car was back with RDR today for the remap. they put on the new n75j valve and it gave us an extra 3-5lb tourqe and improve the power curves quite nicely. but new problem. the car is randomly losing boost pressure.

at one point we had it running nicely at 17psi and then it just lost it and stayed at 12psi. there are no fault codes so the only thing we could thing is either a boost leak or a problem with the bosch recirc valve.

we couldnt find any leaks anywhere so the valve was teh suspect. before i replace it with a forge (and yes i know i should have done this before the remap) any thoughts on what this could be??

ta

B

Why did they fit an N75J? It will cause overboosting on a remapped car, I suspect that's the cause of the problem. It holds the wastegate closed for longer than the ECU expects which confuses it and so it backs the boost off. I can't believe the remapper has fitted it, if they wanted to increase boost why not do it in the map or is it a generic one?

Who is RDR?

Why did they fit an N75J? It will cause overboosting on a remapped car, I suspect that's the cause of the problem. It holds the wastegate closed for longer than the ECU expects which confuses it and so it backs the boost off. I can't believe the remapper has fitted it, if they wanted to increase boost why not do it in the map or is it a generic one?

are you sure?

we fitted this part becuase the first time i went in we were getting fault codes on teh original n75. so i replaced it with the n75j under the impression it will help things out. problem is that i will need to replace it again with a std n75 but i'll have to buy one as mine is faulty.

Anyone else got any thoughts? do you think i should still replace the recirc valve?

RDR - red dot racing in watford. really nice chaps, fairly knowledgeable i thought.

are you sure?

we fitted this part becuase the first time i went in we were getting fault codes on teh original n75. so i replaced it with the n75j under the impression it will help things out. problem is that i will need to replace it again with a std n75 but i'll have to buy one as mine is faulty.

Anyone else got any thoughts? do you think i should still replace the recirc valve?

RDR - red dot racing in watford. really nice chaps, fairly knowledgeable i thought.

Ask any of the better known mappers and they'll tell you to use a standard N75. Anything else just means the wastegate doesn't do what the ECU tells it to. Sorry.

Is the remap generic or custom?

shoot ... the remap is a custom one. means i have a duff n75j :( oh well i guess i'll have to buy a recirc valve and another n75 ... shoot again. what your saying makes sense becuase we arent really getting any fault codes so everything looks like it should be fine but for whaterever reason the car just backs off the power.

we suspected the recirc valve is on teh way out becuase it's making a slight popping sound when it's taking pressure.

shoot ... the remap is a custom one. means i have a duff n75j :( oh well i guess i'll have to buy a recirc valve and another n75 ... shoot again. what your saying makes sense becuase we arent really getting any fault codes so everything looks like it should be fine but for whaterever reason the car just backs off the power.

we suspected the recirc valve is on teh way out becuase it's making a slight popping sound when it's taking pressure.

A decent DV like the Forge 007P is a good idea for a remapped car as the standard ones fail even on standard cars. It'll be the N75 that's backing the power off. Have RDR checked the standard DV for you? It's very quick and easy to check if the diaphragm is split.

we did a basic check but i am not sure if it's the proper way to do it. how would you test a DV to see if it's split??

i just found some more posts on teh n75 and people are saying avoid the j version becuase it had adverse affects !? annoyed i didnt find these when i ordered the part the first time round.

Easiest way is take the DV off, push the diaphragm up then put your finger/thumb over the vacuum nipple and see if it holds. If the diaphragm is split it won't hold vacuum and just spring back into position.

Easiest way is take the DV off, push the diaphragm up then put your finger/thumb over the vacuum nipple and see if it holds. If the diaphragm is split it won't hold vacuum and just spring back into position.

nah im pretty sure we are sweet on that front.

can someone confirm if this is the right part code for the n75 -058906283F

vagparts have two of these - and my original one is in a bin in watford somewhere :eek:

F should be the original one. Which the code ends with F. J is the one you have at the moment isn't it?

F should be the original one. Which the code ends with F. J is the one you have at the moment isn't it?

well im off to skoda in redditch to see if they have the part. if they do i'll swap it out and we'll see. we left the mapping on the idea being that if the recirc valve sorted it everything would be sweet. im gonna go back to them in 2 weeks to recheck everything.

big thanks guys and also to RDR. they have spent nearly 6 hours on the car already.

B

if it was a boost leak then there would be fault codes same as faulty DV there are normally fault codes.

shoot ... the remap is a custom one. means i have a duff n75j :( oh well i guess i'll have to buy a recirc valve and another n75 ... shoot again. what your saying makes sense becuase we arent really getting any fault codes so everything looks like it should be fine but for whaterever reason the car just backs off the power.

we suspected the recirc valve is on teh way out becuase it's making a slight popping sound when it's taking pressure.

You dont have a duff N75J, it just doesnt work well with a remap.

Can anyone confirm whether the police spec chipped models had an uprated DV? Im guessing they would be standard. Mines still standard and has been on for a few months and works fine still.

I would imagine a Police car would still be running the OEM valve.

As for the boost issues, the ECU looks at many values when setting boost but two key ones are boost requested and achieved. If you have access to VAG-COM you can log these and check. Unless the map is expecting to see the extra boost that is being achieved then it will do the safe thing and drop some off.

I would imagine a Police car would still be running the OEM valve.

As for the boost issues, the ECU looks at many values when setting boost but two key ones are boost requested and achieved. If you have access to VAG-COM you can log these and check. Unless the map is expecting to see the extra boost that is being achieved then it will do the safe thing and drop some off.

Stu how would i go about checking the boost expected/achieved with vag-com?

Edit sorry to bring an old thread up.

baloo247 what made you goto RDR?

Do they still use the mobile RR?

Stu how would i go about checking the boost expected/achieved with vag-com?

Edit sorry to bring an old thread up.

Using Measuring Blocks

http://www.ross-tech.com/vag-com/tour/m-blocks.html

You need to establish which blocks indicate requested and actual and log rpm as well.

normally on a straight road in 3rd gear at around 2krpm floor it up to the red line for each run you do.

Cheers Stu