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The mkiv Supra Owners Club

Engine Knock - what causes it?


nigelc

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Originally posted by nigelc

Could the BOV be causing any problems, and is it worth putting stock back on?

 

Well I suppose if its leaking badly/fcuked and drawing in lots of air after the metering, in theory you'd run very lean and cause it to ping. BUT if its leaking that much, the car would run awfully all the time, I doubt that it would idle well/at all and it would be generally running bad.

 

If you've still got the old one it's probably worth swapping back to the OEM one, just to eliminate it, as its not a difficult job but I think my money would be elsewhere :)

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Originally posted by geoffvalenti

Well I suppose if its leaking badly/fcuked and drawing in lots of air after the metering, in theory you'd run very lean and cause it to ping. BUT if its leaking that much, the car would run awfully all the time, I doubt that it would idle well/at all and it would be generally running bad.

 

If you've still got the old one it's probably worth swapping back to the OEM one, just to eliminate it, as its not a difficult job but I think my money would be elsewhere :)

 

Think I'll do it to eliminate it. I didn't think it would be relalated, but at the point of trying anything at the moment.

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Just a thought.

 

Have you checked the ignition timing? You should be able to get an inductive timing light to work on No. 1 cylinder lead and shine it onto the crankshaft pulley. Timing should be 10 deg BTDC. Theres not a lot you can do to alter it but at least it eliminates something else.

 

Whilst you've got the plug cover off, check the cam timing. Turn the crankshaft pulley until the marks line up at TDC, then look at the camshafts to ensure that their marks align. If you cant see any marks turn the crankshaft through 360 deg and look again.

 

Another long shot, but any port in a storm :)

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Originally posted by richardharmon

Can you get timing lamps that work off the 12V feed to the plug-top coil packs then? I often wondered how one would check the timing on the TT?

 

No, but if I remember correctly No1 plug is on a lead rather than connected directly to a coil pack. You can connect your timing light's inductive pickup to that.

 

Either way just connect the light to the coil pack HT lead that involves No 1 cylinder

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Originally posted by geoffvalenti

No, but if I remember correctly No1 plug is on a lead rather than connected directly to a coil pack. You can connect your timing light's inductive pickup to that.

 

Either way just connect the light to the coil pack HT lead that involves No 1 cylinder

 

There's no HT lead for any cylinder, all the coils are plug-top. I suspect the only way to do it is to get some sort of HT lead with a spark plug top on one end and a plug socket on the other, take out coil pack No 1 and use said HT lead to connect the spark plug to the coil pack. Anyone else done this another way?

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Originally posted by richardharmon

There's no HT lead for any cylinder, all the coils are plug-top.

 

Yes there is! The coil packs connect directly to one plug and have a lead coming from them which go to another plug. Its a wasted spark system so both plugs fire but only one is at the correct moment IYSWIM :)

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Originally posted by richardharmon

There's no HT lead for any cylinder, all the coils are plug-top. I suspect the only way to do it is to get some sort of HT lead with a spark plug top on one end and a plug socket on the other, take out coil pack No 1 and use said HT lead to connect the spark plug to the coil pack. Anyone else done this another way?

 

You dont need a lead evn on a non vvti you can use a timing light ;)

 

Dude:flame Dev

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Okay, my mistake, I didn't know the VVTi system used a wasted spark system, the standard engine has a coil for each plug. Seems like a step backwards to me!

 

Okay, so now that's cleared up, how do you use a timing light on a non VVT-i engine, put the inductive pick-up round the 12V feed? Sorry to hijack the thread, I just wanted to know :stupid:

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  • 4 weeks later...

Update!

 

Well, the car is sorted. Big thanks Paul Whiffin and the boys at Thor.

 

Turns out the knock was on the car probably due to a combination of the following:

 

broken MAP sensor

standard fuel pump

dodgy fuel filter

 

Those were the problems before the tuning started (but unknown at that point).

 

Tuning involved:

Lower decat

Megan Racing exhaust

FCD

Cold Plugs

 

After the tune up, the knock got worst, and the parts above were change for new or uprated parts. Knock remained...

 

Ended up with Thor for a rather long session, and net result was:

 

The HKS FCD was causing the knock.

 

An unexpected culprit to say the least!

 

My advice to all is if you are trying to find a fault, don't forget to check your new parts even if they were added after the fault, as sods law says it's there staring you in your face!

 

Once again, big thanks to Paul.:cool: :cool:

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