High Compression High Knock
Dec 24, 2007, 09:08 AM
#17
Hello Guys,
I am lukasz4turbo's co-worker and I'd like to clarify things a bit because I can see he was misunderstood.
The problem is not with tuning the car rather that it won'r run properly in standard form. AS a rule we won't tune cars that don't run normally. It's not a prolem of retarding ignition, adding some more fuel and getting rid of knock but why it won't run on standard mapping, we already found this leaky valve, but it seems it's not all.
Surprising are those hgh compresion numbers compared to service manual, original question of Lukasz was intended to find out if this is more common. We have some Evo 7 and 8 in our workshop that have smaller cylinder preassures even though they have lower head height and we can hardly explain that.
Anyway whenwe have solved this we'll post something up to let you know what was it, but we always look for interesting input of course
I am lukasz4turbo's co-worker and I'd like to clarify things a bit because I can see he was misunderstood.
The problem is not with tuning the car rather that it won'r run properly in standard form. AS a rule we won't tune cars that don't run normally. It's not a prolem of retarding ignition, adding some more fuel and getting rid of knock but why it won't run on standard mapping, we already found this leaky valve, but it seems it's not all.
Surprising are those hgh compresion numbers compared to service manual, original question of Lukasz was intended to find out if this is more common. We have some Evo 7 and 8 in our workshop that have smaller cylinder preassures even though they have lower head height and we can hardly explain that.
Anyway whenwe have solved this we'll post something up to let you know what was it, but we always look for interesting input of course
Do you even listen???? Those number that you recorded ARE NOT high. They are NORMAL number.
Dec 24, 2007, 03:21 PM
#18
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Dec 29, 2007, 04:35 PM
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Jan 2, 2008, 06:30 AM
#24
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Small update from here, maybe someone will have suggestions:
(to remind you it's on 100% standard mapping)
knock count 24 at high load
we swapped with correrctly running car:
-ignition system including plugs
-fuel system
-intake from filter to turbo including MAF
-ECU
-knock sensor
double checked cambelt and balancer belt
changed to 100 octane fuel
fitted 1.5mm gasket - dropped to 12bar compression
still high knock
I must say this is the weirdest story I have ever seen.
(to remind you it's on 100% standard mapping)
knock count 24 at high load
we swapped with correrctly running car:
-ignition system including plugs
-fuel system
-intake from filter to turbo including MAF
-ECU
-knock sensor
double checked cambelt and balancer belt
changed to 100 octane fuel
fitted 1.5mm gasket - dropped to 12bar compression
still high knock
I must say this is the weirdest story I have ever seen.
Jan 2, 2008, 01:36 PM
#26
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Knock could be easly and loudly heard on stethoscope.
Buthe most miraculous thing is that it disapeared today - knock count <6, we are testing and will update soon.
Now this is becoming weird...
Buthe most miraculous thing is that it disapeared today - knock count <6, we are testing and will update soon.
Now this is becoming weird...
Jan 2, 2008, 06:23 PM
#28
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that is starting to sound like a rod issue waiting to get worse if the knock was there and can be heard trough a stethoscope and then its all the sudden lower, or i agree you have something hitting or loose.
Jan 2, 2008, 07:04 PM
#29
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We are currently doing some millage with logging equipment, stethoscope etc. to see if anything returns. I start to suspect diesl fuel contamination - small amount of diesel fuel can faul octane levels to become very low and is hard to detect. But this would be strange after we went through two refills of 100 RON fuel.
I will write more tommorow. The weirdest problem I've ever seen so far.
I will write more tommorow. The weirdest problem I've ever seen so far.
Jan 2, 2008, 10:29 PM
#30
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Just out of curiosity, have you checked the fuel pump? Is the fuel presure good?
What did you change with the fuel system?
How did the plugs look when you changed them?
What did you change with the fuel system?
How did the plugs look when you changed them?
