Crack in VR coil pack

[timthetinyhorse 0]

Well I think I may have answered my own question about the non starting corrado, I only checked one cylinder for a spark and presumed the rest to be ok but after taking a look at the coil pack it is cracked so I'm presuming I have no spark on some of the cylinders.

 

This would explain why it tries to fire then fails in a sort of rythmick order....

[vw rule 19]

Yes it would but you still need to check all of the spark plugs in turn,

if you have no spark at all or if it's very weak then the plugs will be dripping wet with fuel (hence vehicle not starting)

Have you checked all the plugs ??

 

You say you've spotted a crack in the coil pack, this crack is it in the insulation at the top where the HT leads plug in to ?

Some coil packs fail when cracked but some still work as normal.

I take it you've already checked the distributor cap and rotor arm for damp or for any wear as this will course similar simptoms.

I would check these just before the purchase a new coil pack.

 

One thing you can do just to make sure,

is to disconnect the main feed coil plug so that the coil pack won't fire,

remove all the spark plugs and then get someone to crank her over and see if fuel if poring in to the cylinders if it is then the ECU has blown,

if there is just a fine pray mist in the cylinder and the top face of the piston is slightly damp then it is firing ok out of the injectors.

 

The spark plugs when fitted in to the cylinder head complete the earth circuit, (they earth through the head and have live power running through them via HT leads)

and so if you have a weak or no earth to the engine block or head then the plugs won't fire.

 

I believe you said that you've already changed the coolant temp switch and there was no difference,

so I'd say the fault lies with in the ignition system.

 

One thing though if and when you replace the coil pack, if there is no difference then I'd check the immobiliser,

just to make sure it is disarming as some immobilisers do cut the power to the ignition coil pack but not fully,

and so let it work but not enough to start the car (which will give you the symptom you have now)

 

 

Hope this helps

 

Si :thumbleft:

[timthetinyhorse 0]

Thanks for the info.

 

How do I check the rotor arm and distributor??

[daves16v 1]

If you have a coilpack then you don't have a distributor and rotor arm.

[vw rule 19]

I believe the very early Corrado VR6 had a coil pack and distributor, which of course had a distributor cap and rotor arm fitted,

this was from 1992 to around late 1993 (I have seen a very early 1994 VR6 Corrado with a distributor - but these are rare)

The coil pack on this VR6 has just the one HT lead (the king lead) going to the distributor cap, which then powers all the 6 HT leads from the distributor cap,

to the spark plugs.

The distributor cap is fitted to the distributor it's self by two curved clips,

these clips are fixed permanently to the distributor via hinges and clip over the side of the distributor cap to retain it in place,

you simply just flick off the clips off the cap using a small to medium size screw driver, them remove the cap and you'll see the rotor arm in side.

Normally the rotor arm and the distributor cap contacts bur up which affects the power of the spark (this should be checked on a service)

 

All the later Corrado's mainly from late 1993 or early 1994 up to 1996 didn't have the distributor or the coil pack with just the King HT lead powering the distributor cap,

they changed to a larger more powerful coil pack which powered all the 6 HT leads directly to the spark plugs.

So if you've got the early type engine you'll be able to check the distributor cap, if not then you'll just have the more powerful coil pack on it's own.

 

Don't forget that the crank sensor tells the coil pack when to fire so if you have no spark, check this sensor for cracks.

Most or all sensors are magnetic as they pulsate off a metal toothed ring and so can have small metal filings sticking to them,

which can make contact between the sensor and the metal toothed ring coursing it not to work correctly.

 

There are really two main reasons why a petrol vehicle won't start: NO SPARK

NO FUEL

 

Or if you've got too much fuel going in to the engine this wil course the car not to start,

it might be worth checking the fuel pressure regulator,

when these go wrong they can course the car to :

 

NOT TO START UP

A MISFIRE (poping slightly out the exhaust)

BLACK SMOKE OUT THE EXHAUST ( which means it's running far too rich)

FUEL IN THE VACUUM HOSE (this means the inner seal /daiphragm is leaking fuel,

when the engine is switched off, if you remove the regulator vacuum hose and you find fuel in there then replace the regulator,

as this vacuum hose should always be dry.

