idle problems
 

I have a 1988 supra turbo 7m gte and it idles about 1400 rpms and when I adjust the idle screw to bring the idle down under 1000 it starts smoking. It seems to be white smoke. The smoke stops when I jump the idle back up. What should the idle be and is this normally. I bought the car about 2 weeks ago and the guy i bought it off of says the motor is stock and he rebuilt it and only has 8000 miles on the rebuilt. Im just a newbie at this so any help would be great. By the way the engine codes are 51 and 71.

Can't help you with the 71 code, but that 51 code is most likely a throttle position sensor out of adjustment, causing your high idle. And for future reference, you shouldn't need to adjust that screw on the throttle...

Check here to set the TPS

Thanks for the reply. I am in the process of checking the tps. I have been doing some reading on the tsrm. Yesterday I checked contunity on my tps and with no clearence it showed no contunity. I backed the top screw out of the tps and got a little play and it showed contunity. The bottom screw is a pain to get to. I will try to get to the bottom screw today and adjust it. If it is out of adjustment will it cause it to smoke at low idle.

The smoke probably wouldn't be from the TPS. I'm not sure what could cause white colored smoke other than a BHG, or some sort of liquid vaporising

I finally broke the bottom screw loose on my tps and adjusted it. I had good results out of it but I let it sit for about 2 hrs and went back to start it and it stayed around 1400. It was fully operating temp. so I starting taping the tps and the idle kept coming down. I guess the switch inside is bad. It seems like it starts smoking when I push the throttle at low idle. Do you think maybe the dashpot not set right could cause this smoke on deacceleration. When it starts smoking it throws alot of water out the exhaust. It will cover your hand. Do you think I need to replace my tps.

I'd say that if you have to tap the TPS to get the inside to move, then you should replace it. The one I had actually melted the plastic piece inside, so I replaced it with a junkyard unit and it worked great. Be aware, though, that there are 2 different style's of TPS's. One has an all plastic housing, the other has a metal (or at least metal looking) plate on the backside of it. Plugs and resistance are the same between the two, however the points where it contacts the throttle body are in different locations. I ended up swapping out my throttle body for one off of a Cressida because that was the only TPS I could find, and of course it was different than mine.

I"m hoping that someone else on the forum here will chime in to help you out with the water from the tailpipe, as I have no personal experience with anything like that.

I replaced my tps today and it works fine. The old one that I took off the car was defective. The spring inside of the tps was the problem. My idle is fine now and I set my dashpot. I drove it down the road and back to my house. Ok I left my car idling and about 2 minutes it started smoking but when you press the gas and hold it the smoking quit. Any advise would help. It still looks white smoke to me.

Most likely if you head gasket isn't blown it's coming from you iscv (idle speed control valve or iacv same thing) There's a coolent hose running thorough the iscv on 7mgte's. Maybe there's a leak in there causing it to smoke at idle. When you get on the gas it closes the iscv causing the smoking to stop.

Thanks for the reply. I was wondering if the big 3"exhaust that I have on the car would have something to do with it. It is a drager exhaust from hks. I have 3" downpipe to. When it idles about 800 the exhaust starts to sweat and it starts blowing white smoke. When I idle it up to about 1000rpm the sweat goes away and the smoking stops. Is it possible that at 800 rpm that the exhaust is not flowing fast enough causing the pipe to heat up and sweat. Going back to what you said about the isc. When I replace my tps I had to take the isc off to get to the tps. I figured while I had it off that I would check the opening and closing of the isc and the resistance. It all checked out but I did not exam it for cracks like you said. Just curious what you think.

solution
 

more than likely u have a leaking injector chech each one. at higher idles the fuel from the injector is being burned, but at lower rpm there is un burned fuel, what color is the smoke, black (fuel) white (tranny) blue/grey(oil), if hg is blown check oil for water in it, or lots of water coming from exhuast

The car starts smoking around 800 rpms and it is white smoke and alot of water coming from the exhaust but when you idle it up to 1000 rpm it stops smoking and the exhaust dries right up. What do you think.

Exhaust and muffler if new tend to have condensation (water vapors), it's okay to see some water come out of the tail pipe. The white smoke would mean it's a coolent problem. Have you checked your oil to make sure it's not milky? I can only think of three reasons why you would have white smoke coming out of your tail pipe. Head gasket going, coolent line connected wrong, or cracked or broken iscv.

I'd recheck the iscv and oil to make sure there's no problems there. Then check the coolent lines to make sure they are all connected to the correct place. There's a few manuals in the forums that show how the coolent lines go.

Hope you find the problem :)

I run synthetic oil in my car and I check it regular and no signs of milky oil. I will check the coolant lines and I will recheck my isc valve. The guy I bought the car off of sayed he rebuilt the motor and had put studs in place for the head. He told me about the notorious hg problem with the supras. I would like to rule out the hg being bad but you never know. Any help would be great. When it idles at 800 rpm the water is bad inside the exhaust but at 1000 rpm idling it dries up and does not smoke.

im sorry to be the one to tell you this... but that happened to me aswell... and it was right after doing a 3 layer MHG job on the car i did it all myself brought the block and head to be surfaced and all that good stuff and when the car was all together it started doing that so i drobve it for a few months and that just made it worse... i brought it to my machanic and he took a look at it and it turns out the pressure from the first start cracked my MHG and caused all of that bs your going through. SORRY AND GOOD LUCK!!:mad:

the only water is getting into your exhaust if from the head. anywhere else it would have evaporated before it got out. i'm afraid the last guy is right. it's likely not a bhg because of the head studs, so it must be a crack somewhere. not a good thing unfortunately...sorry man