I ordered 10 of these for real cheap. If any of you guys experience limp mode in your 00+ chipped 1.8, then this may help you out. This is used to clamp the map sensor so that it only sees 17psi max. I've always had a problem overboosting in my car if I take it to redline through every gear. It usually ends up in limp mode-by 4th gear. I'm sick of it. PM me your address if you may need one. I've noticed that this usually an issue with a k03 GIAC chip on dbw (map) engines.

 

you might still hit limp mode, get the 4.3. I tried both befor upgrading, and hit limp mode with the 4.7 as if i didn't install the thing. never had issues with the 4.3. heres a diy I found if interested http://forums.vwvortex.com/showthread.php?1484504

 

I second the 4.3 1w. I ran that set-up for a while using the 4.3 and never went into limp. I think that the 4.7 was used for chipped cars maybe? I tried the 4.7 first and I was more limp than (fill in the blank with dirty comment) I'm not too sure, but I know for a fact that a 4.3 won't set you in limp no matter how might you boost.

 

4.7v 1w still puts me in limp, i spike 24lbs though. ordered some 4.3v 1w we will see how they go.

 

It should depend on what chip you have. 4.7 diode will only let the map see 17 psi. I know that most of the time my manifold gets 18-20. GIAC is a 1.2 bar chip, I think, so hopefully this fixes it. If not I'll buy 10 4.3 diodes for $2 shipped.

 

Warning:
This mod removes the overboost safety and should only be used when running a EBC that has a over boost alarm/limp mode feature. Should never be used with a N75 valve alone since that could fail allowing the turbo to boost to 30+psi which in turn can cause major damage to the motor.

onepoint8tee - What year is your car? The GIAC chip for the 2001 is 1.2-1.45 bar depending on what gear your in, the GIAC chip for the 2000 is going to be closer to 1.1-1.2 bar.

If you clap off the map sensor off too low causing the actual boost readings to be 300+ mbar lower then the requested boost the ecu can still put you into a limp mode and will throw a boost deviation code.

 

I agree with your logic, but the k03 is way out of efficiency much past 20 psi, and I'm pretty sure it couldn't reach or maintain anywhere close to 30 psi at the manifold... Right? But yeah, an overboost disclaimer is appropriate.

My car is a 2000. Boost gauge and vag com both register ~18psi with spikes to ~20-22psi. I have compared requested vs actual boost with vag com in the past, and it's almost always overboosting near redline and wot. I always get a boost regulation:negative deviation fault and limp mode. I've tried using a different N75 valve, mbc,etc. I would expect to be put in limp mode if actual is more than requested, but not the other way around. Are you sure about being put into limp mode if actual is less than requested? I'm sure a fault would pop up, but I don't see how this could hurt the engine. When I used a mbc and capped it at 12 psi- I'd never go into limp mode even though the ecu was requesting ~18psi or so.

300mbar is like 4.5psi right? If my ecu asks for 18psi, and I'm getting that +/- 3psi, clamping the map at 17psi should be fine, no?

 

Garrett at GIAC used my car to see how far we could push the stock K03 in my 2000 A4, we actually ran up to 26psi on 91 octane. That was my street setup till I pulled the K03 out for a T28 turbo.

The ecu can throw a negative and a positive deviation code. I have seen both back when I had a K03. Most people that get a code for too low of boost usually have a IC pipe/hose that has popped off, but the ecu will also throw a low maf code during that time too.

If you have it happen at high rpms, the problem might be that your boost is dropping below the requested boost level at high rpms and causing the ecu to throw that negative deviation code. Do you have any logs of block 115 when this happens?

300mbar is right around 4.35 psi.



BTW, another thing you might end up running into when pushing high boost on your 2000 is hitting the tq limiter. When this happens the ecu will cut off the control to your throttle pedal forcing you to pull over and turn the car off/on again. Not a pretty sight and I have seen plenty of 2000 owners end up with this issue when pushing big boost out of the K03 and K04.

 

Yeah like I said, I have compared requested vs actual boost with vag com in the past, and it's almost always overboosting near redline and wot. I was having issues with the tq. limiter while using the mbc, but that was happening mid throtle off the line. Anyways... After reading THIS I may try the J valve.. I'm using the stock N75 right now, have tried the H valve and it was better but not completely, but I broke it.. Thanks for the insight.

 

I did the Diode mod and when i get to the top of my RPM i get a back fire. I am running 14 PSI and used the 4.7V diode. Just want to know if it is from a Lean or rich mixture? has any one had this problem.