My '85 MGM, "Maisa"

[87GrandMarq]

What do you mean by "rolling idle"?
My idle is very steady, but the engine shakes irregularly and listening to the exhaust, there's a similarly irregular "plop" sound

I hunted down quite a few vacuum leaks last year, last time there was a very minor leak in the heater controls (from vac tree to inside) also the throttle kicker is supposed to leak a bit yes?
I should go through all the stuff again for sure, first I've got to replace at least the lines that broke today.
Ought to be able to get cheap vacuum hose and fittings from a local parts store.

I'd like to know what all can I plug off temporarily to run the car while doing such vacuum tests.

Surging really, its a common issue with cfi cars. Now the irregularities you describe are present on my 87 mgm as well but I figured it was the engine mounts. I would like to solve that too but its running pretty well and I don’t want my bad luck to rub onto this car some more lol. The ignition switch just went out too, its a great time too since I just started using it as my daily lol.

The throttle kicker is pretty much a small vacuum leak yes.

You could cap off one port on the vacuum tree at a time and the ports on the cfi itself. Just be careful if you are going to drive it like that because you will disable things like power brakes for instance.


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[Arquemann]

I hobbled together the broken plastic vacuum lines with new rubber hose and duct tape.
I should just replace them but I couldn't find the correct F-shape joiners and all the joiners are 2€ a piece FFS. For that price I am not going to just "grab a few of each" as I intended to.

The vacuum line from the fuel tank is split too, I'll get to that tomorrow.
The distributor cap still doesn't sit even on the distributor, it rocks a bit. Only 1 of the 8 contacts is worn a bit less than the others.
I put a timing light on each plug wire and cyls 7 & 8 seem to get intermittent spark loss. Would the coil cause interference that would appear as the timing light not flashing every time? Or do I really have spark issues that bad?

I'll retest anyways later, when I'm not freezing my fingers off.
Tomorrow I'll also check the plugs for any differences between them, dom't know id I'll see anything since I drove it with the o2 unplugged and it smelled quite rich.

[gadget73]

some of the caps don't fit quite right. The one on my Mark VII rocks, not sure why. I tweaked the clips to hold it down a little more securely but when I get bored sometime I would like to figure out what the high spot is so I can file it off and make it sit right.

[87GrandMarq]

How close are the 7 and 8 plug wires? They’re known to cross spark if too close.


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[Arquemann]

Would a dirty O2 connector cause the ECM to get a fouled signal, even if the sensor itself reads correctly?
Packing up stuff yesterday I noticed that the connector is super dirty with black crap.

7 and 8 plug wires go next to eachother on the (I assume) original plastic wire holders.
Should some wires cross and others not? I remember reading something like that somewhere about 302s.
But atleast 7 & 8 should stay far from each other?

[gadget73]

Won't help it any if the sensor connectors are crusty.


If you can seperate 7 and 8 in the wire looms as much as possible it might help. The big key it having space between them, so if you've got clips that will help. Do not zip tie them tight together though.


What does it actually do when you try a KOER test, just nothing? and how are you going about it?

[jaywish]

yes certain wires must be crossed. It is usually shown on the diagram if you look close.

[Kodachrome Wolf]

Here's a diagram with the wire routing from Ford.



While it looks funky how the wires bridge under each other, you can see it does it to get certain wires as far away from crossfire-possible ones. You'll need some wire separators, but it's real simple to get them routed properly.

[Arquemann]

Got some work done today,

Checked the plugs, managed to break only one plugwire, rearranged the plug wires as instructed above. Recut a split end of a vacuum line going to the gas tank.
Also cleaned the O2 sensor connector as best as I could with WD-40, brakleen and Q-tips. I might go back and put some dielectric grease if I find some lol.


4,5 and 8 are obviously quite lean and 7 seems to have been richer than all the others. (some electrodes have scratches from removal)

Here's how the wires look after rearranging them, I had to replace one with an old prestolite spare I found (not in image).

I moved the wires a bit back so they weren't on the coil wire.

The wires are Standard plug wires, Standard 6897, I think.



Drive test as usual, still jerks alot.
This seems to be somehow related to engine RPM.
35mph jerks bad in 3rd, not as bad in OD,
50mph is still quite bad in 3rd, but very slight in OD.
1 & 2 jerks also.
Accelerating with some thought is still buttery smooth. In 1, 2 and 3, I think it drops from OD almost every time I accelerate enough to make the jerkiness disappear.

As I got back home, the idle was a bit smoother in P, in gear its really nice, for about 10 seconds, then it starts misfiring again. Though this time it did not misfire at idle nearly as much, it misfires a few times 1-5, and then runs actually smooth for some time and misfires again. Best the idle has been so far.
It could have just been that the car wasn't feeling as moody today.

[Arquemann]

What does it actually do when you try a KOER test, just nothing? and how are you going about it?

