Have i done a bad thing

[webbywagon]

With my recent running probs, i bypassed what i thought was the N249. I noticed an electrical unit with three hoses going into a T piece on the end of it. One from the actuator, one part of the T piece goes into the inlet pipe which the MAF is connected to and the third somewhere else. I Disconnected the unit and bought a T piece plastic connector and joined the hoses to that. Unplugged the barrell shaped unit with the T piece at one end and the car ran loads better, still only making 6-7 psi boost but not anywhere as near as flat as before. The engine is in my VW Caddy pick-up and has no cats or from what i can see an, n249 valve or the air pump valve either. So have i removed the N75 and if so should it still run or not, i'm very confused now, especially with the low boost as well.Oh before any one jumps in I HAVE DONE A SEARCH and cant find anything.

 

[karlosR]

try and take some pictures and post them up showing where you disconnected the plug from. you may get a constructive answer then mate.

 

[Fl@pper]

http://www.seatcupra.net/forums/showthread.php?t=42406&highlight=n249+bypass

http://www.seatcupra.net/forums/showthread.php?t=115003&highlight=n75+bypass

might help out for starters ?

 

[dannyk]

With my recent running probs, i bypassed what i thought was the N249. I noticed an electrical unit with three hoses going into a T piece on the end of it. One from the actuator, one part of the T piece goes into the inlet pipe which the MAF is connected to and the third somewhere else. I Disconnected the unit and bought a T piece plastic connector and joined the hoses to that. Unplugged the barrell shaped unit with the T piece at one end and the car ran loads better, still only making 6-7 psi boost but not anywhere as near as flat as before. The engine is in my VW Caddy pick-up and has no cats or from what i can see an, n249 valve or the air pump valve either. So have i removed the N75 and if so should it still run or not, i'm very confused now, especially with the low boost as well.Oh before any one jumps in I HAVE DONE A SEARCH and cant find anything.

The N75 (the one you've bypassed) is an electronic solenoid valve that the ECU uses to control boost. It is located in the intake hose near the back right side of the engine. It has 3 connections.
1. Connects to charge pipe = pressure source
2. Connects to wastegate actuator
3. Connects to intake hose – bleed line.
The ecu will pulse this valve at a high frequency to bleed air off from the wastegate line. It does this based on throttle position and engine load. If the valve, or any of the liens connected to it have leaks then there can be severe boost regulation problems. It’s function is similar to the MBC above. To get more boost people often swap in different N75 valves. These different valves simply have a different response characteristic, and will act different when given the same signal by the ecu. They can get more boost, less boost, or even a big boost spike by swapping N75’s.
So possibly your old N75 valve was knackered and you need to replace it??

Cheers

Danny

 

[karlosR]

did it look similar to this? http://www.ecstuning.com/stage/edpd...di&model=TT MKI&submodel=Quattro&engine=225HP

 

[webbywagon]

Yes just like that, so i really need to replace it rather than leave it off, (Dough) i'll take my old one into my local vag dealers then.

 

[webbywagon]

The N75 (the one you've bypassed) is an electronic solenoid valve that the ECU uses to control boost. It is located in the intake hose near the back right side of the engine. It has 3 connections.
1. Connects to charge pipe = pressure source
2. Connects to wastegate actuator
3. Connects to intake hose – bleed line.
The ecu will pulse this valve at a high frequency to bleed air off from the wastegate line. It does this based on throttle position and engine load. If the valve, or any of the liens connected to it have leaks then there can be severe boost regulation problems. It’s function is similar to the MBC above. To get more boost people often swap in different N75 valves. These different valves simply have a different response characteristic, and will act different when given the same signal by the ecu. They can get more boost, less boost, or even a big boost spike by swapping N75’s.
So possibly your old N75 valve was knackered and you need to replace it??

Cheers

Danny

From the links the other guys put up for me it is that valve you speak of, strange how it still runs though. How do i know the right way to put it back on though as i cant remember when i removed it

 

[dannyk]

From the links the other guys put up for me it is that valve you speak of, strange how it still runs though. How do i know the right way to put it back on though as i cant remember when i removed it

It will still run but you'll find it's not doing the turbo any good if it's not controlling the boost correctly, ie the pressure will not be bled off at the correct time and can cause stalling of the turbo etc

I can't remeber the connections, but i know the long one from the bottom goes into the TIP. Can't remenber the others but will have a look tomorrow. Also do you know which variant of valve it is, you can tell buy the last letter of the part number on it IIRC. It will be an F,J,H or something like that. What car did the engine come from?

Cheers

Danny

 

[webbywagon]

It will still run but you'll find it's not doing the turbo any good if it's not controlling the boost correctly, ie the pressure will not be bled off at the correct time and can cause stalling of the turbo etc

I can't remeber the connections, but i know the long one from the bottom goes into the TIP. Can't remenber the others but will have a look tomorrow. Also do you know which variant of valve it is, you can tell buy the last letter of the part number on it IIRC. It will be an F,J,H or something like that. What car did the engine come from?

Cheers

Danny

It came out of a 2001 leon, it's an AUQ with six speed box

 

[dannyk]

It came out of a 2001 leon, it's an AUQ with six speed box

Same engine as mine, i will check this afternoon and tell you exatcly what goes where mate.

Cheers

Danny

 

[webbywagon]

Same engine as mine, i will check this afternoon and tell you exatcly what goes where mate.

Cheers

Danny

Cheers Danny

 

[dannyk]

Sorry mate been busy as.

Anyway, here is the pic

Thats the N75 indicated by the green circle

Hoses:

Yellow goes to charge pipe.
Red goes to wastegate actuator.
Blue (is the longer tube) goes to the intake hose.

And obviously the electrical side would need connected.

 

[webbywagon]

Danny you mate are what forums are all about. Cheers dude much appreciated. I will let you know how it goes as it is having a new four paddle clutch and solid fly wheel, ceramatallic pressure plate and hydraulic bearing, all good for 380 bhp. Then have a vagcom all codes cleared and try again. That will be new....MAF/ MAP/ N75 and cold air charge feed. Fingers crossed.

 

[dannyk]

Danny you mate are what forums are all about. Cheers dude much appreciated. I will let you know how it goes as it is having a new four paddle clutch and solid fly wheel, ceramatallic pressure plate and hydraulic bearing, all good for 380 bhp. Then have a vagcom all codes cleared and try again. That will be new....MAF/ MAP/ N75 and cold air charge feed. Fingers crossed.

Hope you sort it soon mate, i'd also check for boost leaks around all the hoses, not an easy task unless you happen to have a dyno in your shed!! but just check all hoses for cracks, splits etc esp if it is a transplant.

Also if your palnning on that power i hope you have uprated the internals!!

Anyhoo, Sounds like a beast, you'll need to get some pics up, i hope its low as fook with some fat rims!!

Cheers

Danny