 

Check your engine oil level and coolant level,

most VR6 engines do use more oil than the 16 valvers as the pistons are at a 15 degree angel,

like most V6 or V8 engines they mostly do burn more oil than a straight 4 or straight 6 engine.

 

The only other thing that could course the engine not to fire up is very low compression,

but it would have to be really low though,

petrol cars that have low compression say around 50 to 70 PSI should still start up but will misfire.

Good compression on a petrol engine should really be between 150 and 250 PSI

 

I hope this helps

 

Si :thumbleft:

[daves16v 1]

Defo coilpack, see here http://the-corrado.net/showthread.php?76067-more-of-the-storm-red-VR6/page4

[vw rule 19]

Right ok mate the later coil pack then confirmed :salute:

 

Have you tried cranking the engine over with your foot full down on the throttle pedal,

and then with your foot completly off the pedal ?

(with the pedal down you should here more of a drown noise from the engine as it's cranking, this means you have good compression,

if there is now noise difference then there could be a problem)

 

If you have got 100% a spark and fuel then you should be able to start the car by pumping the throttle pedal as you crank it over,

to get your VR6 started.

 

Have you completly checked for a spark from all 6 HT leads ?

Have you checked all 6 spark plugs ?

Have you taken off the fuel feed pipe where it goes to the fuel rail ?

(should be fuel pressure here, as soon as you take that feed pipe off it should pray out for a few seconds,

if it does pray then you've got half decent pressure, if it doesn't pray then it could be the fuel regulator has failed ?

 

I take it you can smell fuel after you've been cracking your VR6 over ??

 

Please let me know what you have checked so I can help you more.

 

Si :thumbleft:

[timthetinyhorse 0]

I have a very strong smell of fuel after cranking the car over, before this started to happen the car used to pop from the exhaust quite a lot and always smelt like it was running rich.....

 

I have not tried all of the plugs for smart just cylinder one and it was good and strong, it's sounding to me from what you have said that it could well be the fuel pressure regulator, when I removed the plugs they were wet with fuel so I'm presuming in this case I'm getting too much fuel??

 

I will check the vac pipe next time I'm looking at the car.

 

Cheers

 

---------- Post added at 8:44 PM ---------- Previous post was at 8:42 PM ----------

 

Also,it won't start with full throttle, it sometimes tries to fire but it dies with a pop from the exhaust.

[vw rule 19]

Hello mate,

 

right ok the plugs will only get wet if the spark is weak or you have too much fuel delivery.

The coolant temp switch tells the ECU how much fuel to pump in when the engine is cold,

and once the engine is warm the temp switch should tell the ECU then to reduce the fuel mixture.

This you've already replaced, but still have a good look at the connector plug and wiring.

 

The only other sensor that can course this symptom as well is the lambda sensor (also known as the oxygen sensor)

this measurers the exhaust waste mixture just before it enters the catalytic converter,

and if it detects too much fuel deposits with in the exhaust waste gas it should then tell the ECU to reduce the fuel mixture,

due to the extreme heat in the exhaust these lambda sensors can become heat damaged over time,

and give false readings or in some cases they can short out and the sensor end tip that's in the exhaust can melt or drop off,

coursing the ECU to dump loads of fuel in to the cylinders via injectors as it can't measure the exhaust waste gas anymore.

You normally get a engine light which is coloured orange come on when these lambda sensors fail.

Which can course the car not to start at all or if it does it will have a slight misfire and be a little under power.

 

What you need to do is to check and make sure there are 4 wirers still connected to the lambda sensor it's self,

plus also check that the connector plug is still plugged in together,

this lambda sensor plug / wiring is normally down the back of the engine near to the rear engine mount drivers side,

the wire then goes up behind the large heat shield to protect if from the heat of the 6 port exhaust manifold,

so you may have to get behind the heat shield slightly to check it.

 

Also you may want to get your Corrado up in the air, i.e jack it up on to some axle stands,

so you can have a look at the lambda sensor, and have a wiggle of the exhaust catalytic converter,

as there is a honey cone mesh like filter inside and some times these break away from there fixings,

and then are able to float around which will rattle and some times can lodge in the exhaust coursing the car not to rev up,

or on some rare occasions they won't let the car star up.

