Non H.O. cam with H.O. again..

[B.D. Magoo]

I have a 85' mustang with 88' sd efi. Acquired another engine for it recently; 30 over pistons, edelbrock performer heads, cobra upper and lower, 1.6 roller rockers, and a trickflow stage 2 cam. The cam is a non H.O. firing order so I've already done my homework for this fix, change to non H.O. ecu or change cam or put a carburetor on it. My question is what would happen if I jumped my signal wires of the O² sensors together? Would it read the fire from number 5 as number 2 so it will stop dumping fuel, or cause irreparable damage to the ecu or O² sensors if it works at all?

 

[Mustang5L5]

The TFS stage 2 cam is the HO firing order. If you splice the o2 sensors together, the readings will be way off. Do you mean to rewire them to opposite sides?

 

[B.D. Magoo]

It is a tfs2 cam and it is not H.O. firing order. Seen the receipt where the guy built it, summit loves this guy now, but when plug wires are set H.O. sounds like the intake gonna explode from all the backfiring. Wire it up standard and it runs well, not great, but dumps fuel while O2 sensors say its lean. Its dumping enough fuel I wont light a cigarette behind it..
I wouldn't know how to set the O2 sensors to read the other side, but was curious if I spliced the signal return wires together what it would do. I have the E cam from my last engine but dont really want to change it yet unless I have no option. Got a guy looking for a non H.O. eec for me but that might be a while so I'm playing around with it until then.

 

[Mustang5L5]

Part number TFS-51402001 on the cam card? Pretty sure that’s a 1-3-7... firing order.

you can’t splice the o2s together. The return signal voltage will be corrupted and it won’t read properly?

 

[B.D. Magoo]

I dont have any of the paperwork now. I bought the engine 4 years ago and shelved it until my exploder motor.. well exploded oops. But I lost all my paperwork for it in a fire.

 

[B.D. Magoo]

Thanks for clarifying on the O² sensors. I was wondering if that would happen. Removing them just wont work bc the last signal the computer got was a lean signal it will lock it in closed loop making all 8 burn rich instead of just 4.

Any other poor man solutions to this?.. cause the only 3 correct ways ain't cheap.

 

[Mustang5L5]

you can swap the wires for the injectors. 5 with 3, 4 with 7. Might need to extend the wires.

You can also swap the pins down at the ECU between the injector pairs.

not the best solution however as now the o2 sensors are sensing 2 of the 4 “wrong” cylinders.

your going down a slippery slope however using this method because if you are still having issues and everything is rewired, it’s going to be hard to climb back out of the hole so to speak.

 

[B.D. Magoo]

Yeah if the cam doesn't match, bc of the O² sensors your pretty well F'd. I've really dug into this before I asked, wiring the O²s together was never brought up as a possibility so I figured I'd ask about it.
So far the only change I have actually made was relocate my plug wires to non H.O. and it went from making popcorn in the intake to shaking the walls.. granted I have a small shop, but still a huuuge improvement.
But if someone thinks of something different I'll gladly try while I'm waiting to hear about a different computer. I've read different things about the VM1 out of a 86 I dont know if its S.O. or H.O. but a friend says he may have one and for free.. I can wait a few days.

 

[Mustang5L5]

It’s a speed density HO computer with sequential injection.

What ECU are you running now?

 

[B.D. Magoo]

8DL I think it is. It's out of a 88GT.

 

[Mustang5L5]

8DL I think it is. It's out of a 88GT.

That’s a 1988 California mass air ECU.

Is the car wired for mass air? Because you mentioned speed density previously. They are wired differently

 

[B.D. Magoo]

No mass air never has had it... I really do have a frankinmutt.. wtf

 

[Mustang5L5]

Welp, that could potentially be the cause of why it’s running that way. A pic of the ECU tag label will help confirm. The ECU pins are slightly changed, the map sensor should be open to atmosphere and its looking for MAF readings.

You really need to ID what you have because mixing and matching harnesses can also free ECUs.

The VM1 should work, but you’ll want to check the o2 harness first to see if it has a jumper on it and if the jumper is in the correct position for a manual trans ECU

 

[B.D. Magoo]

This thing was literally put together with hand me down parts when I was a kid and I've never outgrown it. It went through a few carbed engines then upgraded to the fuel injection for free when a buddy went big block. I took it all out of his car, no mass air on it. Been through a few more and here we are now its my go-kart not a race car just an expensive toy.

 

[General karthief]

Can you get codes from the computer?
It's possible you have also injured the ecu with the miss matched stuff.
This is all fixable though.

 

[B.D. Magoo]

67 o - neutral safety switch fail
81 o - air diverter selonoid fault
82 o - air diverter circuit fault
85 o - purge solenoid fault
84 o - egr vacuum regulator fail

*15 c - power interruption to computer memory, eec keep alive memory (KAM) failed
------------

8 cyl
idle
41 r - O² sensor voltage low / lean
91 r - O² sensor voltage low / lean
33 r - egr valve not opening

8 cyl
wot
42 r - O² sensor voltage high / rich
92 r - O² sensor voltage high / rich
33 r - egr not opening
______-

*I reset all electronics after I installed the engine.

 

[Mustang5L5]

Did it ever run well or you always had issues?

I think the root of the problem is it’s a mass air ECU with speed density wiring and aftermarket parts.



Can you 100% confirm it’s an 8LD? Those codes are better than what I expected.

 

[B.D. Magoo]

Hehehe my dots in my notes made faces lol.
The car ran like a monster with last 3 engines. Stronger every time it rolled out and now it feels like stock and leaves a vapor trail

 

[B.D. Magoo]

It will be this time tomorrow before I can get back to my shop. It's my family shop and it's an hour drive but I can run down after work tomorrow morning.

 

[B.D. Magoo]

And yeah you can tell from the codes I'm running engine only. It does have power steering but even the heater only has on or off.