Author Topic: ignition timing?  (Read 4830 times)

Offline supercharged spaniel

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ignition timing?
« on: January 11, 2009, 01:14:03 pm »
i had my car set up with a timing light/strobe thing to set the ignition timing a while back..afterwards i was never 100% happy with it and felt there was always a bit of a hesitation slightly...anyways thought i would have a bit play.. anyway ive twisted the dizzy back towards the bulk head a bit towards an old timing mark left on the dizzy casing. and a tiny bit further and it drives so much better!  hows this then?  dan knight said his mechanic mentioned that the timing lights are never really a good indication of where the ignition timing should be as the angle of which you point it can change the result you get?  anyway car feels much better and cant hear any pinking so im gonna leave it?

Offline Nick_S

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Re: ignition timing?
« Reply #1 on: January 11, 2009, 01:18:15 pm »
Aye, old skool mechanics like to to it by ear. Did you time it to the 'z' line on the pulley like it says in haynes? Back edge of the pointer is where to line this up to.

Offline supercharged spaniel

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Re: ignition timing?
« Reply #2 on: January 11, 2009, 05:43:50 pm »
i didnt but the garage with the strobe may well have or not...is it ok then to go with what im happy with?  i know the car feels better..you know your own car dont you?  what do you think?

Offline G40supercharged

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Re: ignition timing?
« Reply #3 on: January 14, 2009, 08:21:59 am »
Did you do the timing with the blue temperature sensor disconnected? If not the ECU is trying to correct it all the time and you can't set it properly.

Offline supercharged spaniel

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Re: ignition timing?
« Reply #4 on: January 14, 2009, 11:19:45 am »
yeah i did just unplugged it then set it then plugged it back in..

Offline Fred

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Re: ignition timing?
« Reply #5 on: January 14, 2009, 12:42:33 pm »
Now theres summat i didn`t know so much so that i`ve made a note of it in my
Haynes Manual.

Offline supercharged spaniel

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Re: ignition timing?
« Reply #6 on: January 14, 2009, 02:33:42 pm »
if you didnt though surely when you next started the car it would recognise that the timing had changed? otherwise how would you rectify it?  start the car unplug the sensor fiddle with the dizzzy and plug it back in?  know what i mean?

say you moved the dizzy a bit without unpluging the sensor...tightened the dizzy up...and went on your way?  how would you then rectify the ecu trying to sort itself out? because you didnt unplug the sensor? unplug it and start again?

Offline hayesey

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Re: ignition timing?
« Reply #7 on: January 14, 2009, 02:52:15 pm »
Dan I think you've got the wrong end of the stick, I think Fred is just saying he didnt know you were supposed to do that, not being sarcastic.  Or am I being too trusting?!?  :)

The same goes for adjusting the idle too, if you don't run it up to temp and then unplug the blue sender the ecu will try to fight the changes you are making.  To be honest, I thought the haynes book of lies did say this but it's a while since I read any of it other than looking at torque settings!

Offline supercharged spaniel

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Re: ignition timing?
« Reply #8 on: January 14, 2009, 03:21:06 pm »
oh no im not trying to be funn im trying to understand it properly myself ha ha..i was relating back to g40 supercharges reply not friedberger.

Offline djtez

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Re: ignition timing?
« Reply #9 on: January 14, 2009, 06:49:40 pm »
i had mine set up already from a garage but i fitted a piper cam and engine up fittin dizzy cap and all the usuals ..

ii was worried about timin and got out my strobe.. marked it up and the usual..
its an old skool strobe to there is absolute no definition that i had it right but i set mine to TDC and the went back >>roughly<<  7mm from there..
car ran fine and no issues..
i later took to my local performance garage and they check it out with there electric thing tells you on screen degree's and yada yada yada. .said it was o.k !

Offline supercharged spaniel

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Re: ignition timing?
« Reply #10 on: January 14, 2009, 09:28:39 pm »
well mine had a great big mark stamped on the dizzy and mounting on the head where someone else had marked it...i originally had it on that mark....then thought ill get it timed up in my ownership...tuned out it needed moving away from this mark..apparently....and like i said before it never felt right?  slight dip in power higher up the rev range...anyways ive put it back to the original mark stamped and im much happier...maybe the garage that did it, didnt do it right?  not sure but im happier with it the way it is now! so im leaving it.

Offline G40supercharged

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Re: ignition timing?
« Reply #11 on: January 14, 2009, 11:56:11 pm »
if you didnt though surely when you next started the car it would recognise that the timing had changed? otherwise how would you rectify it?  start the car unplug the sensor fiddle with the dizzzy and plug it back in?  know what i mean?

say you moved the dizzy a bit without unpluging the sensor...tightened the dizzy up...and went on your way?  how would you then rectify the ecu trying to sort itself out? because you didnt unplug the sensor? unplug it and start again?

I think I know what you're getting at.... It doesn't matter to the ECU if you don't unplug the temperature sensor when you change the dizzy position. The ECU gets a reference position for the engine from the hall sensor in the dizzy (which is being driven off the end of the camshaft). The reference point changes as you rotate the dizzy (relative to the camshaft). The internal ignition map gives a difference from this reference position. If you change the reference point by 1 degree it will move the whole map out by the same amount as everything is relative to this reference point. Unplugging the blue sensor with the engine running just tells the ECU you are messing with the timing and idle speed and it stops making any timing adjustments; it's normally making constant changes to hold the idle steady. This lets you set accurate base timing and idle screw adjustments. When you plug the sensor back in it will go back to normal idle control. If you stop the engine before plugging the sensor back in it will still run normally next time based on the new dizzy postion; the ECU doesn't know (or care) that anything has changed. As far as it is concerned the reference point is always the same number of degrees BTDC (regardless of the true position) and the maps are based on this. Starting with the sensor unplugged is seen as a sensor fault.

Modern engines have crank position sensors and the timing can't be adjusted at all other than by changing the ECU program. In a G40 the exact cambelt length affects the relative position of the camshaft to the crank which  affects ignition timing so you need to be able to adjust it - timing needs checking when you change the cambelt. Fitting an aftermarket cam will usually also throw the ignition timing out.

Nick

Offline Fred

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Re: ignition timing?
« Reply #12 on: January 15, 2009, 10:35:41 am »
Honestly, chaps i didn`t know any of this and it certainly makes some good reading.
Glad that it`s been asked and answered.
I`ve not had as yet to time up my G40 engine but i`ve made notes of this post for when i do.
Every day i read some more of my Haynes Manual to familiarize me with issues i will encounter
when converting my car.
Tho know doubt its not all correct but then i`ve got you chaps behind me  ;D
Regards, Fred.