The lambda sensor you can test these with a multi meter,

you need to set your meter to ohms say about 200 ohms and check across the two white wires at the lambda sensor plug (have it unplugged)

you should have a reading of around 1 to 8 ohms, if you have nothing then the lambda senor has burnt out.

Also check you have power to the lambda sensor.

 

Similar ohms test can be carried out on the coolant temp switch,

if you unplug the coolant temp switch plug and connect up the multimeter to the temp switch then you can test the resistance,

the resistance should be high as the coolant in the Corrado is cold as it won't start up.

You simply connect the black multimeter cable to an earth on the car somewhere like a bolt,

or something metal on the engine earthed to the body of the car, then connect the red multimeter cable to the contact on the coolant temp switch,

remember to have the coolant temp switch unplugged.

(resistance should drop down when a sensor can read a hot temperature and be a bit higher when the temperature is cold)

The ohms should be around 200 or more if you get no reading or it's not up to 200 ohms then the sensor could be duff,

Also check you have power to the coolant temp switch and an earth from the loom as this would course it not to work.

 

If you say you've only checked the one spark plug, and it had quite a good spark,

then I would say that the crank sensor is working ok,

but you need to really check the rest of the plugs just in case it is something as simple as a few plugs gone down.

One or two spark plugs not working in a VR6 and it should still start up but it would be missing and spluttering a lot,

but if you have got 4 or 5 plugs not working then she WOULDN'T START UP AT ALL, but you may still hear her just trying to start, just ?

 

You could try a new or decent second hand coil pack ?

But like I say you've got to check all the spark plugs and HT leads to totally rule out the coil pack issue.

 

You could try a decent second hand fuel pressure regulator ?

When you remove the vacuum hose if there is no sign of fuel in it,

and you remove the fuel feed hose as mentioned above to check the pressure,

then chances are the fuel regulator will be ok.

Just bare in mind that the inner diaphragm can still be ripped or pitted and no fuel will enter in to vacuum hose.

Fuel in the vacuum hose is normally the first sign that the fuel regulator is going to fail.

 

The other thing is the air flow meter.

You can test these as well with a multimeter, again set the meter to ohms and test across the terminals,

you should have a reading of 1 or 0 ( one or zero) ohms, if you don't then the air flow meter is duff.

Or switch the ignition on and set the multimeter to volts, (never turn on ignition when testing ohms only for volts)

and connect up the red and black multimeter leads to the air flow meter connector (wiring loom must be plugged in to air flow meter for this)

You may have to remove the air filter and the plastic air in take hose,

(this is the plastic hose from the air filter box to the throttle body as it houses the air flow meter)

With the plastic air intake hose disconnected and the air flow meter plug still connected,

and with the multimeter connected to the air flow meter sensor if you blow in to the hose on the airflow meter,

you should see the volts reading change on the multimeter if it does not then this confirms that the air flow meter is dead.

 

There might be a cam shaft position sensor and when these play up the car sometimes will not start,

I can't remember if there is one on the VR6, there might be ?

These sensors normally tell the injectors when to fire and so if it was faulty could course a none starting issue.

I believe you can set your multimeter to volts and with the ignition on you should have around 5 to 6 volts,

at the cam shaft position sensor with the loom plug still attached.

Now if you get someone to crank over the engine you should see the volts change between 0.5 volts up to 1.5 volts,

if it's not then the sensor could be dead.

 

 

I hope this helps dude.

 

I can't really think of anything else :scratch:

 

You could have it towed to a garage to have it put on to a diagnostic scanner,

but most scanners really need the car to be running for the scanner to be able to go through the ECU correctly,

unless they've got one of the more expensive ones where it's able to see the stored fault codes in the ECU memory chip.

 

I hope you get her running soon.

 

Si :thumbleft:

[timthetinyhorse 0]

Si

 

Thanks for all the info above, I managed to fall down the flat stairs yesterday so I'm not particularly mobile at the moment but I did manage to drive down the garage and take a look at the vac pipe for the fuel pressure regulator.

 

It's been a lcouple of days since I attempted to run the car so I didn't know what to expect, now there is no actuall wet fuel in the vac line however there is a strong smell of fuel when I sniff the line so I presume fuel has been present.....

 

Also the vac line looks fairly badly perished so I presume this could also cause me an issue??

 

Below are a couple of pics, one of the regulator and one of the vac line to make sure I'm looking at the correct thing.....

