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Old 02-24-2006, 06:03 PM   #1
engr
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Default knock sensor going nuts?

I noticed my car has been mushy for the last few days, so I started to look at my logs.. and my IAM dropped to 9.. then I started to noticed my knock sensor signal is going off every now and then.. it seems like it's random, and occurs at idle... so I reset the ECU and do the vishnu trick to get the IAM upto 16.. and watch it start to drop while I'm just cruising because the knock signal is just randomly going to "1". the IAM drop from 15 to 13 while I was idling..

is something wrong with my sensor? or likely a bad tank of gas?
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Old 02-24-2006, 06:45 PM   #2
hondaeater69
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knock at idle i doubt is bad gas. what year car and mods? Knock at idle could be lost cyclinder/compression . . .
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Old 02-24-2006, 10:20 PM   #3
cdvma
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Could be a lost cylinder but it could be something loose smacking into the motor. IIRC he is running a Cobb Stage 2 on a '02 4eat. I'd do a compression test first since its easy and doesn't take much time. Also good info to have.
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Old 02-25-2006, 09:14 PM   #4
engr
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CDVMA is right, mine is an 02 4eat wrx wagon... I haven't had a chance to do another log, but when I was looking under the hood, I saw one of the hoses from the intercooler was loose and not connect.. hopefully that was the cause.. I'll confirm once I get more logs..
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Old 02-25-2006, 11:29 PM   #5
02WRX_BLUE
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Replace the knock sensor and see if you still get random "1" count... I doubt that you would get a knock at idle... Beside if the idle was poor you would get a CEL related to misfire code majority of time...
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Old 02-27-2006, 12:18 AM   #6
engr
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I'm suspicous of the knock sensor, the car runs great and idles fines, doesn't burn oil or act up at all.. I hope it's nothing, and was only the ecu trying to compensate for the hose being disconnected...
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Old 02-27-2006, 12:25 AM   #7
cdvma
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A hose wouldn't create a false knock. It would be metal on metal. Sometimes you get lucky and can find a stock knock sensor in the classifides for cheap. I got one for $5 once!
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Old 02-27-2006, 04:06 PM   #8
engr
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I did some logs this morning, and every looks to be back in order... I believe it was a case of bad ecu learning because of the hose disconnect causing the engine to run very rich. The hose is probably letting out most of the air which the ECU thinks it's going into the engine.. I can't comment on why the knock sensor was going nuts or even draw a relationship to it, but none the less, the problem seem to have been resolved.

Thanks guys.
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