3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? : MG Engine Swaps Forum : MG Experience Forums : The MG Experience

3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #1
Duncan Duncan Cowen Vancouver, Canada 1956 MG MGA 1500	Posted: July 09, 2012 05:44AM Registered: 5 years ago Posts: 1,360

I've been happily running my MGA with the 3.4l using a 1227730 ECM from a 1990 Cavalier, but I know the ECM has the wrong fuel and ignition maps for a 10% bigger engine with cast iron heads (rather than aluminium). I am interested in tuning the ECM myself, but so far have none of the gear required. On the other hand, I've recently come across the info that the 1993 Camaro V6 ECM is non-MAF, so I'm considering swapping to that ECM to improve my "good but not best" state of tune.

But, of course that will involve a lot of messing around, given that the 1993 ECM is SFI and I'd need a new/modified wiring harness as well (rather than simply repinning connectors, as I did when I used a Fiero MPFI harness with the Cavalier MPFI ECM). And then there's VATS on the 1993 ECM - I think?

So then, how much difference is the 1993 ECM and harness likely to make to engine performance?

Does the 1993 Camaro ECM have VATS to deal with (increasing the price and complexity of the upgrade)?

Given the time to rewire the engine compartment to support SFI (either with the Camaro harness OR by adding a few more wires for the separate injectors), is it less time to start learning how to modify the MEMCAL and then reprogram my existing 1227730 ECM?

Thanks for the info and advice folks!

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #2
BMC Brian Mc Cullough Minneapolis, Minnesota, USA 1959 Austin A40 Farina 1959 Austin-Healey Frogeye (Bugeye) 1961 Austin-Healey Sprite MkII "Green Sprite" 1969 MG MGC GT "CGT" 1979 MG MGB → more	Posted: July 09, 2012 07:07PM Registered: 13 years ago Posts: 4,346

Duncan,

We run 99% of our systems on non-tuned 3.4L 93-95 "OBD 1.5" PCM systems. The anti-theft system has 3 wires- ignition power, ground and signal.

http://bmcautos.com/shop/index.php?main_page=product_info&cPath=4&products_id=10

Current price is under $37. Plug it in and go. The PCM can be found used for around $20. If you think you need a tune when done, Marc can now do some tuning on these.

What is quicker and easier is really about your skill level and attention to detail.

Rebuilding your injector sub harness as a 6 rather than two wire is not going to be incredibly difficult.

-BMC.

How to advertise on this website

BMC British Automobile – Minneapolis, MN USA BMC British Automobile is a Restoration and Repair shop north of Minneapolis, Minnesota. Our time is spent solely on British vehicles and British Conversions. MG and Austin are our specialties.

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #3
bills Bill Spohn W. Vancouver, BC, Canada 1956 MG MGA 1958 MG MGA Twin-Cam 1962 MG MGA MkII Coupe 1965 Jensen CV8 1969 Lamborghini Countach → more	Posted: July 10, 2012 08:53AM Registered: 8 years ago Posts: 9,160

Duncan, I have a 93 PCM if you need one and want to go that way.

Having said that, you should be able to run the 3.4 pretty well on the 3.1 ECM.

Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #4
Duncan Duncan Cowen Vancouver, Canada 1956 MG MGA 1500	Posted: July 10, 2012 05:24PM Registered: 5 years ago Posts: 1,360

In reply to # 2116233 by bills Duncan, I have a 93 PCM if you need one and want to go that way.

Having said that, you should be able to run the 3.4 pretty well on the 3.1 ECM.

Bill, thanks for the offer of the PCM - I may take you up on that. You're right, the 3.4l runs pretty well (actually, a lot better than "pretty well!!" winking smiley

on the bone-stock 3.1l PCM. But maybe I've been reading too many of Chris Gill's threads, I've been thinking of chasing down perfection! spinning smiley sticking its tongue out

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #5
bills Bill Spohn W. Vancouver, BC, Canada 1956 MG MGA 1958 MG MGA Twin-Cam 1962 MG MGA MkII Coupe 1965 Jensen CV8 1969 Lamborghini Countach → more	Posted: July 10, 2012 05:34PM Registered: 8 years ago Posts: 9,160

The feedback controls already give you as close to perfection as you are going to get, unless you have sufficiently radical modifications that it takes the engine's requirements outside of the bounds of the standard tables. I don't think that is the case.

We have guys with 2.8 ECMs running 3.1 and 3.4 engines all the time in Fieros with no problems. Only the highly modified engines (like my 3.2 turbo or the 3.4 in the Jamaican) require a retune.

Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #6
1744 Bill Guzman California, USA 1973 MG MGB GT "Green GT" 1974 MG MGB "Punking"	Posted: July 10, 2012 06:17PM Registered: 7 years ago Posts: 4,821

Duncan, this is the place you want to go for ecu tuning. They have the tools you need.

http://www.moates.net/

It is our attitude that will determine the outcome

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Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #7
Duncan Duncan Cowen Vancouver, Canada 1956 MG MGA 1500	Posted: July 11, 2012 12:32AM Registered: 5 years ago Posts: 1,360

In reply to # 2116711 by 1744 Duncan, this is the place you want to go for ecu tuning. They have the tools you need.

http://www.moates.net/

Yes Bill, this is one of the next possible steps. Now that the car is smooth and reliable, I want to play some more, and I'm actually quite interested in learning to tune these ECMs! Of course, the body work required is not going to go away on it's own, is it? sad smiley

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #8
1744 Bill Guzman California, USA 1973 MG MGB GT "Green GT" 1974 MG MGB "Punking"	Posted: July 11, 2012 10:26PM Registered: 7 years ago Posts: 4,821

Long learning curve, I am still learning to tune my megasquirt.

It is our attitude that will determine the outcome

How to advertise on this website

Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #9
Duncan Duncan Cowen Vancouver, Canada 1956 MG MGA 1500	Posted: July 12, 2012 07:20AM Registered: 5 years ago Posts: 1,360

In reply to # 2116672 by bills We have guys with 2.8 ECMs running 3.1 and 3.4 engines all the time in Fieros with no problems. Only the highly modified engines (like my 3.2 turbo or the 3.4 in the Jamaican) require a retune.

Bill, is that with a distibutor or are they using the 1227730 / 1227727 as well?

I guess it wouldn't matter, the advance curves are still in the ECM, not the distributor...

I'll be driving the car again this weekend, so I'll recatalog any issues that remain and decide whether or not to pursue them! I'm pretty tempted to learn to tune though - I'm quite intrigued by

Highway Fuel Mode, among other things!

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #10
bills Bill Spohn W. Vancouver, BC, Canada 1956 MG MGA 1958 MG MGA Twin-Cam 1962 MG MGA MkII Coupe 1965 Jensen CV8 1969 Lamborghini Countach → more	Posted: July 12, 2012 08:25AM Registered: 8 years ago Posts: 9,160

Most of the Fiero guys stick with the distributor as it looks stock. If they want to run the DIS system (coil packs instead of distributor) you need to switch to a slightly later ECM, I believe. I run a 1985 period ECM on my turbo, because it was the only one set up to run a turbo with a positive pressure table in it, but I run around a 1988 Beretta ECM on the Jamaican, which i still OBD 1.0 and chippable, but runs the DIS (it won't run the SFI system, but that is really no loss).

I can see wnting to get into programming from curiosity, but when you don't really have to for the engine you have, you might regret it later if it gets frustrating. OTOH, you might enjoy the intellectual exercise even if you don't need it to run the car.

PS - we should get the two modded MGAs out for a run to Squamish or something this summer. We could even invite some slower V8 powered MGBs along for comic relief..... devil smiley

Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC

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Re: 3.4l V6 ECM: for "nearly perfect" tune, should I retune OBD1, or get a 1993 non-MAF ECM and harness? #11
Duncan Duncan Cowen Vancouver, Canada 1956 MG MGA 1500	Posted: July 12, 2012 11:51AM Registered: 5 years ago Posts: 1,360

In reply to # 2118010 by bills Most of the Fiero guys stick with the distributor as it looks stock. If they want to run the DIS system (coil packs instead of distributor) you need to switch to a slightly later ECM, I believe. I run a 1985 period ECM on my turbo, because it was the only one set up to run a turbo with a positive pressure table in it, but I run around a 1988 Beretta ECM on the Jamaican, which i still OBD 1.0 and chippable, but runs the DIS (it won't run the SFI system, but that is really no loss).

I can see wnting to get into programming from curiosity, but when you don't really have to for the engine you have, you might regret it later if it gets frustrating. OTOH, you might enjoy the intellectual exercise even if you don't need it to run the car.

PS - we should get the two modded MGAs out for a run to Squamish or something this summer. We could even invite some slower V8 powered MGBs along for comic relief..... devil smiley

Bill, I'm looking for excuses to drive it! PM me a few dates, and let's go!

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