Jun 12, 2020
Hello everyone, hopefully I,m posting the in the right thread. So I have an automatic 90 fox 5.0 LX with a lot of different mods. I got the mustang about year ago from a guy who was starting to convert it into a drag car. He got about half way and gave up and I took over the car. I dont want to make it a dragster, just a daily driver with a little pep in it's step. When i got the car, everything but the engine and timing cover was taken out. After a week of putting everything back on, I finally got it started. Unfortunately the transmission was shot and the engine was knocking bad. I got the transmission rebuilt but had to hold off on the engine for awhile. I still drove it every once in awhile just down the street and it ran smooth other than the knocking. I was debating what route to go with fixing the engine and decided to just buy a rebuilt 302 from Mabbco Motors. It took me a few weeks but i finally got the new engine in and got it started. And this brings me to my problems I'm currently having. The engine shakes like its about to jump out of the compartment. When I accelerate, the engine is slow to pick up speed and there is backfiring into the upper intake. Smell of rich fuel while car is running. I can slowly get her up to highway speed but I dont want to drive around with these problems.

CEL codes that are showing up
1. 54 - It sounds dumb but I dont know where my ACT is. There is a explorer intake on the car but the act is not drilled into the #5 intake or the cold air intake. the wires from the fuel wire harness plugs a connector that runs back into the main harness. I'll attach a photo to show what I'm talking about. I've tried to trace the wire back but it gets lost in the main harness.
2. 31 - EGR was deleted by previous owner.
3. 85 - Charcoal canister was deleted.
CEL flashed 9-8-5-4

Things I've done
1. The engine mounts are new and I replaced the harmonic balancer with the engine
2. Checked for vacuum leaks but could not find any.
3. Base idle reset and tuned the timing which trimmed down the shaking of the engine. TPS was bad, installed new one but runs no better
4. switched around the spark wires and ran KOER but still got 9-8-5-4
5. cleaned out MAF and air filter
6. Installed new spark plugs
7. installed new fuel regulator
8. installed new distributor.
9. installed new O2 sensors
10. Installed new Fuel injectors
11. Installed new fuel filter and pump a few months before the new engine
I've also followed the surging idle checklist as best as I could but nothing helped.

Any other ideas would be greatly appreciated. My wife is starting to suspected this car is a dead end money pit and I'm not ready to let my wife go :tss:

This is my current setup. Its not the prettiest but ive spent a LOT of hours in here.
This is the plug that i believe is supposed to go to the ACT. It comes out of the fuel injector wire harness.
act plug.jpg

From what i understand, this is where the ACT is supposed to be on the #5 intake
5 intake.jpg
The blue line is where the wire runes into the main wire harnes
ACT Away.jpg
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You can make an extension for the act plug and install it in the intake tubing or in the core plug of the upper intake (the freeze plug looking thing, looks kinda hoki but works.
Is the engine set up for the HO firing order?
Is the balance weight for the balancer/flywheel correct of that engine? (28 oz vrs 50oz offset balance)
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IT'S ALIVE!! So the shaking like a mad lad has stopped but I will have to wait until later to see if it still backfires. I will have to give credit to General Karthief for helping me find the problem. The engine was set to the HO firing order but is a non-HO engine. I swear i told my engine builder to build for a HO but:shrug:. What is the engine performance difference between the HO and NON-HO anyway? I guess i was too quick to install the distributor the first go around and since the engine started and ran (like :poo: though) figured the HO firing order was the correct one. Also, what would be the consequences or running an engine with the wrong firing order for 20ish miles at up to 60MPH? does not sound like anything is rattling around but we will see.

For the ACT sensor I am still stumped though. There is no ACT plugged into the upper or lower intake. When I was swapping engines I repainted both of them and I saw nothing like that poking out. I bought a ACT sensor and plugged it into the harness ( resting on the valve cover, not installed anywhere ) and the CEL code for the ACT went away. Still hard to follow the wire as it runs into the main wire harness. I don't see any unusual wires popping out of the wire harness where the ACT would have been installed. There is also nothing drilled into the cold air intake so that cant be it. The only loose connectors are the EGR and the plug for the emissions because they were both removed. Just going to tap into the intake and install my new one.
Last question, what would happen if i left the ACT out? just curious since i don't think i ever had one installed....
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Just installed the ACT. I decided to put it into the upper intake because i didn't want to deal with removing the lower again. Drilling and tapping wasn't hard, just worrisome. Had my personal mechanic help me, but his advice is always gibberish.
ACT 1.jpg
act 2.jpg

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