VR6 - Sporadic Starting Problem

[mattwelcer 0]

VR6 ODB2

 

Occasionally it starts fine first time other times it turns over for quite a while (over 5 secs) until it starts and not well at that.

If after it struggling to start i turn the engine off and start it again it starts fine. This happens irrelevant to weather and irrelevant if its been stood for overnight or for 30mins.

 

I have changed the following parts hoping that it would solve the problem; :scratch:

 

Fuel pump

Fuel Pressure Regulator

Fuel lines (complete)

Coilpack

HT Leads

Spark plugs

Crank shaft sensor (in the block)

 

There are no faults stored in memory (checked with VCDS/VAG-COM) and the battery has been checked and has been shown to be OK and fully charged. The starter was new 3 yrs ago but i am unsure how to test it other than taking it out and testing it on the bench with spare battery.

 

What should be the next steps to localise this problem and resolve it? Can anything be monitored with VCDS to check its working as expected, is a compression test required? It does have an immobiliser and the ignition switch was replaced over a year a go.

 

The car has the following mods, bored out to 2.9 with OEM pistons, CNC Stage 1 Cylinderhead, Schrick VGi, SP 263 cams, K&N 57i, Magnaflow cat back exhaust, Autotech lightened flywheel

 

Any hints, tips or information on how to proceed would be greatly appreciated! (and yes i have searched the board but not found anything similar)

[VR6 0]

Ever had a new fuel filter on it?

 

What was the ignition switch changed to? Proper VAG replacement?

[mattwelcer 0]

Yes fuel filter was replaced 2yrs ago, ignition switch wasn't a proper VAG item but an original supplier to VAG (I'll need to check the make)

 

Edit

Also forgot the injectors were also cleaned/serviced last winter too

Edited June 26, 2012 by mattwelcer

[mattwelcer 0]

OK the ignition switch is from "Topran" and was under the impression they are OK

[fla 9]

Sorry but topran switches are no good at all. They're cheap but for a reason..

[mattwelcer 0]

OK i'll get a new VAG one ordered today and see how that goes! :)

[winchbietch 0]

Interested to hear if this fixes it, mine has started to the same over the last few weeks and as yet ive not had a chance to investigate.

 

Paul

[VR6 0]

I would bet a couple of quid that a proper ignition switch will fix it.

[mattwelcer 0]

Yeah fingers crossed, i got the new one last night just need to fit it this morning!

[Thumper 0]

I would bet a couple of quid that a proper ignition switch will fix it.

 

I would say so too, had a couple of raddos with this issue. Used the cheap one and it was utter trash, ordered one from vag and instantly problem solved! Hopefully it cures your problem, frustrating trying to narrow things down!

[mattwelcer 0]

Well not been able to fit it, borrowed the special puller tool (its a Mk3 Golf) everything came apart but there is a "support ring" behind the steering lock unit which is completely crushed on one side and might explain why i have some play in the steering wheel. So new part ordered but won't be here until this afternoon...

[mattwelcer 0]

Ok replaced the ignition switch and the additional part

 

 

and no joy the start problem is still there :(

 

So my next step will be to swap the Schrick and 57i for standard parts and then test the compression. While that's all off I will also double check the timing marks.

Battery doesn't seem to be an issue either as that was charged last night but this morning made no difference what so ever :(

 

Any other things I could try or check?

[seanl82 23]

Have you tried disconnecting the MAF and starting it? Only reason I ask is that if your K&N is the older oiled type, it can play absolute havoc with the filament, and Kill MAFs in very short order. I may be way off the mark, but its worth a try!

[Mike Edwards 0]

If it starts on the second attempt, it can't be the crank sensor. The cam sensor is something else to consider.

 

Does this car stall pulling up to junctions at all?

[mattwelcer 0]

OK still no luck with this problem but seem to have made a little progress.

 

Original intake manifold (easier to check the compression later due to restricted access from the Schrick) and Airbox fitted. But the start problem was still present, also fully charged the battery and no improvement. This was all while we were having 30C here in Germany.

 

However on Sunday the temperature dropped to 15C and hey ho the car started first time Sunday morning!!!

 

Took it for a drive in the afternoon, parked it in the garage and came back a few hours later and the start problem was back. So I think its possibly a temperature related problem, maybe the solenoid on the starter motor isn't good. Because when the car has starting problems the car turns over and turns over then starts, if the engine is switched off and back on it starts straight away without any hesitation.

