I got all the parts off for this job and thought better about the second knock sensor. I went ahead with 2 new ones rather than one, figured I am saving the money on labor, so don't skimp on parts...time is money.

Good news, all codes are clear and no CEL anymore. The odd news, whoever owned this suburban before me was a jacka$$.

So far, I found some botched repairs:
- spark plug in passenger rear (by the firewall) was only finger tight
-all 8 spark plugs they installed were improperly gapped
-they had at some point replaced 2 of 8 plug wires with a different brand
-the PCV wasn't even hooked up to the valve cover. The vac line was there, with the valve in the end, but it wasn't seated in the cover.
-I pulled the fuel rails out and 2 of the 8 injectors were missing their grommets.

It seemed as if someone set about to do a major tune-up and just did a really poor job. It's a miracle there weren't more problems.

I replaced the plugs, plug wires, both knock sensors, PCV, cleaned the injectors, throttle body, intake manifold...I think that's all for now.

Next free weekend will include service for the transfer case, differentials, cooling system flush, brake fluid, steering fluid, and transmission service.

We will have this things sorted out before summer.

 

sounds like things are going good. you never know what some one else has done. thats why when you get a new, used car or truck it is best just to try and cover as much as you can. how many miles are on your burb?

 

try running a couple of bottles of Techron for the next few tanks too to clean up the injectors...

 

And good fix by the way!

 

95K....and two full days of driving with no service engine light= knock sensor success.

 

Thanks, and thanks for the techron tip. There is still a slightly rough idle situation, it's not bad, just not as smooth as I would expect a v8 to idle.

I did clean the throttle body and intake when I had it off. The crud that came out was amazing.

 

When you cleaned the TB, did you clean the Idle Air Control? They will cause rough idle when they are gunked up.

 

I did not. Idle Air control sounds like it has something to do with idle. I will study it in my manual tonight and take a look when I have more than 30 seconds of free time.

Thanks again for the tip. It was super hot and muggy today and it seemed rougher than normal. Its most noticeable in the driver seat. Outside it doesn't sound bad at all....just a low frequency imbalance. Maybe I am just being **** retentive.

 

I have a 2000 Suburban with the 5.3 and 235K miles on the clock... Last week I started to notice the transmission shifting a little slow and figure it is time for a rebuild... Then a couple of days later the check engine light came on... I scanned the code and it is both knock sensors #1 and #2... I cleared the codes and they came back the next day... Could this be the transmission or do I have an engine knock? I don't want to pay to have the transmission rebuilt only to find out I have a motor problem... At that point I would rather sell the truck and get a newer one. The miles are mostly highway miles... All the mechanics in South Florida are crooks and I hate to ask for their opinions because you never know if they are being honest!

 

Welcome to the forum.

Doubt the tranny could set a knock sensor code. Timing or lean mixture might.