207 GTI - THP Engine Issues

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CitroJim
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Re: 207 GTI - THP Engine Issues

Post by CitroJim »

How many miles had the Mini in question done before it finally threw in the towel Mike?
Stickyfinger wrote:Or make a rain collection area that feeds directly onto the engines injectors....the list is long Jim :)
Very inventive :wink: Give s a whole new meaning to the term 'bore wash' :lol:

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DickieG
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Re: 207 GTI - THP Engine Issues

Post by DickieG »

I find it almost criminal that Peugeot Citroen insist that carbon build up on the valves can only be resolved by removing the cylinder head at a cost to the customer of well over £1,000 (my neighbour recently paid £1,300 on their Pug 5008) whereas BMW dealer workshops are equipped with walnut blasters that sorts out the problem for around £300, makes a mockery of BMW's being expensive to service.

Part of the issue with the carbon build up is that as the engine is direct injection the petrol being injected isn't able to wash the crud from the valves as it would on a traditional indirect injection engine.

All these issues makes me think that that the THP engine was designed over the phone and is best avoided, I certainly wouldn't buy one.

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DHallworth
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Re: 207 GTI - THP Engine Issues

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I can only find one Citroen/Peugeot specialist who will do the walnut blasting on the PSA cars. Apparently he uses a BMW machine that has been modified slightly to fit the PSA stuff as the engine sits further back and slightly under the bulkhead on these.

The local BMW dealers almost hang up the phone as soon as you mention it's in a Peugeot. One local BMW specialist has said he needs to see the car first before committing. I've got a funny feeling he'll say he won't do it when he realises that the machine needs to be modified to fit.

The Citroen/Peugeot guy is called SP Tuning in Hinckley. Apparently he Rolling Road tested a car before doing the Walnut Blasting and then again after doing it and found a 30bhp increase just after being cleaned. He said that the inlet port had effectively been reduced 50% in diameter by the carbon build up. Those pictures I linked to in my previous post were actually of his own DS3 at 25k. He reckons that this blasting process needs to be carried out every 25k miles to keep these engines on top form.

From a bit of Google searching the BMW straight 6 3.0 and 3.5 engines are bad for this as well, Jamie from SP Tuning says he's had to do it to a V8 M3 before now as well.

Another thing he mentioned is the PSA diverter valve on the turbo uses a plastic diaphragm which is prone to failing and letting bits of plastic into the turbo. He said that the forge ones he'd tried introduced a bit of lag. The best solution apparently is to buy a VAG valve from a TFSI engine and swap the spring and diaphragm into the PSA housing as the VAG mounting holes are different.

When Jamie bought his machine he ordered it from BMW using the part number and paid for it at the time of ordering. 8 weeks after he paid for it he eventually got a call to say that it was in stock. Apparently if BMW had realised what it was at the time of ordering it they wouldn't have sold him it as it's a BMW specialist tool that shouldn't be available to the public.

Anyway, it looks like there might be a trip to Hinckley on the cards as I'd like someone who knows what they are doing to have a look at it. He's also going to do a "before" and "after" dyne run to see what improvement has come from it.

He did mention that there's very little left that it can be on this car so fingers crossed!

David.

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CitroJim
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Re: 207 GTI - THP Engine Issues

Post by CitroJim »

This thread just gets more and more interesting :) Keen to know how it goes on a visit to SP Tuning David....

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DHallworth
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Re: 207 GTI - THP Engine Issues

Post by DHallworth »

It'll be about 1400 miles just to get the bloody car fixed in the end, Jim!!

Quite looking forward to seeing before and after pictures of the cleaning process as well.

David.

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Re: 207 GTI - THP Engine Issues

Post by CitroJim »

Yes, me too ;)

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Re: 207 GTI - THP Engine Issues

Post by citroenxm »

So.. DI petrol engines have a disadvantage then.. I think id stick to my idi petrols if I had to have one.. less work internally to do..

