Replaced the ECU but still smoke coming from exhaust

Sounds like either a blown motor (rings need replaced) or a bad head gasket or cracked head.
If the rings are bad your car would have felt like it was losing power because the engine will no longer have the same high compression that it's required to turn the wheels. You may have heard your engine knocking or seen a light blue colored smoke coming from your exhaust as a result of your engine burning up oil in the combustion chamber from the rings leaking.
If your head gasket is leaking or your head is cracked you'd likely find milky looking oil when you drain your oil from water/antifreeze being mixed in and noticed a white smoke coming from your exhaust that is actually water vapor coming through the exhaust.
If your car was running rough when you last shut it off try pulling all of your spark plugs and either cleaning them or replacing them all. A bad head gasket or bad rings can both foul spark plugs. A car will run rough with 1 or 2 fouled plugs, but once enough foul it will no longer run at all just sit and crank over. If changing the plugs get's it started for ya, check your tailpipe first for water, if nothing, change your oil. If no signs of water/antifreeze or milky colored oil then it's probably rings.

Sounds like a blown head gasket or cracked block allwing coolant into the combustion chamber. I will affect your heater also if the coolant gets low. Check it.

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supervag k+can

*White milky oil on dipstick = coolant in oil.
*Coolant on sparkplugs = cracked head or blown head gasket
*White smoke = burning excessive oil in the cylinders, which can be caused by a number of things including valve seals, cracked head or blown head gasket.
***All three of these symptoms together, however, means its the head or head gasket. Both are costly but better the head gasket than the entire head.

Sounds like your head gasket is leaking coolant into one or more of the combustion chambers, do you have any water in the oil pan?(does the oil look milky? Or does the oil filler cap have a milky residue along with the overheating and white smoke you have, these are all tell tale sighn of head gasket failure.
Thanks, Frank

If you have excessive white smoke coming from the exhaust, it sounds like your headgasket has blown. Check the water level...is it down? Is your engine oil milky looking? if so you probably need a new gasket. Hope this helps...

It is more likely that the head gaskets are put on upside down or that the timing wasn't correctly set. If water was the issue it would be in your oil and your oil would be a milky white color. If oil was in the radiator system you would see milky white blobs in the radiator. This sounds like the valves are out of time and that leaves a timing issue.

If you are also losing coolant it is likely a blown exhaust gasket. The white smoke is a result of coolant leaking through the exhaust gasket and and being forced out your tailpipe. You can check to see if the head gasket is blown by removing your oil fill cap and checking the oil for a milky brown color. I hope this was helpful.

Check for water in your oil. The oil will look like a milky substance kinda white in color. If this is what you see I recommend you take it to a dealership or a certified mechanic and have your head gasket replaced.

It could be the intake gaskets or even still the head gasket. How about the coolant ? Did you refill with same type coolant ? Have you noticed if it's thick and gooey ? mixing coolants will sometimes produce a thick gooey coolant that clogs up the cooling system. If the car ran hot it could also be a cracked head or block. Warped heads also. Somehow the coolant seems to be getting into the cylinder(s).

It's the ECU. Very common with the early '90s lexus cars. Everyone will say head gasket, but unless your oil is milky white, it's not coolant leaking into the cylinder.
Buy an ECu on ebay for less than $100, it plugs in under the dash, just like a computer printer. Easy fix.