Boost issue.

[Stuart09]

Hey guys.
Was driving along just fine then I lost boost will only boost 3psi Could feel it go. But got to where I was going. On the return journey I had boost back but then started to miss fire and stutter under acceleration and again back to 3psi. Have checked for boost leaks. None. Had a new n75 valve. Done the n249 delete. Anyone had this before.

Cheers

mk1 Leon cupra 1.8T 20v.

 

[mty12345]

Could be loads of things mate, you need to scan for fault codes with VCDS.

 

[Stuart09]

Yeah have done a scan showing nothing. I think it could possibly be a boost leak. My mate had the same problem that was a boost pipe that would pop off and on under heavy acceleration. Cheers

mk1 Leon cupra 1.8T 20v.

 

[mty12345]

Ah right, that's strange.... Was the scan with vcds? If so then what are you fuel trims under block 032

5psi is limp mode, so it sounds like that's what's happening. Turning off the engine and restarting it will reset limp mode unless it's a ongoing fault.

It's definitely worth checking all boost pipes, but a boost leak should show a code really.

Have you changed the fuel filter recently? If not then it might be worth changing that. The fact that it happens at full acceleration would make me suspect that a lack of fuel might be making it drop into limp mode, although i'd expect to see a code for that too.

 

[Stuart09]

No idea never looked at fuel trims. Will need to get another scan to check it out in depth was over at my mates earlier that's when it happens and was just a quick check to see if any fault codes came up never seen anything but we are quite new to vcds. Basically what happened was what was originally written planted the boot and it wouldn't go beyond 0.2 bar.

mk1 Leon cupra 1.8T 20v.

 

[Stuart09]

Would limp mode prevent the Rev's from going past a certain point.

mk1 Leon cupra 1.8T 20v.

 

[mty12345]

No, the rev limit is unaffected, it's just boost that's reduced to almost nothing.( 0.2 bar would be about it)

Scan it again after it next happens as there should be a fault code of some sort when you have a misfire or limp mode.

If not then use vcds to run some logs and then post the results up here. A guide on how to do it below for you if needed. Log blocks 002, 031,115

http://malonetuning.com/assets/files/vagcom_logging_guide.pdf

And the offical VCDS page

http://www.ross-tech.com/vcds/tour/m-blocks.php

 

[Stuart09]

OK thanks. Will get round to that end of the week. Cheers

mk1 Leon cupra 1.8T 20v.

 

[Stuart09]

Ok so got my mate to plug his vag com and got the usual pressure drop and maf sensor signal too high. Also got a few codes for a terminal 30 anyone know what that relay does. But Anyway next port of call is a smoke test to find the leaks. Changed the fuel filter for good measure. Was bit fiddly but no hassle.

Cheers.


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[ibizacupra]

17705 = limp mode
maf too high = limp mode

terminal 30 = battery power dicsonnected

 

[Stuart09]

That would explain the limp mode. And why it cuts out for a second and fires back up. Thanks for that.

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[Stuart09]

Was having another look around as I have not taken it for a smoke test yet. Found a hole in the underside if this pipe. Does anyone know what it's called and where to get 1.
Cheers.

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[Andrewwright]

Crank case breather pipe
Look at this on eBay http://www.ebay.co.uk/itm/322215841045


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[Stuart09]

Thank you for the quick response much appreciated. Cheers

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[Andrewwright]

Best bet is save money and remove the pcv/prv and all its pipework and vent to air or can/air.

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[Stuart09]

Is this split in the hose causing me to have boost problems and limp mode.

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[Andrewwright]

Yep. Split will course too much air in the system and that will evolve to ecu going limp on you. No one likes things to go limp so either fix the split and find the valves are broken and replace them, I'm guessing here because the split is sure sign of age so the other bits will need replacement... Quite costly when you add it up....Or go the other way and remove as i said.

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[Stuart09]

Thanks for that. I found the bit I need to replace for 7 quid so probably going to do that just to get me going and decide what I'm going to do with the rest. Cheers mate.

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[Andrewwright]

Thanks for that. I found the bit I need to replace for 7 quid so probably going to do that just to get me going and decide what I'm going to do with the rest. Cheers mate.

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Check the other bits of pipework...Follow that pipe down and look for splits also, save time and order if needed now. The plastic pipe is prone to crack/split, just be nice down there or you may break it yourself if it's old.

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[Stuart09]

Have had a good look and can't see anything else at the moment. Could barely see the hole on that pipe as it is underneath right on the join for the y piece. Had to remove it to see it.

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