MG TF 160 low power from 2000 to 3750 RPM

As the title says my wife's TF VVC is totally gutless between 2000 and 3750 RPM it then takes off. It starts perfectly every time, idles well but is very inclined to stall, once rolling it is okay up to around 2000 RPM then is very sluggish and then takes off again as the revs get close to 4000. It has had new cambelts (correctly timed), plugs, air filter and the plug leads were changed not long ago. The VVC plugs are in the correct order, it's probably obvious but I can't see the problem

I don’t have a VVC, thereby I’ve not worked on one, but my immediate suspicions would have me look at the variable valve timing set up.

MOT day today and was sailing through (emissions, suspension, steering etc) then just as the car went on the rollers a hose burst, total coolant loss and the test was abandoned. Since they only test cars and no repairs I recovered the car and will look tomorrow evening for the cause. One good thing came out of it, the £25 VW header tank and low coolant alarm worked faultlessly.

Thats bad luck. I bet the MOT tester was nondelighted at having a car explosively piss coolant everywhere too.

I had a look this evening, it's one of those spring type clamps that gave way, the hose came off the spigot. It was fortunate that it happened while stationary in the garage rather than the open road. Due to me being very deaf I have no sound to my low coolant alarm and I must say having a random flashing LED in alternating red, blue and green colours. The MOT tester was actually very gracious about it, perhaps because he was dealing with my wife.

I'm not saying your hose problem was due to it but I believe the VW tank has 1.5 bar cap whereas the TF has a 1 bar cap, this stopped me fitting the VW tank as I thought 50% over what pressure the system was designed for was a bit much. If anybody knows of a 1 bar cap that fits the VW tank I'll fit one in a shot.

You maybe correct about the pressure cap rating but I was lead to believe that the blue cap was okay but the black cap was the high pressure one. I will investigate

I’m all ears on this one, I’ve had the VW tank fitted for a number of years & have experience no problems other than one of our number insisting that I cover up the VW logo with the MG symbol.
That has improved performance no end.
I’ve tried to pin down the significance of the cap colour & when referred to in the VW community they seem to use them at random. It’s only when there is spare part surgery that the worries start.
I only start thinking about the possible ramifications when the subject is raised on here, but it soon wears off.
M

I have done a little research this morning and have found the following information. One source is stating the blue cap is rated at 20psi or 1.36 bar. Others are stating 1.4 bar which seems more likely due to a bar rating being more common on the continent. The black one seems to be rated at 1.6 or 1.7 bar (23.5 psi) which is the obvious reason that you shouldn’t use it. Further reading states that only the Austrian made replacement caps are reliable both for pressure rating and longevity.
Having said all that I believe the fault is all mine, thinking about it last night the spring type hose clamp was about four inches along from the hose. I don’t think it is possible for the clamp to travel along the outside of the hose, certainly not past the end of the spigot, it appears that I didn’t slide the clamp along to be over the spigot. Any way I have it booked in for the MOT test on Monday afternoon which will be an expensive day for us, my wife’s other car has it’s MOT on Monday morning.

You've obviously put more energy into your research than I & thank you for that. The more information you have the better your work can be.
M

For technical info regarding parts I tend to use ebay, if you search for a part then select only those sold by Febi, Febi Bilstein or Blue Point (all the same company, ZF) you will normally find all the info is there ie for a brake disc they will list OD, PCD, Centre Bore, Disc Thickness, Height and Weight. If you want to do a big brake conversion everything you need to know is there in one single source. Mintex also puts out a lot of info but it's only brake related but the Febi group supplies parts for the vast majority of cars.

First off: Congratulations on getting your TF back OTR. I was going to ask, just before you started this thread, but the thread tells the story pretty completely.

On the "Thin Yellow Pipe" thread, you said that you have left the exhaust flap control solenoid connected ELECTRICALLY, as I understand it. If so, that bit of the ECU functionality does not explain the flat spot on this thread.

Apparently, the ECU learns an engine set-up, and can take many miles of driving to achieve an optimum setting. Perhaps that explains your comment (from the "Thin Yellow Pipe" thread: "...........sluggish performance between 2000 and 3750 rpm which is still there although not as bad as it was. I have not had any feedback from the forums but will contact K Maps to see if they have any idea where the problem may lay.


K maps undoubtedly know more about the ECU than either of us, so their advice if replacement of the Lamda sensor does not work will be invaluable.