Post your mileage vs year
Senior Member
Joined: Jan 2017
Posts: 2,320
From: SC
I'm starting to get the same thing on the knock sensor. That is however not at all specific to the Hummers. That problem has plagued the GM LS engines since they came out. What happens is water gets past the stupid foam blocks under the intake manifold and then gets past the old dried out rubber plugs and into the knock sensor cavity. I had to fix this on my GMC truck. You need to get both knock sensors (do NOT get generic ones as they only last a year or less, only AC Delco), a new Dorman knock sensor harness, new set of intake manifold gaskets. Have to remove the entire intake manifold and clean up under it replace the knock sensors, and seal them very well. You will probably get better performance and a bump in fuel economy once you replace them. Its a several hour job to do. Search online for GM truck knock sensor replacement for tips on sealing the new ones and the whole process to replace them. Its actually pretty easy, just a bit fiddly and time consuming.
On mine - I'm holding for a little bit. I'm going to use the opportunity to change the valve cover gaskets, swap to a TBSS flex fuel intake manifold and injectors and 90mm TB while I'm at it. The TBSS intake flows better and nets 10-20 hp.
On mine - I'm holding for a little bit. I'm going to use the opportunity to change the valve cover gaskets, swap to a TBSS flex fuel intake manifold and injectors and 90mm TB while I'm at it. The TBSS intake flows better and nets 10-20 hp.
Junior Member
Joined: Sep 2011
Posts: 5
Yea, I've contemplating doing sensors, but I am obsessed with finding the misfire on my old Acura (tried every easy fix.) Plus its cold outside in the northeast now. I've seen plenty of write ups and some videos, nothing difficult except for not end up with extra bolts
