Semi-solid engine mount problem ?
04-01-2018, 04:34 PM
#1
Three Wheelin'
Thread Starter
Semi-solid engine mount problem ?
I've changed my 997.2 stock engine mounts to semi-solid mounts and initially I felt pretty happy about the mod. However, just this morning while I was taking Fido to the dog park, I notice some hesitation between 3k-4k rpm range. I just wonder if the new engine mounts might have triggered the knock sensor in retarding or advancing the engine. Can someone knowledgeable throw some light as to what it feels when the knock sensor is activated. Would the engine hesitation be a likely cause of the knock-sensor kicking in ?
04-02-2018, 09:32 AM
#2
RL Community Team
Rennlist Member
Rennlist Member
Yes, that's potentially your issue. Jake Raby mentioned this during his engine building class I attended. I have the RSS mounts in my .1 without any issues, but maybe the knock sensors in the .2s are more sensitive or there's a resonance that occurs at a certain or different RPM causing the shut down.
04-02-2018, 09:58 AM
#3
While I agree that doing anything to the car that can change NVH has a theoretical potential to interact with knock sensors this doesnt sound like your issue necessarily.
If the ECU detects abnormal knock sensor activity the IKC system will initiate selective cylinder timing retard until over a specified period of time the knock activity is no longer detected as abnormal. This should feel like an overall decrease in power in the car. Kind of like running the car on a 110 degree day versus in a 50 degree day.
Regardless of any of our theories on this board for you, the only way to really tell what is for sure going on is to get someone to datalog it for you. This way you can see if you are seeing knock or perhaps there are other issues such as misfiring (will not always trigger a CEL until a threshold is met) fuel pressure, or even air metering/leak issues.
Mike
If the ECU detects abnormal knock sensor activity the IKC system will initiate selective cylinder timing retard until over a specified period of time the knock activity is no longer detected as abnormal. This should feel like an overall decrease in power in the car. Kind of like running the car on a 110 degree day versus in a 50 degree day.
Regardless of any of our theories on this board for you, the only way to really tell what is for sure going on is to get someone to datalog it for you. This way you can see if you are seeing knock or perhaps there are other issues such as misfiring (will not always trigger a CEL until a threshold is met) fuel pressure, or even air metering/leak issues.
Mike
04-03-2018, 03:15 AM
#4
Three Wheelin'
Thread Starter
Thanks for the information on this issue.
Perhaps the only way is to live with it for a while to get a definitive cause if the mounts trigger the knock sensors.
I'll change it back to stock mounts to see if the engine hesitation goes away.
Perhaps the only way is to live with it for a while to get a definitive cause if the mounts trigger the knock sensors.
I'll change it back to stock mounts to see if the engine hesitation goes away.
