Mk2 running weak... Advice on where to go fault hunting

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scirocco_ne
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Mk2 running weak... Advice on where to go fault hunting

Post by scirocco_ne » Fri Apr 19, 2019 10:31 am

Well now i know why old sam is smoking these days.

After a service today i pulled the plugs out and the mixture is weak as p#ss

So fitting the new weber has in effect fubarred our engine by messing the mixture up and most likely degrading the rings. The issue has started after fitting it as the old plugs were not like this.

I remember how badly my g60 got internally from running weak. A 145k engine didn't stand a chance :(

So where is the air leak or issue that is causing weak running?I have already changed the pipe to the vac advance and need advice where else to look on the engine? Anywhere that air leaks can occur or things that knock mixture out are what I'm looking for?


I am sourcing a new engine soon and want the issue sorted so i dont wreck another :(

Thanks
Mick



mark1gls
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Re: Mk2 running weak... Advice on where to go fault hunting

Post by mark1gls » Fri Apr 19, 2019 9:13 pm

Carb flange is common problem of weak mixture..

What was the last MOT CO reading?

You really need to find a friendly local garage which you can use there CO machine and adjust the mixture to the correct setting, you just need a screw driver to adjust the mixture screw. not sure what a carb car is set at?

Fuel injection is best at 2% CO...

MAKE 100% sure the timing, ignition system, new air filter etc is all tip top before setting the mixture and idle speed.


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
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scirocco_ne
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Re: Mk2 running weak... Advice on where to go fault hunting

Post by scirocco_ne » Sat Apr 27, 2019 3:10 pm

mark1gls wrote:
Fri Apr 19, 2019 9:13 pm
Carb flange is common problem of weak mixture..

What was the last MOT CO reading?

You really need to find a friendly local garage which you can use there CO machine and adjust the mixture to the correct setting, you just need a screw driver to adjust the mixture screw. not sure what a carb car is set at?

Fuel injection is best at 2% CO...

MAKE 100% sure the timing, ignition system, new air filter etc is all tip top before setting the mixture and idle speed.
Thanks for the advice bud

Its never had any analysis since ive owned it in all honesty.

It had a fresh mot on purchase and has had the weber fitted since with nothing done.

It sounds like my homework is...

Get the dizzy off and clean it all out/ check the mechanical advance, vacuum etc

Fit a new carb flange

Do the timing

And clean the bmc filter out before re doing the carb set up

Then gas analysis to see where im at?

Mick



EDDIE-F
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Re: Mk2 running weak... Advice on where to go fault hunting

Post by EDDIE-F » Sat Apr 27, 2019 10:51 pm

In my experience of bringing a Scirocco back on song it required the following:
New carb flange ahead of all else.
fitted a new bigger cleanable petrol filter in line before a plastic original type.
take out the fuel tank sender and pick up pipe and make the tiny holes in the pick up much bigger with a drill. If these tiny hole block, the mechanical pump will suck air in through the pipe joints. So now any crud gets sucked up to the new filter where you can get it out.
Get a strobe timing gun and set the timing to the mark on the flywheel with the gun knob set to 0 degrees as the mark will be at 18 or 6 BTDC see Haynes manual. Set advance to suit engine type engraved on block under number three cylinder.
I then used a vacuum gauge i got from Machine Mart in line with the distributor vacuum line to adjust mixture screw for maximum vacuum about 21 .
After that the car runs and starts very nice.
In addition i then used a Colourtune plug from Machine Mart to check the burn of the mixture and it appeared perfect.
Car runs and accelerates as you would expect.
I am using a 2E2 Peirberg carb.
Ed



scirocco_ne
Posts: 188
Joined: Wed Sep 19, 2018 11:00 pm
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Re: Mk2 running weak... Advice on where to go fault hunting

Post by scirocco_ne » Mon Jun 03, 2019 4:46 pm

EDDIE-F wrote:
Sat Apr 27, 2019 10:51 pm
In my experience of bringing a Scirocco back on song it required the following:
New carb flange ahead of all else.
fitted a new bigger cleanable petrol filter in line before a plastic original type.
take out the fuel tank sender and pick up pipe and make the tiny holes in the pick up much bigger with a drill. If these tiny hole block, the mechanical pump will suck air in through the pipe joints. So now any crud gets sucked up to the new filter where you can get it out.
Get a strobe timing gun and set the timing to the mark on the flywheel with the gun knob set to 0 degrees as the mark will be at 18 or 6 BTDC see Haynes manual. Set advance to suit engine type engraved on block under number three cylinder.
I then used a vacuum gauge i got from Machine Mart in line with the distributor vacuum line to adjust mixture screw for maximum vacuum about 21 .
After that the car runs and starts very nice.
In addition i then used a Colourtune plug from Machine Mart to check the burn of the mixture and it appeared perfect.
Car runs and accelerates as you would expect.
I am using a 2E2 Peirberg carb.
Ed

I am nearly around to doing the set up now. Have a new flange ready and timing gun.

Where did you get your vacuum reading from to know where to stop?

My car has a weber so i suspect it may not work for me.

Thanks
Mick



scirocco_ne
Posts: 188
Joined: Wed Sep 19, 2018 11:00 pm
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Re: Mk2 running weak... Advice on where to go fault hunting

Post by scirocco_ne » Mon Jun 17, 2019 8:18 pm

I calibrated the co reader today and took a reading off the car before work

Its averaging about . 3 to . 4 to running very weak :-(

New carb flange is now on and a few more bits to fit tomorrow :-)

Then timing and carb set up to see where we are at...

Fingers crossed this gets it running nice and it drives like a rocco should 8-)

UPDATE

It definitely needs more setup work as it is reading even leaner now at . 15 ish. The car drove noticeably better with the new flange on though and seemed to pick up better



scirocco_ne
Posts: 188
Joined: Wed Sep 19, 2018 11:00 pm
fill in the right answer: 15

Re: Mk2 running weak... Advice on where to go fault hunting

Post by scirocco_ne » Tue Jun 18, 2019 7:18 pm

How common are the ducelia ignition parts?

I had a nightmare today sourcing a new arm and cap

Mick