excess vacuum pass test
11-03-2004, 03:31 PM
#1
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excess vacuum pass test Ok I just put two new o2's in my 98z (slow response code I was getting very once in awhile) so I pulled the battery during the install to give the computer a fresh start with the new o2's.
The slow response code is gone now and the car seems to be going fine. Here is the funny part the specifically monitored systems test results passed within a few driving miles. The system readiness test EPA was still pending until today (about 100 miles since PCM reset) and it now shows a pass on the EPA. The specifically monitored systems test results now shows a fail because of a test called “excess vacuum pass test 2“ it says the limit is 10.000 and my value is .9000?
I have searched this board, ls1, camaroz28 and Google and have found nothing related to this test.
The only idea I could come up with is my ls6 valley cover might be the cause. Due to the fact I have no PCV valve “only a line to the intake from the breather on the valley cover. The ls6's do not have a PCV valve but maybe the older PCMs are not setup for this? The PCV system is just a guess.
maybe the EVAP system?
Any ideas? Anyone seen this test fail before? What is the pcm looking for?
Everything else with the car seems fine; I’m using efilive to retrieve this data
The slow response code is gone now and the car seems to be going fine. Here is the funny part the specifically monitored systems test results passed within a few driving miles. The system readiness test EPA was still pending until today (about 100 miles since PCM reset) and it now shows a pass on the EPA. The specifically monitored systems test results now shows a fail because of a test called “excess vacuum pass test 2“ it says the limit is 10.000 and my value is .9000?
I have searched this board, ls1, camaroz28 and Google and have found nothing related to this test.
The only idea I could come up with is my ls6 valley cover might be the cause. Due to the fact I have no PCV valve “only a line to the intake from the breather on the valley cover. The ls6's do not have a PCV valve but maybe the older PCMs are not setup for this? The PCV system is just a guess.
maybe the EVAP system?
Any ideas? Anyone seen this test fail before? What is the pcm looking for?
Everything else with the car seems fine; I’m using efilive to retrieve this data
Last edited by dissonance; 11-03-2004 at 03:42 PM.
11-03-2004, 03:54 PM
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It's EVAP - is your gas cap on tight? 
Test Hex ID - 2
Type of test limit and ID - 86 and C6
Decimal range - –3276.8 - 3276.7 integral index-seconds
The deep web cache saves the day again!
MRK
Test Hex ID - 2
Type of test limit and ID - 86 and C6
Decimal range - –3276.8 - 3276.7 integral index-seconds
The deep web cache saves the day again!
MRK
Last edited by emarkay; 11-03-2004 at 04:01 PM. Reason: spelling
11-03-2004, 06:13 PM
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Originally Posted by emarkay
It's EVAP - is your gas cap on tight?
Test Hex ID - 2
Type of test limit and ID - 86 and C6
Decimal range - –3276.8 - 3276.7 integral index-seconds
The deep web cache saves the day again!
MRK
Test Hex ID - 2
Type of test limit and ID - 86 and C6
Decimal range - –3276.8 - 3276.7 integral index-seconds
The deep web cache saves the day again!
MRK
I did not have a DTC with this so I was not sure maybe the DTC is coming
What else would cause this? EVAP valve problem?
11-04-2004, 10:13 AM
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Thanks again MRK
I took the gas cap off and cleaned the seal around and I also cleaned the tube that runs in to the gas tank...
After reading the links you sent me I found it to be some good reading on the subject so after a cold start the test pass and all is well...
I guess I will keep my gas cap and pick up a little cleaner now.
I did notice that the gasket is starting to crack around the edges so I’m sure I will have to replace it down the road
I took the gas cap off and cleaned the seal around and I also cleaned the tube that runs in to the gas tank...
After reading the links you sent me I found it to be some good reading on the subject so after a cold start the test pass and all is well...
I guess I will keep my gas cap and pick up a little cleaner now.
I did notice that the gasket is starting to crack around the edges so I’m sure I will have to replace it down the road
