Help!?!

[number72002]

Ok, I written before than I was having rough idle (didn't stall), so my '86 Marquis went in to a garage...idiots. They said nothing wrong with my idle...which is true. The idle in gear is the problem. The whole car shakes...good for the back, but kinda embrassing.
Also, and I wondering if this could be connected or caused also by the above problem. When I driven the car for a bit...say 15-20 km, I'll go to accellerate and I hear a kind of metallic tap come from the engine area and I get a lot of smoke from the tailpipe when going from a stop a few times and then it returns to normal. Once moving it's normal. If I punch the gas pedal down hard, that also stops the problem.
Here's more info on the car...
'86 Mercury Marquis Brougham
V6 3.8L engine with only 108,000 kms

If everyone can help, I'd really accepiate it. If I can't fix it, I'm gonna have to ditch it. I live in Northern Alberta Canada and I don't want to be stranded in the middle of winter in -30 Celsuis weather because of this.

[fredjacksonsan]

Hey--check "stalling at red lights" post for some info on this, it may be your idle air valve.

[number72002]

I read that thread, however it seems to suggest the idle air value is on mercurys 87 and onwards...does my car still have something like it?

[fredjacksonsan]

Good luck I'll be interested to see what gives.

[fredjacksonsan]

Mine's an 86, and sure enough it does have the Idle Air Valve. With the shaking and the smoke (sorry didn't look at your post as well as I should have) you may have a burned valve or bad compression on one cylinder, but hope not. I'd start with a good tune up-- plugs, cap and rotor, and replace the spark plug wires if they're old/cracked, and see if that helps. Also, Samurai had a similar problem and plugged some vacuum leaks.

Does the car run smoothly when moving on the highway? How many miles?

[number72002]

95% of my driving is city driving. Work, shopping, kids hockey and crap. I've always maintained a gas log for all my vehicles (good early warning to problems). At the moment the car is getting about 23 miles to the gallon (canadian gallon = 4.55 litres). Highway, I'd guess about 28-30miles/gallon. I have no idea if this is good or not. What do you get?

[number72002]

Also, where is that valve? And how big is it? I've checked for vacuum leaks and can't locate any. But when I changed the carb there wasn't a gasket there and I didn't put one in. So that might be a problem. I couldn't buy a gasket at the time, couldn't locate one. Tonight I pulling the carb off and making my own.

[Samurai0]

Hi, I recommend you don't make your own gasket. Buy one at a local parts shop. Unless your make a gasket out of gasket material, you risk the same vacuum leak, and a burning piece of paper/and the smoke going into the cylinders.
Goto http://www.rockauto.com for the part.

Why run the risk of damage for a $10 part?

[fredjacksonsan]

Uh oh, I was talking about fuel injected motor, you've got the carbureted version. Same thing applies to the vacuum leaks, they can hurt performance in a carbureted car also.

Has the carbureter ever been replaced? That could be your problem also - the fuel mixture might not be right for idle. (You could also rebuild the carburetor).

Your engine will be much simpler than the fuel injected version, so the tune up/wires, vacuum leak and new carb should help out alot. One thing I didn't think about before is the possibility of the timing chain being stretched. Does your car idle rough, then smooth out progressively as the rpm's build? Like starting from a light, is it smooth when you give it the gas or rough until you get moving some? If rough for awhile, it could be the timing chain.

23 mpg sounds good for in the city; I got 26 hwy when I got the car, then put some larger tires on it and haven't seen 20mpg since. Don't put bigger tires on, even if it's a sale!

Samurai's right, buy the right part.....

Good luck with it.

[fredjacksonsan]

Whups, didn't read in detail....no gasket when you changed the carb, that's probably a big part of your problem right there!