Happy to join this community! Mostly looking for help though...

[Arquemann]

New member here, greetings from Finland!
A few weeks ago I picked up this turd:

1985 Grand Marquis LS 302 CFI w/ 101k miles and a lovely dark red plush interior.

Biggest issues so far:
Stalls/shuts off a lot when stopping or going at very low speeds, idles rough (shakes and stumbles, stalled a few times too, RPM seems fine though), most of the time when trying to maintain speed or decelerating it's really jerky and stumbles sharply. When accelerating its completely fine and seems to run good, runs "alright" on fast idle when cold. Fires up really nice most of the time, but with a puff of black smoke.
I've replaced: Plugwires, cap and rotor (stalling stopped for 3 days), then plugs. Nothing changed since. I've also emptied half a can of carb cleaner at the CFI unit and ran a botle of injection cleaner through the fuel system.
Car had mostly sat for the last 3 years, so problems probably coming from that.

Other than that, it's awesome! Rides excellent otherwise, no clunks, rattles or squeaks. All the lights work, AC blows reeeally cold, cruise control worked 2 of 25 times and the interior is in really good shape (apart from being slightly sunburnt being a Florida car), dash isn't cracked and only a little bit of rust on the door bottoms and trunk edges. The paint is totally faded and feels like sandpaper when washing it and the vinyl top used to red but was shoddily painted white. Also I need to get the hubcaps off but I have no tool for the lockbolts...

Any and all advice greatly appreciated!

[Tiggie]

Welcome. My favorite color combo.

On the hubcaps, I used an angle grinder with a cut off wheel to cut slats in my lock bolts, now they go on and off with a large screwdriver.

My gut says you may have an EGR problem. Could be dirty, or the valve could be bad, or a vacuum issue to the valve. Have a look see and see if it has vacuum, moves under vacuum, and if it’s clean inside.

[VicCrownVic]

Welcome!

+1, grind a slot in each locking bolt to get the hubcaps off with a large screw driver.

[knucklehead0202]

Welcome! Sounds like you could possibly have a vacuum leak as well. I don't know the usual issues cfi cars have but this sounds like classic vacuum leak to me. Spray starting fluid or any other flammable spray around the intake manifold, vacuum lines, etc. to see if idle changes. You may have already checked this but just throwing it out there.

[clutch47]

Welcome...
LOTS of info here.
How's the price and quality of fuel in Finland.?
I'm finding out my car really likes 91 or better octane fuel. I don't normally buy anything else but I thought I'd give it a shot.

[Arquemann]

So, I removed the EGR valve and checked it, it seems usually black and sooty on the inside, leak-tested it with carb cleaner, nothing from the piston, but a little bit seeped out from the stem. The diaphragm seems fine from giving it a suck (I don't have a vacuum pump so I can't test it properly). Put a new gasket and some gasket maker, back it went and plugged the sensor and the vac line. Started it for a second but idle was still quite rough. I'll check tomorrow how the car reacts to unplugging and plugging the egr valve and corresponding vac line. Gonna ring a few friends if they might have a vacuum pump to lend.
I'll also check leaks with the starting fluid as knucklehead0202 mentioned.


@clutch47 In Finland gasoline is rated in RON, we got E95 and E98 "premium", which roughly correlate to 90/91 and 93 octane in the US. To my understanding, fuel quality is excellent here. And oh boy you yankees are gonna love the pricing! Currently, a liter of E95 is €1.45-1.55 and E98 is €1.60-1.70 per liter. That's $6.38 and $7.00 per US gallon, by the current exchange rate. And the closer you get to the metropolitan area, the more expensive it gets.
Roughly a third of Finlands passenger cars are diesel powered, and currently diesel is about €0.20-0.25 cheaper per liter. Though there's an extra fuel tax for diesel cars which makes diesel only worth if you drive over 25k KM in a year. As my MGM is gas-engined my yearly tax is only 365€, compared to my previous car's ('03 Audi A4 2.5TDI) 816€. And I won't even get started on insurance...

[87gtVIC]

Welcome to the forum. I hope you can get things sorted out and enjoy your car even more.

[Arquemann]

Update:
Idle does not change whether the egr valve vac line is on or off, plugging the line with my finger doesnt change anything either.

(egr valve missing in image)
The thicker of the circled lines tees off almost immediately and one line goes to the egr valve and other to the MAP sensor (I googled the part no, because I had no idea...)

