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 j::D put a 20v in it...

[Golf Loon]

just torch it that wil fix it lol j::D .

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

[h100vw]

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

I like this one, happened to me with my G60 Passat. Plenty of spark, lots of fuel, no running.

Check the timing marks.

Can't be the oil pressure cos Matt wouldn't get any compression readings.

Gavin

[Golf Loon]

The bottom pulley does not have marks on, so we made our own by pulling no 1 plug out and feeling with a screwdriver. The Cam pulley has the mark directly upwards which lines up with the mark on the cover.
Then setting up the dissy and should start.

I guess the top could be 180 out, it has apparently been somewhere else for a clutch and to be made to start :? I hate taking on secondhand problems.

Maybe I`ll try turning the top 180 tomorrow.

I have rebuilt the starter from three dead ones, so hopefullw will be able to start the biach.

I`ll keep you posted.

Matt

[Jmac]

Mate in doing so take the cam cover off and check the lobes are pointing up, incase you are full revolution out. Take the bung out the gearbox bellhousing and line up TDC there, the diamond cut out or O/T lines up with the pointer.
Good luck man
Jmac

[Silver Caravelle]

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

Maybe so. However, If I purposely disconnect the knock sensor plugs on my Caravelle, it will not start.

Anyway that it for my suggestions.

[Golf Loon]

Ok, so today I removed the fuel rail as the motor still sounds real fuelly.
Took it apart to change the injectors.

The only replacements I could find have a different colour on the top. From a Golf 3 2L. How different could it be? Whacked em in and no.1 was pouring with fuel, took it all back out again and changed the split o ring. all together and it nearly starts.

Nearly, but not nearly enough. Am wondering if it is the wrong size injectors. I reckon it should start and run rubbish at least. Have all the batterys on charge and am gonna get some aeostart tomorrow and try again.

Anyone have any input?

[gregozedobe]

Anyone have any input?

You have said previously that the spark wasn't real flash. If it is marginal out in the open air then it might not be strong enough when it is in the combustion chamber under high pressure with (possibly too much) fuel in the mix as well.

If it is still getting wet with petrol in the combustion chamber I'd be suspicious of too much fuel, as it should only be getting damp.

I seem to remember a rough spark plug test we used to do with old two stroke motorbikes (always fouling spark plugs) was to hold the spark lead about 2-3 mm away from the top of the spark plug as you cranked it over. If you couldn't see a good, clean spark from the lead to the plug terminal the plug (or the ignition) was suspect. Make sure you hold the plug lead with something very well insulated or you might get a nasty electrical shock.

Failing that then it is (as previously suggested by Jmac), time to go back to first principles, taking nothing for granted and pretending you haven't worked on it at all (ie make sure it is getting air in at the right time, correct amount of fuel, reasonable compression pressure, good spark at the right time and it has to go boom ! )

[Golf Loon]

Got hold of a second hand manifold today.
Changed the throttleboddy, still the same, changed the injector rail and it started, ran for a minute, then stopped.
I reckon we will clean the plugs tomorrow and hopefully it will consistantly start.

[DVR68U]

lol this one has been a pain hey
cheeers brenton

[Golf Loon]

lol this one has been a pain hey
cheeers brenton

Always the way when you take a job on as a favour. :?

[Golf Loon]

Still no go. Makes spluttering noises but wont go.

Rigged up a crude node light from an LED and the fuel rail is not pulsing correctly. It is intermittant at best.

Has to be ecu. Damn.

Opened up the ecu, no obvious burnt tracks etc.

Anyone got a 1996 on 2L ecu for a transporter?

[gregozedobe]

While you are waiting for an ECU, you might be interested in :

Checking all fuel related electrical connections ?

Checkin for broken (internally) wires ? (Unlikely I know, but easy to check with a multimeter, and imagine how you'd feel if you did get and install another ECU and you still had the problem ? :( )

[lorraine]

What with your starting problems and my husbands problems with the starter motor on our T4, my husband suggested maybe we should get together and have a big bonfire!!

[Bora Sport]

Someone once told me that if the coil fails it stops the fuel delivery as well. If the spark isn't too flash then maybe the coil is suspect.

[Jmac]

Never heard of the coil doing that ???????????SPark is the output from the coil and that is not measured, only thing linked to the coil via the Ecu is the Hall sender. Im sure that would have been the 1st thing Matt changed.
Loon check the pulse from the centre wire of the hall sender should pulse with crank and the 2 outer should be ground and ign live.
Jmac

[Golf Loon]

Thanks guys. Finally laid this rest today.

T4 dissy is not the same as Golf 3! The Transporter has no crank angle sensor so needs 4 windows in the dissy, the G3 dissy only has 1.
2 Lessons there, 1. assume nothing, no 2 if you change a part and its not that, change it back.

Oli noticed the dissy thing, thanks mate.

Also scored a replacement ecu and the van now starts and drives sweet as.

The original ecu starts the van and makes it hunt up and down and stall sometimes. If I put the replacement one in its all good.

Phew, feels like a weight off my mind and thank God it now works.

[gregozedobe]

So it was the ECU all along. Oh well, hopefully it will run forever now and you won't get any more mystery problems to solve on it. Sounds like you might have spent more time on it than the whole vehicle was worth :)

Just curious, if you got another similar problem vehicle, how would you go about diagnosing this time around (assuming you didn't have a replacement ECU readily available) ?

[VW Convert]

So it was the ECU all along. Oh well, hopefully it will run forever now and you won't get any more mystery problems to solve on it. Sounds like you might have spent more time on it than the whole vehicle was worth :)

Just curious, if you got another similar problem vehicle, how would you go about diagnosing this time around (assuming you didn't have a replacement ECU readily available) ?

Refer Lorraine's previous post? j:

Cheers

George

[Jmac]

Some golf 3 have 1 window in the diz and some have 4, same goes for the Transporter. The 1 window is only a No1 reference point in conjunction with the Crank angle sensor. Great to hear its running, and yeah a good lesson for anyone trying a diz on their Golf 3 too as this is also the case. Some have G28( crank sensor ) and some dont.
Anyway it does feel good when you crack it hey. Obviously all who have posted including myself assumed all the bits being tried were the same.
Ah well it goes, thats the main thing, there is always one that will test ya and like you say its the favour ones that normally do!!!!!! Been there got the hat,pen teeshirt the lot hey LOL
Onya mate
Jmac;)

[Golf Loon]

Just curious, if you got another similar problem vehicle, how would you go about diagnosing this time around (assuming you didn't have a replacement ECU readily available) ?

I`d be very careful about test units being exactly the same.

I would use my trusty LED stuffed in the fuel rail connector to check whether the injectors were pulsing. With the dodgy ecu it does not pulse, but does dump fuel when you stop cranking :???:

I reckon checking and rechecking the basic is the key to most problems.
And hey every day is a learning curve, its good to learn things. :D

[gregozedobe]

With the dodgy ecu it does not pulse, but does dump fuel when you stop cranking :???:

Yes, that was rather misleading, wasn't it :)