A Grand Marquis far from home - Life with my 1988 Mercury Grand Marquis GS

[Tynnerstroem]

A question for you all - leaving yesterdays Cars & Coffee the car ran at a really high idle when I started it. Putting it into gear it was still running really high and the car wanted to go - it was almost like I was keeping my foot on the accelerator somewhat, leading to me having to ride the brakes in low-speed areas. At first I was thinking there was a vacuum leak somewhere but I've checked for vacuum leaks using a smoke machine and haven't found any. Then I thought of the Idle Air Control valve (RockAuto image below for reference) - could that be the culprit here? I remember I cleaned out the inlet which had a lot of residue but never removed and cleaned the IAC. I tried removing the electrical connector from it with the car running and the car didn't die, and from what I understand that's a sign that its not functioning properly. Do you guys think its a good place to start? And if I do this job, are there any other related parts I should be swapping out while I'm at it?

[friskyfrankie]

I know people have had luck cleaning it out - say with carb spray but AWAY from the electrical part. That being said, in addition to cleaning the port, I would replace it with a new unit, if you can find an OEM - great. If not get a QUALITY aftermarket one. Now a days, however, replacement parts have become a real "crap shoot" so there is that to consider.

[Arquemann]

Either that or a sticky throttlebody. Vacuum leaks would've been my first guess too.
EFI compensates for the lean mix with extra fuel so the rpm rises, just like if you'd press the throttle.

Also why does your signature say LTD Crown Victoria?

[kishy]

Certainly a good place to start, but I'd start with cleaning rather than replacement. It's a notoriously difficult part to buy a good one of - anecdotally speaking.

I am suspicious that a chunk of carbon may have lodged itself in the valve half of the part (note the part can be disassembled into two halves - the valve, and the solenoid that acts on it).

Also worth noting that unplugging it is not necessarily supposed to stall the engine, but particularly if it's idling high, it should significantly stumble and fall to a very low idle. Other possible problems could be an issue with your throttle cable or related parts, so make sure the throttle is actually closing all the way to its stop screw. A vacuum leak as you noted could also do it.

[Tiggie]

Clean the IAC. If it's idling high, usually it's electrically functional and just sticking. You can take the electrical portion off and do a really good cleaning the rest without concern for the electronic portion getting soaked.

I unplugged mine this week for the same reason. I honestly like the low idle and it certainly beats randomly revving up at stoplights. But it's my beater wagon so it's a bit different than a nicer ride.

[sly]

+1 try cleaning it first. Also, check the cruise cable to make sure it's not pulling or hanging up.

[Mainemantom]

I agree with cleaning first. It is also possible that the gunk buildup due to ethanol gas. Before I changed to ethanol free gas I had a similar issue. Sprayed the linkage and TB cured the problem

[friskyfrankie]

Always good to try and clean it first but I am leery as I have seen it either not last long or not work at all so I'd be ready to replace it just in case.

[DerekTheGreat]

...DerekTheGreat I'll try to get some shots for you next time I'm out there! It basically looks like a two-barrel carburetor under there. The car doesn't run good at all currently. It cranks real good and fires right away but wants to die, even if you keep working the accelerator. If you do get past that it runs great on all seven cylinders. I remember we managed to get it to run on its own, after which it could be turned off and then back on with no issue an hour or two later. However the next day it was back to status quo, so we are speculating that one of the injectors is leaking fuel, making it hard to start after it has not run for like a day or more, but easy to start after just an hour or so, since it might not be leaking enough for it to be hard to start after relatively little time. We shall see.

I picked the Grand Marquis up today for tomorrows Cars & Coffee event - the last of the season, to be held at His Majesty The King's official residence (I know I know, old world shit but I'll give our King a pass - he's a car guy after all and has a vintage Shelby Mustang, a 1989 Grand Wagoneer and a vintage Porsche among other cool cars), a castle just outside of the city. Perfect environment! The drive home was wonderful and the car feels really good.

Cool pics, aside from that thing which has no right to wear a Mustang badge or be compared to one. Mistakes were made.

