Compression Values TOO HIGH!! HELP! Is this a problem???

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Mar 18, 2004 | 10:33 PM

Silver90Quattro

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Compression Values TOO HIGH!! HELP! Is this a problem???

Did a compression check on my '88 90q, 233,557 miles. I did not have the throttle open, just cranked the motor until the gauge needle stopped. I pulled the fuel pump fuse, and disconnected the coil wire, but did not ground it (what difference would this make?)
These are the values I came up with:

#1 = 228
#2 = 228
#4 = 225
#5 = 225
#3 = 220

The Bentley says the factory values should be 147 psi to 205 psi. How can I have over the factory values?? I read on the forum that carbon deposits can cause higher readings, but this much higher?? Seems like a lot to me. Do I have anything to worry about? If I have higher compression than factory, theoretically that means I have higher performance/higher horsepower thank stock?!?!

I am confused and need help understanding why I got what I got for values.

Thanks very much!

Mar 18, 2004 | 10:39 PM

Evol

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You need to have the throttle wide open, crank about 5 rotations, and pull all the plugs out.

Mar 18, 2004 | 11:23 PM

Silver90Quattro

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Re: You need to have the throttle wide open, crank about 5 rotations, and pull all the plugs out.

I realize I kind of made it harder on my starter by not doing those things, but can you give me any indication as to why my values are higher than stock/new? Is it beacause of carbon deposits on the pistons, which would raise the compression? Do I need to be worried with such values?

Thanks for your response to the post.

Mar 19, 2004 | 12:46 AM

TabulaRasa

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Re: You need to have the throttle wide open, crank about 5 rotations, and pull all the plugs out.

First you need to follow the correct procedure for the compression check.

I think your readings are high because your procedure is wrong, not because you in fact, have super high compression.

No pinging = no problem.<ul><li><a href="https://forums.audiworld.com/other/msgs/2482732.phtml">Click!</a></li></ul>

Mar 19, 2004 | 12:54 AM

Silver90Quattro

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Re: You need to have the throttle wide open, crank about 5 rotations, and pull all the plugs out.

Thank you for your reply.

Why would it matter if the throttle plate was open and the plugs out? The only thing I could see it doing, would be to decrease the load on the starter.

Forgive my question again, but how would doing these things effect compression INSIDE the cylinders?

Thanks again for your thoughts.

Mar 19, 2004 | 07:43 AM

Blake@NWAutoSalon

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*HIJACK* Audi Coupe 0, Deer 1

Mar 19, 2004 | 11:16 AM

absolutcq20v

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Re: Compression Values TOO HIGH!! HELP! Is this a problem???

My CQ had one higher cylinder a few years back (#1 IIRC). I ran some carbon treatment through and tested it again; no real change. The delta was something like 32 lbs and then dropped to 29 lbs.
And yes I pulled all plugs and pinned the TB open (and disabled the fuel pump?) :P

And this was a month ago in #1...

<img src="http://pictureposter.audiworld.com/13357/valves3.jpg">

<img src="http://pictureposter.audiworld.com/13357/valves2.jpg">

<img src="http://pictureposter.audiworld.com/13357/piston2.jpg">