2000 Leon Cupra boosting problems

jimmer84

Active Member
Apr 13, 2013
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Hi guys,

I am having a bit of a problem with my 2000 Leon cupra. If I want to accelerate hard, I can use 20% of the throttle and the car will pick up and go really well, but if i use more throttle than this the car will start to misfire and feel very much like the boost is being pulled back if that makes sense?
It has gotten worse recently to make it feel like i have mentioned above, but before this, if i floored it, the car would have gone to full boost no problem, but then nearly instantly it would have pulled the boost back and not accelerated as hard which makes me think that there is an actuator problem or something that is controlling the boost to make it "pull back"

I have had folk saying that these engines suffer from leaks in the pipes that make the engine not boost properly.


Does anyone have any ideas or knowledge of what it could be or what i can do to fix it?

Thanks
 

mty12345

Active Member
Jun 17, 2011
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Hi mate, the first thing to do is scan for fault codes. Second thing is to check for air leaks, both in the boost pipes and PCV pipes.

The ECU controls boost via the N75, so it could be pulling it back for any number of reasons......These engines are pretty complicaed and without fault codes it's just guessing, it could be any number of things.
 

jimmer84

Active Member
Apr 13, 2013
18
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Thanks fpr the reply mate, I have looked for air leaks but to no avail, i should have mentioned that my car does have an n75 delete, etc. All works well except being on full boost lol .
 

mty12345

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Jun 17, 2011
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No worries.
You have a N75 delete?!? Are you sure it's the N75 and not the N249?

If it's the N75 then how is your boost controlled now?
 
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jimmer84

Active Member
Apr 13, 2013
18
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Yeah I will get the car checked for fault codes.

And sorry your right it is the N249 delete that was done. To be fair when I did it there wasnt very much difference but didnt make anything worse so I just left it like that. It has been driving fine for a year after this was dont until recently.
 

mty12345

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Jun 17, 2011
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Ah right mate, i thought that was probably what you meant, it's an easy mistake to make. But yeah, as long as the N249 bypass is done properly and not leaking then like you say it wouldn't cause this issue.

If i had to take a guess, it could be that the fuel pump is starting to fail and can't deliver enough fuel to cope with full boost, but that is just a guess. The fault codes should point you in the right direction and save you spending on parts that you don't need.

Unless you have a friendly mechanic or a mate with VCDS then it'd probably be cheaper to buy a code reader off ebay rather than pay a garage to read it. When you get a code http://wiki.ross-tech.com/wiki/index.php/Category:Fault_Codes is the best place to look it up to see what it maens and how to fix it.

If you need help with the code then probably best to start a new thread in the main mk1 section (this is in FAQ's) as it might not get seen here........ You need to scroll right to the bottom of the Mk1 page and use the 'new thread' at the bottom, (the top one is for FAQ's) bit of a confusing design.
 
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jimmer84

Active Member
Apr 13, 2013
18
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Your a legend Matty, lots of great info there to help me out!

I may look into on eof these readers....is there any types to specifically get?

I have serviced the car recently with all items replaced, but fuel pump would make sense but as you say without a computer check it could be wasted money so will get onto that. Ill keep you up todate.

Thanks again
 

mty12345

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Jun 17, 2011
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No probs mate. Lots of people have bought one of these recently, http://www.ebay.co.uk/itm/UK-KW808-...051003&hash=item2ed274b36a:g:jEkAAOSwbqpTtRLa
They're about as cheap as you can get a reader for, but are enough to read and reset most engine related fault codes. They also allow you to read a limited amount of data live from the engine.

At the other end of the scale you have VCDS that allows you to read manufacturer specfic engine codes, run data logs and graphs, and also read and rese codes from other modules in the car such as the alarm, airbags, abs, central locking etc etc. https://www.gendan.co.uk/product_VCV23.html
 
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jimmer84

Active Member
Apr 13, 2013
18
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So I got the reader in today so tried linking it up, but says there is no connection to the car. I tried checking the plugs and all is fine, etc. I did notice however that the engine management light doesnt come on with the ignition, would this indicate there is no power getting to the socket or something like that?

I had alook to see if there was a fuse for the ecu light but couldnt see anything.......I fear I am missing something incredibly obvious lol
 

mty12345

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Jun 17, 2011
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Have you got the ignition in the number 2 position when trying to connect? Think fuse number 12 is for the OBD2 socket, so have a check of that. If the fuse is ok then the fact that the light doesn't come on probably means someone has put tape or similar over the inside of the dash binacle to try and hide a problem. I had tha happen on a previous leon i owned.
 
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jimmer84

Active Member
Apr 13, 2013
18
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Yep the ignition is in the number 2 position, all lights come on as normal, except the ecu light. Ive owned the car for 4 years now and as far as im aware it did used to come on.

Checked all the fuses and all seems fine with them. The car has been on diagnostic machines before wen ive owned it so a bit baffled to why its not working for me.

Also on another note, I reset the ecu thinking it might make a difference, but the car is now running a bit worse than before, even a little rough on idle and as soon as your even at quarter throttle it gets very jerky and doesnt really want to accelerate very much. When I change gear just driving normally the exhaust lets out the odd pop too lol. Now Im starting to think could this be related to a dodgy coilpack?
 

mty12345

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Jun 17, 2011
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It will have reset the fuel trims when you disconnected the ECU. Give it a day or 2 and see if it improves as it relearns the values.

Not sure on the code reader mate, faulty perhaps? Can you try it on a mates car to see if it's the reader or car at fault?
 

jimmer84

Active Member
Apr 13, 2013
18
0
Well a wee update on the cupra, I havent been able to get the code reader onto another car but after a long day of driving after resetting the ecu the car seemed to smoothen out the acceleration. I then got a set of coilpacks and the car was back to normal again with no hesitation or lumpiness while accelerating so was very chuffed! But then alas it gradually has gone back to being a little lumpy on acceleration again.

Pretty stumped and thinking there must be an air leak somewhere?