I understand now why the esj or prv engines are cleaner. . The injectors keep the valves clean..

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DHallworth
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Re: 207 GTI - THP Engine Issues

Post by DHallworth »

Spot on, Paul!

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Re: 207 GTI - THP Engine Issues

Post by RichardW »

The system appears to be a bit Heath Robinson.... here is the (apparently official) instructions from BMW, which a) advises the making of an adaptor for the N73 engine from a coolant hose and b) discarding the official operating instructions!!! BMW Instructions. I imagine that as this sort of engine gets more common and engines go back to needing a periodic de-coke (progress!!) these things will be available from the aftermarket tool makers.

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Re: 207 GTI - THP Engine Issues

Post by xantia_v6 »

The "PCV delete" modification is described at: http://www.e-tuners.com/index.php?s=12&t=299

It is not quite as drastic as might first appear (blocking off the crankcase ventilation), as there are 2 ventilation paths, the path (post-throttle) which is blocked off and another to a point ahead of the turbo (and throttle) which is only opened when the crankcase pressure rises above a threshold.

I don't know whether to do this or not to a post 2010 engine...

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Re: 207 GTI - THP Engine Issues

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xantia_v6 wrote:I don't know whether to do this or not to a post 2010 engine...
If it helps you with a decision my neighbours 5008 is a 10 plate.

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Re: 207 GTI - THP Engine Issues

Post by xantia_v6 »

It is all very confusing. Most sources say that the PCV was upgraded in march 2010, which would be half way through the 10 plate period. servicebox does not indicate any changed part numbers at that time, so maybe the parts were upgraded without changing any numbers.

It is also puzzling that the 200 HP version had the "primary" PCV path blanked off, but the 156 HP version didn't.

It seems that the engine versions which had the PCV hose deleted at the factory also had a different camshaft cover (which incorporates the PCV valve). I would expect that it would be better to change the cover as well, but I don't know if they will otherwise fit.

Something else I just grasped is that the PCV to manifold hose is under pressure when the turbo is spooled up and the throttle open, so there is a non-return valve to stop the PCV from pressurising the crankcase, under those conditions, crankcase fumes use the other path via the input of the turbo.

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DHallworth
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Re: 207 GTI - THP Engine Issues

Post by DHallworth »

I spoke to Jamie at SP Tuning on the phone about this problem in great detail the other day. He says that the problem with blocking it off is that it does pressurise the crank case and he's seen people with a lot of problems from doing that.

He said that fitting an oil catch can will help reduce it, but in his experience it's only by about 10%.

In his opinion from having seen the valves that have been badly coked up the majority of the oil comes down past the valve seals. If you look at pictures of the valve, the oil looks like it's dripped down from the top as if water drips down something and freezes. He reckons that there's no real cure for it and the best thing is to have the walnut blasting process carried out every 25k miles.

The local BMW specialist that I spoke to on the phone has agreed to do the work on the 207. It's going in on Thursday. He's going to take the inlet manifold off and use an inspection camera to check it. If it needs blasting he's going to take pictures of it and set about doing the job for the cost of £300 then take an after picture. If it doesn't he's still going to take a picture but only charge an hours labour for taking the manifold off and putting it back on again.

The car is provisionally booked in to be rolling roaded again at 4pm on Friday so that we can see how she's running have had all this work carried out. :)

Fingers, toes and everything crossed we've finally gotten to the bottom of it!!

David.

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CitroJim
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Re: 207 GTI - THP Engine Issues

Post by CitroJim »

David, fingers crossed here too...

Valve stem leakage is even more unforgivable on a modern engine! Needing the 'walnut blast' doing every 25k is akin to the old chore of decoking and grinding the valves every 25K or so as was normal back in days gone by...

I'm really quite horrified to be honest....

How we progress in some ways and yet go backwards in other...

So, how much does this regular blast of the walnuts cost then?

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DHallworth
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Re: 207 GTI - THP Engine Issues

Post by DHallworth »

£300 a shot, Jim.