Sooooo.... Gonna replace some vac lines and maybe a T-fitting?

[sly]

Looks like you may need to clean out said EGR valve. That's a a lot of carbon build up on those ports. If the vacuum lines are cracky or really soft and squishy, then replace them. If they are firm and have no cracks, they should be fine. The EGR valve may be stuck open too. This is where having a vacuum pump (hand held is good enough) to pull a vacuum on it to make sure it's working at all would be a good thing.

[Arquemann]

The EGR vac line doesnt actually go to the intake as I mentioned previously, it goes to the egr solenoid mounted on the valve cover.

This line shown here goes to the egr.

The vacuum lines going to the egr seem fine, the egr actually gets vacuum, but the egr diaphragm moves only a little and only when revved.
I'm going to go buy a vacuum pump possibly today. I was just wondering can I hook it up to the intake side of the solenoid-to-intake -vacuum line? Can I just unhook a vac line off the intake and check it for leaks with a vac pump?
Also from my chilton manual I read that the EGR has to hold 19 In of Hg. for 5 minutes


An idiot only in hindsight...

[Arquemann]

Quick update: I got a vacuum pump, I quickly tested just the egr valve, it leaks. Doesn't hold pressure. Nada.

Could that be the issue I've had all along? From what I've read there's not really any vacuum from the egr solenoid at idle, so would the vacuum leak affect idle then?

[Tiggie]

As long as the valve isn’t hanging open, I don’t think it would affect idle.

Something to do while the EGR is off for replacement, run a wire down the passage ways and start the car. It will blow out a bunch of carbon and help the new valve from getting stopped up with crud

We’ll continue to troubleshoot if problems still persist after valve replacement.

[sly]

If the valve is leaking THROUGH and not just down... it could cause a problem. I'm not totally sure on how they are made so I can't say whether that's possible or not, but yeah, if the valve is hanging open and not seated properly, it'll cause no end of problems.

[gadget73]

Common CFI problems, in no special order

EGR valve sticking open from carbon
EGR spacer being packed up with carbon, this is only on iron intake cars. The aluminum intake ones have the EGR boss cast into the intake, the iron ones have a plate between the CFI unit and the manifold that can be removed and cleaned. AL intakes you just have to chip it loose.
vacuum leaks
loose timing chains, this is a big one, they have plastic cam gears and when the chain jumps the valves bend.
bad plugs, wires, cap, rotor
ignition pickup in the distributor
gummy linkages on the side of the CFI unit that cause the high idle to stick or not engage


there are probably a bunch of other things that I'm forgetting, but other than the timing chain its mostly just old car stuff. The chain you can test by removing the distributor cap and using a breaker bar to rotate the engine back and forth manually. If the crank rotates any significant amount before the rotor turns, the chain is suspect. When the chain gets loose, the timing is unstable and you get bad running problems. You can also sometimes see this with a timing light, the mark will seem to jump around when checking the timing.


The valves on these are pretty simple. Its got a port in and a port out, and the port out has a tapered metal plug in it. When vacuum is applied, that plug pulls back and lets gas flow through. When carbon gets stuck between the pin and the seat, the valve never fully shuts and exhaust gas flows all the time. The vacuum side of it is just a diaphragm. It can leak or not and it won't affect whether or not the exhaust gas side of it works properly.

also, the position sensor is under vacuum on these. If the O-ring leaks, the sensor is damaged, or if its not installed correctly the valve will not hold vacuum. Honestly at this point a new valve and sensor wouldn't be an awful idea. That way you know the parts are all good. Just make sure the holes down in the intake aren't packed up with carbon.

[Arquemann]

To recap a little:
Plugs, plug wires, cap and rotor changed.
EGR leak tested with carb cleaner, exhaust side does not leak and seats well, though it seeps a bit through the stem. Diaphragm side does not hold vacuum at all, ill have to check the sensor o-ring.
Intake warm air flap diaphragm is toast, plugged the line with a bolt.

Currently the vacuum line to the egr valve is plugged with a bolt. I'll check the egr sensor o-ring when I have the time. Looking to buy a new egr valve and sensor.

It's just that next friday i'm going to roadtrip to Pieksämäki Big Wheels and back (800km), and I'd like to temporarily remedy the stalling issue as much as possible. As I'm not sure if I can get a new egr valve before that.