1989 TBI Omni Turbo Conversion - SMEC or MS ?

[1984rampage]

Have been out of the TM game for a while now. Selling my GLHS and picking up an 89 TBI Omni.

What is the best plan of action for converting the omni to turbo electronics ?

I've heard that the 89 Caravan SMEC harness is a direct swap, but wouldn't it be too long and have the incorrect headlight wiring ?

Would converting the car to megasquirt make more sense ?

Hoping to hear some input on the different ways to get this thing boosted.

Thanks!

[contraption22]

Headlight plugs should be easy enough to change. I think a number of people have done the minivan harness swap.
Gotta ask why you'd be selling a factory turbo car to go through the trouble of converting a tbi car.

[1984rampage]

Headlight plugs should be easy enough to change. I think a number of people have done the minivan harness swap.
Gotta ask why you'd be selling a factory turbo car to go through the trouble of converting a tbi car.

Few reasons. First is I'd be saving quite a bit of extra cash. Second is I've always wanted an Omni more than the charger. Third is I have so many parts laying around that it wouldn't be that difficult. Finally the Omni is 100% rust free,straight and has AC, while the charger has a few issues that I don't feel like dealing with at the moment.

[iTurbo]

The Caravan harness is definitely not a direct swap. I mean sure, the bulkhead connector will plug right in. But you will probably have to get wiring diagrams for both cars and repin some things within the connector because of differences between the vehicles and option content differences. I have done this before and it worked OK, but some of the sections of the harness were quite long for the L-body and you end up with redundant extra turn signal connectors, extra unneeded relays etc etc.

I have also converted an '89 Omni TBI harness to Turbo II. That is also a lot of work, but you would end up with a harness that fits just like stock. This would also require a TII donor harness such as from an '89 Daytona Shelby. You just need to add certain things like the additional distributor plug, AIS/TPS, additional fuel injector driver wiring, and a few pins on the SMEC connector. Not for the faint of heart, but if you are willing it can be a fairly elegant solution. A thorough understanding of Chrysler fuel injection is a must and it might help to read up on this Gary Donovan's "Mopar Port Fuel Injection Explained" section 10 first at thedodgegarage.com

[1984rampage]

Does anyone else have more input ?

I feel that both endeavors would be a similar amount of work, with megasquirt requiring a higher learning curve.

[Vigo]

If you can read a wiring diagram and back terminals out of connectors without breaking them i would convert the existing harness rather than modifying a donor harness.

As for Megasquirt, i'd have to see a list of what it can do that A: modified stock electronics cant do, B: you actually care about, before i can say it's a great idea. It's a lot of work just getting BACK to where the stock computer starts, and there's a very good chance that it will NEVER run quite as well under 'normal' use as the stock computer setup. I think Megasquirt has to have specific payoffs before it makes sense. What would they be for you?

[cordes]

I would convert the stock harness to TII. It should be pretty darn simple. I'm finishing up a carb to SBEC harness conversion and that was pretty intense due to the way I'm running all of the wiring in the car now. Everything will be over by the battery. Nothing will run across the firewall and the only things to go over to the pass side will be the lights.

[1984rampage]

If you can read a wiring diagram and back terminals out of connectors without breaking them i would convert the existing harness rather than modifying a donor harness.

As for Megasquirt, i'd have to see a list of what it can do that A: modified stock electronics cant do, B: you actually care about, before i can say it's a great idea. It's a lot of work just getting BACK to where the stock computer starts, and there's a very good chance that it will NEVER run quite as well under 'normal' use as the stock computer setup. I think Megasquirt has to have specific payoffs before it makes sense. What would they be for you?

I am honestly not sure what megasquirt would offer more than the stock ECU. Both give the option of complete control over fueling/timing/boost etc. Most likely the car would run better on the factory stuff due to the massive amounts of R&D Chrysler put into developing the stock electronics.

Would any T2 SMEC harness work as a donor ?

I would convert the stock harness to TII. It should be pretty darn simple. I'm finishing up a carb to SBEC harness conversion and that was pretty intense due to the way I'm running all of the wiring in the car now. Everything will be over by the battery. Nothing will run across the firewall and the only things to go over to the pass side will be the lights.

That sounds pretty intense ! Do you have any pictures of the setup ?

[cordes]

I am honestly not sure what megasquirt would offer more than the stock ECU. Both give the option of complete control over fueling/timing/boost etc. Most likely the car would run better on the factory stuff due to the massive amounts of R&D Chrysler put into developing the stock electronics.

Would any T2 SMEC harness work as a donor ?



That sounds pretty intense ! Do you have any pictures of the setup ?

Not too many good ones right now. I'm using Delphi connectors so that there are only a couple of them that I need to undo in order to pull the motor. I need to get back out in the garage and finish it off. It's super close to being done. I think I just need to bolt on the top half of the two piece and then finish off the sensors.

Here are a couple brief videos about the project although I'm not sure how much I get into the wiring aspect.

[tryingbe]

As for Megasquirt, i'd have to see a list of what it can do that A: modified stock electronics cant do

On top of my head.

1. Get rid of the distributor and use a waste spark coil pack setup.
2. Able to add a E85 sensor and adjust the calibration as need with the % of E85 in the system and display E85 content.
3. Blue tooth connection between the ECU and computer.
4. Auto A/F tune.

[Vigo]

Well there's a good start on part A, then part B would be which ones does the owner actually care about.

I've always thought that if i ever follow through with a couple of the swap ideas i have right now that i would do all the wiring across the trans to the motor like Cordes is doing. That's more or less the way the V6s are set up and i just think it is 'cleaner'.

[1984rampage]

Decided to go SMEC. It should provide any features needed for the power I will be looking to make, cost/installation/learning curve is better, and it will look factory under the hood