Poor Start Up and Emissions

So my Golf had its MOT last week. It failed with corroded rear brake lines and CO emissions. The test centre kindly said they would adjust the mixture for me on the re-test, to lower the CO content, which they did. Since then, the Golf has been reluctant to start, taking about 20 seconds of spluttery turnover before it will idle by itself. Even then, it will bog when i touch the throttle. It's fine after a minute or two of warm up and starts fine when still warm.

I looked back at the certificates, and the Golf failed with 7% CO but they turned it down to just 0.97%, when it only needs to be lower than 4.5%? is it safe to turn the mixture up myself and leave it until the next MOT? i can't measure the emissions myself so i would be judging on how well the car is running rather than what a probe is reading out the back end.

Hi mate,
Which engine is it ?



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lhasadreams said

Hi mate,
Which engine is it ?



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1985 1.8 GTI

You would not want it higher than 1.5%

Clogged air filter will increase emissions, how does your look?
What fuel are you using? adjusting the idle speed and timing may help.
Mixture is the last thing you should touch, timing and idle speed then mixture if all the ignition side of things are in good nic.
1 - 1.5% is fine so yours is about right now.  

was the starting issue fine before the MOT or only after? spluttering etc… 

lhasadreams said

You would not want it higher than 1.5%

mark1gls said

Clogged air filter will increase emissions, how does your look?
What fuel are you using? adjusting the idle speed and timing may help.
Mixture is the last thing you should touch, timing and idle speed then mixture if all the ignition side of things are in good nic.
1 - 1.5% is fine so yours is about right now.

 Okay, thanks guys, i guess ill leave the mixture alone for now  The air filter is only a couple of months old, and looks that way. The spark plugs are a similar age and i believe the HT leads have been changed at some point.
I use any fuels tbh, mostly the unleaded from Tesco.
The idle is around 1000rpm already.

Deandubya said

was the starting issue fine before the MOT or only after? spluttering etc…

Yeah i feel it has been a lot worse since. She always took a minute to warm up, but would fire up after 3-4 revolutions.

I have a new suspicion that it could be the fuel pump?

It seems a little noisy, to the point to where i can hear a whirring sound from the back of the car when i'm sitting in it at idle. And that is over the slightly 'ticky' engine and above average exhaust note.

When i've been cranking it to start, the fuel pump is still whirring when the engine splutters and dies. Is this normal for the fuel pump or is it not providing enough pressure the prime the system or something?

I'm not very mechanically minded nor do i know the ins and outs of a Golf    

Gti run best on super unleaded, worth changing over to super and you may need to advance the timing a little if someone before has retarded it to run on normal unleaded. If they did not retard the timing your timing is out so could affect running.
I could not get my car run smoothly on normal unleaded and was lacking a little bit of poke and lumpy tick over, I've switched back to super unleaded.

mark1gls said

Gti run best on super unleaded, worth changing over to super and you may need to advance the timing a little if someone before has retarded it to run on normal unleaded. If they did not retard the timing your timing is out so could affect running.
I could not get my car run smoothly on normal unleaded and was lacking a little bit of poke and lumpy tick over, I've switched back to super unleaded.

Thanks a lot, i definitely try switching the fuel over before trying anything else