new member: intake pressure test
02-21-2003 | 08:23 PM
#1
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From: Shetland, UK
new member: intake pressure test
Hi,
This is my first post to Rennlist but I have been following postings on this forum for some time and found it an invaluable resource.
I have been experiencing an overboost problem with my 944. To try and diagnose it I did an intake pressure test to 7psi and found some things I'd like some opinions on.
The BOV diaphram was torn. I think it's unlikly but is it possible for the damaged BOV to cause my overboost problem?
The cycling valve was leaking heavily from around the top and around the electical connectors? has anyone else seen this?
The idle stabiliser valve was leaking from the electrical connectors?
The line going from the J-boot to the small contol valve in the top RH corner of the engine bay (not sure what it is)was losing all the pressure. I had to disconnect the line and plug it before pressure would build up? I know this is normally not subjected to boost pressure but should it be open like this?
Can some one please tell me if these situations are normal. I'm particulary concerned about the cycling valve which is BRAND NEW.
Cheers Kenny.
1991 944 turbo (no mods)
Shetland
UK
This is my first post to Rennlist but I have been following postings on this forum for some time and found it an invaluable resource.
I have been experiencing an overboost problem with my 944. To try and diagnose it I did an intake pressure test to 7psi and found some things I'd like some opinions on.
The BOV diaphram was torn. I think it's unlikly but is it possible for the damaged BOV to cause my overboost problem?
The cycling valve was leaking heavily from around the top and around the electical connectors? has anyone else seen this?
The idle stabiliser valve was leaking from the electrical connectors?
The line going from the J-boot to the small contol valve in the top RH corner of the engine bay (not sure what it is)was losing all the pressure. I had to disconnect the line and plug it before pressure would build up? I know this is normally not subjected to boost pressure but should it be open like this?
Can some one please tell me if these situations are normal. I'm particulary concerned about the cycling valve which is BRAND NEW.
Cheers Kenny.
1991 944 turbo (no mods)
Shetland
UK
02-21-2003 | 10:46 PM
#2
Race Director
Joined: Jul 2001
Posts: 14,075
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From: Santa Barbara, CA
Welcome Kenny! Here's your problem:
"The cycling valve was leaking heavily from around the top and around the electical connectors? has anyone else seen this?"
The cycling valve (boost-solenoid) sends pressure from your intercooler pipe to the wastegate to open it and regulate boost. Any leaks along the way in the rubber hoses or the CV itself will result in your turbo building more boost than intended. Also check for leaks in the rubber lines before and after the CV. Don't try to disconnect them from the CV though, because you'll break it and cause an even worse leak.
"The cycling valve was leaking heavily from around the top and around the electical connectors? has anyone else seen this?"
The cycling valve (boost-solenoid) sends pressure from your intercooler pipe to the wastegate to open it and regulate boost. Any leaks along the way in the rubber hoses or the CV itself will result in your turbo building more boost than intended. Also check for leaks in the rubber lines before and after the CV. Don't try to disconnect them from the CV though, because you'll break it and cause an even worse leak.
02-22-2003 | 08:17 AM
#3
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From: Shetland, UK
Danno,
I have checked all the lines from the banjo bolt, through the CV and onto the wastegate. They're are all fine.
The CV is BRAND NEW. I replaced it then the overboost problem began. The old CV leaks the same way. You can hear it hissing out of the electrical connections.
I assume then no one has seen a CV leak like this and they are meant to be completely air tight?
I don't want to buy another new CV if they're made like this.
Cheers Kenny
I have checked all the lines from the banjo bolt, through the CV and onto the wastegate. They're are all fine.
The CV is BRAND NEW. I replaced it then the overboost problem began. The old CV leaks the same way. You can hear it hissing out of the electrical connections.
I assume then no one has seen a CV leak like this and they are meant to be completely air tight?
I don't want to buy another new CV if they're made like this.
Cheers Kenny
03-08-2003 | 06:58 PM
#5
Three Wheelin'
Joined: Jun 2001
Posts: 1,688
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From: Winterville, NC
I just pressure tested mine today and noticed it leaking in the same place, around the electricle connectors.
I also could hear a lot of flow thru the tube that connects to the oil separator. I read that this line should be removed at the J tube and plugged. I did this and also noticed flow thru the valve for the charcoal canister...no leaks, but could hear it flowing.
I would think that leaking around the cycling valve is not normal.
I also could hear a lot of flow thru the tube that connects to the oil separator. I read that this line should be removed at the J tube and plugged. I did this and also noticed flow thru the valve for the charcoal canister...no leaks, but could hear it flowing.
I would think that leaking around the cycling valve is not normal.