 

Therefore could this definitely be the starter motor or could it be something else that would be affected by heat/humidity?

 

I plan to take the starter motor out this week and take it apart to see if the carbon brushes are OK etc.

How can a starter motor be tested to see if it turns over "quick enough"? As the engine does seem to turn over "slower" when starting but once the engine has started and been turned off and started again it turns over much quicker and therefore starts as expected.

 

I hope to get a video posted too to show the start problem better.

[dr_mat 0]

I would say you really, really, need to do a VAGCOM scan on the ECU and look to see if your engine temperature sensors are working right..

[mattwelcer 0]

I assume you mean this from the VR6 cooling guide? :scratch:

As I only changed all three sensors last year with new VAG parts.

 

Temperature reading check

If you think you've got problems, it's always worth checking that the dash readout is actually correct. New senders are only a few quid from VAG and worth swapping if they're the old, crusty originals. Then at least you know you're not chasing phantom faults. The older and crustier they get, the more insulated they are from the actual water and thus, the less accurate they are.

 

If you plug the car into VAG-COM, it will display the temp that the ECU is reading (i.e. from the blue sender) so you can compare that to the reading on the gauge that's coming from the yellow sender and see if you've got a mis-match.

[Gareth192001 10]

Daft question but have you checked for a good earth. Had a problem over the weekend wouldn't start i had a massive voltage drop between the battery and starter motor. I remove the earth cable cleaned it up and bang all good.

[mattwelcer 0]

I have checked the earth strap on the gearbox and that was fine any other's i should be checking?

[Gareth192001 10]

Can you check the voltage between the battery and the starter motor. There shouldn't be anymore then 0.5v drop earth wire is on the starter motor or very close not east access

[mattwelcer 0]

Think i have found the problem! :D

 

The battery!

 

I got hold of some jumper cables and started it with the aid of my Leon and it started first time! So it would seem the battery has enough "juice" to just turn the car over and start it but not quite enough to turn it over properly. I have a C-TEK charger which i have been using to charge it. But i will now try re-conditioning it and see if that helps. If not then i guess i'll need a new battery. I'll report back in a few days after reconditioning the battery to see how it goes.

 

Might see if i can borrow a battery of someone as well see how it starts then.

[dr_mat 0]

You can tell everything you need to know about the battery condition with a voltmeter and a load tester ..

A lot of people have the former, but not many people have the latter!

The C-TEK should have kept the charge up, so you *shouldn't* have any issues, but if the battery is getting on a bit, or has been badly discharged and left flat in the past, it might just be too late for it ..

[mattwelcer 0]

Yep a load tester would be handy, i am pretty sure it is the battery as it was last year completely discharged (left the ignition on over a 24hr period while on a car lift).

But after we charged it (with the aid of a 2nd fully charged battery and a charger) it seemed to be OK, i guess not... :(

 

I'll see how it goes tonight as the recondition program seemed to be done within 2-3hrs last night, so just left it on normal charge for the rest of the night, disconnected it this morning and put it back on normal charge again.

 

If the battery is dead, what AH value is recommended for the VR? At the moment I think it is a 62AH Battery from Banner, the car is fully specced, Climatronic, heated seats, cruise control, Gamma Radio with 6disc changer and Nokia DSP. Would a higher rated battery be better?

[dr_mat 0]

It's unusual to kill a battery just by letting it go flat once for a short period of time, it usually has to stay flat for a while to sulphate badly.

60+Ah will be fine, it's only really required for starting the car. Adding gadgets doesn't increase the starting load .. !

[mattwelcer 0]

OK quite odd, the battery was reconditioned and fully charged, first start of the car - fine!

Next start was also fine so took it out for a quick test drive (15-20mins) and everything was OK. Put the car back in the garage and then came back to it about an 1hr+ later.

 

Tried to start and the same problem as before it cranks and cranks and then slowly springs into life.

 

I have put the battery on charge again, will test it tonight and see how it starts and also take it for a drive and it leave again. Then try starting it after an 1hr or should it not start as quickly as expected i'll try jump start it with the jumper cables.

 

I assume if it then starts straight away with the jumper cables the battery is knackered and not holding enough charge/amps to initially turn the engine over??

Edited July 4, 2012 by mattwelcer