Tried to do the KOER like the KOEO.
I have a test light that's like a flatblade screwdriver. I carefully put the tip in the STO, then the wire and from the test light to the battery plus.
For the ground I have a wire with a small male spade connector that fits snugly in the STI, other end has a spring clamp that I usually ground to the alternator bracket.

Just like you instructed in an earlier thread, I start the car, then connect the ground to the alt bracket.
And nothing happens, the test light wont blink no matter how long I wait.

I turn off the car and put the key back to run without starting, the KOEO test starts as it should.

[gadget73]

hm, what happens if you ground the STI with the key off and then start the engine?

[Arquemann]

Guys!
We have progress!

I checked the spark again, all seems consistent, but:

Unplugging the SPOUT instantly smooths out the idle, I went for a very short drive without romping on it much. It doesn't seem to jerk like usual, though it feels off. A bit uneven but less and in a different way.
SO, TFI bad? Distributor? Or what else affects ignition timing?

[Tiggie]

It will feel off without the SPOUT in because it never advances the timing.

I went though this with a Ranger recently. Mine ended up being the newer TFI was crap. I know you have replaced yours already.

[Arquemann]

I can't get a TFI locally, I'll buy from RA.

Should I go for the Motorcraft one or the cheaper Standard Motor Products? There's another cheaper SMP under "economy" parts.
I dunno about the cheaper random brands.

[87GrandMarq]

I personally would buy a good used one or motorcraft one.


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[Arquemann]

The fast idle did work at some point but does no longer. The mechanism is wrong somehow and it's not engaging and the pull off is leaking too.
I think I'll order the pull off vacuum diaphragm at the same time.

If the TFI module fixes the jerkiness, and with the fast idle making starting easy, I'll have this thing in a really good situation engine-wise.
Only thing really is the EGR acting wonky, but it might fix itself along the way or I might just delete it.
And then the cruise control, definitely.

[gadget73]

The pulloff drops the high idle out, the puck has an internal spring that engages it. Pull the puck off and make sure the tang didn't break off otherwise it won't engage the linkage. You should see a tab sticking into the area where the puck is, and the inside of the puck should have basically a fork that grabs the tab.

Change the pickup too if you're ordering parts. Distributor has to come out and apart to change it. Or just swap the whole thing. You need one with an iron gear. Its not a real difficult teardown, dist comes out, drive out the roll pin on the gear, press the gear off. Remove the roll pin in the metal thing above the gear and slide that off. Shaft comes out through the top. Pickup has I think 2 screws holding it in. Put the distributor back together. Don't beat the gear on with a hammer unless you have absolutely no choice. If you do, make sure you have the top of the dist shaft resting in a block of wood. A press is the much better tool here, if the shaft bends you're not going to be in for a good time.

[Arquemann]

So, I managed to break something again.

Choke spring and the tab are fine, I think I just put the spring in the wrong position when I changed the TPS last summer.

And there in the pic you can see how magnificently I screwed up. The choke pull off screws were kinda tight, I soaked them both in WD-40 from both sides, top one broke loose with big effort. The bottom one was a bit more painful, the screw head started to crumble, I managed to break it loose, then I heard the nice "tink" when something small falls into the depths. But the screw was still on the screwdriver...
As you can see, the corner broke off the choke pull off housing, which seems to be a single piece with the CFI unit. Great.

I think the steel screw had corroded so bad to the aluminium housing, that the 35yo brittle aluminium gave up faster. I found the broken off bit so I might try to fix it with chemical metal or so on.
For sure I can say that no one has ever opened that pull off, ever. The vacuum diaphragm was disintegrating and the shaft is pretty rusty.
Didn't get to snap a pic of the shaft and stuff, the spring was fine atleast.

Instead of cursing about the broken off bit, it started hailing quite a lot, then continued with a lot of snow.



I ordered the choke pull off diaphragm, Motorcraft TFI module and a Cardone Reman distributor from Rockauto. The cardone had a wholesale closeout conveniently, there would've been an autoline version that comes with the module, but I wanted the Motorcraft module.
I decided against buying the dist pickup separately since I don't have a press, I'm a bit uncomfortable hammering anything precise, and the price difference with just the pickup vs the discounted whole distributor was too good to pass up.

[matth825]

It’s a chunk of money but If can’t repair the throttle body:


https://www.ebay.com/itm/NOS-OEM-For...kAAOSw2Nhcm-Ik


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[Arquemann]

It’s a chunk of money but If can’t repair the throttle body:


https://www.ebay.com/itm/NOS-OEM-For...kAAOSw2Nhcm-Ik


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I think I can find a used injection unit locally.
The choke isn't really a big issue, I'm not going to drive this in the winter anyways.
I'll get to it when I get the engine running properly, maybe someone can tack-weld the corner back, or something like chemical metal or I'll just rig it somehow with a washer or a clamp.
All it needs to do is to hold the diaphragm tight, no torque wrench needed.