Ignition fault or vacuum?

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Rob 400e
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Ignition fault or vacuum?

Post by Rob 400e » 23rd March 2020 - 5:26pm

Nothing else to do so went for a spin bearing in mind the car has been running great!
I join the motorway and accelerate to 70mph no issues drive for about 15 mile and decide to come off the motorway and head back. Drive down the exit ramp to the roundabout and the traffic lights are on red the car comes to a halt and the engine starts to bog down so much it stalls. The car is Auto. It fires up on the button and runs sweet I then select drive to move off and it bogs down again so much it is rocking the car so I flick it into neutral until ready to move off.sets off up the access road back onto the motorway sweet as a nut and accelerates to 70mph no issues. Come off the motorway again and same thing bogging down until accelerating any ideas?
Type 411 Le four door auto .
1965 Beetle

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purplepeter
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Re: Ignition fault or vacuum?

Post by purplepeter » 23rd March 2020 - 6:40pm

I can't be much help with FI
But have you thought of Fuel Filter?
Talk nicely to her

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broady_6
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Re: Ignition fault or vacuum?

Post by broady_6 » 23rd March 2020 - 8:52pm

Agree with peter, check for a fuel issue first. Im not very expereinced on FI either.
The sultan of swing

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 23rd March 2020 - 9:07pm

Bogging down because it is too weak or too rich when in D on idle. I'm thinking too rich, rather than lean ?

Being an auto makes things more difficult to diagnose too.

Does it bog down when cold and in D as well, or only when hot.

I'm thinking maybe the cold start injector is staying on, but that's just a guess. You could always pull the electrical connector off and see if that makes a difference
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 23rd March 2020 - 9:33pm

Cheers guys for the input. It’s definitely running rich the plugs are jet black but it’s always run rich, the thermal switch is also disconnected. I’ve never had this issue before. The throttle valve is correctly adjusted as well. I wouldn’t know about cold injector, but no issue when first started all was smooth.
Type 411 Le four door auto .
1965 Beetle

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 23rd March 2020 - 9:39pm

Which "thermal switch" is disconnected ?

Auxilliary air valve and thermo time switch are necessary for proper running

The 5th / cold start injector is located on the central manifold. If you remove the electrical connection it cannot inject (but if it is broken it might just dribble fuel in)

Have you downloaded and read the a D-Jet diagnostic manual ? It's worth spending an evening or two getting an understanding of how it all works
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 23rd March 2020 - 11:03pm

Hi David, that makes sense the switch is brand new but was not connected I asked the previous owner why that was he said for some reason it didn’t work properly he replaced the switch and still no joy. However he said it’s only employed for a couple of minutes so can be left disconnected.search me! I’m wondering if the air distribution box is faulty hence the rich running but that’s another matter, however it runs really well plenty of power. Yes I have a few manuals on the D tronic system all a bit over my head.
Type 411 Le four door auto .
1965 Beetle

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broady_6
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Re: Ignition fault or vacuum?

Post by broady_6 » 24th March 2020 - 8:55am

Id be surprsed if the thermal switch is only working for a short period? Or is there more than one? The engine will need some means of knowing how warm it is in order to adjust the mixture accordingly.
The sultan of swing

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 24th March 2020 - 10:08am

Exactly what I thought! But he says it’s cold start only. Been having another play today and plug lead no 3 was not clicked on properly and refuses to. I’m ordering a new set from Just Kampers. Hopefully this will cure the problem.
Type 411 Le four door auto .
1965 Beetle

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 24th March 2020 - 9:31pm

Rob 400e wrote:
24th March 2020 - 10:08am
I’m ordering a new set from Just Kampers.
I would get a better quality set from elsewhere.........
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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purplepeter
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Re: Ignition fault or vacuum?

Post by purplepeter » 24th March 2020 - 10:35pm

Speak to Mike Dempster

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 26th March 2020 - 9:50am

Cheers. I don’t know of Mike Dempster, does he have a company or a member on the site?
Type 411 Le four door auto .
1965 Beetle

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purplepeter
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Re: Ignition fault or vacuum?

Post by purplepeter » 26th March 2020 - 10:39am

Miketyp3 on here

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 26th March 2020 - 1:10pm

Cheers will try and contact him.
Type 411 Le four door auto .
1965 Beetle

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 26th March 2020 - 1:29pm

Just tried to send Mike a message, doesn’t seem to seem to be successful. I clicked on message icon wrote message and added Mike as recipient pressed submit. Doesn’t appear to have sent. Is this the correct way?
Type 411 Le four door auto .
1965 Beetle

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 26th March 2020 - 1:37pm

It goes into the outbox.

When read it moves to the sent messages

You have an unread message from me ;)
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 26th March 2020 - 2:04pm

Yes read your message, wish I was more techie it’s a struggle being thick.
Type 411 Le four door auto .
1965 Beetle

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 26th March 2020 - 2:18pm

Nah, you've got it now, the question on sent messages comes up frequently for new users
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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packers1712
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Re: Ignition fault or vacuum?

Post by packers1712 » 26th March 2020 - 3:53pm

Rob,

Regards the temp sensors/thermal time switches, I'm not too familiar with Type 4 set up but the Type 3 uses 2, one for measuring temp at the cylinder head above no 4, if it is disconnected the engine wont run its kind of a failsafe as long as it has an out put that is too hot the engine will run, the other is more of a traditional sensor that tells the ECU to inject for longer when it reads cold and progressively shortens injection duration as the engine warms up, if this one is disconnected the ECU defaults to a long injector open duration equalling a rich mixture.

Doug.

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 26th March 2020 - 5:52pm

Yes I get that, however if I connect the thermal switch in the centre of the intake manifold it hunts, disconnect no hunting. I’ve no idea.
Type 411 Le four door auto .
1965 Beetle

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packers1712
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Re: Ignition fault or vacuum?

Post by packers1712 » 26th March 2020 - 10:31pm

Unfortunately looks like you are going to have to do some in depth component tests to try and diagnose the cause of the hunting!

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937carrera
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Re: Ignition fault or vacuum?

Post by 937carrera » 26th March 2020 - 10:48pm

I agree

Hunting generally used to be put down to the auxiliary air valve IIRC.

From what we know the system does not have all the components connected, and as each of them performs a function it isn't going to run properly until each of them is sorted. Then it will all be sweet :)

Starting point I suggest would be ensure each component is actually wired correctly against the wiring diagrams. Assume nothing as it seems like a previous owner may have been messing.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 27th March 2020 - 5:17pm

Yes I agree I need to sort a few things out. I don’t think it’s that far off, overall it runs very well just a couple of issues occasionally.
I need to sort the stalling issue first then I think move onto the hunting, I’m feeling optimistic well let’s face it I’ve got plenty of time to get it sorted! Thanks for the input guys.
Type 411 Le four door auto .
1965 Beetle

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packers1712
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Re: Ignition fault or vacuum?

Post by packers1712 » 28th March 2020 - 12:18pm

You're welcome good luck and let us know how you get on as its all good info for help trying to diagnose problems for others in the future!

Doug.

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Rob 400e
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Re: Ignition fault or vacuum?

Post by Rob 400e » 28th March 2020 - 3:16pm

Update, my new plug leads turned up, and yes the quality is not good in comparison to the originals. So I just replaced the faulty plug cover with a new one, locked in ok. Fired the motor up all seemed well no missing, went for a quick spin down the motorway to the (supermarket) it ran smooth with plenty of power. Then disaster came off motorway to set of lights same problem missing and stalling. Some of the guys think fueling is the problem, would that more than likely be a sticking injector?
Type 411 Le four door auto .
1965 Beetle

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