Hooked up the Durametric today and ran codes and found a p1255 code. Haven't seen this code before. I haven't done any work to my car lately other than an oil change a couple months ago and exhaust install back in March. I've noticed some things lately which is why I decided to check for codes. In high gear (4th and up) car hasn't been holding boost consistently. Sometimes I will hit the throttle and the boost will only hold around 0.6bar and other times its just fine and hits 1.0-1.1 bar. Sometimes right after the car only pulls 0.6 bar, I let off the throttle and get right back on it and it will pull 1.0-1.1 bar like nothings wrong, weird. Its not consistent. Car always hits 1.0-1.1 in lower gears. I also saw a readout of 1.4bar on the boost gauge at one point for a moment in second gear (not sustained just a spike) so I doubt that it is relevant but just thought I'd mention it since I haven't noticed that high boost before. My performance mods are basic, EVOMSit K16 tune and Europipe exhaust. Anybody know what all causes this code? boost leak, diverter valves, other things? I was going to do some data logging tomorrow or Sunday when I have some time. Any ideas on what would be good to log to help better diagnose this code? Thanks for any help you can give

 

P1255 is a code due to "boost upper value exceeded". One of the possibility is the N75 valve or one of the sense line going to it is leaking. I would look at the sense lines condition and also the suction lines going to the waste gates. Here's two links related to overboost problem ....


https://www.6speedonline.com/forums/...rging-fix.html


http://pistonheads.com/gassing/topic...t=814410&mid=0

 

Thanks for the links JP. After looking at the N75 DIY thread it does sound like he did have some similar symptoms. I'll definitely take a look at the N75 valve and check the wastegate lines.

 

Happy if I can help you! This valve is really cheap only $22.00 at Sonnen part# 99660515500....

 

N75 valve is ordered. Hopefully that resolves the issue. I'll post back once I replace it with hopefully good news. Although I probably won't get a chance to do the work for a couple weeks. Got a Vegas trip planned this weekend!

 

JP, thanks a lot for your help. Very much appreciated because I am pretty sure you were right. The N75 was in fact the problem. I did a detailed response on the issue over here if you want to read. Thanks again. Rep points awarded!

N75 DIY Thread - Overboost or surging fix

 

This is nice to see somebody who was able to fix his own car! I am really happy for you and "Yes" you deserve a rep point for your effort. Congratulations!

 

Thanks! I do love working on my car even if it is frustrating at times getting everything sorted out. In the end though it's satisfying to know you did it yourself. I try and do whatever work I can myself that is within my range of abilities on all my cars.

 

I'm sorry but, while the part may $22.11, the shipping is $13! Via UPS Ground fer gossake! For that tiny thing? Ridiculous! How about $5.35 via USPS Priority Mail and it's there in 2 days instead of 5, for 1/3 the cost? I'm all for vendors, but when they dangle "low" prices then gouge on shipping, I'll take my bidness elsewhere.

Cheers
Mikey

 

before ordering N75s valves you could have logged it... theres a way to log the duty cycle...
with that said, I bet its not going bad but rather lines to or from it... thus by replacing it your actually sealing up the leak... if not the same problem will persist..

how about a friendly boost leak test lol