Excessively high vacuum from SuperRam?

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Nov 11, 2005 | 01:02 AM

Aidoneus

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From: Maple Grove Minnesota

Excessively high vacuum from SuperRam?

Complete rebuild on a 90 L98 with SuperRam base, runners and plenum pulling really excessive vacuum, so much so that it's actually physically difficult to remove the oil cap from the valve covers due to the suction. Idle on throttle body seems to need to be set pretty high to keep the engine from killing when shifting back into drive (1200 in neutral). Any ideas?

Nov 11, 2005 | 10:18 PM

dock351

Burning Brakes

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From: Geneseo Illinois

St. Jude Donor '06

Nov 11, 2005 | 11:36 PM

Corvette0096

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From: Vancouver,Wa.

Sounds like your PVC system is pinched off some where.

Nov 12, 2005 | 11:08 AM

Eike

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From: Germany

I have a problem with the vacuum, too. But insted of to much vacuum, I have not enough.
The cruise control doen't work and the brake booster just works one time how it has to.

Thinking of an electrical vacuum pump and an aditional reservoir. Any ideas?

Nov 12, 2005 | 01:04 PM

CFI-EFI

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From: The Top of Utah

Quote:

Originally Posted by Aidoneus

Crankcase vacuum is not normally an issue. The pressure in the bottom end is generally positive, not negative. What you have is a massive vacuum leak from the intake system to the crankcase. Your crankcase must be well sealed for the engine to idle even as low as 1200 rpms.

RACE ON!!!

Nov 15, 2005 | 07:39 PM

Aidoneus

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From: Maple Grove Minnesota

Quote:

Originally Posted by CFI-EFI

We have a WINNER!! Upon further investigation by my local engine shop, it was determined there were 5 massive holes in the base intake manifold (4 of them are 3/4" NPT and the 5th one is 3/8") that were supposed to be plugged. Apparently, the holes are there from Accel during the manufacturing process in order to provide access to various parts of the intake for machining. These are sent out from Accel with plugs installed in these holes, but when my first engine shop installed it, apparently they removed them and never replaced?!?!? Not that surprising since this is the same shop I'm suing in court tomorrow. I'll keep you guys posted.

Nov 16, 2005 | 02:43 PM

CFI-EFI

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From: The Top of Utah

Quote:

Originally Posted by Aidoneus

It was the only possibility that made any sense to me. I have the advantage of having experienced the same thing every time I lose a patch from my manifold. When I first came across the problem, I was cruising on the interstate. When I took my foot off of the accelerator to slow down for my exit ramp, I had no engine braking. I slipped my shifter into neutral and I had a 1600 rpm idle. As we both know, now, it was a MASSIVE vacuum leak.

RACE ON!!!