MK1 Golf GTi Timing Belt and Tensioner Replacement

I been reading that Tesco fuel is rubbish. The super unleaded I put in was from Tesco. Could it be a fuel quality issue?

These cars was made for super unleaded fuel, 98RON is what they say but I find anything from 97RON upwards is fine, normal unleaded is 95RON so you need to retard the timing by 6 degrees to run that type of fuel but I found I had a lumpy tick over and lack of power, I used more fuel when I ran normal unleaded for a year so I changed back to super unleaded.

All water cooled VW from 1974 ish can run unleaded petrol as they all had hardened valves as unleaded fuel was the norm in Germany.

Lumpy running when first starting when cold might be down to leaking fuel injectors as to much petrol is in the cylinders and the plugs are "wet" as the extra fuel burns off the engine runs ok. Try unplugging the 5th injector (unplug the blue electrical connector) so no extra fuel is added when cranking.

Could be problem with warm up valve (WUR) or dirty auxiliary air valve (AAV) you can remove this the clean it out with carb cleaner as it can get gunned up. Guides etc in the Haynes manual.

Mixture to lean?
Timing not quite right?
Old HT leads, spark plugs, dissy cap, rotor arm?

My car is a daily and I drive 250 miles a week so I fill up on a regular basis and I've found no difference in running or performance in using Tesco, Sainsbury's or the odd fill up on shell optimax.

I would not be looking at the fuel type for lumpy running when cold.

The fuel accumulator works by holding the fuel pressure in system when the car is hot and makes no difference when the car is cold, if problem with accumulator then it takes some cranking when restarting the car is hot, eg filling up at a petrol station etc…

Thanks for your feedback.

So just to summarise:

* If I use super unleaded, then I can keep the 6 degrees BTDC factory standard timing.

* If I use normal unleaded then I need to retarded the timing by 6 degrees.

Is this correct?

Yes that's right.  

So I guess that's why the previous owner had the timing out as he probably was driving on normal unleaded.

Just a question, so if I was to run it on normal unleaded, what is the exact setting for retarded timing? What do I need to look our for?

Just a question, ref the idle valve, are there any tips on how to set this? I mean winding it in completely and then how many turns out?
This morning the car started one time but little sluggish for a minute then ok.

I only recently started using super unleaded, before that was running on normal unleaded. May be there is still mixture with the old fuel.

I don't think there is any guide to how many turns on the idle screw (screw at back of the throttle body) but only adjust it when the car is nice and warm.

I set mine my by increasing the idle speed to about 1100 rpm then give the engine a couple blips on the throttle the lower it to 1000rpm and blip the throttle again and check it's still at the right idle speed.

950 to 1000 rpm is what you are looking for, I run mine at 1000 rpm as I find things start to rattle if at lower idle speed and in the winter the engine is under extra load with headlights on, heater blower, rear screen dismister etc…

Have you tried disconnecting the electrical connector to the 5 th injector as mentioned in my other post?

Not sure about any timing marks as I don’t use them or a timing gun, I set mine by advancing the timing till the engine “pinks” under load the retard it a little till the engine stops “pinking”

Just checking you did disconnect the vacuum hose going to the dissy the plug the end when setting the timing with a gun?

Hi mate,
Yes I disconnected the vacuum when setting the timing.
Yes I have also noticed that my car starts rattling under 1000 rpm. Especially when it drops below 950.
I will try to set the idle again, first I will check the rubber o ring as I heard a cracked ring can effect the idle.
The timing is spot on 6 degrees BTDC so I am happy with that.
If I get it around 950 to 1000 when warm, I should expect the cold start to be around 1100 rpm?

Not sure what year your car is as the fuel injection system did change slightly over the years as VW added stuff to help with running etc. My car when cold is the same idle speed 1000rpm as when warm but 1100rpm is ok as long as it drops down to 1000 rpm when warm.
I've a cabriolet 1988.  

I have a 1983 Tin Top GTi (A Reg)
Ref attached pic, does this device control the idle?

No that controls the electric ignition, you don't have a idle stability valve on a 83 car, so your higher cold idle could be right.

Info on idle stability valve in this thread, you can see a good diagram which briano1234 posted but his car is from the US and has air con so some of the parts are different to UK cars.

https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=helllllpppp%2Fcan-anyone-tell-me-what

You may want to remove the AAV (auxiliary air valve) it's behind the inlet manifold but you can just about get some Allen keys in the to undo the bolts to remove it and clean it out with some carb cleaner as it does get gunked up.

If you look half way down the thread above you can see my post and near the ISV you can see the 5th injector and the blue electrical connection, unplug that and see if the cold start is any better, it may take a little more cranking but as no extra fuel in sprayed in but you should be able to tell if extra fuel is in the cylinders, on my old injectors I ran for about 15 months with the 5th injector as my injectors was leaking so I fitted a new set, I’m on my 3rd set of injectors as I found they last about 10 years or 100,000 miles approx before I’ve had to buy some new ones.

Best to pull out the injectors and test for leaks and spray patterns to see if they are faulty as new injectors or now getting expensive.
 

Do you have a Haynes manual?

If not get the brown one like this, the 1.8 engine is very similar to the 1.6 and fuel injection system is the same so it will cover 99% of your car.

It will tell you how to test the injectors, and a lot of other parts of the injection system.

https://www.ebay.co.uk/itm/VOLKSWAGEN-GOLF-JETTA-SCIROCCO-MK1-HAYNES-MANUAL-1974-1982-inc-1-6-GTi-GLi/253331189957?hash=item3afbb730c5:g:wNQAAOSwbtNaEwwG


If if you did want a manual to cover the 1.8 engine then get a red Mk2 Scirocco manual as that does cover your engine.

https://www.ebay.co.uk/itm/Volkswagen-Scirocco-Haynes-Workshop-Manual-1982-1990/183017732687?hash=item2a9cb4fa4f:g:Rp4AAOSwp7FaW4rU


 I’ve got to use the 2 manuals for my car as I also have a different fuel tank etc to the tin top cars….