SBEC options

[WickedShelby88]

I am just curious what years had SBEC 1's and 2's. Also is a TBI and TURBO SBEC the same for 91 and up or would I have to find an SBEC from a turbo car if I want to use it.

[Turbodave]

Pretty sure the TBI SBEC doesn't have the injector drivers needed to run a turbo car.

[WickedShelby88]

Well how hard is it to convert from SMEC to SBEC if you have a donor harness. Are there a lot of differences at the bulkhead connector I would need to address? Wanting to do an MP ATX SBEC for my upcoming lancer drivetrain.

[MiniMopar]

The body wiring changed quite a bit between the LM/SMEC and SBEC cars. More devices are driven by the 2-wire bus from the SBEC. Why do you have your heart set on the SBEC?

[iTurbo]

I have converted my Shelby Lancer to SBEC. I'm using an entire underhood harness from a '91 Lebaron GTC and SBEC from a '90 turbo/MTX Caravan.

The swap ended up being much easier than I though it would be. There was almost no difference in the bulkhead pinout configuration between the SL and GTC other than slightly different option content between the two vehicles. The biggest problem I had to deal with was the bulkhead shell. The SL used a male 50-pin connector but the GTC uses a female 50-pin connector. I had to cut and splice the correct bulkhead on but I took my time and made it as neat as I could. All splices are soldered and have a double layer of heat shrink tubing, and wrapped up in friction tape.

At first I was going to convert the car to SMEC using an '88 Lancer Shelby TII harness. My SL was on it's second OE (LM/PM) harness and was already a tattered mess. Later I found the '91 GTC harness and wanted to use that instead because it had the Power Distribution Center, which is an underhood module behind the battery that houses all the modular fuses and relays. This eliminates all fuse links which is a godsend. Another big reason I made the switch to SBEC is that I'm converting the car to TIII and will be using '91 TIII SBEC. This will require a little more work in relocating some connectors but the foundation is there.

[WickedShelby88]

It seems to be a superior engine controller and they aren't in high demand right now. The yards are much more full of cars with those and harnesses because most of the SMEC cars are dwindling away. I don't know for a fact but I thought I heard that it is a sequential fire injection as well. I'm thinking I could definitely get more fuel economy and performance with one then with a SMEC. I imagine the bus drive could be avoided to some degree. Just kicking around the idea of something better without going stand alone.

[iTurbo]

Yes, it is sequential. Four separate injector drivers going out from the SBEC. Curiously, my MPG went way down after the conversion. First I attributed this to the fact that I was using +20 injectors, so I installed some stock injectors and the fuel economy is still pretty bad. I can only assume now that it's because I'm using an SBEC calibrated for a 2.5L and I'm still using 2.2L. I have a narrow-band O2 gauge and it still goes into closed loop just fine, but it seems to peg the 20th light more often than it should. I would probably get a custom cal for it, but I'll be installing the TIII this summer anyway so I live with it.

One thing that stumped me during the conversion was the two wires for the "CCD bus". The wires existed in the GTC harness but there was no where to put them on the SL firewall connector. Car seems to run just fine without it going anywhere....I don't know what they are for.

[MiniMopar]

They are sequential, yes, but don't expect any huge fuel efficiency gains. I had the same problem with the bulkhead on my Daytona and decided it would be less work overall to keep the stock body wiring. Of course, I was trying to adapt it in the opposite direction.

[WickedShelby88]

I suppose the main superiority would be dyno tuning if I was going for high horsepower being able to tune the injector timing to each individual cylinder versus batch fire. I know when you compair an LT1 to an L98 in chevy terms the sequential is what really made the significant improvement in fuel economy and I'm hoping to do that here as well. No I don't expect anything huge, but when they eventually implement emissions testing I think the SBEC will be a safer bet. Timing tables and fuel scaling are a bit different from 2.2 to 2.5 IIRC. CCD Bus goes to the BCM I believe to perform certain functions along with some lighting function I think. Jeremy, I'm surprised it worked out so well for you with using the power distribution box along with the other wiring. A GTC would be what I need to look for and being as the auto cars are more common this may work out in my favor. Are the wiring harness sections which make the difference between auto and stick easily disconnected and swapped? They seemed to be that way when I took apart the harness on the Shelby Z I parted, but that was a SMEC harness.

[iTurbo]

Barely any difference at all between the MTX and ATX harnesses. The MTX uses a two-pin reverse light switch whereas the ATX uses a three-pin reverse lockout switch in the same location (topside of trans). They are pretty much interchangeable. If you want to use a auto harness with a manual trans setup, all you have to do is ground the brown/yellow wire that goes to the three pin switch. The three pin connector will push right onto the two-pin reverse light switch. All turbo/auto cars were non-lockup but the TBI/auto cars did have a lockup solenoid.

The harness is working great in my car though. It wouldn't start on the first try because I was missing a maxi-fuse for the ASD relay, but has run fine with no codes ever since. Underhood appearance is definately improved with the PDC. The weatherpack connectors are generally more reliable in the SBEC harnesses too, as well as being much less bulky than a LM/PM harness.

[WickedShelby88]

Definitely food for thought. I was contemplating getting a later A413 so I could take advantage of the LTC. Is the brown and yellow the neutral safety switch or what? Weatherpack connectors are a godsend. When I was working as a diesel fleet tech all of the lighting we wired in would get weatherpacks.

[iTurbo]

I think so, but it's been a while since I looked at my wiring diagrams. I do know the starter relay will not work if brown/yellow isn't grounded though.

[WickedShelby88]

Okay then that would be the case here. I remember working on a guys spirit a while back and he couldn't figure out why it wouldn't crank since I couldn't hear the relay click I was able to quickly trace the problem to a bad switch at the trans. Well then who here can tell me if the SBEC or SMEC is a smarter or just as good I should say setup as MS?