172 Cup pointers for a slight running issue

[RS172Nick]

Wondering if the masses could give me a few pointers on usual suspects.

Ok my car a 2003 172 Cup low mileage example sub 60k has a little issue.

when left parked up for a few hours and started from cold I can feel a hesitation low speed jerkiness until warmed up. It's not seriously bad but would indicate to me something doesn't feel quite right. I've owned plenty of 1.8t VAG cars in the past and it's very similiar experience to a dirty throttle body or a leaking vac pipe.

First thing I did was clean the cup's throttle body a few weeks back which hasn't cured the issue but was worth doing anyway.

Another issue is when the cars warm say at least 30mins run time the rev limiter seems to be lower than the indicted rev counter red zone and the car will hit the rev cut earlier than anticipated.

I don't thrash the car and have mechanical sympathy but on a spirited drive this also tells me something doesn't seem quite right.

I know the rev cut is lowered when these cars are not at fully working temperature so I'm now thinking I might have a sensor issue, my train of thought is a temp sensor although my coolant temp gauge has never moved over half way and stays solid at half way. would I be right in assuming the rev limiter is on oil temp and not coolant temp?

My oil is fresh and clean it is castrol edge 5w30 fully synthetic and dephaser is quiet as a mouse.
Is the grade of oil right for these cars Vvt system?

Fuel used is always super unleaded and tried all the major brands current tipple residing in my tank is shell's super unleaded expensive offering.

I would like to have a good look over it at the weekend at the usual suspects so I will be removing plugs checking for obvious issues like oil leaking down the spark wells etc and I will also take the crank sensor out for a clean as I've experienced a very odd cold start this week only done it once but when fired up it was really low rpm and felt like it was going to cutout but it had a few moments and picked back up to cold start idle speed. Not done it since but I know something is showing signs of failing hence any advice on where would be best to look would no doubt help me slim down some areas of attention.

Thanks in advance

Nick

 

[Dan@SJM]

The jerkiness is something these cars are renowned for, a remap certainly helps them.

Low rev limit is usually down to a faulty thermostat/temp sensor. Changing both, will cost less than £50.

The oil is incorrect. It is supposed to be 5-40.

 

[RS172Nick]

The jerkiness is something these cars are renowned for, a remap certainly helps them.

Low rev limit is usually down to a faulty thermostat/temp sensor. Changing both, will cost less than £50.

The oil is incorrect. It is supposed to be 5-40.

Thanks for the info Dan shall look at changing thermostat and Temp sensor.

Bugger about the oil it was only done recently by previous owner as I haven't owned it that long so suppose that's probably a good thing as at least it hasn't done many miles on the incorrect oil so I'll drop it and put the correct 5w40 in instead.

Just read through all its history and every service receipt bar the last one it has had 5w40 oil why it was changed to castrol edge 5w30 on last service is a mystery as it was even serviced by the same garage. Probably had an offer on....

 

[warwickstingray]

Fuel economy oil in most cases. Not so good when you use your car.

 

[RS172Nick]

Little update.

Replaced the oil with the correct fully synth 5-40 and had a good look around no obvious signs of anything wrong.

Removed airbox to have a look at the CTS location and thermostat for future reference if i have to replace both. Whilst airbox was removed I removed the crank sensor to inspect it. mines the older black plug type and it was fairly dirty no fluid contamination but just really dirty gave it a good clean and refitted it.

So as my process of elimination goes so far it feels like I have cracked the jerky cold start issue

Runs lovely no cold start jerking over last two days and the car does feel smoother and picks up nicer probably a placebo effect but when you get used to how a car is behaving you just know instantly when something feels better.

Not had chance to test the low rev limit issue yet as had family in the car last few days but will be a bonus if it's cured that fault as well.

Will update my findings on the rev limit when I can.