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850 idle erratic 850

posted by B.B. on Sat Aug 21 14:41 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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The engine revs maybe 2000 when starting then settles down to
maybe 900 or so. This has happened after clearing the blocked EGR
valve and intake manifold ports. Whatto check for the idle adjustment?

The engine has settled down a lot since that job, so I'm guessing
that maybe there was some junk hanging up some of the vacuum motors,
and maybe that stuff disappears or blows out or somehow gets where it
doesn't mess up the vacuum system.

The engine also quit throwing a lot of oil around the base of the tranny.
Yet there's still some oil leak there. Do the oil leaks associated with
a plugged EGR stop after a while after the blockage is cleared?

I can't find a vacuum leak by using brake cleaner around the usual subjects,
and wonder how to test the EGR valve?

Thanks, Bill

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850 idle erratic 850

posted by KlausC on Sat Aug 21 15:18 CST 2010
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last visit: Fri Oct 24 10:15 CST 2014

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There is no vacuum motor (except for the cruise control), all of the vacuum is produced by the pistons sucking in air.

My first thought was a leaky fuel pressure regulator. Any fuel leaking into the manifold after shut down will cause the engine to rev higher at start up. Depending on the year, the vacuum line from the FPR usually ends at the vacuum tree above the throttle body. BTW, have you cleaned the throttle body?

Sometimes, it take a while for the computer to realize that the EGR has been cleaned. A couple of weeks can be required for the computer to adjust.

If your car is a non-turbo, clean and check the PCV and the small line for blockage. A blocked PCV is the worst thing for oil leaks.

Klaus
--
Two great Volvos, a 1967 220 and a 1998 V70R

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850 idle erratic 850

posted by B.B. on Mon Aug 23 12:48 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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Hi Klaus,

>If your car is a non-turbo, clean and check the PCV and the small line for >blockage.

My car is NA and I don't think there is a PCV valve? There's a flame trap
that I threw away.
I did find a small vacuum line plugged and the EGR and intake manifold
plugged and cleared that stuff. I cleaned the Throttle body, mass air sensor,
and the car ran ragged for a while, with what seemed like giant vacuum failures
showing up with the brakes being messed up. Maybe there was some giant vacuum
leak with some chunks of that crap getting stuck in the EGR diaphragm?
It's got better and now the only funkyness is that the car races some at startup

What do you think about oil leaks from a plugged intake manifold/EGR,
will they quit after clearing the blockage?

After doing that job, I'm wondering if it's possible to remove throttle body
and EGR valve body and smack the blockage out of the intake manifold without
removing the manifold (Which is a serious pain where you sit down)
How long does it take to clog up that EGR port? Is it a function of
miles , time or what?

Regards, Bill

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850 idle erratic 850

posted by KlausC on Mon Aug 23 14:14 CST 2010
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last visit: Fri Oct 24 10:15 CST 2014

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Depending on the severety of the oil leak, many will slow down a lot after restoring the vacuum needed for the crankcase gases.

Give it a few weeks. The exhaust cam seal can be easily inspected, and I suggest doing so. You do not want to be driving if it is almost out, the oil dumped out of that is a real mess.

I do not live in the EGR area (CA and New England). I suspect a lot of rich running, poor gasoline, and stop and go driving will help clog it up faster. It is a pain to clean, but that will need to be done. Do you really want to push cement into the manifold?

Klaus
--
Two great Volvos, a 1967 220 and a 1998 V70R

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850 idle erratic 850

posted by B.B. on Tue Aug 24 09:21 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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I'm wondering if you could remove the throttle body and EGR valve body,
then knock the junk out of the intake manifold port either from the inside
outwards or put a shop vac on the opening and smack the plug out with a punch from outside, and capture the debris with a vacuum.
This would avoid the PITA of removing & replacing the intake manifold.

Where are the idle adjustments- Maybe a throttle position switch?
My idle is funky and sometimes too high.

Bill

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850 idle erratic 850

posted by KlausC on Tue Aug 24 09:27 CST 2010
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last visit: Fri Oct 24 10:15 CST 2014

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The idle adjustment is a function of the throttle position switch and the ECM, not a screwdriver.

If there are vacuum leaks, that will also mess up your idle.

Klaus
--
Two great Volvos, a 1967 220 and a 1998 V70R

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