1986 Manual Swapped 5.0 Misfire + Other odd issue

LinkedInLincoln · Aug 12, 2024

Hello everyone.

I've got a 1986 5.0 engine in my Lincoln Mark VII and it's been giving me some issues after a manual swap.

For starters, I've been getting an odd stutter/bucking which has typically only happened when letting off the throttle but now it's starting to cut out
while accelerating. Once I'm over 2800 - 3000 RPMS it clears up but it's been getting annoying to drive with this issue. If I push in the clutch, give it a rev
, and let the clutch go it seems to help it a little. This probably occurs when the car is cold and warmed up.

I've checked out my salt and pepper shaker connections cleaned them out and replaced them with some dielectric grease but I'm still getting the same issue.

Another issue (Which could be related) with the car is on occasion the RPMS will hold for about 8 seconds after pushing in the clutch coming up to a light. When I'm stopped
the engine is at around 1500 RPM and then it will drop to idle.

I've cleaned out the IAC, checked the voltage on the TPS, and have it set to 0.98. Is there any other things I should check? I'd like to get this issue resolved soon because it's getting
worse every time I take the car out.

Noobz347 · Aug 12, 2024

Have you pulled codes?

LinkedInLincoln · Aug 13, 2024

Noobz347 said:
Have you pulled codes?

Hello there I pulled the codes with the car off. The car has all the emissions deleted so it throws 81, 82, 84, and 31.

I tried to do a running code scan but the car just stalled out

Noobz347 · Aug 13, 2024

There is pretty good chance that the ECU itself is at fault.

We have seen a [rash] of this happening over the last year to year and a half.

If you have access to another ECU, try it. If not, I would suggest https://www.theecuexchange.com/

LinkedInLincoln · Aug 13, 2024

I just managed to pull the codes on a KOER test. I got 84, 44, 31 and 94.

A cylinder balance test resulted in 6 and 7. I'll have to look into that a bit further but I don't know if it would be causing issues unless the spark plug wires themselves are the problem.

I will try out a different ECU though and see how it does. Thank you for the reply.

Noobz347 · Aug 13, 2024

LinkedInLincoln said:
I just managed to pull the codes on a KOER test. I got 84, 44, 31 and 94.

A cylinder balance test resulted in 6 and 7. I'll have to look into that a bit further but I don't know if it would be causing issues unless the spark plug wires themselves are the problem.

I will try out a different ECU though and see how it does. Thank you for the reply.

That's an idea. Run the engine tonight once it gets dark and see if there's any arcing.

LinkedInLincoln · Aug 13, 2024

The cylinder balance test never lies.

It's time to feed this engine a new set of spark plugs.

General karthief · Aug 15, 2024

Noobz347 said:
That's an idea. Run the engine tonight once it gets dark and see if there's any arcing.

Good idea boss, but let's take this a step or two farther.
First the plugs, get some regular copper cheap azz plugs, don't need those high dollar irrideum gold plated V stuff.
the only code I would be concerned with is the canister inop code (31?), is the purge valve and related stuff hooked up?
Now swap'n computers? Not something I would do if my computer is the original, I'd send it in to ECUExchange, I think sticking another computer in can induce other problems unless that one has been gone though and matches my car exactly, these things are 30+ years old and crude by todays standards,
Also a good 'tuneup' ie: plugs, wires, cap and rotor,, also this is 'speed density ' so vacuum leak(s) has a adverse effect. Stuff like fuel filters are often neglected, also a quick look at the hard lines for fuel, a pinched fuel line will starve an engine.I
Just some thoughts from an 'old guy'
After all 'Old Guy's Rule'........right?.......RIGHT??
Anybody? O well, I tried

LinkedInLincoln · Aug 15, 2024

General karthief said:
Good idea boss, but let's take this a step or two farther.
First the plugs, get some regular copper cheap azz plugs, don't need those high dollar irrideum gold plated V stuff.
the only code I would be concerned with is the canister inop code (31?), is the purge valve and related stuff hooked up?
Now swap'n computers? Not something I would do if my computer is the original, I'd send it in to ECUExchange, I think sticking another computer in can induce other problems unless that one has been gone though and matches my car exactly, these things are 30+ years old and crude by todays standards,
Also a good 'tuneup' ie: plugs, wires, cap and rotor,, also this is 'speed density ' so vacuum leak(s) has a adverse effect. Stuff like fuel filters are often neglected, also a quick look at the hard lines for fuel, a pinched fuel line will starve an engine.I
Just some thoughts from an 'old guy'
After all 'Old Guy's Rule'........right?.......RIGHT??
Anybody? O well, I tried

Hello General Karthief! Thank you for your reply

I've addressed all the vacuum lines on the car and had the upper intake manifold off to redo all the lines underneath it. The charcoal canister is hooked up and I also did new lines down to there. This might be the place where I have to put my effort into.

