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Unread 02-09-2010, 01:17 PM   #1
PolakX
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High Idle, High Pitched Whine, Black Soot

A little background, I just recently finished replacing all the engine gaskets on a 97 TJ 4.0L that I bought a year ago. Prior to replacing everything it would POUR white smoke out of the exhaust like no tomorrow.

Now however I have the following issues -

A high (varying idle) between ~800 - ~1300 RPMs.
A high pitched whine coming from what sounds like the manifold region, it doesn't seem to be coming from belt / pullies.
Black soot on the ground if I give it a decent amount of throttle in neutral.
Low Oil Pressure / Check Gauges Light

Im thinking the idle, sound, and exhaust might be from the intake / exhaust manifolds having a slight gap in the seal? If not would one of the vacuum tubes coming off of the manifold cause it?
I replaced the vacuum line going to the reservoir since the vents were only working on defrost.
I also cleaned the throttle body with a toothbrush (which really got it cleaned up nice) and I replaced the IAC.

As far as the oil pressure goes, Ive replaced the Pressure sending unit, and the oil pump (I put everything back together only to realize I forgot the gasket on the pump, bad? Should I put it on immediately?)

As an FYI I checked the pressure in all of the cylinders and if I recall correctly they were all at 120.
The engine will also throw a code for Target Idle Not Reached, but it did it once then went away for like 2 weeks then came back, I cleared it and it hasn't returned yet.

Any suggestions?

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Unread 02-09-2010, 04:58 PM   #2
wushaw
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Yup it sounds like intake leak or vacuum hose off.
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Unread 02-09-2010, 05:09 PM   #3
Mean Max
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Quote:
Originally Posted by wushaw View Post
Yup it sounds like intake leak or vacuum hose off.
Exactly, IMO.

It sounds like the vacuum leak is responsible for the varying, high idle, and it also sounds as though the 02 sensor has compensated for the leak by going "full rich" resulting in the black soot.

Max
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Unread 02-09-2010, 07:33 PM   #4
PolakX
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Quote:
Originally Posted by Mean Max View Post
Exactly, IMO.

It sounds like the vacuum leak is responsible for the varying, high idle, and it also sounds as though the 02 sensor has compensated for the leak by going "full rich" resulting in the black soot.

Max

Sounds like a plan, I'll take a look Saturday in a warm bay
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Unread 02-11-2010, 11:53 AM   #5
PolakX
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On a follow up, would a bad seal/connection to the crankcase vent tube have anything to do with it? Referring to #s 4 and 6 in the picture ...
crankcasevent.jpg  
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Unread 02-15-2010, 06:46 AM   #6
PolakX
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Just a follow up for anyone that maybe searching the same problem in the future ...

I removed the intake / exhaust manifolds, discarded the gasket, cleaned both the manifold and the block, applied new gasket and reinstalled. While putting the manifolds back on, I checked each port after I tightened bolts to make sure they were still sealed properly.

Once everything is back together I fired it up and all the problems were solved.
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Unread 02-15-2010, 07:34 AM   #7
MisfitSeven
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also just for future referance, this is the tightening sequence for the intake/header bolts:
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