twilson380

Hey guy's I'm new to the Cobalt SS world and am needing some help. I've been googling and looking through all sorts of cobalt forums and forums specific to vehicles with the LNF and haven't found anything except people who went and got their vehicle warrantied when they got the code and never posted what the fix was.

So anyway, I just bought my car and had a tune that was done by a shop in Houston, TX. The car is completely stock besides the tune. It's pushing about 23 psi and is about 270hp and 290tq. It was running fine for about 2 months after I got it and then it started throwing this Knock Sensor code this past weekend with just a small amount of power loss.

I thought maybe I got some bad gas, so I added some additive to remove water and boost octane and it went away from about 20 minutes and then came back on and has not turned off.

I'm wanting to get some ideas of what you all think might cause this. I will be checking the knock sensor itself to see if it's just gone bad (car has 103,000 miles, but the engine was replaced under warranty at 89,000 so it's practically brand new. Pretty sure they kept the same sensors the sensors and what not though).

Any help you guy's can offer would be great,

Thanks in advance.

umrdyldo

iTrader: (1)

So either you are getting excessive knock or one of your sensors or sensor wiring is bad.

I'd start with logging the car. See how it's actually running. HPTuners or a Bluetooth adapter

ECaulk

iTrader: (6)

Judging by the code there is an short in the wire going to the knock sensor or from the knock sensor to ground

twilson380

Well I got under the car this weekend. It everything looked good, Wiring, Sensors, they even tested out fine. The code didn't call out there being a short or too low of voltage. I was looking on Pro-demand and apparently there are 3 or 4 different codes that are thrown for these things.

I was searching around for what might of been the cause and got onto hptuners.com and seen where people who were running around the same amount of boost that I am had some minor knock that would cause the code to be thrown off and on and when they went to a colder spark plug it eliminated the issue (they were logging it on their turner I guess because they were able to see the degree of timing that it was off). So I went ahead and tried getting the colder plugs and so far after swapping plugs to the next step down (NGK (6509) LTR6IX-11 Iridium IX Spark Plug) it's seemed to get rid of the code so far.

If that's what fixed it, I guess it was due to the *correct* AC Delco spark plug getting too hot and causing pre-detonation. None the less, I'm glad to have my car back to normal

thanks guys for the input!

Hope this info helps anyone with the same problem

umrdyldo

iTrader: (1)

Was this the first time you have replaced the spark plugs?

What was the gap on the plugs you pulled out?

Most do not recommend lower temp plugs unless running higher power. Most just adjust gap lower than stock

twilson380

I'll have to get back to you on the gap size. Didn't even cross my mind. They were replaced with the new engine about 15,000mi ago.

ECaulk

iTrader: (6)

I highly doubt its the plugs fault. Unless you're running a monster of a turbo pushing over 600whp you don't need anything other that stock plugs.

The code does call out for a short to B+ or GND of bank 2 sensor, here are the specific LNF codes https://service.gm.com/gmspo/mode6/p...F%20Engine.pdf