The Cursed T4

[Golf Loon]

OK. We have this T4 2L that I cannot get to start.

It turns over and has petrol to the engine, but will not start.

So far we have checked and rechecked the timing.
Changed 30 and 167 relay.
Changed dissys, car, rotor, brand new leads, coil, plugs
Fuel pressure reg, fuel pump
Ignition switch.

I have swopped another ecu, not expecting it to start and run, as this is a coded car, but if it starts and cuts out, its the ecu. Nothing, exactly the same.

Temperature Sensor

It has heaps of fuel, maybe too much and OK spark, not awesome, but enough to make noise you would think. Sometimes a splutter, but no bang.

Engine has 140 compression on every cylinder.

WTF it shouldnt be this hard on a 2L.

Any ideas? My only thoughts for tomorrow are MAF, Intake sensor and Oil Pressure. Oh yeah and we killed the starter today too

[DUB 20V]

just torch it that wil fix it lol put a 20v in it...

[Golf Loon]

just torch it that wil fix it lol .

Trust me, that has crossed my mind.

[gregozedobe]

Some random, oddball thoughts which may (or may not) provoke a productive line of thought (admittedly all weird stuff, but that's because you seem to have covered most of the conventional suspects already) :

What was the immediate prior history ? eg it was starting and running OK until we changed the timing belt (or whatever).

Is the spark "OK" when under compression (as opposed to when the spark plug is sitting outside the combustion chamber) ie is it still producing a reasonable spark when the plug is in the head ?

Is the spark being produced at the correct time (and not 360 degrees out of phase - it would still look OK on a timing light if it was happening on the exhaust cycle rather than the compression/ignition cycle ).

Does it have a crankshaft position sensor ?

Any sign of an aftermarket kill switch (typically on ignition or injector electrics) ?

Are the plugs getting wet with petrol, or just damp ?

Blocked exhaust ? (although I would expect it to start and run for a few seconds at least).

Is air being sucked into the cylinders and blown out through the exhaust ?

Is there a broken engine mount allowing the engine to move so much it is allowing something to touch or stretch too much, thus stopping the engine from starting ? Try levering the engine into a different position and see what happens (this is one I have known to happen to a petrol T4 - drove the owner nuts for 18 months or so).

Well that lot will give you some things to investigate for a while anyway, let us know what it turned out to be when you do get it fixed (even if it is embarassing for you , as that will add to the collective knowledge pool )

[TDI Dude]

Tend to agree with gregoz.. I'd lay bets its a sensor, more than likely a crank or cam sensor (if fitted). When hitting a brick wall like this I always find its best to leave the problem and walk away for awhile, then when you get back to it a solution normally presents itself. Good luck with it though and let us know what is was when it gets running again.

[Golf Loon]

Plugs are wet, almost like overfuelling, but it could be cos we have cranked it for so long.

It does not have a crank angle sensor.

It could be an intake sensor.

I thought there would be an immobilizer, but the under dash loom looks virgin and unmessed with!

I`ll keep you posted.

[gregozedobe]

Plugs are wet, almost like overfuelling, but it could be cos we have cranked it for so long.

I thought there would be an immobilizer, but the under dash loom looks virgin and unmessed with!

Might need to dry plugs and combustion chamber and try again, petrol just won't burn if there is too much for the available air (seen that in action on Mythbusters - just goes to show you can learn something useful from watching TV ) . Just watch out if you crank it over with the plugs out and sparks still happening - you might just get the right air/petrol ratio outside the combustion chamber, add ignition source and BOOM !!!

If it was a working (non VW) immobilizer then I'd expect no petrol and/or no sparks at all.

[Silver Caravelle]

A couple of other suggestions.

Is the knock sensor (s) connections OK. It will not run if these are not connected or have faulty connectors.

Is the Mass air flow sensor/air flow meter connected?

Cheers,
Scott

[Golf Loon]

We removed the plugs and cranked the motor to remove all fuel and then fitted new plugs earlier in the piece. It still made no noises. Bizzare. It has spark, although it is not super stong.

I`m thinking MAF more and more. Am gonna need to find a starter first.

[Jmac]

You mentioned oil pressure - not so common on the T4 but ive had a couple of A4s and Golf Gti doing the same. The oil pressure was too high keeping the valves open. Took agaes but when it was discovered the oil filter was slackened to lower the pressure and it ran, pissed oil but pinpointed the fault. Just a thought.
Silly question but this thing was dead on arrival right???????

[Golf Loon]

Thanks Jimmy. Yeah it was DOA.
I agreed to look at it cos it is the guy who collects my scrap cars van and as it was only a 2L, I thoughtit would be easy! Always the way huh.

[aprr32]

Sometimes the crank pulley for the timing belt wears the the cast in key,so the cam and ignition timing go out far enough to prevent running. Pull the covers off and check and see if the timing marks line up.
Peter

[Jmac]

Peter very good point mate , seen that one with a TDI Audi 80. We set up the valve and pump timing then ran it, it would run ok then turn to crap. All the timing out again. Thats what it was a stripped keyway.
When you check all the timing does it need adjustment or is it bang on????? Sounds like the timing is out a mile, as in 180 degress of ign timing.
I know what it feels like to start throwing stuff on to diagnose. Might pay to start from the absolute basics again. Fuel , Air and spark at the right time and it should go ( but i dont need to tell you that, just talking out loud) So Diz cap off and set up number 1. Valve timing at number 1 ( incase you are 360 degrees out) and check the rotor arm is pointing to number one on the dizzy. (hasnt stripped belt teeth and belt still intact at the same time?????????) Wish i was there to help ya. Being DOA did it just die or progressively choke????
Jmac

[Silver Caravelle]

Have you checked the knock sensor (s)?

[aprr32]

I've seen enough dead knock sensors and they don't seem to make any difference to normal running and starting except under heavy load and the pinging doesn't stop