finally getting somewhere with my boost problem - KO4

[thenofjboy]

as the title says, slowly but surely! i have a 98 AEB passat with a KO4, stock exhaust mani, 5 bar FPR, stock injectors , FMIC, baily DV, silicone hoses etc... previously i have been only boosting to around 15psi. i check N gapped the plugs, replaced the breather hose & a check valve but i haven't pressurized the system since i replaced the breather hose. I also got a flat in there and moved the actuator a lil too.
anyways i finally got to disconnecting the N75 from the WG. & WOW haha obvioulsy more boost but it came on way quick and my KO4 never sounded so good :) especially driving through enclosed roads where i can really hear it spool.
So i get home and put the N75 back on the WG & its raining now but i drove for a min and was only boosting to 15psi.
I gota look at the tubes on the N75 but is it bad? maybe my DV? i checked & did that pressure test and it seems to work but i think it could open more inside the dv, ill try to post pic and explain.
thanks in advance

[djwimbo]

What software are you running? If the "chip" is only written for 1Bar 14.5-15psi, that's all you're supposed to boost to.

It's possible you have an N75 failure, if you have another one, try and swap it out. Otherwise just go pick up a ball/spring MBC and use that instead. (leaving the n75 hooked up electronically)

[kevin12]

This happens every winter for people that run a N75 valve. In very cold temps you will notice that you end up running less boost because the N75 does not adjust to force the turbo to stay at a set boost level. The much lower IAT's are the reason you see lower boost readings at the IM.

Mike talked about this in another thread thats almost identical to this one. It could be your problem since Jersey has just recently gotten pretty cold.

[thenofjboy]

Mike talked about this in another thread thats almost identical to this one. It could be your problem since Jersey has just recently gotten pretty cold.

yeh it has gotan cold, cant wait to hit the mt! :) but even when i got the KO4 software during the summer, i wasnt really impressed. i was running better well boosting higher when i had the KO4 with the KO3 software. i boosted to around 17 give or take.
I was thinking maybe i got the wrong chip at AWE? but im going to either look into a new N75 and or MBC...

o yeh i need a tan arm rest cover too! :)

[thenofjboy]

What software are you running? If the "chip" is only written for 1Bar 14.5-15psi, that's all you're supposed to boost to.

It's possible you have an N75 failure, if you have another one, try and swap it out. Otherwise just go pick up a ball/spring MBC and use that instead. (leaving the n75 hooked up electronically)

GIAC KO4 from AWE. So i should hook it up in parallel with the N75? Or just leave the N75 removed from the WG? i gota read up more on the configurations..
TIA

[djwimbo]

GIAC KO4 from AWE. So i should hook it up in parallel with the N75? Or just leave the N75 removed from the WG? i gota read up more on the configurations..
TIA

You shouldn't remove anything from the wastegate. If you get a ball & spring style MBC, you can use it in the same location and with the same hookups as the N75.

However, to prevent the CEL from turning on you either have to leave the N75 electrically hooked up, OR pick up a 30phm resistor and jumper the terminals of the connector.

Personally, I have a "bleed" valve and the N75 hooked up simultaneously, but that's more effort than what's needed.

For what it's worth, my car hasn't "lost" it's boost spike in the cold. It was 23*F the other day and it still spiked 18 and held, with a normal taper to ~10psi at redline.

If I had to do it again, I would either do a EBC, or one of these.

[kevin12]

Yeah thats pretty odd not quite sure whats going on man but definitely check things out and I'm also thinking of getting one of those Hallman MBC that djwimbo linked ya too. Supposedly they are the best when it comes to MBC's.

Haha yeahhh I've been looking for a tan armrest cover forever. Mines in pretty bad shape from the previous owner.