MOT Time how can i put my car in Limp Mode?

[ian4455]

My S2 (3b) is finally ready for an MOT, since i'll be leaving the car at the garage how can i create limp mode incase of any joy riders ?

Thinking of disconnecting N75 pipe from wastegate.

[prj]

Disconnect the N75... but it will throw a code.
Or - take out the spring from the wastegate. That is even more effective than disconnecting the N75, your car will be effectively naturally aspirated.

[ian4455]

Thanks, I'll remove the spring.

[prj]

Test it as well, should be quite funny

[driftin jo]

don't do that !! you will then have no boost control, not even spring, will just overboost and potentially destroy your engine if all safeguards are not working properly.

You could however disconnect the connector (electrical) to the N75, this will give you low / spring boost only .

[mcandmar]

Unpluging N75 will stop the fun. But i am not sure if that will force it into limp home mode, i would be worried about emissions if it did as it may disable O2 control?

[ian4455]

....reason being i've a Hybrid RS2 running 330cc injectors and 4 bar FPR, didn't want anyone else driving if you know what i mean!

Ok so whats the best then, thought without the spring the valve would open under exhaust pressure ?

[driftin jo]

If you unplug the n75 connector you will get ~200 hp period, turbo does not matter, unless you have a none stock spring.

[Al Wyn]

Best way and the way i always do it Ian is to book the mot appointment and then be there when its being done...you also get a chance to have a good look at the underside of the car when its up in the air.

[Jamo]

Agree with Al, or just remove the fuse for the N75

[prj]

don't do that !! you will then have no boost control, not even spring, will just overboost and potentially destroy your engine if all safeguards are not working properly.

You could however disconnect the connector (electrical) to the N75, this will give you low / spring boost only .

You got it completely the wrong way around.
If you remove the spring, the wastegate will always be open due to nothing being there.

Please think.

1.4 bar spring - 0.4 bar boost
1.9 bar spring - 0.9 bar boost
No spring - no boost.

What you describe will happen if you insert a solid puck instead of the spring or disconnect the lower wastegate chamber.

[driftin jo]

You got it completely the wrong way around.
If you remove the spring, the wastegate will always be open due to nothing being there.

Please think.

1.4 bar spring - 0.4 bar boost
1.9 bar spring - 0.9 bar boost
No spring - no boost.

What you describe will happen if you insert a solid puck instead of the spring or disconnect the lower wastegate chamber.

I didn't mean the spring, in the first post said he was going to disconnect the pipe to the waste gate.

When I was writing my reply no one had replied yet, I can see how it may look if I was saying don't remove the spring, I should have replied with quote from first post.

[prj]

Ok, sorry, I thought you replied to me.
My bad

[sidrick]

Best way and the way i always do it Ian is to book the mot appointment and then be there when its being done...you also get a chance to have a good look at the underside of the car when its up in the air.

Best advice here and what I was going to suggest.

[WabTheKing]

Best advice here and what I was going to suggest.

i agree, then you can go out with them on the handbrake/brake test as it has to be done on the road or similar as the brake tester will only 2wd iirc?