Srutherford

Hello all thanks for having me I am asking for some help. I have searched and searched on this and can't figure out my problem I will explain what I have and what I have done so here goes.

I have a 92 lwb 4x4 f150 with a 302. The engine formed a knock and I had a gt engine from a 93 mustang it had been swapped to carb. I researched and found basically it was strait forward swap. Just different intake and firing order. So after I intalled engine it fired up but was missing new plugs wires cap button and dizzy. I set base timing at 10 deg btdc The engine back fires through intake under a load seems to far advance or lean. I discovered if I pull no 3 and nun 4 injector connectors there is no change in engine tone same with 5 and 7. How ever if I pull 1 and 2 or 6 and 8 it will change tone. So..... I thought after some homework I need to change the injector wiring to match firing order of the ho/Windsor well still no change. What gives am I missing something do I need the truck cam and go back to the old firing order and if so what cam as theses are roller lifters. Please help.

Thank you
Silas

GMtraitor

Looks like you did everything right maybe running lean what your plugs look like? Maybe they can confirm lean condition. Main thing is switching to h.o firing order

Injector order shouldn't matter on a 92 because of batch fire with speed density

qdeezie

You did not need to change the injector wiring. On speed density setups the wiring is the same for both the HO and non HO firing order. Change it back.

imp

Injectors in 5.0 HO engines (Mustang) are BIGGER than those used in F-150 5.0s. Old PCM is failing to provide correct fuel delivery calibration. Either use truck 5.0 injectors, 14 Lb/hr, gray color, or replace PCM to use the HO 19 lb/hr injectors yellow color), which would also require ADDING mass air capability.


See here for description: http://www.fiveohinfo.com/fox/ignition.html


imp

Chris_1

iTrader: (1)

I take it you swapped on your truck intake so injectors should be fine. As mentioned, speed density can handle either cam. The mustang cam will suck in the truck (no torque) but that shouldn't cause the problem.
I'd go back to basics, make sure the distributor is in properly, recheck the base timing (SPOUT out), make sure you're using the right timing mark, etc.
I can't think why unplugging injectors doesn't affect the motor - recheck all your wiring, especially your engine harness plug. Are all the plugs firing ?
Maybe check if all the injectors are getting a pulse - I think you need an LED test light for that.
And a wet/dry compression test may be in the cards.
Did you hear the thing running in the mustang ?

Srutherford

Thanks guys well I will switch the injector wiring back But for what it's worth I only have 25-30 psi of fuel pressure shouldn't I have 50 ish and mine is dual tank

Srutherford

Thanks guys well I will switch the injector wiring back But for what it's worth I only have 25-30 psi of fuel pressure shouldn't I have 50 ish and mine is dual tank and 180psi comp dry and 189 190 wet

Modular man

Ya that's alittle low should be 35 -60 psi have u changed ur fuel pumps? . If not I'd got with sum better high pressure pumps. Change ur filter to while ur at it

Srutherford

Yes lol it has two new pumps and filter. And sending units as a matter of fact the rear tank is brand new as well. I unplugged the the regulator vacuum line and no change at all. It just baffles me that I can pull the number 5,7,3and 4 injector plug and I get no change in tone num 5 and 7 are brand new injectors. If I pull no 1,2,6,or 8 I get a drop in rpm and a worse miss. Here is where it's crazy. I plug no 6 with 5s harness baaam picks back up there same 7 to 8. Would this little change in pressure cause that? I would think no 1,2 6 5 and 6 suffer seeing that they are furthest away. Idk I'm baffled. Would it cause a issue if this engine have a higher lift cam and carburated. Not really sure it does. Just asking would the ecm be able to adjust to that. I really am thinking about just puting the truck cam back in but which one seeing that this is a roller engine

Modular man

Unplugging injecters like that should make it run terrible no matter wat ones. That's just crazy lol