j7 gkk
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Registered: 16th Jun 05
Location: Sheffield
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has anybody have this go wrong with their car? its causing my car to slight misfire and a lack of power throughout the rev range especially after abot 5000 rpm, and its drinking fuel, is this what it should do?
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Will94
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Registered: 1st Nov 02
Location: Nr. Ipswich, Suffolk
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Well the knock sensor just reads the octane rating of the fuel and adjusts the ignition timing to match, so it may cause a missfire but wouldnt affect fuel economy i dont think.
More likely to be bad plugs/leads and even more likely to be a dodgy coolant temp sensor, as this can cause it to run rich causing mis-firing and naff MPG.
Change these, leaving the leads till last since they'll probly b the most and i reckon they'll sort it 4 ya 
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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is management light coming on? and when?
got 3 spare knock sensors for your car here. £10 each
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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quote:
Originally posted by Will94
Well the knock sensor just reads the octane rating of the fuel and adjusts the ignition timing to match, so it may cause a missfire but wouldnt affect fuel economy i dont think.
More likely to be bad plugs/leads and even more likely to be a dodgy coolant temp sensor, as this can cause it to run rich causing mis-firing and naff MPG.
Change these, leaving the leads till last since they'll probly b the most and i reckon they'll sort it 4 ya
what
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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i could write an essay on knock sensors and how they work, but i doubt it would help you much.
how do you know its the knock sensor? fault code 16?
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Will94
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Registered: 1st Nov 02
Location: Nr. Ipswich, Suffolk
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ok sorry i got it wrong, but its to do with adjusting the timing to run correct for the octane rating of the fuel that its running on... correct?
Not far off 
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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it is a crystal based sensopr in the back of the block betwwen cylinders 3&4. senses 'pre ignition' or 'knock' on the engine. it allows the engine to run as close to the 'knock' point as possible, therefore allowing it to run very close to the optimum timing for efficiency and performance.
if there is a fault with a knock sensor the ecu will retard timing by 4 degrees to prevent 'pre ignition' so that the engine runs safetly, although this can have an adverse effect on fuel economy and performance
ah bollox, you got me started now
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MR2Mike
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Registered: 20th Jan 05
Location: Old Trafford. Drives: MR2 N/A
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corsa808 is right, that octane shit before is bollox
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Will94
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Registered: 1st Nov 02
Location: Nr. Ipswich, Suffolk
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only going on what i heard!
and besides, pre-ignition or knock can be caused by a change in the octane of fuel ACTUALLY mike
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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quote:
Originally posted by Will94
only going on what i heard!
and besides, pre-ignition or knock can be caused by a change in the octane of fuel ACTUALLY mike
yes, a difference in octane will change the point of pre ignition, but doesnt directly have an affect on the operation of the knock sensor
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Cybermonkey
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Registered: 22nd Sep 02
Location: Sydney, Australia
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the knock sensor is also very simple on its design, meaning its not very likely that it is faulty.
As said above, i suspect it is something else like CTS.
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Cybermonkey
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Registered: 22nd Sep 02
Location: Sydney, Australia
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in fact scrub that, it could be a huge number of things. Fuel filter/pump? injection problem?
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j7 gkk
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Registered: 16th Jun 05
Location: Sheffield
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thanx for all your replies, ive put on the sensor and so far so good, although its still drinking fuel!!! corsa808 i wish i knew that you had the sensor before i ordered it it was £47 something from vauxhall!!! i am still having problems withit running warm though the temp gauge is up and down lol, bought new plugs and leads so i will give that a go, thanx again for the replies
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