Ah, so the 8th cylinder checked out permanently and now the best it can do is 7? Does the oil smell like gas? That's a tell-tale sign of it running rich or leaky fuel injectors or both. I have NFC about how those work, but the service manual would provide some information, if not great information. Beyond that, get a fuel pressure gauge and a fuel injector tester dealio which allows you trigger them via a button. A noid light and a voltmeter with an ohm setting are valuable too. I did that with our '93 F-150, thread here: 1993 F-150 Flare Side - GrandMarq.NET - Panther Headquarters. I think those tools were very valuable with determining that my fuel infectors were actually good. I thought maybe a fuel injector or two might've been leaking or not firing at all, but the noid light confirmed all 8 were getting a signal, the ohm meter told me all 8 were within tolerance, fuel pressure gauge showed me none were leaking and the fuel pressure gauge + injector tester told me they were all contributing acceptably.

As for the high idle issue with your Mercury, try disconnecting the IAC while it's running. If the IAC is contributing to the problem, the idle should come right down the point the engine almost stalls. If the idle barely changes, either the IAC is hung up or there's a vacuum leak somewhere. 2nd to last, as others mentioned the throttle linkage could be sticky and not allowing the throttle to close all the way. Lastly, the throttle position sensor could be bad. When the computer sees voltage over 1.0, it commands the IAC to open a bit. Dealt with that on our '93 F-150 as well. See, having the ability to hook a scan tool up would allow you to see what the computer sees without getting dirty. Roadmaster +1

[Tynnerstroem]

Thank you all very much for your input! I am generally hesitant towards "repairing" parts as opposed to just buying new, since parts are so cheap for these cars anyways, but I suppose I'll try to with regards to everyone's advice in here.

DerekTheGreat You are correct! Haven't really performed a smell-test on the oil but the car runs super rich. My dad has the factory shop manual for it so I'm sure he'll be able to work it out, the next step is indeed to ensure that all injectors function properly.

I'll leave you with this shot that someone took of me leaving the Cars & Coffee. Car looks good! At least in motion on blurry pictures.

[Tynnerstroem]

More wrenching this weekend! I'm finally feeling like I'm making progress, slowly being able to tackle quality-of-life issues rather than existential mechanical ones. The first order of business was the Idle Air Control (IAC) thing, which I took apart and cleaned as thoroughly as I could. This is probably just what the doctor ordered, as it was properly nasty in there. I had an idea to put it through an ultrasonic cleaner, but the axle or whatever it is that movies inside of it felt like it was a sort of plastic, so I didn't want to risk it - instead it got a good cleaning with brake cleaner. After also cleaning the outside of the IAC, I saw that it had an E6-part number, instead of the E8-number that I would expect for a 1988 car. After all that, back on the car it went.
I noticed that when I tried the car afterwards, it ran fine but when I put the throttle to the floor it paused for a second, almost as if it tried to take a deep breath before then revving up. This happened both in Park and under load. The car is fine to drive but I'm wondering what might cause it. Some sort of self-calibration that needs to be made? I didn't unplug the battery so maybe that has something to do with it?

While on that, I noticed these two hoses that looked really tired. They look almost like water hoses, but it can't be water running up to the throttle body. Does anyone know what these are? Vacuum?


Next up was both window motors in the rear. I heard them spinning but nothing was happening when I bought the car. Both windows were not all the way closed, which I had suspected since I kept hearing noise from them while going down the road. On the right-hand side, the motor had already been out once, since holes were already drilled.








Awesome to finally have them working again! On the passenger side, I had feared that the lock actuator was on its way out since it didn't pull the lock pin all the way down, but I lubed it up good and now the power locks work great in the rear. On the driver's side, the window mechanism had actually seized up! With a lot of lube and working it manually up and down, it came back to life. Being able to put both rear windows all the way up, I noticed that they'd been almost 1cm (0,4 inches) from being properly closed, which would explain:

• The amounts of outside noise coming in when driving.
• That the car was kind of wet inside in the rear when I bought it. I noticed on the back of the door panels that they have been wet as well, and you can kind of tell because they are a bit skewed.

