'79 LTD High Idle?

[Heather]

So, I went over to my gramma's today to give the LTD it's weekly start.

I've kinda noticed it before, but today it was VERY noticeable.

While in park the LTD is idling VERY VERY high. It's loud and like it can't choke itself.

However, when put into a gear (reverse, drive, etc) the high idle stops - and it seems to run like normal. Also, when I put it into gear, even with my foot on the brake of course... It lurches - like it has a ton of power built up with nowhere for it to go. While I was sitting in it, letting it run for a little bit, in park... I also noticed a very low pitched thrumming sound. Is this being caused by the cold weather? It's only in the 30's here right now and it is a carbeurated vehicle. I don't see why the cold would cause it though as the high idle does stop when put into gear.


Any ideas?

[andymac0035]

A lot of times a carbed vehicle needs to be "knocked" off of fast idle with a jab of the throttle.

[Heather]

Even if I press the gas while parked it still idles extremely high.

Also, forgot to mention, as soon as it is put in park from being in gear, it goes right back to idling way too high.

Maybe I'll take video of it next time I go over to start it.

[Nathan in MI]

Does it go away after the car is warmed up a bit? Like Andy said, it's normal for them to run a little fast when first started, but you should be able to hit the gas once and have it slow down again. If not, I'm guessing that either the high idle is sticking on for some reason, or perhaps you have a vacuum leak. Do you hear any hissing or whistling noises coming from the engine? And remind me again what carb is on this car?

[andymac0035]

Are you letting it warm up before pressing the gas?
Carbs have a "fast" or "high" idle setting and they need to warm up before they come down off of it. Sometimes they "stick" or don't want to come down from fast idle (on their own) and you have to give the throttle a decently strong shove to knock the carb off of fast idle.

If your doing all of that then there is probably more to it.

[andymac0035]

If I remember right it's a motorcraft 2bbl and not a VV.

EDIT- I'm thinking of a different member's 79' car......But don't many of the 79' models have an older style motorcraft 2-bbl and a C4 instead of the AOD and VV carb?

[Heather]

I had the car warming up or 10 minutes without the idle slowing. It didn't do this when I purchased it in the fall.

The motor is so loud while in park that I wouldn't be able to notice a hissing or whistle.

I did notice during the last couple of winter start-ups that for the first 10-20 min or so the car has a lot of white smoke/steam (can't tell which) coming from the tail pipe.

I still smell gas very strongly outside (not while in the cab) while the car is running. When I picked it up in the fall it had a bad fuel pump and needed a diaphragm in the carb. I could smell gas inside before those were fixed.

I had it towed over to gramma's this fall for storage in the garage... and when it was loaded onto the tow truck I did notice a significant amount of coolant come out from under. I attributed that to the angle at which it was hooked up for towing (why they didn't bring a flat bed I have NO idea... my GMs and this car have ALWAYS been put on a flat bed.)

Yes, it has the motorcraft carb.

[andymac0035]

Yes but which one?
Your car could have an old-school 70's style motorcraft two-barrell carb, or it could have a Variable Ventury (I probably spelled that wrong, but that's what "VV" means) and it'a also a motorcraft carb.

Either way though, it doesn't sound like it's running right. I seem to recall you were less than happy with the garage that worked on it.

[Heather]

I believe it's the 2 bbl. Not entirely sure. Never really checked into it. My mechanic may know, but then again... He's probably forgotten.

[Archangel]

Hate to be THAT asshole, but should this be posted in this forum?
http://www.grandmarq.net/vb/forumdisplay.php?f=10

[Nathan in MI]

If it's the Variable Venturi, it will actually say "Variable Venturi" on the top of the carb body, and it looks like this:



The fuel smell from outside the car is a bit concerning - you probably have a fuel leak somewhere. I'd start looking for wet spots on the fuel lines, because I'm willing to be you're losing it somewhere, which has a tendency to be dangerous and expensive.

Also, the coolant probably has a genuine leak. I don't think it's related to the angle at which the car was towed; that shouldn't matter.

And back to the original problem, I'm going to guess that something about the high idle linkage has just gotten stiff from sitting, because I remember you saying that this isn't your daily driver, so I'm guessing it doesn't get driven much. The moving parts of the linkage need to be lubricated and I'll bet it will start behaving itself once again.

[gadget73]

79 ought to be a 2100 or a 2150, not a VV as far as I'm aware. Fuel smell could be a leak, or it could be the choke not coming off and making the engine run rich. I'd suspect a bad choke heater coil, or maybe its unhooked. On the side of the carb opposite the throttle lever you should find a round hockey puck thing with a wire plugged into it. If the wire is off, thats your issue. See if its getting warm too. It should get slightly warm to the touch if its operating normally.

and yeah, it ought to be in the general tech area *moved*

[91grandmarquis]

My moms 85 cutlass ran like that we had to replace something on it that I cant remember because I was like 13 and didnt care, It was either the idler arm or something to do with the choke.... Anyway she still idles at about 20mph when its cold, you can usually knock it down with a couple good revs after it runs a bit though. Now it has developed some lifter knock, so that is what it is. But It always idles high till you knock it down, sometimes it does stick so to speak though.

[Heather]

Thank-you for moving this. I couldn't decide what forum it should have been in.

Anyway... If there is a fuel leak and a coolant leak I'll be a little upset... As that was what I had worked on when I purchased the car! I just had the fuel pump and water pump replaced, and the carb worked on. I definitely DO NOT want to blow up another water pump or have more issues with fuel leakage. =-|

Ugh... Alright... I also have no way to tell if it IS leaking fuel other than wet spots because the damn fuel gauge has completely quit working.

Is there a mechanic around SE MI in either Macomb or Oakland Co. that KNOWS these cars? I'm not much of a mechanic myself and I need help! My normal mechanics are good, but obviously not as good as I need them to be. I need an expert on panthers!