this is way out in left field but i have a carbed ls1 in my maro and have an efi intake and so on but none of the sensors harness or computer for it. i went carbed bc it was around 3500 at the time to buy all the stuff to run injected and only 600 for the carb setup. my question is can i use the spare maf 165 computer system on my ls1 since i have spares of all that stuff from the 89 gta tpi swap i did into a 78 chevy pickup. i am running a 6010 msd box to run the coilpacks and it has the tach output on it. i was wondering if i could use that output to supplement the ign signal to the 165 ecm. i have everything to do it if i can and it would be the only way i could afford to inject my beast, especially since i dropped a bunch on all the tuning stuff for the obd1 and only needed it for one vehicle. any suggestions would be helpful and if it is crazy just tell me. i wanted to run the maf style since i have all the sensors and the computer and a spare harness.

 

Well.....

This seems like somthing I'd try and do. LOL

Yes, it is possible to run the LS1 with the '165, however, depending on your skill level, it won't be considered "easy".

The most difficult part in making it work, is not with sensors, or injectors, or any of that, but the ignition system itself. I'm not familar with the MSD box for the LS1, though I do know of it, and some basic functions that it has. If it is like any other MSD product that I have used, it won't have any way of using the ECM to control timing. There is a way to use the tach output from the MSD, but requires a circuit to interface with the Ref Hi (purple/white) wire so that the ECM knows that the engine is running and at what speed. This would give you fuel control only, which is still IMO better than a carb, but not taking the full benefit of going EFI.

If I was to perform an EFI swap such as this, and had to use the '165 for whatever reason, such as already having it, as in your case, I would also swap out the entire ignition system.

There are two possible routes to take. One involves adding a dizzy to the engine, and there are kits available, IIRC MSD makes a front mount dizzy for the LS1, but may need to be matched with a belt drive system, again, I haven't really paid attention to how those dizzys were installed, I have just seen it on several LS1s. This would allow you to use a GM dizzy ignition module, to interface with the ECM, and allow timing control. It was a similar concept that I used on my Datsun's L28 I6 engine to get it running on a GM ECM initially.

The other option and the route I would personally persue is to look at using a DIS ignition system from another GM vehicle.

The easiest to interface, due to the simple reluctor wheel needed, and simple sensor set-up would be the DIS system from the LT5 found in early to mid '90s Corvettes. The problem here, and you may have already guessed, is the dificulty in finding these DIS modules, and/or the price of them, due to their limited numbers of production.

The more easily found route would be to use the NorthStar DIS system, since they are very easily found at auto recyclers, and fairly inexpensivly too. The difficulty here is that it requires a very specific reluctor wheel with multiple notches (52 seems to ring a bell), spaced very specifically, and no, they are anything but evenly spaced. This system also requires two crank position sensors mounted a very specific distance apart in order for the DIS ignition module to know what cylinder(s) is(are) at TDC, and what coil to fire at that time. There are also changes required to the bin in order for the timing to be correct. I don't recall the specific offset in timing that the NorthStar uses, but I know my 6 cylinder coil packs used an offset of 60*, which had to be added to the timing, otherwise, when ECM timing control was enabled, the timing would be 60* retarded. This is a difference between a dizzy based ignition system and a (GM) DIS ignition system.

There is plenty of information in this forum about the different ignition systems and bin changes needed for each.

 

it was just a thought. i figured it would be a PITA but was worth checking into. the msd only has a linear (2d) timing table with provision for adv/ret through a map sensor for load adaptations, which i have set up. definitely dont want to give up my coil per plug set up though because it has enough juice to throw a wicked 3" spark (wired it up wrong at first and found out the hard way lol) and seriously outperforms any previous coilpack or dist. set up. i just wanted to ditch the carb and was thinking about either this or getting one of the standalone systems from retrotek speed. i'm just tired of always having to tweak it every time the weather changes and not having decent drivability when it's tuned for max power and visa versa. dont get me wrong the car screams but i do way more driving in it than i spend at the track so i'm kinda at a crossroad here. thanks alot for the input though but i may have to bite the bullet and buy a good setup for it

 

plus my msd uses the factory 24x internal reluctor wheel on the crank and a cam sensor to run the coil packs and if i recall the ls1's were the only ones to use that setup so i would have to find some kind of converter or use the tach output from the box and then still wouldnt have ign controll through the computer but i'm mainly concerned with the fuel control than anything. the msd does alright but i wish it had a provision for a knock sensor so i dont have to hook it up to my buddys dyno which has a knock pickup just to tweak the ign.