Strange Knock-like Sound

[sub205 5]

hello,

 

can anyone explain the strange noise the knocksensor picks up when in over run fuel cut mode?

first i thought it was knock, but after i noticed its still there when fuel cut is active, i realised it must be some other thing.

 

strange ...

 

i'm listening to the engine via the knock sensor and an amplifier.

[hcmini1989 16]

hello,

 

can anyone explain the strange noise the knocksensor picks up when in over run fuel cut mode?

first i thought it was knock, but after i noticed its still there when fuel cut is active, i realised it must be some other thing.

 

strange ...

 

i'm listening to the engine via the knock sensor and an amplifier.

pre igntion usually the cause. im not sure how to adjust it on megasquirt as i have`nt starting tuning mine yet. can you retard the igntion sliightly.but if fuel cut means theres no fuel going in maybe theres unburnt fuel still in there

Edited October 4, 2009 by hcmini1989

[sub205 5]

pre igntion usually the cause. im not sure how to adjust it on megasquirt as i have`nt starting tuning mine yet. can you retard the igntion sliightly.but if fuel cut means theres no fuel going in maybe theres unburnt fuel still in there

there is no fuel left. wb tells me that. lambda 1.52, how its supposed to be.

 

someone else told me it could be the bearings. but they are fine.

[hcmini1989 16]

there is no fuel left. wb tells me that. lambda 1.52, how its supposed to be.

 

someone else told me it could be the bearings. but they are fine.

check around the engine for anything loose could be something really stupid like a loose bolt vibrating that the knock sensor is picking up .can you hear it i mean just by listening or is it just on the knock sensor .is it on idle when it knocks or reving or under load.

[sub205 5]

check around the engine for anything loose could be something really stupid like a loose bolt vibrating that the knock sensor is picking up .can you hear it i mean just by listening or is it just on the knock sensor .is it on idle when it knocks or reving or under load.

its at 2500-4000 rpm (possible up to higher revs) and under middle loads.

i'll record it tomorrow and post a mp3.

[hcmini1989 16]

its at 2500-4000 rpm (possible up to higher revs) and under middle loads.

i'll record it tomorrow and post a mp3.

pinking maybe ?.but then it shouldnt really pink with no fuel in there .as you said best record it maybe some one else can shed some light on it

[sub205 5]

pinking maybe ?.but then it shouldnt really pink with no fuel in there .as you said best record it maybe some one else can shed some light on it

knock is 6.7khz aprox.

this sound is about 300hz-1khz maybe.

significant lower ...

 

at least big end bearings are good, i used turbo diesel ones with a slightly higher clearance, but me and some others are using them for years in every built engine without any problems.

only drawback is a little less idle oil pressure. maybe this could be the cause of the sound... but thats all hypothetical, i have to record it and post it.

[sub205 5]

... deleted, new recordings soon ...

Edited October 5, 2009 by sub205

[sub205 5]

... deleted, new recordings soon ...

the sound seems to be just an overloaded amp used to pull the knock-signal to a usable level.

 

i'll know more in 2 weeks after putting the car on the rollers for finetuning.