I am so confused, I know knock is bad and comes from fuel pre igniting, and I have also heard that poly engine mounts cause knock.

I have a poly engine mount and ingalls, but how do i know if im getting any knock from them? I know my car vibrates and it runs normal to me, but are there any huge signs that i should be aware of?


Basically. How do you know you have engine knock? (without any guages, can you feel it?)

 

you can hear it at wot if you listen close.
when tuning was done on my car the solid mount came off and the stocker back in, car was pulling quite a bit of timing.
either log it with hpt or get an aeroforce, only then will you actually know how many degrees you are knocking.

 

You better not feel the knock. The problem with poly mounts and such is the stiffness can cause normal engine vibrations to look like knock to the knock sensor, causing a false knock signal. When the PCM sees knock, it will pull timing until it goes away. If it is real pre-ignition knock, that will happen right away, problem solved. If the sensor is reading vibrations wrong, then it will continue to pull timing until the engine has lost enough power to change the vibrations. There is no obvious way to tell without a scangauge unless you can feel the car pull timing. You won't hear it or anything like that.

 

Great explaination! My problems must be caused by bad vibrations then.

 

so I should get a AEROFORCE Interceptor Gauge to monitor it?

This isn't like a car blowing up problem (false knock causing engine wear) as much as it is a car going slower than it should be by sensing the knock when it isn't really happening?

 

Thanks.

I think I may be getting the same problem, but I wont know until I get my Interceptors. I felt the car pulling back the power on me last night, boost was normal and no backfiring, just a little timing pull, but it was after a few hard runs and the car doesn't usually do that. I also never had the poly trans mounts until about a month ago. Not sure what was going on. My car might have been mad from the races I ran with it. A SRT4 with a 20G turbo and a 1JZ supra, back to back, both only pulled me a little but I think my car was just upset

Correct. Won't blow you up, just cost you power.

 

Great And I have extra money to spend. I may know what my next buy may be!

 

Buy me one too!!

 

For some time I've thought about my exhaust rattling being the problem when also the possibility of a clogged cat but here lately I've thought it also might be my ingalls....it's on the hardest setting plus the bracket is bent slightly.

 

has anyone here actually proven that mounts can cause knock retard? Cause that doesnt really make any sense seeing that knock sensor work off sound not vibrations.

Knocking (also called pinking or pinging)— colloquially detonation—in internal combustion engines occurs when air/fuel mixture in the cylinder has been ignited by the spark plug and the smooth burning is interrupted by the unburned mixture in the combustion chamber exploding before the flame front can reach it. The engineered combusting process ceases, because of the explosion, before the optimum moment for the four-stroke cycle. The resulting shockwave reverberates in the combustion chamber, creating a characteristic metallic "pinging" sound, and pressures increase catastrophically.

A knock sensor consists of a small piezoelectric microphone, on the engine block, connected to the engine's ECU. Spectral analysis is used to detect the trademark frequency produced by detonation at various RPM

So no your motor mounts are not causing your knock sensor to detect false knock. Unless your motor mounts are making a sharp metalic pinging noise through the engine.

 

Look around on Intense's website, they even sell a bunch of dynomat to wrap your knock sensor to reduce susceptibility to vibration causing false readings. Yes, the sensor picks up noise, but noise can be caused my more than just detonation. The sensor is tuned for a certain frequency dependant on the engine itself, materials, construction and such. If some combo of other parts is causing a similar frequency noise under certain conditions, it will see knock that isnt really happening.
Granted, this is a rare phenomenon, not something that happens all the time or to everybody. But it does happen.

Look at the current generations of hybrid V6 cars from Honda. They have had to adapt active engine mounts to cancel vibration, and use Active Noise Cancellation to eliminate "booming" frequency noise from reaching the passenger compartment. That is caused by a perfectly normal engine when only running on one bank of cylinders. A tuned engine with solid mounts can cause far more vibration and noise, in conjunction with higher rpms and stiffness can raise the frequency of the noise to ranges where it interferes with the sensor.