86trNZam

Hi Guys,
I want to program my own chip. Admittedly, my 1986 TransAm is not fuel injected and with the modifications, so far, the computer doesn't do anything other than timing and fan operation. However, I would like to modify these if possible. My present problem is this… I have searched far and wide for information and ECU / TDF files for my E.C.M but have come up with a blank!
Does anyone have any information, or know where I can find information, for an E.C.M number 1227169 (late '86, LG4, 305CID, 5 Speed-Manual, 4bbl)? It only has a plugable 24 pin PROM so I assume it's using 32k. A memory map or ANYTHING will help. Have tried all the recommended sights I come across but they all seem devoted to E.F.I only. I'm beginning to feel I'm the only one in the world with a 4bbl version F-Body! Any ideas or contributions would be most appreciated. Many thanks…


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1986 Pontiac TransAm - LG4 - Vin H - 5 Speed Manual - Righthand Drive - Performer Intake - Holley 4160 600 - No Cat - no emmission equip.

TRAXION

I can honestly say that I have encountered no information on your BIN

You might try searching the GMECM archives using your ECM ID to see what (if any) info is available. But, I haven't seen anything.

Tim

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• Program your own PROMs!. Read my article to get started!
• Research and Experiment before asking questions.
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TRAXION's 1990 IROC-Z
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86trNZam

Thanks Tim... Have tried there... Just checking out the easy ways first... Guess it'll be the hard way... will soldier on regardless. Thanks again.

PerthZ28

I would be interested in anything you can find about these proms Zam. Please let us know if you come up with any info.

Thanks.

Nemesis

Hi trNZ, I'm from Christchurch with a 83 Berlinetta LG4 no emissions, w/ Performer, headers and 3" pipework, but running the Quadrajet still. If you get any info would appreciate it. I know someone who can get me a chip burned just need the data.

Cheers.

Blade

If you find anything interesting... please share with the rest of us so next time this question is asked we won't be clueless. hehe


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92 Z28 5.7
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steve8586iroc

Hey guys, I have to play dumb on this one. I know what the computer does on efi equiped cars but how much control does it have on a carb equiped car? Does it control air/fuel ratio as well as ignition, fan, egr, ect...?
Just curious I guess.

Steve

Grumpy

It does have an O2 feedback so it does do more then just timing.

It's a prom, so not erasable, might try reading it as a 2716.
Might not at all look normal inside (compared to an EFI bin).

Might be time to converting to TBI

86trNZam

A short answer to 'what does the E.C.M do in the carburetor version'…
My factory service manual lists the following controlled devices…
1: Mixture control solenoid (Carburetor mixture)
2: Electronic throttle kicker (Carburetor idle solenoid)
3: Transmission converter clutch (Not used with manual)
4: Electronic spark timing
5: Air injection divert valve
6: Air injection switching valve
7: Exhaust gas recirculation solenoid

It also lists the following information sensors…
1: Differential pressure (VAC)
2: Barometric pressure
3: O2 Sensor
4: Throttle position
5: Coolant temperature
6: Vehicle speed
7: Electronic spark control knock sensor

Interestingly enough, it appears the cooling fan is not controlled by the E.C.M. Coolant temperature is used, from what I can gather, for timing. I know with my '86 the car gives a surge at a particular temperature as the E.C.M seems to change to a different timing curve.
Will keep uoy posted as to any info' I can get. Thanks...

NickG

Can you read out the image in the current PROM? If so, email it to me. Spark tables are fairly easy to locate.

Nick

GMTech

You probably don't want to hear my solution. You could do what I did, I had an '87 LG4, and I ditched it for TPI. I put the Speed Density TPI on my LG4 and it made a huge difference.

As for what the LG4 computer does, it works on air/fuel a little, via the M/C solenoid, but even that is limited. You can't fully control a carb. Once the secondaries kick in, its all "carb". So if you want more fuel, invest in some secondary rods. See the carb board for some good choices.

