rs2 timing belt changed, wont start!?

[Jamo]

http://www.s2central.net/aby_ecu_codes.html

[adamw]

bit of a update,

i got the vag-com pluged in and it came up with a few codes: G4 and G28. cleared the codes but still wouldnt start, it was offering to start but wouldnt fire, which got me thinking about the timing being slightly out... checked timing marks again.. spot on.

"count the teeth on the belt" dad said

so i counted the teeth on the new belt(151) and counted the teeth on old belt(150)......... now how many teeth should be on a RS2 timing belt?

if there is 1 more tooth on the timing belt and it is set to original timing marks for the RS2 (1 tooth back) would the timing be out???

cheers adam

[AndyP]

I'm sure the RS2 belt is 150 and the S2 is 151, the RS2 belt I bought this week is marked up 150, part no. 034 109 119C. If you've got too many teeth and the marks line up then the timing will be out, sound like you need another belt.

[adamw]

ok looks like i will get a new belt then.

could someone explain why if the marks on the flywheel and cam sprocket are correct the number of teeth on the belt can affect the timing??

cheers adam

[adamw]

can anyone shed some light on my timing woes^^^

cheers adam

[jade]

I think even if your timing belt a tooth forward or back your car will start the hall senser only count the amount of revolution after the car is started the crank sensor registers top dead centre if timing is in the right place easy to check cams & top dead centre

i would look some where else

[DJones]

can anyone shed some light on my timing woes^^^

cheers adam

The extra tooth is not going to be the answer to your problem, it will just mean you have more slack to take up when tensioning.

You say it is trying to fire.. Not related to a cam belt change but have you got fuel pressure..

[S2central.net]

Just checked - AAN & ABY use 151 teeth. The RS2 doesn't !

However - I don't think it really matters here... The tooth spacing is the same. The only reason RS2 belt is a tad shorter is cause of the smaller water pump wheel (for faster spin vs ABY). Shortening by one tooth means the same tensioner is used as ABY - you've probably had to go nearer the max tensioner position with your longer belt.

[driftin jo]

The Ecu can tell TDC from flywheel but it does not know if it is TDC on compression or exhaust so it can't fire the ignition until it gets signal from the cam sensor. Once it is running it does not need the cam sensor signal and if i am right you can disconnect it when running and it will still run. IT will not start without it though.
Maybe you have disturbed the wires when doing the belt and you are not getting cam ref signal.

[S2central.net]

Well done Jo - I like it when others take the time to learn.

Let me elaborate this one further.

The purpose of the camshaft sensor is to tell the ECU what phase the engine is on - it needs this to differentiate the arrival of crankshaft reference pulses which obviously occur twice as often.

I hate to keep saying it - but only an oscilloscope can determine if you are getting good pulses. Its impossible to test those sensors properly in any other way. Search the forum for waveforms I provided in the past.

[adamw]

Just checked - AAN & ABY use 151 teeth. The RS2 doesn't !

However - I don't think it really matters here... The tooth spacing is the same. The only reason RS2 belt is a tad shorter is cause of the smaller water pump wheel (for faster spin vs ABY). Shortening by one tooth means the same tensioner is used as ABY - you've probably had to go nearer the max tensioner position with your longer belt.

just as i thought! got the new one coming anyway just to keep things right.
how can i check fuel pressure? there is fuel getting to the rail tho...

cheers adam

[S2central.net]

Your fuel pressure hasn't suddenly stopped... If you are getting fuel to the rail thats enough for now.

Back to your post about codes in VAGCOM. With the engine off its normal to see G28 (rpm) fault - but not G4 (crank ref)... Check the codes again and if G4 is there then I'd pursue that.

There is precious little you can do to test the G4 and G28 sensors - they should both show approx 1k ohms across pins 1 & 2 with a resistance test - but that doesn't tell you everything. For example the G4 sensor itself might be electrically perfect but if the crankref pin has fallen / broken off (it happens) then you get no signal.

I've heard of another scenario where swarf like remnants of an old clutch bearing stuck to the magnetic face of G4 or G28 and that caused all manner of running ailments.

The resistance test is worthwhile though - it might locate a bad sensor - but more likely bad contact or ground if this car ran fine before the belt change.

Have you checked all the earth straps already ?

[lcsmith]

Hi Adam,

I got my Cam Position Sensor from Quattro Corner, really helpful guy, I received it two days later, it was £100 no VAT!

If the front end of the car is off then it's no bother to change the sensor.

You can test the sensor with and LED 5v tester, here's the quote from S2central from my thread;
"Theres a 3 pin plug onto G40. With a 5V LED you can hook up a quick test at pin 2 (TWO) of G40 - you should see it pulse OFF every camshaft revolution"
You really need an LED tester though, so you can see it blink/pulse, it blinks quite quick so a multi-meter wouldn't pick it up.

I've PM'd S2central about my ECU, so I'll just have to wait and see, I am really missing my car now though!

heres the link to my thread: http://www.s2forum.com/forum/showthread.php?t=35600

Cheers

[adamw]

lcsmith: thanks for the info

the timing belt was ment to be here today but the the ****ers didn't order it!!

i just dont understand why it wont start... its not like i disconected any wires or anything?

cheers adam

[GazzaG60]

adam i feel i have a similar issue but mine will start but i think like paul and jo said the ecu is not sure what part of the cycle its in. mine sounds like 3 subarus running side by side at the moment. i too did have the belt off the cams prior but mine run for a day or so great after then conked out on me.

gonna try and solve it this weekend and go from there really . any improvements on yours?