[Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

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yokomomr4bx
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Location: Cardiff

[Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Hey guys,

Very frustrating issue that has come about in the past week, and only 3 days before we're set to drive up to Scotland!

The engine really struggles to start after it's been sat overnight. Plenty of fuel going in as you can smell it when it's been turning over. When it's still warming up it will miss a beat when sat at idle or if accelerating gently it will not fire (no boost). When it's fully warmed up it runs smooth and pulls cleanly under boost.

Spark plugs are a grade colder but have been gapped down and I'm reluctant to believe a BKR7E plug is the reason for poor starting?? Please tell me if colder plugs make that much difference in cold weather though!

I was placing my bets on the distributor and rotor, however I've whipped them off and had a look and they look much better than ones I've taken off in the past with no symptoms. I was thinking the gap between the rotor and contacts may be just too big when cold but once warmed up closes up enough? Don't see how that results in it firing eventually and very reluctantly though :/

Would really appreciate some ideas being thrown at me here! Thanks.
Bear87
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

Hi mate,
Plugs shouldn't make that much diffrence as long as they are gapped correctly.
Of you are fairly happy dizzy and leads are okay I would put money on a faulty capacitor on the ECU. As these cars are getting older its becoming increasingly common.
Could also be a weak coil? It's quite easy to test with the BGB. You can download it from shinny if you don't already have a copy.

Hope that may help :thumleft:
yokomomr4bx
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Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Thank you for your reply.

Got the ECU out and apart, there are 2 capacitors that have suspect connections to the board. Both are 10uf, one on the bas and one on the sister board.

Image

Image

Are these the capacitors that are commonly subject to problems?

Thanks again.
Bear87
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

From memory yes they are the most common two. If they leak alot they damage the printed circuit board underneath so they are definatly worth replacing even if it isnt resolve to the issue.
You can get them from maplin for penny's. Although it's worth putting in the best quality you can find. Get some electrical circuit cleaner too and use a cotton bud to clean off any acid that has leaked.
yokomomr4bx
Posts: 216
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Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Soldering the new pair on as I type, 38p from Maplin. As you say, even if it isn't the issue, I can't drive around with capacitors like that now I've seen them!
Pauln
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Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

Yep, well worth doing. Those two always seem to be the first to leak and if you don't catch them in time can do serious damage to the tracks, as I found out the hard way.

The fault seems to be more common in the rev2, but it may be that they used the same batch of caps in early rev 3.

Hope that sorts it out. If it doesn't, and you do need a spare distributor cap and rotor arm to try, I've got spare rev 2 items here Ed, but I don't know if these are the same as on the rev 3.

Paul
Bear87
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

Let us know how it goes! Like paul I also learnt the hard way! Looks like you may have caught them early enough!
yokomomr4bx
Posts: 216
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Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Well the new capacitors are on chaps. Was only a little on edge when I flicked the key :cyclops: engine runs fine as normal so at least we haven't made the problem worse! And definitely a great call to check them, wouldn't have looked in there until it was too late. Will have to see how it starts tomorrow morning.

Image

Image

Thanks Paul but I believe the rev 3 dizzy and rotor are different to the rev 2 (fairly sure anyway, hopefully someone will correct me if wrong) but thank you all the same.

The only other thing I can think of is water collecting around the connector between the coil and the primary lead, bit of a dead spot for water dripping down, but if that were the case I would expect it to cause issues after every rainfall.

PS. On a side note, does anyone happen to know what circuit these two capacitors are associated with?
Pauln
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

yokomomr4bx wrote:The only other thing I can think of is water collecting around the connector between the coil and the primary lead, bit of a dead spot for water dripping down, but if that were the case I would expect it to cause issues after every rainfall.


I agree, if it was water related you'd normally expect the same problems every time after heavy rain, as can be the case when the outer plastic is cracked on the coil.

If you continue to have problems, it might be worth starting the car after dark as any possible tracking issue on the ignition leads etc should be clearly visible. I did have one set of aftermarket leads where I found the wire was a poor push fit the the plug cap - just pulled out without any effort at all.

yokomomr4bx wrote:PS. On a side note, does anyone happen to know what circuit these two capacitors are associated with?


I'm afraid not. I believe those are decoupling capacitors just used to suppress "noise" on the power supply to the ICs, so when they fail the ECU would probably continue to function without them, unless you were unlucky. The real issue is the damage the gunk that comes out of them can do to the tracks on the circuit board. Which is why it's always a good idea to make sure to remove any traces found.

I first hit this issue when I pulled away, and within a few hundred yards the engine management light started randomly fading in and out, even though the car seemed to be running OK, I returned home straight away as I didn't fancy pushing my luck to see if I could find if anything had actually stopped working :)

When I opened up the ECU the adjacent tracks were in a real mess. So bad in fact that I didn't even bother trying to bridge the damaged sections and started looking around for a replacement.

