Morning start issues

[aris]

I have an AGG 8v MK3 GTI - and have been having problems starting in the morning.

It cranks over ok, but doesn't start apart from a couple of rumbles as if it is firing on one or two cylinders. Eventually it does start up after much coaxing, and from then on it is OK. No problems starting again for the rest of the day.

I've been googling and searching the forums here and the consensus seems to be to change the:

1) Ignition coil
2) Rotor arm and cap.
3) leads
4) various relays
5) various sensors (such as the coolant temperature sensor).

I'd like to get some advice from you all on what to do here. It is a '97 model - a bit long in the tooth, but otherwise a good vehicle.

I'm wondering if this isn't all moisture related as we have had a bit of rain and this issue has really only been happening for the past 3 or 4 days. I also had the car cut out on me when I drove through a puddle. It eventually started again. I'm not sure if these two issues are related.

As a test I left the car idling and then splashed some water on some of the components inside the car to see if there was a short of some sort being caused by water. I could not reproduce the issue at all!

Thanks in advance.

[aris]

So it happened again this morning. Took many cranks, and what sounded like misfires to get going, but once it did get going (keeping the accelerator down did help), the engine worked 100% - idling was perfect, and no other power issues at all.

So i'm thinking - could this be a fuel issue - and once it gets going, there is enough fuel available in all the cylinders to run - or is this an electrical issue - where once the engine is cranking over, it is able to supply enough power to the ignition coil to spark the plugs.

If this happens tomorrow morning i'm going to switch the car off straight after it starts up and see if it gives the same problem. Could it be that the battery is not supplying enough power in this cold weather? Perhaps it is a combination of ignition coil slowly failing and the battery now supplying just enough power? When the engine finally cranks over and starts, the alternator supplies the needed boost of power, and charges the battery enough for the rest of the day (plus it gets warmer) to start the engine subsequently?

This issue only happens in the mornings - all subsequent starts in the day seem fine. Also while attempting to start in the mornings, it does very much sound like not all cylinders are firing.

My guess is the ignition coil - but i'd rather not spend 50 quid replacing that if I do not have to.

[SammoVWT]

Could be a number of things, you need to narrow them down. Checking the battery is a good start. When was the fuel filter last changed?

[aris]

Could be a number of things, you need to narrow them down. Checking the battery is a good start. When was the fuel filter last changed?

About 6 months ago - so it is fairly new. I'll try to check the battery voltage before I start. I'm thinking that if I get it started, then switch it off immediatley then try and start again - this also may be a test of the battery. I would think that there would not have been enough time for the alternator to charge the battery sufficiently to start it up easily again - does this sound like a good test?

[SammoVWT]

The best way is to stick a multimeter (Volts) across the battery terminals while the car is off, and while its running, 13.5-14v running, at least 12V while its not.

Off and <12V battery is dying, less than 13.5 while running, indicates an alternator problem.

If that doesnt help, I would see if you can get a code scan done with VAG-COM, it may register a fault.

[aris]

I went to work a bit later than normal this morning - and it started first time. It was fairly warm though at 6C, whilst yesterday it was about 0 or 1C (had to scrape ice off window). I'll try the multimeter and VAG-COM also - many thanks for your help.

Do you think this might be the ignition coil? There certainly seems to be enough power to crank the engine - is it possible that there is not enough for the coil to spark the plug?

[aris]

This is still happening intermittently.

I'm starting to think it is an electrical issue - perhaps due to condensation.

I drove through a puddle at speed last week and the car died. Upon trying to restart, I had very similar symptoms to my morning start issue.

I'm wondering if i'm not getting condensation forming in the morning or in the evening before which is shorting something out.

If so, where is the most likely places for this condensation be be causing a problem?

Thanks,

[SammoVWT]

Sounds like your distributor/cap might be getting damp/wet - condensation will conduct the charge away from where it needs to be, or possibly make a permanent connection so everything gets grounded.

I'd give the cap a clean with some wd40 and let it dry and see how it goes then (WD40 is a water disperser)

[aris]

Sounds like your distributor/cap might be getting damp/wet - condensation will conduct the charge away from where it needs to be, or possibly make a permanent connection so everything gets grounded.

I'd give the cap a clean with some wd40 and let it dry and see how it goes then (WD40 is a water disperser)

Do you think I should open it up and spray, or are you just talking about the outside of the cap?

Perhaps a replacement cap and rotor may be in order - I don't think they have been replaced in some time.

[SammoVWT]

You should be able to unclip the cap and inspect it for wear/condensation (you should see 4 metal studs inside which are the conducting points) - i'd try that first. If it looks worn you may need to replace it anyway but it could be worth a try to save a few quid, not that the rotor/cap costs that much to replace anyway - but every little helps :approve:

I have heard instances where people cover the dizzy with some sort of heat restant plastic bag as i think some of the mk3 engines have distributors which are prone to being splashed/wet from rain/puddles etc.

Luckily I can chuck mine through a puddle a few inches deep and it still holds up. Im not sure what would cause it, unless the plastic shrinks/dries out due to heating and cooling all the time, possibly exposing a gap small enough for condensation to form (Just a theory!). Still worth looking at, did you manage to code scan it in the end?

[aris]

Ok, but if I do spray WD40 - where should I spray it? Inside the cap?

