1986 TBI Replacement

[tsa256]

Hello everyone, looking to put a TBI into my 1986 2.8 Comanche. I've looked around and heard that the Holley 502-4 http://www.summitracing.com/parts/HLY-502-4/ is a direct bolt on and works very well. My question is what else do I need to complete the swap? Do I need a new ECM, some people say I do and some say I don't could someone please provide insight on the parts I need as well as any tips you could give me for the swap.

 

Thanks

[Eagle]

The ECM in your Jeep is set up to (partially) control a dumb carburetor. I seriously doubt that it can do anything with the Holley aftermarket injection. Does the kit include an ECM? You'll need (I assume) an oxygen sensor, and a computer to read the O2 sensor and control the injection.

[deziped]

I thought those had carburators on them. And if that be the case, TBI won't work without somthing telling it when to squirt.

[alleydog]

You could use the whole setup from a 87 small blazer. You would need the distributor, intake manifold, throttle cable and all the sensors off the blazer engine. I'm pretty sure the heads are the same as your 86, so it should bolt right on. You will also need an electric fuel pump, inline with 15 lbs pressure. If you get the factory wiring diagram, it's not that difficult to wire up. Basically, 2 or three grounds, a couple B pos, and a couple ignition switched positive.

[tsa256]

Thanks for the insight. I did a little more research and came across this article http://www.4x4wire.com/tech/60degreeV6/ . It says that the 2.8 ECM will handle the TBI just fine. Does anybody know if this is true? If not are there any good TBI kits that come with all the other hardware needed to use a TBI in place of a carb.

 

Thanks again.

[alleydog]

I think what they mean, is IF you have a 2.8 TBI, you can use the 4.3 throttle body with a 2.8 TBI ECM. I personally think the 4.3 injectors will be too big for a 2.8. I ran TBI on my 400 small block, with a large bore Holley TBI unit, it ran OK, but you kinda had to feather the throttle in or it would hesitate. The other thing about TBI is that it's a speed-density system, and you must run a stock or very mild camshaft, or it will load up at low rpms.