using a GM v6 ecu for a 4 cyl?
12-27-2005, 12:46 AM
#11
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Join Date: Oct 2005
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
Are you sure that's actually a 727 ECM and not a 747? I guess they could have used the 727 on the 4.3 CPI engines, but I don't know.
If you are dead set on using the one from a TBI system then I'm sure it could be done. Edelbrock has done an MPFI conversion using a TBI ECM for the GM trucks, so it can be done.
One problem that I see is that the sampling rate inside the ECM is really slow. Also, something you might want to keep in mind is that the 747 and 746 TBI ECMs weren't meant to run MPFI. This is of course assuming that you are intending to run MPFI. I can only assume that this the case.
GM did use TBI on a 4 cylinder engines, such as the 2.5 in Fieros, Grand Ams, and on the earlier J bodies just to name a few.
Another thing, since this is HMT, the 749 ECM is already set up to run boost with a 2 Bar.MAP sensor. This one is used in the Syclones and Typhoons with a turbocharged 4.3 MPFI engine.
I still suggest using an ECM such as the 730, 727, or 749 to run a four cylinder engine. Again, the code in these computers has been very thoroughly hacked. The much higher sampling rate inside the computer would allow much improved control when come fuel and ignition events. If the service number on the ECM that you are going to use is 1227727, then go for it.
Here are a few links to check out.
http://www.diy-efi.org/gmecm/
http://www.diy-efi.org/gmecm/ecm_info/
http://www.diy-efi.org/gmecm/compone...o/sensors.html
http://www.thirdgen.org/
Dammit! It seems that I have been out of the GM OBD1 loop for too long. I had more sites, but some seem to have gone by the wayside.
If you are dead set on using the one from a TBI system then I'm sure it could be done. Edelbrock has done an MPFI conversion using a TBI ECM for the GM trucks, so it can be done.
One problem that I see is that the sampling rate inside the ECM is really slow. Also, something you might want to keep in mind is that the 747 and 746 TBI ECMs weren't meant to run MPFI. This is of course assuming that you are intending to run MPFI. I can only assume that this the case.
GM did use TBI on a 4 cylinder engines, such as the 2.5 in Fieros, Grand Ams, and on the earlier J bodies just to name a few.
Another thing, since this is HMT, the 749 ECM is already set up to run boost with a 2 Bar.MAP sensor. This one is used in the Syclones and Typhoons with a turbocharged 4.3 MPFI engine.
I still suggest using an ECM such as the 730, 727, or 749 to run a four cylinder engine. Again, the code in these computers has been very thoroughly hacked. The much higher sampling rate inside the computer would allow much improved control when come fuel and ignition events. If the service number on the ECM that you are going to use is 1227727, then go for it.
Here are a few links to check out.
http://www.diy-efi.org/gmecm/
http://www.diy-efi.org/gmecm/ecm_info/
http://www.diy-efi.org/gmecm/compone...o/sensors.html
http://www.thirdgen.org/
Dammit! It seems that I have been out of the GM OBD1 loop for too long. I had more sites, but some seem to have gone by the wayside.
12-27-2005, 01:47 AM
#14
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Join Date: Feb 2003
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
No, but blundar, Speed Phreak, and I have been drunk at Pikas' house in MD. I dunno what sn he goes by, probably Silverback, but he's as big as the legends proclaim. 6'7", and outweighs me, blundy, and Dick without looking fat. I occaisionally get an email from him where he affectionately calls me Stick Boy.
Grumpy has his engines built by Dave Williams, who hosts a mailing list I am on. Mean Gringo Bob is their buddy and a mentor of mine, and an all-around loose cannon. Maybe you've seen the wrath of a MGB techno-flamewar. My *** still hurts two year later.
Grumpy has his engines built by Dave Williams, who hosts a mailing list I am on. Mean Gringo Bob is their buddy and a mentor of mine, and an all-around loose cannon. Maybe you've seen the wrath of a MGB techno-flamewar. My *** still hurts two year later.
