Smoking at idle

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Tom Kelly

Active Member
Joined
Jun 23, 2016
My 86 just back from a fresh rebuild. Runs great. Steady as a rock and smooth as a baby's behind. But I noticed light smoking evenly from both tailpipes(whitish and smelling like exhaust, not water or oil I think, nothing dripping)) Smoke increases if I step on the throttle in neutral but not apparent when driving. All scanmaster readings are normal except I noticed that O2 reading at idle doesn't fluctuate but stays steady at 875. O2 normal at cruise and WOT. I have the turbo tweak chip. Tail pipe is sooty. Just running too rich at idle? What would cause this? Engine now has about 300-400 miles since rebuild.
Thanks for your input.
 
White smoke is coolant being burnt in your engine. Check your coolant level and keep a close eye on your oil color. Sounds like a small amount and it might be solved with GM seal tabs added to the radiator. There are many opinions on antifreeze use but if you just rebuilt it I wouldn't run antifreeze until you're confident there isn't coolant mixing with your oil.


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ScottHeidinger said:
White smoke is coolant being burnt in your engine. Check your coolant level and keep a close eye on your oil color. Sounds like a small amount and it might be solved with GM seal tabs added to the radiator. There are many opinions on antifreeze use but if you just rebuilt it I wouldn't run antifreeze until you're confident there isn't coolant mixing with your oil.


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Thank you for your response. Yes, white smoke = coolant. Of course, it's not always that clear. Is the smoke really white? Or is it a dark white? I have been monitoring oil and coolant. Oil is spot on perfect level and clarity as is the coolant. Of course, the smoke is slight. What do you think about the high O2 level at idle? Isn't it supposed to jump around except t WOT?
 
Mine stays steady around .571-.599 at idle after it's warmed up. It bounces looking at the power logger and a 0 frame here and there but the rest are steady in that range. I know the sensor will not read right until it's warmed up. What version chip is it?


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ScottHeidinger said:
Mine stays steady around .571-.599 at idle after it's warmed up. It bounces looking at the power logger and a 0 frame here and there but the rest are steady in that range. I know the sensor will not read right until it's warmed up. What version chip is it?


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Actually not sure what version. Came with the car. Funny, I've just been fooling around with the settings and noticed the IAC at warm idle was down near zero so adjusted it up a bit (to 15) Idle TPS is now at 38. For some reason the idle O2 is now jumping around like when cruising. Open loop still in operation. Also I noticed dripping of clean water at both pipes even after engine totally warmed up. So smoke might be moisture or might even be the remnants of oil in the exhaust from when I blew the head gasket (hence the rebuild). Think I need to give this a little more time to see how it goes. Engine runs perfectly and idle and throttle response are superb. I do appreciate you taking the time to offer advice.
 
Sounds like you are runing rich at idle .try taking Alil fuel out at idle see if it helps
 
Tom Kelly said:
Would that be accomplished by raising the IAC?
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There is acouple ways to do that and that's not one of them . You can go in your chip if u have a TT chip and take away Alil fuel . Or you can lower the fuel pressure Alil . What's your fuel pressure at now ? It should be 42 psi with the vacuum line off . What is your tps set at and your IAC ?
 
dank GN said:
There is acouple ways to do that and that's not one of them . You can go in your chip if u have a TT chip and take away Alil fuel . Or you can lower the fuel pressure Alil . What's your fuel pressure at now ? It should be 42 psi with the vacuum line off . What is your tps set at and your IAC ?
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Alas you have already arrived at the threshold of my level of (in)competence. I do have a TT chip but do not know how to get in it. The Fuel pressure is at 34 in idle (vacuum connected) and generally goes up 1 psi per 1 increase in boost, Idle TPS is now .38 and IAC has been upped to 15 (from 5) As just recently mentioned, this seems to have "unstuck" idle O2 readings which now jump around similar to when in cruise. Smoke has all but gone at least for now. Time will tell. I am going to give it a few days to see if things are better. Variables are 1. A new engine, 2. Rebuilt turbo, 3. Possible oil still in exhaust from head gasket separation, and 4. My limited knowledge. I am an old timer who just graduated to the GN from my 66 GS. No turbo experience at all except of course my 1983 Nissan Pulsar NX Turbo (in 83) which went through three turbos before Nissan disowned it (LOL) Thanks for your input
 
Okay I have my tps set at .42 and my IAC 15 . My fuel pressure is at 42psi with the line off . You will have to search for your instructions on your chip on the internet if u don't have a hard copy . You have to do the good old foot stomp method to change settings in the chip which the instructions will explain .
 
dank GN said:
Okay I have my tps set at .42 and my IAC 15 . My fuel pressure is at 42psi with the line off . You will have to search for your instructions on your chip on the internet if u don't have a hard copy . You have to do the good old foot stomp method to change settings in the chip which the instructions will explain .
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So I found the chip instructions in my pile of paperwork. (Version 5.7 non emissions) It seems straightforward enough. It's dark out now so I will get into this tomorrow. Pencil marks on the instructions seem to indicate that parameter 1 has been set to 144 which, if true, would translate to +12.5% fuel at WOT in all gears. I am assuming that idle fuel is not adjustable? No indication of how the other three parameters might have been set. I will check this tomorrow and I will also reset idle tps back up to .42. I think I have already learned something tonight. Thanks again.
 
Dam that's a lot of fuel I would take that down to 135ish and see if it helps .
 
Tom Kelly said:
So I found the chip instructions in my pile of paperwork. (Version 5.7 non emissions) It seems straightforward enough. It's dark out now so I will get into this tomorrow. Pencil marks on the instructions seem to indicate that parameter 1 has been set to 144 which, if true, would translate to +12.5% fuel at WOT in all gears. I am assuming that idle fuel is not adjustable? No indication of how the other three parameters might have been set. I will check this tomorrow and I will also reset idle tps back up to .42. I think I have already learned something tonight. Thanks again.
Click to expand...
No prob just post up your findings hopefully you can get her runing like a champ
 
dank GN said:
Dam that's a lot of fuel I would take that down to 135ish and see if it helps .
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Yeah. Well I have to check tomorrow to see what all four modes have ACTUALLY been set at and then determine if they are right for me. thanks again.
 
If the battery was disconnected as it should be when you pull an engine your settings should have reset to the original chip settings.


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Your probably just burning off condensation that has built up in the exhaust while it was being rebuilt and any coolant that got into the exhaust when the head gasket blew. The black soot is from running rich and normally it's from WOT not idle. When you go WOT and see a black cloud behind you it might be running too rich.


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Remove power to the ECM will bring Erics default settings back to 128 for all parameters. Post a pic of what Eric has written on the inside of the chip. Be sure to kill power to the ECM when removing/replacing the chip.
 
1986 Buick GX1 said:
For every 3 gallons of gas that is burned, 1 gallon of water is produced as a byproduct, hence the steam and condensation.
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Yes. I just don't remember that happening before the rebuild. Today I am going to check all my chip settings and also make sure tps and iac are within range and then give it time to see if it settles down over the next few weeks. Smoke is not enormous but very visible. Seems only at idle or just off idle. I will update this post if things change. Thanks to all for contirbuting
 
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