Crickleymal

As I suspected it's nothing to do with the piping. It was all as clean as a whistle and even when I replaced it all it made no difference. Doesn't seem to be the N75 solenoid either.

It couldn't be the N75 solenoid could it? A quick perusal of the VAG codes here http://wiki.ross-tech.com/wiki/index.php/00575 could also finger the solenoid which I think might be above the fuel filter? MAlc

Which pin is the output? There are three pins, one is obviously connected to a ground plane, so that leaves two others. It's a little tricky to apply power while the ECU is dismantled so could you let me know which is which please? Malc

So you think I'm getting a spike on the output of the MAP sensor? Could be worth a go I suppose. Doesn't quite explain the tipping into limp home mode at 2000 rpm though but I'll give it a go. If you have got a spare sensor PM me and we can work out a price Malc

Extracting the ECU and changing the pipes made absolutely no difference. All the pipes were as clean as a whistle and there were no leaks or holes anywhere. I changed all the pipes just to make sure. Had a good look round the fuel filter and changed one slightly dodgy vacuum pipe but still NBG. Code reader still says MAP sensor so I reckon it could be a faulty sensor I suppose. It looks easy enough to change (I am an electronics engineer) so does anyone know of a source of MAP sensors for these old crates? Malc

Oh yes I appreciate that and I will look at it this weekend. It's just that I can't detect any leak which I would expect if the pipe was broken and the fault is so reproducable that I wouldn't expect a split pipe to give identical results. Malc

Just bought a H4 bulb for my motorbike from Motaquip.

Yes I know, I've replaced that pipe.

Silly question but all this happened after I changed the fuel filter. It couldn't be a dodgy filter could it. I know the codes say MAP sensor but the fault is consistent which doesn't really indicate a sensor failing.???

recap so far. Changed fuel filter and found the ECU boost pressure sensor pipe frayed through so I cut the frayed bit off and reconnected it. Since then have been having numerous limp home faults which reset if the engine is switched off. I've replaced the MAF sensor and tried blanking the EGR valve. All no good. I had the codes read on Monday and the only one, apparently, was the MAP sensor. If you blew/sucked on the pipe that I shortened it seems as though there was no resistance indicating another hole. So I replaced the pipe as far back as the accelerator pedal i.e from the engine manifold right back through the engine bulkhead to just above the pedals. Now if you suck/blow there is no leak. However the fault is still there. The fault I now realise is not random. It will occur in exactly one of two situations. A] when you accelerate hard in 4th or 5th gear and when you get to about 3200-3500 rpm or B] if you pootle along on 4th or 5th at about 2-2500 rpm when it will slip into limp home mode without you realising until you have to accelerate. It will also occur with or without the pipe connected and seems to happen (although I'm not so sure about this) once the engine is less than cold. I'm beginning to think a call to the Seat garage is called for. I'll have the ECU out at the weekend but as the fault is so specific I'm not sure what to do.

Only the PD engines have the MAP sensor in the air charge pipe from the intercooler. One last quick question. If I blow down the pipe leading to the MAP sensor there is very little resistance. I would have thought that if you were sensing pressure the pipe would feel like a dead end. SO presumably (hopefully) the pipe is split and not the senosr damaged? Malc

Yes I did see that thanks. A quick google for Alhambra MAP sensors showed only one or two versions so I was hoping it was a separate entity. Oh well a job for the weekend Ifear. Malc

Ok I've had the codes read and the only fault is the MAP sensor. This is at the other end of the pipe I repaired I presume? Is it easily get atable? Thanks Malc

Oh that makes me feel sooo much better :) Any idea where I can find the engine code i.e. the type of engine just so I can be sure I'm getting the correct stuff? Thanks

If you're just after normal halogen bulbs then Motaquip are usually quite cheap. If yuou can find a branch that is. My local branch seems to have gone out of business.

Well now it does go into limp home mode I have discovered, either when the engine is working really hard (which can be mighty inconvenient I can tell you) or just at random when you can't tell. Disconnecting the pipe seemed to make it better but now I'm not so sure. I would say the probelm is worse with a hot engine but as I don't drive it hard until it's warmed up.... I tried a friends code reader at lunchtime but it was ODB2 and wouldn;t connect. So I'm getting my friendly local mechanic round on Monday as his place has an all singing all dancing code reader. It's probably something really stupid and obvious but I just can't see what at the moment.

31/1/12 And the answer is yes. Removed pipe and let it dangle where it was. Went out for a spin and no limp home mode. The car does seem pssibly slighty less responsive but on the other hand it's now back to where it was before I repaired it. 1/2/12 Well almost fixed. Coming down the motorway it was fine until I sat at 50 mph in the roadworks. Then it switched to limp home but as I was only doing a couple of thousand revs I didn't notice it until I tried to accelerate afterwards. Switched off and back on and it was fine for the next 15 miles

Ah pity you didnt mention that earlier! This is the boost pressure feed to the boost sensor located in the ECU. Well As I cut out the manky bit I assumed that it would be ok. The bit I removed had a hole in it so I cutout the section with a hole and replaced it where I found it. I'll go and have another look at it. If I disconnect it i.e. replace the hole the problem should go away yes?

Well I tried a new MAF sensor (Bosch so the same sort as the one I took off). It's made no difference. Where do I plug in the code reader? Someone has leant me one but don't know where it goes or even if his (RAC ODBC)will connect. I did notice a little cloth covered tube (about 3mm internal diameter) leading from the plastic pipe (about 50mm diameter) coming up from under the front of the engine was worn through. I cut out the worn section at the same time as I replaced the fuel filter and then all this trouble started. The problem only happens in 4th or 5th gear.

Thanks. I took it out and didn't have any security screw bits so I couldn't extract it from the casing. I did swill it in paraffin but it made no difference. I might get my friendly mechanic to read the codes.

Its much more likely its a duff MAF sensor. If you get a new one, make sure its the right one for your engine. We have cases on the forum of people buying from fleabay and even Eurocarparts and thinking they eliminated the sensor - but they got a wrong/not working one. They are about

Alhambra 1.9TD 1997 I appear to have a problem with either my turbo or the EGR valve. If I give it some welly the engine revs up to 3000 rpm then goes flat i.e. limp home mode. Switching it off an back on seems to fix it for a short while. I tried putting some Forte cleaner in the tank but to no avail so far. I bought some EGR valve blanking plates off ebay and fitted one to the exhaust side of the valve this morning. Took it out for a run and if anything it's worse now. Although it only seem to happen if I give it welly in 4th and 5th. 2nd and 3rd seem ok. I have seen on an Audit forum http://www.audi-sport.net/vb/a4-s4-forum-b5-chassis/107121-un-sticking-your-tdi-vnt-turbo-vanes.html that using Mr Muscle foaming cleanser on the exhaust side of the turbo might fix it but a) it seems to be a right swine to get to the turbo and b] obviously I'm a bit nervous about doing this. Does anyone have any other ideas please? Malc

Indeed it is, thank you. Sorry about the delay in replying, holiday then whooping cough (yes really!) intervened.

What about the EGR valve? I had my Alhambra do something similar and someone suggested that might be the cause. I gave it an Italian tune up and it seems to be OK now though. Oops re reading the original post properly I see you've tried that. I did try to delete this post but found I couldn't.

Thanks. I've got the 1.9 TD (lower power) engine so it looks as though that will be covered. It's mainly mechanical and engine things I need eg, where's the fuel filter and how do I change it and how often? Malc