Hello,
I am troubleshooting an issue on my '97 J80. In this troubleshooting I have the upper intake plenum off the engine and am testing the two VSV's on the bottom of the upper intake. One is for fuel pressure, the other is for the EGR. The EGR VSV meets the resistance measurement across the terminals. When 12V is not across the terminals, it flows air between the two ports. When 12V is applied, it holds vacuum. The question I have is if the VSV is supposed to release that vacuum immediately when 12V is removed across the two terminals. Above 10 in-Hg my VSV holds the vacuum when the 12V is removed. From 10 in-Hg to 15 in-HG it will slowly bleed off the vacuum and below 10 in-Hg it will release the vacuum. At 20 in-Hg it holds the vacuum permanently. I let it sit for 20 minutes and it was still holding the vacuum, even with the 12V removed. The fuel pressure VSV does not do this. It opens the valve the second the 12V is removed.
I am thinking I need to replace the EGR VSV. It is original also.
Any comments or help would be appreciated.
Thanks,
Mike
I am troubleshooting an issue on my '97 J80. In this troubleshooting I have the upper intake plenum off the engine and am testing the two VSV's on the bottom of the upper intake. One is for fuel pressure, the other is for the EGR. The EGR VSV meets the resistance measurement across the terminals. When 12V is not across the terminals, it flows air between the two ports. When 12V is applied, it holds vacuum. The question I have is if the VSV is supposed to release that vacuum immediately when 12V is removed across the two terminals. Above 10 in-Hg my VSV holds the vacuum when the 12V is removed. From 10 in-Hg to 15 in-HG it will slowly bleed off the vacuum and below 10 in-Hg it will release the vacuum. At 20 in-Hg it holds the vacuum permanently. I let it sit for 20 minutes and it was still holding the vacuum, even with the 12V removed. The fuel pressure VSV does not do this. It opens the valve the second the 12V is removed.
I am thinking I need to replace the EGR VSV. It is original also.
Any comments or help would be appreciated.
Thanks,
Mike