When a replacement turned up the first thing I did was to open it up to check the capacitors. Luckily one of them was only just showing signs of leaking and the gunk hadn't reached the circuit board yet. Needless to say I replaced both to be on the safe side.
yokomomr4bx
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Ahhh ok, likely not an essential circuit then, I had wondered as much. Very glad I did them now though!

So I'm completely wrong, there is no difference between rev 2 and rev 3 distributor caps and rotors, don't know quite why I thought there was! :-k

Is the offer of a dizzy and rotor still available Paul?
Bear87
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

It was only rev 1 dizzy that was different as it had the locking tabs on it for the HT leads. They do suffer with ignition issues alot so it's always worth changing dizzy cap and rotor etc when possible.
Silly question but the spark plug holes aren't filled with water or oil are they? Heavy rain and snow can get under the lid and it causes misfires
yokomomr4bx
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Yes you’re right, had it in my head each revision was different! Indeed, it’s well known the 3sgte is a tad greedy on ignition components, I will feel more at ease ruling them out.

Good thought but no they’re not, dry as a bone.

It’s strange, years ago I had idling problems and it was the dizzy cap, hadn’t been changed for goodness knows how long before, to the point that the sprung centre carbon electrode was completely absent, and yet the engine still ran albeit the spark would be blown out on boost. I think it’s surprising how much abuse the components can take with optimal ambient temperature but as soon as it’s out of that range, symptoms will show.
Pauln
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

yokomomr4bx wrote:Ahhh ok, likely not an essential circuit then, I had wondered as much. Very glad I did them now though!

So I'm completely wrong, there is no difference between rev 2 and rev 3 distributor caps and rotors, don't know quite why I thought there was! :-k

Is the offer of a dizzy and rotor still available Paul?


Happy new year.

Yes you're welcome to borrow them Ed to see if it makes a difference. Both were working OK on the car, so I just kept them as spares when I routinely replaced some of the ignition components.

Paul
yokomomr4bx
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Thanks Paul, dropped you a message :thumleft:
yokomomr4bx
Posts: 216
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

If anyone was interested in the outcome of this little tale, the car drove faultlessly to Glasgow and back, including driving through the most appalling motorway conditions I've ever experienced in the Uplands close to Glasgow. Our cars really weren't made for effectively driving underwater and I believe I've found the limit of the 3SGTE's durability in adverse weather, namely dense sustained road spray combined with a petrol spill across the carrigeway - I think the atomised fuel and water coming into the air intake in such relentless volumes upsets the ECUs control of the current fuel map and induces a spark retard (or advance?) to try and make sense of the extra fuel. Either way, I would not wish this experience upon anyone when 2 feet away from a lorry up-hill!

On a side note, if anyone is keen to have any capacitors replaced on their ECU and is not feeling especially confident with their soldering ability and would prefer not to pay what imagine to be an excessive bill to a specialist, I would be more than happy to change them for a more reasonable fee and can provide examples of the standard of my solder work to anyone interested.
Pauln
Posts: 850
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Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

Well if the cars still running OK after a journey like that, at least you know you've fixed the problem Ed, which is good news :thumleft:

Paul
Bear87
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Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

Really glad had all worked out for you! I think you could find there is a good few guys and gals on here would be grateful for a professional job on there ecu's as second hand units are getting so hard to find!
yokomomr4bx
Posts: 216
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Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Thought I had put this one to bed...alas no. Wouldn't start again this evening. Plenty of fuel. Just no spark. Occasionally when cranking it fires for the briefest of seconds but can't sustain it. Very strange one this as it drove faultless to Scotland and back and yesterday to Cheltenham and back from Cardiff. I'm once again open to suggestions!
Bear87
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Location: Essex

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

Few things I would check. If it's not starting make sure if it's a rev 1 or 2 engine the AFM plug is clean and fitted tight. If it's rev 3 onwards you won't have this.
It may be your not getting a ign signal to the ecu of there is no spark. You would need to go through the book for the test proceedure. I can be the pick up inside the dizzy is gunked up? I clean mine off every year, often metal shavings from work dizzy cap can stick to it or moisture getting into it.

When your starting the car is the engine management light showing before you turn it over?

Is the tachometer needle moving at all when the engine is cranking?

This could be a faulty coil or ignitor ( most often its due to a bad earth because of a rusty bracket!)

Again the above can be tested with a basic multimeter.
yokomomr4bx
Posts: 216
Joined: Sun Jan 20, 2013 3:06 pm
Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Yes it's a rev 3, brand new distributor and rotor fitted last week. No EML on when cranking. Unsure on the taco moving if I'm honest, I haven't ever noticed!

I replaced the coil last year with a pretty cheap one (£25), and there's a part of me that wants replace that and start throwing parts at it, but that isn't a very efficient way of diagnosing!

Agreed, first call will be a resistance check on the coil followed by a gap check on the distributor itself (not the cap) and a resistance check on the pickup coil, will try and do this with the distributor still on the car, failing that I'll make a dodgy little mark to align the distributor with upon reassembly.
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