I did notice that this rubber seal moves with the window on both sides - is it supposed to?


Also, these rubber trim things (if they have a more proper name, do let me know) are so dried up and brittle. Can they be found new still? Perhaps NOS on eBay?


Finally while putting everything together, I noticed that this thing that the door latches into was missing a screw and that the remaining two were lose. The rear doors shut kind of poorly and probably need adjustment (since I don't think the guys that painted it did that as well as they did in the factory), but this probably didn't help.

[Tynnerstroem]

When I bought the car, the guy gave me this thing, supposedly a code reader for the EEC-IV system. The book says it's for Fords, but the label on the machine itself clearly says GM. Might it be of some value still?


Another question for you seasoned professionals - do note that when I put the car in gear, the indicator does not go all the way down.

On the image here the car is in D (with overdrive). I guess I have two questions regarding this:

1. Is this a hard fix? I'd like for it to properly show what gear it is in.
2. Could this be affecting my parking brake release? So my car has this hissing sound coming from underneath the dash, which I am fairly certain comes from that half-moon shaped thing that I've since learned controls the parking brake release, which is supposed to happen when you put the car in D. However it has never worked since I bought it, and I've just figured it's due to the vacuum leak. However yesterday, when I pulled the shifter further down (to check how inaccurate the reading of the gear was), I noticed when I got past D with overdrive and into what is then D without overdrive, it actually worked and released the parking brake! When I get to D without overdrive, it reads as if it was in D with overdrive. So I guess my question then is, is the vacuum assisted parking brake release tied to what gear it indicates that the car is in, more than what gear it is actually in?

[87gtVIC]

The e6 on the iac just means it was engineered in 86. Was the first year for sefi. just the same part still used in 88.

Yes the two hoses are coolant hoses leading to the egr spacer.

You can purchase aftermarket dew wipes for the outsides of the windows. There are some threads around covering that.


There is a plastic collar underneath the steering column covers attached to the shift tube which you can adjust to match what gear the pointer is pointing to. The plastic is very fragile at this point in life. be careful.


Cannot comment on the auto e brake release as mine was deleted functionally before I had got the car.

[Arquemann]

- The door panels are cardboard or something similar, so overtime moisture and water that trickles inside the doors will warp the door panels. The worse your dew wipes / window scrapers are, the more water will seep in. My door panels are also warped, some more than others, even though the interior has newer been wet. Humid environment, rain and age.

- Replacing the dew wipes isn't a fun job but not hard, mostly tedious because precision is very important. Did one window on mine because the glass alignment was screwed up. I used non-model specific stuff of RockAuto.

- Rear seal of the rear windows is supposed to go up and down.

- Do your door striker pins have a plastic sleeve on them? If not, buy new sleeves or new strikers before wasting time messing with door & latch alignment.

- The automatic parking brake releases when the car is running and the trans is put in a forward gear. It stays engaged in P, R & N. The vacuum valve you hear leaking is a complete piece of shit which doesn't want to stay aligned, leaks easily and is basically impossible to rebuild. Unhook the vacuum line off the firewall distribution block, plug the nipple, and get a manual release on the emergency release under the dash. I rigged up a handle from a Taurus, looks correct. Or you could find a lower spec panther with a manual release and grab that stuff.

- The parking brake release system isn't tied to the shift indicator, they are separately attached to the shifter arm. You can try wiggling the shifter in gear, it might stop the leaking. I did that all the time for a couple years until I got bored of the hissing and unhooked the auto release.

[friskyfrankie]

In reference to the "shift indicator" it may already be broken and if so, can sometimes be repaired with a zip tie to keep the "ring" connected (you will see exactly how it works when you have it apart). I did it on my friend's '88 CV and it has been fine for years. It is possible to find a new one, on EBAY, sometimes, but it may be $40-60 USD. Zip tie, for the win!