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mike100 · 02-17-2011

my NOx was pretty high when I transferred from the previous owner's smog (the rest of the numbers were real low), but I think it was elevated combustion temps due to running lean. It had a large vacuum leak under the plenum which caused it idle at 1200 rpms all the time and would never slow down.

I may have wiped a little bit of the DAG off the lower half of my t.b., but it still idles below 1000 rpms now and slows down on the road when you let off the accelerator.

to test for a leak:

1) take off the inlet duct and air filter housing
2) clamp the vent hoses that come from the cam covers so they can't bypass air to the engine
3) get a real stiff box or notebook binder and block the front of the air horn when the engine is idling.

if it still runs at 700-800 rpm's, then it has a big air leak somewhere else...if it chokes it, then all the air is going through the throttle body and/or IAC valve. I don't see wiping away some of the DAG making it hang at 1500 rpms.

02-17-2011	#9
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: High Idle my NOx was pretty high when I transferred from the previous owner's smog (the rest of the numbers were real low), but I think it was elevated combustion temps due to running lean. It had a large vacuum leak under the plenum which caused it idle at 1200 rpms all the time and would never slow down. I may have wiped a little bit of the DAG off the lower half of my t.b., but it still idles below 1000 rpms now and slows down on the road when you let off the accelerator. to test for a leak: 1) take off the inlet duct and air filter housing 2) clamp the vent hoses that come from the cam covers so they can't bypass air to the engine 3) get a real stiff box or notebook binder and block the front of the air horn when the engine is idling. if it still runs at 700-800 rpm's, then it has a big air leak somewhere else...if it chokes it, then all the air is going through the throttle body and/or IAC valve. I don't see wiping away some of the DAG making it hang at 1500 rpms.