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86trNZam

Thanks for your suggestions, However I have several reasons for not swapping to EFI of any description... First off, These cars are reletively rare in New Zealand and second hand injection gear is pretty much non-existant. Second, new kits such as those supplied by Edelbrock although very nice cost aprox $2000.00 us, this equates to around $4000.00 nz! Third, the Holley 600 I am using works great and it would be a shame to put all those sensors and 'stuff' back on with the end result being an over-complicated setup with emmision control which is not needed here(I'm a great believer in K.I.S.S).
I would like to point out here also that my carburetion is totally seperate from my E.C.M so fuel is not a problem. I simply wish to improve the timing curves for optimum. As far as mechanical is concerned, a top end make-over is on the horizon as well as a better exhaust setup.
Thanks Nick, I will take you up on that, I have to find some spare time at work to remove and read my chip as all the EPROM gear is there. Kind regards... Geoff.

Nemesis

Yeah same here, I just want to set some more aggressive timing curves. I've already changed my secondary rods, air valve position and spring tension. I've seen Hypertech chips for the HO so why not burn one for the LG4??

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Ken73

Just a thought, but has anyone considered using a TBI-based (already hacked) ECM to control things? I know 86trNZam is looking just to control timing, so it would suit him well - but doesn't the primary metering solenoid in the Q-jet have relatively the same impedance as a TBI injector?

Ken

84FTA

Yes, I am currently working on a TBI ECM controlled CCC. I've finally taken the Q-jet apart and I am looking for a newer TBI truck in a junkyard to work off of. The sensors for TBI and CCC are almost identical, so I was going to get it working first. At worse I'd need a signal converter for the M/C seloniod. The two reasons I switched to a newer ECM was for the speed and the programability. One of my feels about the 'suckiness' of the CCCs are the computer times. Updating every 1.25 seconds is not exactly a perfomance piece.

However, this idea is starting to fail on me. As mentioned by GMTech even if I get the M/C seloniod to keep the fuel mixture perfect, it will only do it for the primaries, which leaves me back to age old hanger and rod guessing that is supposed to seperate this project from regular carbs. Only solutions I've come up with this would be to put on two Q-jets and lock the secondaries shut but it wouldn't idle to well and would likely create many problems plus the airflow would be extremely limited. The second idea is searching for a CCC that has both computer controlled a/f mixtures in the primaries and secondaries. I have yet to find one though.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

Ken73

84FTA, I'm not sure but I don't think such an animal even exists (CCC carb that has both primaries and secondaries controlled by ECM.) Have you looked in any Rochester Carb books?

Also, after some thinking, doesn't the CCC carb go to "full open" during WOT operation? I'm not sure a TBI ECM would do that. Might want to look into the operation of the TBI ECM's vs. the operation of CCC carb ECM's. I believe the sensors are all identical, however.

Now, the second thought on that is that the newer ECM will control the primaries at ALL times, and the O2 sensor will help you tune the newer ECM to help makeup for the secondaries lack of ECM control. Instead of the primaries being "full open" they can be tuned to give a proper A/F mixture even with the secondaries gushing fuel forth. Use the primaries to fine tune the operation of the secondaries. You'll still want to get your secondary rod/hanger combo "close" but it won't have to be quite as perfect as you'll be tuning it via ECM afterwards. Might be a bit more difficult, but definitely worth it.

It's definitely untreaded waters though, so take any and all precautions. Don't cut your original harness if possible; make a PCB adapter so you can plug your old ECM in at any time and drive. I've found that no-name PCB's are thinner than Radio Shack PCB's, which are the same thickness as GMECM PCB's. Intermittent contact with the cheaper (thinner) PCB's tends to make everything run erratically.

Ken

Ken73

Looked through the C3 crossreference and looked to see what TunerCat supports to boot; Look at the 1228062 ECM. Might be a good candidate to work with? Came on small V6's (that I assume probably used single barrel TBI's?) Check to see, of course. If I were you I'd look to see what Tunercat supports so you've at least got that portion easy to work with. No sense in complicating things by picking out one he doesn't support.