 

 

 

Thanks for all the help so far.

[vw rule 19]

Yeah that vacuum hose really needs replacing it's seen better days by the looks of it,

if you say you can smell fuel in that old vacuum hose then the fuel regulator might be weak.

I'd replace the vacuum hose with a new one and try starting the car again.

After that if she still doesn't want to start then your going to have to start changing parts over,

may be starting with the fuel regulator ?

The fuel regulator keeps the fuel system pressurised in the return fuel line back to the fuel tank,

so after cranking the engine over you should really have pressure in the fuel lines,

like I say if you remove the feed fuel line it should spray out for a few seconds,

and that goes for the return fuel line as well.

But you'll have to crank the engine over twice, once to check the fuel feed line,

and then again to check the return line both should be on or around the fuel rail.

(because when you remove a fuel line the pressure drops and so you need to crank over the engine again to build the pressure back up)

 

 

Hope this helps mate.

 

Si :thumbleft:

[timthetinyhorse 0]

Cheers dude, don't suppose you know the spec of the vac hose for the regulator do you?

 

Think that sounds like a good course of action, I will change the vac line and if I have no joy change the regulator itself, I tried to remove the regulator today to take a look at it but I couldn't get it out, I'm sure with a bit more time it will free up though.

 

Thanks for all the info mate it's a real help, I'm back to work tomorrow but on nights so if I can source some vac hose I will give it a go.

 

Cheers

[vw rule 19]

Hello mate sorry to hear you fell down the stairs. Oh I see are you practicing then for the long jump :bonk:

 

I think you can get vacuum hose that is oil & fuel resistant, but to be honest you should be ok with ordinary vacuum hose,

if you take the old vacuum hose with you say to Motorbitz or Halfords you should be able to match it up & purchase some from there,

if not may be off Ebay or you could try your local back street garage i.e vehicle repair shop.

 

New vacuum hose should only be £3.50 to £12.00 tops, you might have to buy it in half meter or one meter lengths ?

The cost might be a little higher if you purchase some off Ebay or Amazon as you may well have to pay for carriage as well ?

I think the diameter of the vacuum hose you need is around 3.5mm (that's the ID = inner diameter)

 

Take it easy mate, hope you get her going soon.

 

Si :thumbleft:

[timthetinyhorse 0]

Ok thanks very much for all the info you have provided!!

 

I will get some hose tomorrow and give it a go.

 

Would I be correct in thinking if the hose is damaged there won't be a strong enough vacuum for the pressure emulator to function correctly?

 

I'm almost convinced its flooding that is my issue....

[vw rule 19]

The fuel pressure regulators have been known to be stuck open and so can let more fuel through than is needed.

But yeah if the vacuum hose was split then yes you would lose fuel pressure (hence car not starting)

 

You say your car is over fueling then it could be something different.

But if you read the other sections of this thread I've already listed the possible courses:

 

Spark plugs not firing.

Coolant temp switch not working (faulty switch or no power to switch)

Cam shaft position switch not working (faulty switch or no power to switch)

Lambda sensor not working (but your car should really still start up)

Fault with in ECU it's self (meaning it's just poring fuel in)

No compression in cylinders (meaning the air & fuel mixture won't be compressed and car won't start)

 

You need to do your self a list of items to check / replace, then tick them off one by one,

so that your not going in circles.

 

I take it your battery is ok, because even though your car cranks over,

if the battery is low then your car my not start as the electrics need as certain amount of power.

 

I think your going to have to start changing bits over.

 

The only other thing with your VR6, is it a manual or auto gearbox ??

It's just that with the auto boxes they normally only start up with the gear shift stick in the park position,

as the gear stick has to press against a switch, but yours cranks over doesn't it.

 

This is hard for me as I'm not there looking at the car so I'm not able to hear / see / smell things.

 

I hope you get her going as the VR6 is a great car.

 

Si :thumbleft:

[timthetinyhorse 0]

Just read all this properly, I say over fuelling but of course it could be flooding as a cause of not starting and been constantly turned over......

 

Going to try and source some hose and go from there replacing the regulator then the coil pack.

 

Think this could be the right hose? Vagcat says the hose is 3.5mm x 2mm, I'm presuming the 2mm relates to the wall thickness but this shouldn't be too important?