12-27-2005, 02:01 AM
#15
0.0 BAR
Join Date: Oct 2005
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
Haha. Good ----. I've seen you on PGMFI.org along with of course blunder. Didn't ever post much, but I learned a shitload from your guys work.. Yeah, I know, a ------- leach. Kinda thought it would've been funny if we were both on the same boards. Hopefully I will get one of my ------- projects finished.
Sorry SLAPPYNUTS, not trying to hijack your thread.
Sorry SLAPPYNUTS, not trying to hijack your thread.
12-27-2005, 03:15 AM
#16
0.0 BAR
Join Date: Jan 2005
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
although I don't post much on thirdgen.org, I still have my 86 TA..........
OK, If not for me and Joe Sabo, would Blundar have given up on the 1g CRX ZC swap, never to have touched a ECU?
Will I get laid Saturday?
OK, If not for me and Joe Sabo, would Blundar have given up on the 1g CRX ZC swap, never to have touched a ECU?
Will I get laid Saturday?
12-27-2005, 05:50 AM
#17
1.0 BAR
Thread Starter
Join Date: Oct 2005
Posts: 216
Re: using a GM v6 ecu for a 4 cyl?
Yea it probably is the 747 ecu(I'm a dumbass like that).It must be fast enough to run a motor that has twice as many ignition events as we are going to be using so it should be fine in that respect.Right?
The reason for choosing this ecu is because they are in tons of vans/trucks/suvs and easy for anybody to get for under $20 with a hunk of harness.
The same ecu will aslo run on hall and VR dist pickups and it is already speed density and can easily be set up for FI.
I do have alot of experience hacking ECUs on motronic cars so that end of the job should be fine.
The main part that I am concerned about is the injector drivers and if they will work in a batch fired situation.I would imagine one driver could run atleast two high imped injectors as is,and two injectors on a 4 cyl would drive about the same as one injector on one plane of a v8 intake manifold I would assume.Any thoughts on this?
The reason for choosing this ecu is because they are in tons of vans/trucks/suvs and easy for anybody to get for under $20 with a hunk of harness.
The same ecu will aslo run on hall and VR dist pickups and it is already speed density and can easily be set up for FI.
I do have alot of experience hacking ECUs on motronic cars so that end of the job should be fine.
The main part that I am concerned about is the injector drivers and if they will work in a batch fired situation.I would imagine one driver could run atleast two high imped injectors as is,and two injectors on a 4 cyl would drive about the same as one injector on one plane of a v8 intake manifold I would assume.Any thoughts on this?
12-27-2005, 02:02 PM
#18
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Join Date: Oct 2005
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
If you are worried about finding harnesses then all you would have to do is repin the harness from a truck or van to use with any of the ECMs mentioned above.
As far as the injector drivers are concerned, The TBI uses a peak and hold injector driver. And form what I have read those big *** TBI injectors only have an impedance of 1.2 ohms. So in theory you could take advantage of this circuit and run two DSM injectors per driver. The problem of firing scheme comes into play though. The TBI does not use a true batch fire scheme,. Instead of firing the injectors all at once it fires in an alternating fashion 2 times each per engine revolution. If we were to use companion cylinders to find out which driver circuit should go with cylinders, then I guess this could be sort of made into a bank to bank firing scheme.
Since we are talking about an inline 4 cylinder engine it would not truly be bank to bank, but it may work. Since each injector event is triggered by an ignition event then that would drop the 4 pulses to 2 pulses per revolution. Say we have a firing order of 1342 then 1 and 4 could receive fuel from injector 1 and 3 and 2 could receive fuel from injector 2, like in a waste spark system. Granted, the pulse timing would have to be correctly offset relative to intake valve opening. I wonder if Edelbrock did something similar to this in their MPFI conversion kits? Given an SBC with a firing order of 18436572, then possibly cylinders 1467 on 1 and 8352 on 2. This would involve grouping two pairs of companion cylinders together. Hmmm. I wonder?
If you desire to use P&H injectors then the 749 would be optimal. From what I have read, that seems to be the main hardware difference between the 730 and 749. The 730 can be used with boost if you use the mask from the 749 and tune from there.
I realize that the se ECMs can run a vehicle with twice as many ignition events, but the slowness that I am talking about is the time the computer takes to respond to what the inputs are telling it. If nothing else, trying to tune with the slow *** 160 baud ALDL stream will provide you with vague tuning information.