Ken

84FTA

Unfortuneatly I won't have a stock harness to retain. The L69 harness is trashed and the LG4 harness doesn't have the provisions the L69 used (like knock sensor) plus it's had a few run-ins with the headers from the previous owner.

I don't plan to run straight off the injector pulses until I get some measurements from a correct operating CCC and a correct operating TBI engine then cross reference them, with all luck they will be close or easily converted.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

Ken73

Good, then you're looking into it a little deeper and not trying to throw it on your engine.

I thought about it a little more last night and figured the '8062 wouldn't be a good idea; it's for 4 cylinder and 6 cylinder cars. That wouldn't be a big deal except the spark timing would probably not work properly (if it worked at all.) That being said, might just go with the '7747 - it's been hacked to death and is available all over the place.

Also, I looked in my Rochester book last night and apparently they made some Q-jets that had an (aux) electric accelerator pump in addition to the electric primary M/C solenoid, but no mention was made of an electric secondary M/C solenoid.

What measurements do you need from a TBI engine and CCC engine? Try measuring the impedance of the M/C solenoid.

Ken

84FTA

Measurments are along way off yet. I still have to get to the parts stage which won't be for probably a year . It's one of those back burner projects, got other things I need to concentrate on unfortuneately (real life sucks, eh?).

The aux. electric accel pump is a good addition. That might come in handy because the rumor is on high HP engines the accel pump on the CCs are too small. Does that book have anything about 2-bbl CCCs with aux. eletric accel pumps? I could in theory hook them together and have them fucntion like a DP but without the bad gasmileage and other problems associated with them.

------------------
1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

Ken73

Well, I spoke with Grumpy and he told me that doing a CCC carb with a TBI computer is a no-go. He's tried it and the TBI components physically work faster than the CCC carb solenoid, so it just won't work. I guess your only option then is to figure out the tables in the original CCC system.

Ken

84FTA

Perhaps. Soleniod technology has advanced greatly in the last couple of years. The whole idea of the exp was the computer being faster . Like I said, back burner idea, and if I have to create some sort of converter circuit I can push the seloniod to limits without overkill.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

86trNZam

Back again...
Has been some time but have finally got off my a*se and read my PROM. Just for interest sake there seems to be a 12x12 timing table at 03D Hex. Have posted the BIN file at ftp://ftp.diy-efi.org/incoming/ as 1227169.bin, doc and ecu. If anyone can fathom out the rest of the BIN please let me know. Cant even see a checksum!(Maybe there isn't one?)
The original PROM is a 1k maskable but can be substituted with a 2532 EPROM with the code starting at 0C00 Hex. Haven't actually changed and tried anything yet but have compared it to an aftermarket strip chip. The main changes being in the high load end of this 12x12 timing table and what I assume to be the fuel mixture control around 0200 Hex.
Please feel free to make suggestions or comments on this BIN. Many thanks... Regards.

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1986 Pontiac TransAm - LG4 - Vin H - 5 Speed Manual - Righthand Drive - Performer Intake - Holley 4160 600 - No Cat - no emmission equip.

79frankenstein

Hello i have a 86 camaro with a 79 5.7 350 4bbl. is there any point for me to have this computer in the car because i don't have TPS or any other computer driven sensors on the engine. so is it ok to just take it out

86trNZam

Hi... I have changed my fuel system several times and always kept the original ECU purely for Ignition and timing. If you are still using the original HEI system then your ECU should run the Ignition from the original Temp, MAP, Air Density and Knock sensors (RPM is derived from the HEI). If you are not using the original HEI then, I guess, you probably dont need it. Hope this helps. Kind regards... 86trnzam.

Tuvix

Sorry if im asking another dumb question, but I dont fully understand what im trying to do.
I have a 1984 trans am, its got a rochester quadajet carb with the two connections that are for the ECM, The carb has died on me, So I was wondering if I could remove this carb and use a standard carb without the computer controls? And if so how would this affect the car?

Its an automatic version, The fan is connected straight to the engine, There is no aircon. If you need anymore info please Let me know
Thankyou

Tuvix1701@hotmail.com