[SammoVWT]

Yeah, remove the leads (remember the orientation, it might be worth marking the leads 1,2,3,4 along with positions on the cap too) - unclip - wipe, then spray generously, wipe the excess (make sure its lint free, as you dont want a burning cotton in the cap!), let it dry out then plug it all back in.

It should remove some of the oxidisation on the conducting pins aswell

[aris]

Cleaned the cap - didn't help (didn't look all that bad either.

I finally did a vag-com and it said the following:

Chassis Type: 1H - VW G/J/V Mk3
Scan: 01,02,03,08,15,25,56

-------------------------------------------------------------------------------
Address 01: Engine
Controller: 037 906 025 R
Component: SIMOS 4S 2104
Coding: 00000
Shop #: WSC 01317
2 Faults Found:
00522 - Engine Coolant Temperature Sensor (G62)
27-10 - Implausible Signal - Intermittent
00525 - Oxygen Sensor (G39)
27-10 - Implausible Signal - Intermittent
Readiness: N/A

I'm thinking that an oxygen sensor may well have a bearing on this - what do you think?

Are these two sensors easy to change?

Thanks,

[SammoVWT]

Both sensors have an impact on fuel duty provided, moreso the O2 sensor, but the coolant sensor could be making the mixture to rich, depending on whether its failed open or not (0V etc), sounds like it could be the sensors or a breakage in the cabling.

The O2 sensor will be on your exhaust somewhere, im not sure if you will have 1 or 2 sensors (depends on your engine). These are quite easy to replace, but they may be seized in the exhaust if they havent been changed for a while, so may need soaking with WD40 for a while to loosen the thread.

The coolant sensor should be near your thermostat somewhere, but im not 100% sure as im not familiar with the specifics of your block.

You should be able to identify it, as it will have a coloured band and around where it screws/plugs in, with 2-3 wires coming off it. (most of the time these are plug and play and should have a connector on to make installation nice and easy)

Be aware you should get a genuine o2/coolant sensor, as the cheap counterparts are either faulty, or not in the correct range. The genuine parts may cost a bit more, but will save you wasting your money on duff parts.

When you change your coolant sensor, you will lose coolant - it may be worthwhile to make sure you have the correct coolant and do a coolant change while youre there.

[golfdude76]

Hi, i had simular issue... i only use my mk3 once every 2 weeks roughly and the starting was getting less and less reliable and one morning i tried to start it and the battery was completly dead and was a complete non starter, so i replaced the battery and it failed to fire up... i ended up replacing:

spark plugs,
dizzy cap
HT leads
rotor arm

it eventually fired up after winding it over for ages and nearly flattening battery again, but it was quite lumpy due to the moisture in the elects, but after i long run to london and back from sussex it was fine.... back in action :-)

[aris]

I did a bit of googling and I think the biggest culprit will be the coolant temperature sensor. I'm probably running too lean for a cold start. Will give this a change and take it from there. It seems easy enough to change - i'll be sure to have some spare coolant on hand!

My engine code is AGG - GTI 2.0

My O2/Lambda probably needs replacing anyhow - but if it is in the exhaust, i'll have that done professionally.

[SammoVWT]

If its throwing up a fault for both, the chances are they both need replacing, as they independant parameters.

The O2 sensor is quite easy to get to if its before the cat, you just need to have the correct socket to get to it, ive got a nice snap-on one which is perfect for the job. I think it was a 21mm, or 26mm hex (cant remember), but its a funny shape to allow you to get it past the cable.

[aris]

Any recommendation on where to buy genuine parts online?

[SammoVWT]

Eurocarparts are usually on the money, every part ive bought from them has been spot on.

I've had a rather poor experience from allparts, their databases arent up to date/good.

[aris]

Yes, but would a coolant sensor from Eurocarparts be the equivalent of a genuine one?

The one I found on their website is made by Topran - and as there is no image available, i'm not even sure if it is the right one :-)

I could go to my local VW dealer, but that is a bit of a pain in the **** to get to after work.

http://www.eurocarparts.com/ecp/c/Volkswagen_Golf_2.0_1998/p/car-parts/engine-parts/fuel-and-engine-management/engine-management-sensor/?460440720&1&7f66bb606dc11ac50ccc190315fd4682969f2124&OTSE

[SammoVWT]

Topran seems ok, (probably best to check with the Guru - aka Crasher) I think the genuine parts will go down as the original make. They wont necessarily say VW or have the images. But the parts are always correct for me.

Like my brakes are the original specified brakes from VW, but they are PAGID.

VW specified doesnt mean it has to have VW parts on the name, same with the oil - VW recommend Castrol Magnatec, but it doesnt have to say the part, just the VW spec next to it.

Normally if it says 'Recommend' next to it, its the genuine one.

For example my distributor is bosch. But its still a genuine part.

[aris]

Ok, I have a Eurocarparts near my work - i'll pop in and pick one up.

[aris]

Ok, so I changed the coolant sensor and all seems to be OK!

I found it very difficult to insert the new sensor, so I used the old gasket which seemed to have more square edges rather than the new gasket which was round. I'm hoping this will not be a problem - I can always swap it out again - but I just couldn't press the new one in with the new gasket without damaging it. I'm thinking maybe there is a special tool to insert it?

Thanks everyone for your help. Car is 15 years old now - on its last legs - will probably replace it this year.

I'm still on the original clutch after 120k miles!