J.R.

Its possible I misunderstood this, can you explain it in better detail?

There is your problem! When EGR is commanded the ECU expects to see a corresponding decrease in the filtered air passing through the MAF sensor, your EGR is not passing any gases and the MAF is passing the same volume of air because you have blocked the cooler , a sensible thing to do AFAIK but you need to take measures to prevent the ECU doing what it is supposed to when EGR flow is impeded. The solution is an EGR emulator/simulator available on ebay for £99 or maybe more now from an Eastern European seller, I have been running one for 4 years and 60K miles without any problems.

Especially as they think it has an AC clutch pulley which the majority of VAG vehicles have not had for over 2 decades and yours 100% does not, it has a shear plate pulley. The noise might not be the pulley bearing, it could be the shaft bearing on the pump but unlikely if the AC is still working, the pulley bearing is more exposed and has a much harder life.

It will show system pressure, static in your case, the high side pressure in a functioning system. It will also show compressor shut down code, one of which is for low system pressure. It sounds like a slow leak whether ot be where you think, the Skoda dealer or elsewhere, if the system pressure has been lost then get someone to evacuate the remainder and do a vacuum test, if this does not reveal the leak then a nitrogen pressure test or if it was at atmospheric pressure then there is nothing really to lose by doing a compressed air test.

Were Roomsters ever made with stop/start? I had always thought they were a hybrid of very old Octavia and Fabia tech, part of their continued appeal to me, if they had made a 4x4 TDi version I would have one in a flash but given the low tech niche vehicle ethos I can see why they didn't.

For sure avoiding the grief of the actual adjustment by using the location pins is the way to go, the measurement is fairly easy. My rear axle was slightly out of alignment, the front a long way from not using the guide pins but also perhaps the frontal impact which wrote the vehicle off, I needed to adjust both as I could not move the front axle far enough to align with the misaligned rear but I could not get enough purchase laying on my back to release the rear subframe fixing bolts. My compromise solution was to pull the front axle to the rear with a ratchet strap before tightening to front fixing bolts to FT torque!

Loose (normal) or untightened ie unscrewed enough to release the pressure?

I knew when I saw the notification that once again I had missed the engine type in the thread title , that cannot be seen when you are reading the posting, I look to the LH side where the engine type is often shown and its blank.

Not really, just some DIY to make a fixture to hold a laser spirit level and a cardboard target, once done its 10 minutes to take measurements from all 4 wheels and some reflection on what corrective action to take. Even if a technician can do a 4 wheel alignment set up in that time you are going to be charged an hour. My set up cost nothing, I already had a laser spirit level with a broken vial, the other parts were scrap material.

That is the correct function of the cap to prevent overtightening and to give a positive feedback that it is correctly tightened. Like so many new posters you have asked a technical question regarding your engine without specifying what engine and fuel it is. If it is an EU5 diesel then I would suspect the EGR cooler.

No, effectively the front axle will likely no longer be parallel to the rear axle and will also be displaced sideways. Correction is simple but the measuring and setting out time consuming.

I have just thought, while the gearbox is out is a good time to replace the propshaft rear Guibo joint if it is perished, the propshaft has to be moved forwards to remove it which is all but impossible with the transmission fitted, you have to move the whole engine forward. My Guibo is still sitting on the shelf 4 years later and each time I have to show it to the CT tester who wants to fail the old one showing him that the splits he sees are actually moulded into the new one!

I used a pair of ratchet straps around the engine support bar, its better to have someone help you at that stage, they can progressively release the straps from above (make sure they know what they are doing and that you can trust them) while you manoeuvre it from below. 4 eyes are better than two (one in my case) and if it all goes Pete Tong the person above can call the ambulance! If you have moved it one cm then its ready to come out.

I never removed the flange nor the DPF, the whole transmission unit came out and went back in relatively easily but I worked slowly. That was all I had to go on, I worked out a few things along the way where I differed from what Youtube would have me do like leaving the steering rack in situ but hanging in space. My biggest error was being ignorant of the existence of and need for the subframe locating pins, the car crabbed severely afterwards and would ditch dive if you released the steering wheel which was well off centre when driving in a straight line. If you need advice on how to realign things without paying a fortune to someone to use a 4 wheel alignment set up that they probably dont really understand then I am your man but thats for later, it seems you are about ready to drop the transmission. I hope you have raised the front end really high if you are intending dragging it out from under the car.

