Absolutely correct. I wasted time checking the wiring before coming back to the actual sensors. Thank god they are mounted on the outside of the block and easy to get to and not under the intake manifold.
I agree 100%. I. have a class A M.H. with the 8.1 Vortec engine. Had an issue with check engine light coming on. Scan revealed knock sensors. Replaced with aftermarket sensors. Several more instances of C.E. light with scan again pointing to knock sensors. Check wiring, all good. Remove aftermarket sensors, replace with AC Delco sensors. Couple years since with no further issues.
I had Corsa on my last 2 Sierra's. Loved first one, disappointed with second one (re-engineered due to AFM). I now have a Borla S=type on my AT4. Love it. (It is QUITE loud on cold start, but settles down to a throaty rumble)
Careful on this. I had a minor dent issue, that required NO parts replacement and involved NO INSURANCE COMPANY repaired. Payed for out of pocket and IT STILL APPEARED ON A CARFAX. Shop that did the work could not explain how it happened. Shop manager stated they do not report repairs to any agency. The only logical explanation was the information was attained from the shops computer system due to it's accuracy.
I have a 19 AT4 5.3. Prior to this I had a 12 Sierra SLT 5.3 with AFM. I also used the range box on my 12. I hated the V-4 mode. As of right now I do not have a Range box for the AT4, but I do plan on getting one. If you REALLY listen for it you will hear subtle differences in the exhaust tone with the Borla. These new trucks also have a decal burble as they downshift, much the same as my old tweaked 5 speed stick IROC Camaro did when downshifting. Nice little rumble. Under acceleration you WILL hear the Borla in the cab. Cruising along you will not, the road noise will be louder. These new trucks have DFM, which is different from AFM. With AFM the SAME 4 cylinders are deactivated every time. With DFM ANY cylinder can be activated or deactivated. It may run with 2,3,4,5,6,7, or all eight cylinders, depending on what power is needed. From what I understand running the Air Conditioner will keep all 8 cylinders activated. I am not a fan of any cylinders being deactivated. I bought a V-8 because I WANT a V-8. I don't give a rats ass about MPG. But Federal regulations are forcing the manufacturer to come up with ways to attain mandated ratings. Does the truck sound as good as my old 2004 Pro Sport Sierra with the 5.3 and the Corsa duals and no AFM/DFM? Almost, which is good enough for me. And if you used a Range Box, your truck should NEVER go into V-4 mode.
If you look at the exhaust system you will see a flapper valve prior to the stock muffler on 5.3, and I believe one before and one after the muffler on the 6.2. Its a little restrictor that is inside the pipe. It opens to allow exhaust flow under acceleration, but closes back up as the RPM's come down. The screens are just that, sections of metal screen on the inside (towards spare tire) of both tail pipes. This is done to minimize drone. A cat back eliminates all of that stuff. I put a Borla S type cat back on mine, Very happy with it.
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