Downshifting causing SES? Please help!
Downshifting causing SES? Please help! I've been having trouble getting my car fixed at Cross Pontiac here in Louisville. It was kicking an SES code showing "Knock Sensor low voltage" To remedy this problem it has been in 4 times. The first time they did nothing but tell me that it "shoudln't" be doing that. The second time they replaced a supposedly faulty wiring harness. After the second time, the SES light came back on ten minutes after picking it up. I took it back again, this time they replace both knock sensors and the same wiring harness. Five days later, SES again. This time they replaced the PCM. Less than a day later SES light again. This time I call and they say that according to the GM tech support, the only possible cause of this is my driving habits!
GM is saying that it showed my down shifting at 2200 RPM with, get this, the TPS showing 0% open. They are saying that that is what is causing the knock sensor code. Has anyone ever heard of this? Is there any chance in the world that they aren't just BSing me? If the Throttle plate was at 0% wouldnt the engine be off? Help guys... I want my car fixed. I am going up monday morning to talk to the manager and would like as much firepower as I can find to argue the point with him.
Thanks in advance.
GM is saying that it showed my down shifting at 2200 RPM with, get this, the TPS showing 0% open. They are saying that that is what is causing the knock sensor code. Has anyone ever heard of this? Is there any chance in the world that they aren't just BSing me? If the Throttle plate was at 0% wouldnt the engine be off? Help guys... I want my car fixed. I am going up monday morning to talk to the manager and would like as much firepower as I can find to argue the point with him.
Thanks in advance.
Re: Downshifting causing SES? Please help! They are looking at "freeze frame data" . The pcm stores this info when the code was set. This is what the car/engine was doing when the code set.Throttle at 0% is closed throttle. All they get is a specific data stream of the second the code set. If you got an M-6 they cannot tell what gear you where in. It is odd that your setting knock codes at 0%/closed throttle though. 
Re: Downshifting causing SES? Please help! It is an M6. I didn't know it they could tell what gear it was in. But the other thing I was wondering was if it was throwing a code at the same RPM all the time, why would it matter what i was doing with gear selection.
TECH Fanatic
Joined: Feb 2002
Posts: 1,640
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From: Austin, Tx.
Re: Downshifting causing SES? Please help! I'll try to find my freeze frame data of when I was throwing a knock sensor code.
btw-It was a bad knock sensor.
...and just because they replaced the knock sensors and wire harness doesn't mean they didn't pinch a wire or reinstall a bad knock sensor.
btw-It was a bad knock sensor.
...and just because they replaced the knock sensors and wire harness doesn't mean they didn't pinch a wire or reinstall a bad knock sensor.
TECH Fanatic
Joined: Feb 2002
Posts: 1,640
Likes: 0
From: Austin, Tx.
Re: Downshifting causing SES? Please help! Here's the freeze frame data.
Diagnostic trouble code P0327
Module Engine controller ($10)
Description Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
Fuel system status bank-1 and bank-2 B1=$02,B2=$02
Calculated load value 3.92 %
Engine coolant temperature 167 °F
Short term fuel trim: bank-1 -2.34 %
Long term fuel trim: bank-1 -3.13 %
Short term fuel trim: bank-2 1.56 %
Long term fuel trim: bank-2 -3.13 %
Fuel pressure 0 kPa
Manifold absolute pressure 2.61 psi
Engine speed (Revolutions Per Minute) 2371 rpm
Vehicle speed sensor 39.8 mph
Mass air flow 1.53 lb/min
Throttle position 4.31 %
TCC 72
Exhaust gas recirculation valve sensor 0.59 V
Fuel tank pressure 1.41 V
Exhaust gas recirculation valve 0 %
Engine coolant startup temperature 82.4 °F
Desired idle 800 rpm
Injector pulse width cylinder 1 1.45 ms
Injector pulse width cylinder 2 1.51 ms
Desired linear exhaust gas recirculation valve position 0 %
Barometric pressure 14.4 psi
Commanded air fuel ratio 2 14.6 :1
Engine run time 246 sec
Misfire current status 255
Odometer when first code set since cleared 2392 miles
Odometer when last code set was cleared 2837 miles
Freeze frame counter 2
Freeze frame pass counter 47
Freeze frame not run counter 20
Electronic throttle control indicated pedal position 0 counts
Electronic throttle control indicated throttle position 0 %
Percent desired throttle position 0 %
Percent pedal rotation 0 %
Trans output speed 0 rpm
Current gear 1
Diagnostic trouble code P0327
Module Engine controller ($10)
Description Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
Fuel system status bank-1 and bank-2 B1=$02,B2=$02
Calculated load value 3.92 %
Engine coolant temperature 167 °F
Short term fuel trim: bank-1 -2.34 %
Long term fuel trim: bank-1 -3.13 %
Short term fuel trim: bank-2 1.56 %
Long term fuel trim: bank-2 -3.13 %
Fuel pressure 0 kPa
Manifold absolute pressure 2.61 psi
Engine speed (Revolutions Per Minute) 2371 rpm
Vehicle speed sensor 39.8 mph
Mass air flow 1.53 lb/min
Throttle position 4.31 %
TCC 72
Exhaust gas recirculation valve sensor 0.59 V
Fuel tank pressure 1.41 V
Exhaust gas recirculation valve 0 %
Engine coolant startup temperature 82.4 °F
Desired idle 800 rpm
Injector pulse width cylinder 1 1.45 ms
Injector pulse width cylinder 2 1.51 ms
Desired linear exhaust gas recirculation valve position 0 %
Barometric pressure 14.4 psi
Commanded air fuel ratio 2 14.6 :1
Engine run time 246 sec
Misfire current status 255
Odometer when first code set since cleared 2392 miles
Odometer when last code set was cleared 2837 miles
Freeze frame counter 2
Freeze frame pass counter 47
Freeze frame not run counter 20
Electronic throttle control indicated pedal position 0 counts
Electronic throttle control indicated throttle position 0 %
Percent desired throttle position 0 %
Percent pedal rotation 0 %
Trans output speed 0 rpm
Current gear 1
Re: Downshifting causing SES? Please help! Thanks a lot for the info. It came in handy when talking with them this morning. They agreed that it wasn't my driving habits and are working to fix it now. Don't know what could be left, they have replaced the knock sensors, wiring harness, and PCM.