The weirdest issue by far that leads me to think I have a sticking IAC is on random occasions when I push the clutch in coming up to a light the engine will hold its RPM's at 1800 and then it will go back to idle after a couple of seconds. Does this sound like something that could be related a sticking IAC? I've had it off for cleaning before but maybe it just needs a straight-up replacement

I've also done a fuel pressure test on the car and nothing seems abnormal with the fuel pressure while bringing it through the RPMs so I don't think it's a fuel delivery issue. It has all its jerking and bucking issues while going down the street with the accelerator pedal let off. And when I mean jerking and bucking it's like a mechanical bullride if you don't push the clutch in

General karthief · Aug 15, 2024

You still got the original mark VII computer?
a malfunctioning purge canister system should not cause your issues.
I'm not sure but the mark VII may have s different computer operation than a HO computer, at one time non-HO engines had the old firing order, HO engines have the 351 firing order and it's not just a simple plug wire swap.
You don't mention modifications so I'm kinda stabbing in the dark.

LinkedInLincoln · Aug 16, 2024

General karthief said:
You still got the original mark VII computer?
a malfunctioning purge canister system should not cause your issues.
I'm not sure but the mark VII may have s different computer operation than a HO computer, at one time non-HO engines had the old firing order, HO engines have the 351 firing order and it's not just a simple plug wire swap.
You don't mention modifications so I'm kinda stabbing in the dark.

Sorry for not mentioning that part. It isn't an HO car; it is the original computer in the car. The computer still reads all the codes for KOEO and KOER tests. I'm more than less now trying to figure out with at cruising speeds I'm feeling the engine. It does perfectly fine when you are on it over 2500 RPMS but it starts to stumble, hesitate, and buck once you let off or near idle RPMs.

At cruising speeds when the engine is nearing idle speeds going 60 km/h you can feel the engine stuttering a bit which is probably more pronounced when going into higher gears. It seems the only way to get the violent jerking to go away is to push the clutch in and then the engine immediately idles perfectly like nothing happening.

The car has never had issues with hard starting and it has never flat-out died on me. I'm starting to get a bit lost at this point now on where to focus
my energy regarding diagnosis. The engine codes so far have not pertained directly to my issues

General karthief · Aug 16, 2024

Forget the codes.
like I said, you may have the wrong computer.
let me do some research for ya.
be back in a minute

Noobz347 · Aug 16, 2024

LinkedInLincoln said:
The cylinder balance test never lies.

It's time to feed this engine a new set of spark plugs.

That plug is burned [lean].

You need to be hunting around for a vacuum leak someplace. Hoses, gaskets, inlet tubing etc...

You said this is an 86 so am I right that it has no Mass Air Sensor?

Toss up a clear image of your engine bay when you have the chance.

Noobz347 · Aug 16, 2024

General karthief said:
Forget the codes.
like I said, you may have the wrong computer.
let me do some research for ya.
be back in a minute

Didn't he say that it ran good at one point tho?

General karthief · Aug 16, 2024

What year Markll?

Noobz347 said:
Didn't he say that it ran good at one point tho?

good In the higher RPMs is what I understand, see, the question here should be, does the computer match the engine? If the computer is running the engine on the wrong firing order things are happening at the wrong time. Also some Mark lls were CFI (central fuel injection) which only has, what 2 or 4 injectors (can't remember).

Noobz347 · Aug 16, 2024

General karthief said:
What year Markll?

good In the higher RPMs is what I understand, see, the question here should be, does the computer match the engine? If the computer is running the engine on the wrong firing order things are happening at the wrong time. Also some Mark lls were CFI (central fuel injection) which only has, what 2 or 4 injectors (can't remember).

Yeah, I'm not 100% clear on what's going on. Along with the engine bay image, a pic of the EEC would be good too.

LinkedInLincoln · Aug 16, 2024

Noobz347 said:
Didn't he say that it ran good at one point tho?

Noobz347 said:

That plug is burned [lean].

You need to be hunting around for a vacuum leak someplace. Hoses, gaskets, inlet tubing etc...

You said this is an 86 so am I right that it has no Mass Air Sensor?

Toss up a clear image of your engine bay when you have the chance.

Click to expand...

Here is a picture of my engine bay (Please ignore the dumb cold air intake. I'm putting that factory box back in as soon as I have to take out the other one for cleaning)

LinkedInLincoln · Aug 16, 2024

Noobz347 said:
Yeah, I'm not 100% clear on what's going on. Along with the engine bay image, a pic of the EEC would be good too.

Here is a picture of the EEC's numbers

General karthief · Aug 16, 2024

Ok, year of lincoln?

LinkedInLincoln · Aug 16, 2024

General karthief said:
Ok, year of lincoln?

1986 Mark VII

1986 Manual Swapped 5.0 Misfire + Other odd issue

Member

Stangnet Facilities Maint Tech... Er... Janitor

Member

Stangnet Facilities Maint Tech... Er... Janitor

Member

Stangnet Facilities Maint Tech... Er... Janitor

Member

Attachments

wonder how much it would cost to ship you a pair

Member

wonder how much it would cost to ship you a pair

Member

wonder how much it would cost to ship you a pair

Stangnet Facilities Maint Tech... Er... Janitor

Stangnet Facilities Maint Tech... Er... Janitor

wonder how much it would cost to ship you a pair

Stangnet Facilities Maint Tech... Er... Janitor

Member

Attachments

Member

Attachments

wonder how much it would cost to ship you a pair

Member

Similar threads

Privacy & Transparency

Privacy & Transparency