

So...back to square 1. I map out my wants, the needs...and I come up with...a factory PCM! Maybe....

My thought? Using a '96 SSEi PCM, reflashed to utilize S1 L67 tables. I would only need add 4 sensors (MAP, rear O2,knock, and trans temp), build a harness to hook right into the factory '93 PCM location (this means scuttling an unused, or better yet, bad PCM), and replace the ALDL with OBD2. I can monitor data in real-time much easier and with greater precision. Also allows me to plug in an Aeroforce Plus, it enables me to be S2-ready, should I ever need to build up another powertrain.

This is something that I have given a great amount of thought into. It'* doable. Well within my budget and capabilities. And gives Jinx yet another "first" on the club Is it necessary? Probably not in this stage, but might very well be needed in the coming year. And could also provide better control over S1s that have been modded if this idea works.

Thoughts, suggestions, know-how....I need to hear them. And please nothing negative, as I feel this idea is well worth taking the time to try out.
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Old 10-29-2007, 11:58 PM   #2
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I fully investigated standalone engine and fuel management systems, and found them to be cost-prohibitive.

I've pushed pretty far into the S1 'PCM confusion zone' with very little trouble.

What exactly are you trying to achieve? I've had pretty good luck tuning mechanically to avoid problems, and tricking the PCM to give me features and performance that didn't exist.

Car runs like a champ except for the fuel injectors that can't keep up.

(newbie injectors are HERE....probably get them tomorrow)
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Old 10-30-2007, 08:48 AM   #3
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It'* more of an exercise in exploration for me. I'd love to be able to have just one scantool for all my cars (in fact, this idea would probably benefit the 94-95 crowd more as we have that funky coding), plug in an Aeroforce to watch almost any condition, and be able to reflash the PCM w/o having to remove the MEMCAL everytime I have/need to make a change to programming.

Adding an extra knock sensor would definately help me keep an eye on my Frankenmotor, as it is more susceptable to knock than it needs to be. In fact, OBD2 should have an even greater diagnostic scope than what us S1 guys have at the moment.

I too have found that almost all the standalone PCMs are costly, and very few have trans controllers built into them. After making a comparison between the newest MS computers and the GM OBD2 computer, I think the OBD2 comp wins hands down, and very little adapting needs to be done to it (though the way I am going, the largest adapatation would be the go-between harness from the new PCM to the old harness in the cabin), plus GM Tuners can reflash the OBD2 to use custom S1 tables, but still retain the diagnostic capabilities of the OBD2 system.
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Old 10-30-2007, 09:11 AM   #4
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I like the idea of using a newer gen PCM with different programming.

You can get around the rear O2 in the programming, that won't really be a true need. Is the trans temp something you feel is easy to add to the trans? Map should be plug and play, that leaves knock.. I wonder if the system can work off one sensor instead of two.

When you say using the stock 93 pcm location, this might be a challenge with the size difference of the 96. Or is that merely to hook the wiring in so you can keep the stock wiring harness?

Easiest method would probably be to swap the engine harness and adapt it to the S1 connectors and locations.
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Old 10-30-2007, 10:36 AM   #5
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Quote:
You can get around the rear O2 in the programming, that won't really be a true need.
I was thinking the same thing. Though I should upgrade the existing O2 to a 3 or 4 wire setup.

Quote:
Is the trans temp something you feel is easy to add to the trans?
Should be fairly easy to. Sensor really doesn't care where it is located, so long as it is monitoring trans temps. Bottom of the oil pan is one possible place, in-line with the exhaust-fluid is another posibility.

Quote:
I wonder if the system can work off one sensor instead of two.
S1 blocks have two knock sensor locations. L27s up front, L67 in the rear (until they came with dual sensors). I left the L27 sensor in place, unconnected. I am sure I can run a new wire to make it active.

Quote:
When you say using the stock 93 pcm location, this might be a challenge with the size difference of the 96. Or is that merely to hook the wiring in so you can keep the stock wiring harness?
I would more than likely tuck it under the dash somehow, but yes I am planing on using the stcok 93 harness, plugs and all. This is why I would need, in addition to the newer PCM, an old, dead PCM to rip the mating connectors from so I can fashion an interface harness.
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Old 10-30-2007, 10:45 AM   #6
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Originally Posted by sandrock
I would more than likely tuck it under the dash somehow, but yes I am planing on using the stcok 93 harness, plugs and all. This is why I would need, in addition to the newer PCM, an old, dead PCM to rip the mating connectors from so I can fashion an interface harness.
That'* what I figured the spare pcm was for. You'll probably also want both sides of the firewall connector to add wires to both sides. (additional sensors).
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Old 10-30-2007, 01:19 PM   #7
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I think you can do well more than you would even want to with:
TunerCATs RT Tuner + definition file (tune in real time)
An Ostrich Emulator from Moates.net (replaces the prom and connects to a laptop)
And EFI Live v4 + appropriate analog-digital converter (laptop based scaning)

You'll still need a stock bin to modify for your car since the emulator isn't a chip reader.. But, either myself or someone else could read the stock memcal for you.

I'm using the RT Tuner with a Ostrich 1.0 I got off ebay for $100.
I tried a DIY kit for analog to digital conversion but I'm having trouble with it. Eventually, I'm going to just make my own. I don't want to pay $80 for the Moates cable.

I'm also in the process of testing a cheap wideband kit. I'll post results when I'm finished.

Edit-
You'll need a chip adapter for the Ostrich.
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Old 10-30-2007, 01:22 PM   #8
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What can you Tune or change with the TunerCATs RT Tuner...?
can you change the Speed limiter? and shift points and other things like that?
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Old 10-30-2007, 01:29 PM   #9
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Quote:
Originally Posted by bandit
What can you Tune or change with the TunerCATs RT Tuner...?
can you change the Speed limiter? and shift points and other things like that?
You can change pretty much anything you can think of. BUT it is VERY overwhelming and NOT straight forward. I barely know enough to do what I want and I've asked tons of questions and researched for days. There isn't a wealth of information for MAF only based setups. OBD2 Series 2'* have MAP and MAF.
In otherwords, this isn't easy..

I checked the Ostrich tuner and it will work with the 93 eprom type. You will still need a chip adapter from Moates though.
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Old 10-30-2007, 01:46 PM   #10
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Those are ideas I am also willing to entertain. However, the more things get piggybacked, the more these things tend to trip over themselves. With the OBD2 setup, there will be zero piggybacking. I'd also like to be able to have one code scanner for all of my cars, instead of having to borrow a certain someones scanner. OBD2 allows that to happen. And again, I think the OBD2 computer can process data faster and better manage the engine better than a rehashed original PCM.

That last statement is VERY important to this motor that it will eventually control. L67s generally don't like knock, but can live with and through it. Boosted L27s on the other hand, aren't as robust. With everything that has been done both on and off this forum, this motor needs a solid, well-proven management system that is quick to respond. And widely available, with a sizeable knowledgebase.
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