The RPM is not dropping, if it did drop that fast you would be thrown forward against the seatbelt. The indicated rpm is dropping on the rev counter at the same time as a stutter or misfire, likely to be an ignition fault given the erratic tachometer.

Vacuum gauges are very very useful but Ignition timing is the last thing I would use one for, I'm very very suspicious of that marking, any vacuum leak or valve burning will start with a slight drop in idle vacuum getting progressively worse, it's crazy for them to state the area to the left of the green zone is exclusively indicative of retarded ignition. That goes back to the 60's and 70's when all sorts of claims were made about and plastered over things to increase their perceived value. I would advise the OP to set the timing using a strobe and the manufacturers timing marks, if they want to experiment outside of that setting then only do so if they have a good experienced ear above all be able to recognise pre-ignition and detonation, 40-60 mph timed runs in top gear will reveal the optimum setting which will be a range and I'll bet the manufacturers timing setting falls bang in the middle. Thankfully its not something that many of us have had to contend with for decades. Finally dwell angle on a Kettering ignition system is critical and far more precise than the points gap, a dwell meter is definitely worth investing in, a vacuum guage equally but not for setting ignition timing in my view/experience

I have been timing engines with strobe lights and by ear for 50 years and never heard of doing it with a vacuum gauge. OK I admit the last 25 of those 50 years there has been no timing to do but I still have an ear for it. I am assuming that you swing the timing until you get the maximum vacuum reading? - That would correspond with the maximum idle revs before the engine hunts from over-advance, I do that by ear but critically you must then swing the timing back to the point where the revs just start to fall again and lock the distributor at that point, if you set it to maximum vacuum it will be over-advanced which can be catastrophic for the last generation of Kettering ignition vehicles with their lean burn mixtures. Setting the timing by ear on an early 6 volt VW air cooled engine results in far better performance and economy but the engine will not start the solution is to wire in a latching relay to the ignition circuit with a push button latching circuit, you crank the engine which will turn vigorously without the ignition working against it and shout "CONTACT!" out the window when you press the button, preferably wearing an Erwin flying jacket and Biggles scarf 😀

Definitely an oven cleaner enema required, I lived with the symptoms on my MK1 for several years (before joining Briskoda) until I had deduced what the problem was, the enema cured it and I did it another once maybe twice when the limp mode reoccurred very infrequently.

You will probably find that it will continue to start with its usual vigour, if it doesn't then definitely replace it. Is it time to replace? - Probably, not starting the vehicle after sidelights left on for 30 minutes indicates it has little reserve capacity remaining after 10 years of service, I dont suggest you have it tested as the results will be exactly that. If it continues to start OK then you have time to source the battery you want at the price you want, I would suggest upgrading to the larger capacity 060 version which seems to fit snugly in all the Skoda battery trays (take measurements to check), the cost is little more, sometimes even less for a significant extra capacity.

Also movement/stickiness in the vacuum advance mechanism and baseplate.

It will not affect timing for the reasons you have stated. As vehicles have not had distributors for 30 + years now be very wary of any replacement rotor arms, distributor caps, coils and condensors, the latter were of questionable quality even back in the day. Fit manufacturers original second hand parts if you can find them, it doesn't take Einstein to manufacture a pattern part rotor arm but many are completely non functional.

Nice find! It amazes me how much people have to pay to have the things replaced when they are easily repairable as you have shown.

40° is double the slope of the steepest road in the UK.

Are these new features applied to your older glasses by software update?

Not in a million years outside of a mountain in the Sahara desert, mine has been seriously abused and I do mean seriously the oil temperature rose a little on very long inclines on the hottest days but still well within safe limits and fell back down afterwards, coolant temperature never rose, fans never cut in. This has been the suffering endured by all of my VAG vehicles since the last century, in all that time the radiator fans have never even once cut in! Aside from when the aircon has been used of course.