Frankenharness

[Shran]

Has anybody actually done the 2.9 harness mod where you splice in two more injector plugs for use with a V8?

It sounds a little ghetto but insanely tempting - I am using a speed density 5.0 engine from an '89 Crown Vic, the injectors on those are bank fired, right? So adding one more on each bank doesn't seem like it would be an issue at all.

The 'Vic had two O2 sensors - would that pose a problem? Is it necessary to have two, or would one right after the y-pipe like on a 2.9 work?

I'm assuming this all uses the 2.9 computer?

Let me know if this is really stupid, but in my head it seems like it will work and I've heard the rumors. I am trying to avoid using the 5.0 harness because I'm having a hard time finding wiring diagrams to splice it into my truck.

 

[stegomon]

hmmmm i like this idea

 

[Teddyzee]

If you want life to be easier, you could get a speed Density Mustang harness pretty cheap.

Sound like the mods you mention will work... But who knows.

99% sure I have a pinout diagram for your car. If you want to use that harness, simpy follow the diagram, test continuity of each circuit to see where they go (from ECU to connectors) and it will work.

I'm not at home, I'll post it within the hour.

 

[Teddyzee]

Sorry, I don't have the diagram.

 

[Shran]

No prob, thanks anyway for looking. I thought that my swap should be close enough to the one Dishtowel did in his B2 but his harness is way different than mine.

I do have a wiring diagram for the car - but it is not very good and so far seems very inaccurate. I am considering just buying the AllData subscription for it but this 2.9 harness thing just seems crazy enough that it might work.

 

[Psychopete]

It sounds a little ghetto but insanely tempting - I am using a speed density 5.0 engine from an '89 Crown Vic, the injectors on those are bank fired, right? So adding one more on each bank doesn't seem like it would be an issue at all.

I think the set up on my '87 Grand Marquis was sequential 14lbs. I looked at a cheapo diagram for both my 87 and your 89 and it is showing they are sequential injection. Not sure what would happen if you ran it batch fire, but you'd have to add more wiring if you used a 5.0L computer and it looks like you'd have to re-pin a ton of stuff. I think figuring out the right harness would be the way to go, but that is just my opinion. If you have the harness, look at the injector wiring and see if they have similar wires (red is obvious, but the others will probably be all different colors). Seems like you'd have to extend and swap connectors in the harness, sounds like a big can of worms.. Carb, intake, dist (w/ steel gear) would take care of this issue in a hurry.

 

[Shran]

Hmm, yes, looking at the diagrams I have it looks like you're right, the car is SFI and the 2.9 is bank fired.

I have been doing some more reading and it looks like most of the truck 302 engines were bank fired, so it should at least run, theoretically. Looks like there are only 3 wires from the ECU to the injectors on the 2.9 so it would be minor splicing.

I think one would just about have to run the 2.9 computer, repinning the ECU connector for the 5.0 computer would be a major pain in the ass and way more work than it's worth. Just seems like since they're both speed density engines with the same sensors, it should, again in theory, work.

I was really going to do a carbureted engine. I had one all cleaned up and ready to drop in. I wanted fuel injection bad since I play in the rocks and off camber stuff a lot, but it's what I had... then I found the 'Vic and my mind was made up.

 

[cammeddrz]

ok i have done this on more than one tbi camaro that had 2 injectors. i used to make money on the side by swapping in the tuned port injection manifolds it works but on two of the ones i did in less than a year the added impedance from the extra injectors fried the injector drivers that are internal to the computer.


btw "impedance" means resistance usually measured in ohms. so in layman's terms it put more load on the injector drivers

 

[Mac]

A lot of the F-150's ran batch fire also but think teddy has a better solution using the Mustang stuff (?). I have the wiring diagram for the '89' Ranger if that would help.
Dave

 

[Shran]

ok i have done this on more than one tbi camaro that had 2 injectors. i used to make money on the side by swapping in the tuned port injection manifolds it works but on two of the ones i did in less than a year the added impedance from the extra injectors fried the injector drivers that are internal to the computer.


btw "impedance" means resistance usually measured in ohms. so in layman's terms it put more load on the injector drivers

Yeah, that makes sense. I was slightly worried about that. But for your application - you're adding 6 more injectors, right? I don't know how much more just two more injectors would add but it doesn't seem like it would be excessive.

A lot of the F-150's ran batch fire also but think teddy has a better solution using the Mustang stuff (?). I have the wiring diagram for the '89' Ranger if that would help.
Dave

Agreed, I wish I had a Mustang harness because it would be a lot easier, at least in terms of identifying wires. Just trying to use what I have at the moment and possibly do some experimentation for those of us that are OK with speed density setups.

Could you post or email me the diagram you've got? It's gotta be close to the '86 I'm swapping into, and anything will help!

 

[cammeddrz]

yeah only adding 2 more injectors likely won't be so bad.

 

[cammeddrz]

i have alldatapro here at work (all vehicles, not just one) tell me what diagram specifically you need

 

[Shran]

i have alldatapro here at work (all vehicles, not just one) tell me what diagram specifically you need

'89 Crown Vic, base model, 5.0 - I guess a good pinout of the ECU and a diagram of the engine harness, starting, and fuel pump circuits should do.

THANKS!

 

[cammeddrz]

 

[fordmike1]

Has anybody actually done the 2.9 harness mod where you splice in two more injector plugs for use with a V8?

This would not be a good idea as each computer has a stratagy table built in to them for each vehical and the engine it has in it. In other words it wont make the correct adjustments it needs to make the engine run correct in the many of diffrent situatons it will see or could see.