Mk2 engine timing

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Mk2 engine timing

Post by richvans on Wed Feb 13, 2013 11:25 am

The Haynes manual mentions a vacuum gauge to be used along with the strobe for checking/setting timing. Can anyone recommend one?

My timing strobe seems to have vanished since i last timed my carbed X19 when it was running quite a few years back now, Can anyone recommend one suitable for the Uno?

Also does it make any difference adjusting timing on the Uno's engine with ECU compared to how i used to do it on a carbed engine, twisting the old Dizzi!

Any other tips?, soz only really done the timing on oldschool carbed engine before!
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Re: Mk2 engine timing

Post by Louie on Fri Feb 15, 2013 8:56 am

I thought you can only change the UT timing by an adjustable cam pulley as timing as a function of the ECU.

remember reading on the old TC site that twisting the dizy dose nowt to the timing on the UT bot don't remember why. Remember thinking that there if there is a rotor arm fixed to the end of the cam (for MK1) and you twist the dizi cap the phase of the pickup prongs would shift in relation to the rotor arm.

Guess I was thinking about a mechanical breaker (as on the 903cc) where the coil is always energized and the points provide the pulse or breakerless distributor on the 999cc where the pickup is inside the distributor and registers the phase shift.

Turbo setup reads TDC from the crank pulley as well as rpm sensor from starter ring gear on the flywheel. Suppose I'd forgot that the ECU could be pulsing the coil thus controlling the timing of HT input to the distributor. suppose that would enable the ECU to control timing some what even with a dizy.

Hows the Haynes say to adjust the UT timing? I can't remember.
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Re: Mk2 engine timing

Post by Louie on Fri Feb 15, 2013 8:58 am

No I still don't get it - hows the adjustable cam pulley change the spark timing in relation to TDC?? or is it just valve timing :S
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Re: Mk2 engine timing

Post by richvans on Fri Feb 15, 2013 9:37 am

quote - Hows the Haynes say to adjust the UT timing? I can't remember.

It doesn't say, just to follow the instructions on your strobe! hence this post!

I think the Haynes manual i have is confusing because it covers several models. I'm sure i read somewhere you can't alter the timing on the Uno's injection system, then read in the Haynes you need a strobe!, which is how i used to do it on the X19!

I'm getting a bit of a splutter at full revs, but i guess it could be a few things, just thought first it might be the timing!
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Re: Mk2 engine timing

Post by Louie on Fri Feb 15, 2013 9:56 am

how much boost you running and is the over boost cutout switch still plugged in to the loom lhs of plenum IIR?
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Re: Mk2 engine timing

Post by richvans on Fri Feb 15, 2013 10:50 am

Yeah the over boost is unplugged and tapped up!

Boost is about 0.9 in 3rd and 4th which seems to pull well, its 1st and 2nd that it seems to splutter on and the boost doesn't get as high on the dash or aftermarket gauge

Thinking now it could be fuel starvation, (i noticed it on a track day when there was less than 1/4 tank left splutter in all gears on some corners!, maybe in 1st the acceleration is slopping the fuel about and missing the pump!) i'm planning to get a FSE power boost valve, for when i put on the T25/forge actuator, intercooler etc, maybe i should try it before hand, just change one thing at a time. Although i thought they would all compliment each other.
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Re: Mk2 engine timing

Post by gtirx2 on Fri Feb 15, 2013 12:01 pm

I have not really looked into the ignition timing to deeply on an uno or any car tbh as you are normally quite limited to what you can change/adjust.

As far as i know or think i have read is that the base timing on an uno is only in effect at idle or possibly while the engine is in vacuum,even then though the microplex may be playing a part in the readings,i know on a gtir you have to unplug the tps and get it to idle below 1000rpm for it to read correctly with a strobe.
I have not much of a clue tbh lol
I think/thought the microplex takes over the ignition timing once on boost and the advance/retard is dependant on how much pressure the map sensor in the microplex is reading,i have read somewhere the microplex is good for up to 1.5bar,not sure again tbh.

Like louie says i lose my understanding of it when i think well the spark can only jump the rotor to cap at a certain point so it must have an effect.
Only thing i can think of is the rotor arm end is pretty large and as the cam degrees doubles in relation to crank degrees i wonder how much of a working window(in crank degrees) the rotor to cap has to send a spark?
Proberly more than you think,but like i say i would have to think about it lol

I am sure if it was miles out you might have an issue though.

As for cam timing i am pretty sure this is totally seperate and is only to do with the opening and closing of the valves/valve timing.
The only way they are linked is that the dizzy is cam driven,but due to the fact that you are ment to adjust the dizzy/rotor arm when the engine is at tdc so that the middle of the rotor arm is inline with a small cut out on the dizzy body, would sort of imply that the cam could be set any where and as long as the dizzy is adjusted to be inline with this notch when the cranks at tdc the ignition timing should be ok.

I think ignition timing is only really crank/piston postion dependant,nothing to do with the cam?

Yeah sounds like you are getting fuel surge,if not it maybe also worth checking your plug gaps as this can also cause a simular issue around max torque/coming on full boost,tighten the gaps and see if it sovles it.

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Re: Mk2 engine timing

Post by richvans on Fri Feb 15, 2013 9:38 pm

Ok guys thanks for the replies Very Happy i'm still not sure about the timing! but i've got a few other things to check

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