I also completely understand what you are saying about the abundance and cost of the 747. They are everywhere. A 730 and a727 are still in pretty high demand so they bring a much higher price from a private party. Although, the 730 was used in quite a few vehicles, so it should be fairly readily avail\able. Forget about trying to just walk into a yard and find a 749 for $20. That ---- is not going to happen.
In conclusion, I still stand by using the 730 ECM for running a MPFI with any number of cylinders. Whatever you decide make sure that you thoroughly research the GM hardware and code. One of the best sites for research is http://www.thirdgen.org/. Look around in the classifieds section and find the DIY PROM, TPI and TBI boards. I do not claim to be an expert on this subject by any means, these are merely my suggestions based on what I have read.
Hey Bone that's a CLEAN *** TA
. Any mods, times, etc?
As far as the injector drivers are concerned, The TBI uses a peak and hold injector driver. And form what I have read those big *** TBI injectors only have an impedance of 1.2 ohms. So in theory you could take advantage of this circuit and run two DSM injectors per driver. The problem of firing scheme comes into play though. The TBI does not use a true batch fire scheme,. Instead of firing the injectors all at once it fires in an alternating fashion 2 times each per engine revolution. If we were to use companion cylinders to find out which driver circuit should go with cylinders, then I guess this could be sort of made into a bank to bank firing scheme.
Since we are talking about an inline 4 cylinder engine it would not truly be bank to bank, but it may work. Since each injector event is triggered by an ignition event then that would drop the 4 pulses to 2 pulses per revolution. Say we have a firing order of 1342 then 1 and 4 could receive fuel from injector 1 and 3 and 2 could receive fuel from injector 2, like in a waste spark system. Granted, the pulse timing would have to be correctly offset relative to intake valve opening. I wonder if Edelbrock did something similar to this in their MPFI conversion kits? Given an SBC with a firing order of 18436572, then possibly cylinders 1467 on 1 and 8352 on 2. This would involve grouping two pairs of companion cylinders together. Hmmm. I wonder?
If you desire to use P&H injectors then the 749 would be optimal. From what I have read, that seems to be the main hardware difference between the 730 and 749. The 730 can be used with boost if you use the mask from the 749 and tune from there.
I realize that the se ECMs can run a vehicle with twice as many ignition events, but the slowness that I am talking about is the time the computer takes to respond to what the inputs are telling it. If nothing else, trying to tune with the slow *** 160 baud ALDL stream will provide you with vague tuning information.
I also completely understand what you are saying about the abundance and cost of the 747. They are everywhere. A 730 and a727 are still in pretty high demand so they bring a much higher price from a private party. Although, the 730 was used in quite a few vehicles, so it should be fairly readily avail\able. Forget about trying to just walk into a yard and find a 749 for $20. That ---- is not going to happen.
In conclusion, I still stand by using the 730 ECM for running a MPFI with any number of cylinders. Whatever you decide make sure that you thoroughly research the GM hardware and code. One of the best sites for research is http://www.thirdgen.org/. Look around in the classifieds section and find the DIY PROM, TPI and TBI boards. I do not claim to be an expert on this subject by any means, these are merely my suggestions based on what I have read.
Hey Bone that's a CLEAN *** TA
. Any mods, times, etc?
12-28-2005, 03:03 AM
#19
0.0 BAR
Join Date: Jan 2005
Posts: 0
Re: using a GM v6 ecu for a 4 cyl?
86 TPI had the "peanut cam".........
15.98 bone stock except for Vette 2200 stall vert
Homemade PVC 3" intake, Flowmaster exhaust, 225/50/15 DR's for better gearing, 3.27 rear w bad posi......15.0
Motor is tired, has 118k miles.........
Pic from the 3.27 rear install............
Car is from Cali and Las Vegas
15.98 bone stock except for Vette 2200 stall vert
Homemade PVC 3" intake, Flowmaster exhaust, 225/50/15 DR's for better gearing, 3.27 rear w bad posi......15.0
Motor is tired, has 118k miles.........
Pic from the 3.27 rear install............
Car is from Cali and Las Vegas