 

http://www.ebay.co.uk/itm/1x-Black-cotton-Overbraid-Vacuum-Hose-3-5mm-VH009-/321027452991?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4abeba303f

Edited February 26, 2013 by timthetinyhorse

[Southie 10]

Its £9 per meter at VW with a min order of 1 meter, they should stock it too

 

Or if your not in a rush PM me you address and ill send you some

[timthetinyhorse 0]

Cheers southie,

 

I think I will call down the dealer at the weekend as i think im going to replace the regulator anyhow due to the smell of fuel in the hose. I'm on nights at the moment so I'm in no real rush. Thanks for the offer though.

 

Rob

[vw rule 19]

Yeah that's right mate, that's the vacuum hose you need, 3.5mm should be ok and if it's got a wall thickness of 2mm, then great :thumbleft:

 

After you've fitted the new vacuum hose if you remove all the spark plugs and then crank her over to get rid of all the moisture in the cylinders,

then refit your spark plugs and try starting her again, you never know it might work :)

(Remember that you might have to disconect the coil pack connector plug as you don't want the HT leads to be firing,

when you crank her over with the spark plugs removed, AS THERE COULD BE FUEL VAPOR COMING OUT THE CYLINDERS)

 

If you need any more help, then just give me a shout.

 

Si :thumbleft:

[timthetinyhorse 0]

Managed to take 5 min today to pull the plugs out as I'm waiting for a new fuel pressure regulator coming and they looked fairly black so I'm presuming this means it's rich? Would they be blackened from trying to start as t he aa man cleaned them when they were out when the starting issue first happened but it hasn't run since, pics below show plugs, all we're dry and not wet as I expected to see.........

 

All 6 plugs.

 

 

This was the worst of the lot.

 

 

Gave them a good clean up and need to dig my feelers out to check the gap, I think the Bentley states 0.7mm.

 

 

Cheers

 

Rob

[vw rule 19]

Hello Rob,

 

A good spark plug should be slightly tanned on the electrode as this shows the engine is running correctly,

(meaning it's running at the correct temperature & is burning a good fuel mixture)

 

yeah those spark plugs of yours were a bit coked up with oil & fuel deposits (looks like it is running a bit rich)

You might be burning some oil as well Rob.

Those spark plugs you normally change them every 15,000 to 20,000 miles with the 2, 3 or with the 4 electrodes as they've got a longer life span.

 

I'm not too sure if you can adjust the electrode gaps on these plugs (I don't think you can) as there normally set up when made.

The centre contact should be round if it's oval at all then you should really replace them with new.

 

Si :thumbleft:

[timthetinyhorse 0]

Ok I will take a look at the electrode at some point over the weekend also,

 

Not sure about burning oil as the car uses very very little, the thing that I'm puzzled about is the fact that the car only ran for about 30min when the aa started her and then has never run since and the plugs were that black even though they were cleaned when the aa fired the car??

 

Should have the new fuel pressure reg next week so I can get that fitted and then I should know if I need to start looking at the coil pack also.

 

Thanks for the help

[timthetinyhorse 0]

Today more progress was made with the non starting issue......I removed the fuel pressure regulator and found that ISPs looking almost brand new so no worries there.......the coil pack however was a different story!!

 

I removed it after noticing a fairly bad crack in the plastic insulation on the left as shown below. The first shot shows the bottom of the coil pack with a few cracks and the 2nd shows the state of the pack after the bolts were removed and the plastic as good as fell off, the metal is exceptionally badly corroded which would tell me this coil is destroyed......

 

 

 

I started to strip the coil down and more plastic was crumbling away and the extent of the mess was pretty clear, the layers of metal were separating and some on the corners had begun to snap off.......

 

 

 

 

So the solution here it would appear is going to be replacing the coil pack and not the fuel regulator as I first thought, not all bad ough as it now means I have a spare regulator :-)

[Supercharged 2]

That's not original but looks pretty old tbh... new genuine one is the way to go!

 

If you've bought one I'd be tempted to change the FPR too - if only for the new O ring seal

[timthetinyhorse 0]

You know what sort of price I'm looking at for a new coil pack from the stealer? I'm presuming I'm correct in thinking the could most certainly be the cause of my car not starting and having very black plugs..