I've got aD16Z6 in a 93 Del Sol with 200,000 miles.

If I'm on the highway and floor it for over 20 seconds (over 5k RPM), then let off the gas, I see alot of grey smoke billowing out behind me.

Any idea what causes this?

 

Bad rings is a good guess. Do both a dry and wet compression test. If the wet numbers are a lot better then the rings are going.

 

valve seals?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stock_honda_coupe &raquo;</TD></TR><TR><TD CLASS="quote">Bad rings is a good guess. Do both a dry and wet compression test. If the wet numbers are a lot better then the rings are going.</TD></TR></TABLE>
wrong, wet test is always going to be "better" then dry...... if the wet test numbers are even and the dry test is not even then your rings are going.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Murk ’EM &raquo;</TD></TR><TR><TD CLASS="quote">
wrong, wet test is always going to be "better" then dry...... </TD></TR></TABLE>

True, thats why I said a lot better. The oil seals the rings giving better numbers in the case of worn rings.

 

http://autos.yahoo.com/maintai....html

Heres all you need for after your compression test. Great info.

 

sorry your all WAY off gray smoke is not from oil. rings and valve seals are forms of oil leaks. Oil smoke is blue.

gray smoke is at fuel problem. gray is a shade of black and with black being a very rich fuel smoke gray is when the ECU trys to adjust for the rich reading and the Cat does its job and burns som of the fuel but not all of it.

It's the map sensor had this in three different hondas and non of them had a cel just gray smoke at WOT if held to long get a new map and it will go away.

 

gray smoke can come from oil burning also.

 

well oil in small amounts and in smoke form is blue it's only gray if it burnning in the open air and he would be using like 4 Qt's a mile if that was the case. plus the back of his car would be black and greasy from all that oil.

 

Fuel is black. Light blue/grey dark blue is oil. It can even look white if you burn enough oil. Just don't confuse it with white steam from coolant and water.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Solster &raquo;</TD></TR><TR><TD CLASS="quote">well oil in small amounts and in smoke form is blue it's only gray if it burnning in the open air and he would be using like 4 Qt's a mile if that was the case. plus the back of his car would be black and greasy from all that oil.</TD></TR></TABLE>

The back of the car isn't black and greasy. I have a brand new O2 sensor that's hooked up to an Autometer A/F meter that says I'm running stoich at WOT above 5k RPM. Compression is in the 180's across the board.

From everything you guys posted, I guess the next thing is to check the MAP sensor.