[jturboawd]

Peers,

I have a very modified N55 with a speedtech kit. I have been struggling with tuning for 6 months daily (DD car ) I had timing issues with MHD alone and boost control issues with JB4. Some can be found here:

https://www.n54tech.com/forums/showthread.php?t=54932

With MHD people are tweaking the PID system and WGDC base tables for boost control. This alone is a HUGE topic with many variables that you can review with some searching. I decided to stick with (after coming back) with my JB4 for reasons described in the above post. Therefore I could not change the PID variables. I needed better boost control with the JB4. What I was experiencing is HUGE oscillations post tip in (up to 6 psi). It was like flooring, letting off, and flooring again. I tried dozens of things because I thought it had to be the BMS PID system. Terry suggested his thoughts is it must be the VE of the engine. I fought this until nothing else worked lol.

Assumptions:
1. Factory turbofold is VERY restrictive and therefore using ANY aftermarket manifold will significantly reduce pre turbo manifold pressure
2. Stage 3 turbos flow much more at a given pressure

Hypothesis: High turbo manifold pressure will increase force closing exhaust valve and have high resistance of flow from cylinder to manifold in all scenarios other than soon after ignition. Higher flow at given pressure will increase the flow into combustion chamber and increase the ability to communicate with turbofold. It seems VERY reasonable that the vanos settings, especially at tip in, would be different between a stock turbofold vs a stage 3. One part of this is true for the PS2 but not to the extent that it is for the stage 3 kits. I think it is VERY hard for a fast spooling stage 3 (aka speedtech 7670). Big single top mounts shift the spool point to where the vanos settings are already very different compared to stock turbo tip in. I have a A2W set up so my actual ride might be the MOST effected by this lol.
Experiment: After trying everything in the above I tried the following:
1. Increase IN (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).
2. Reduce IN (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).
3. Increase EX (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).
4. Reduce EX (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).

From this I saw vanos has a HUGH effect (good and bad) at tip in control. the one that made the MOST difference (drastic) is 1. From this point I tool #1 from above and:
1.1. Increase EX (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).
1.2. Reduce EX (warm) vs stock table at 2750 and 148 by 5% and blend to lower RPM and load (but not upper).

For both it was not as good as just 1

From this point I took the original #1 and further increased
1.3: Increase IN (warm) vs table #1 at 2750 and 148 by 3% and blend to lower RPM and load. Increased the 6000 and 148 by 3% and blend to lower loads.

Conclusion: For MY car the original #1 worked VERY well. Total I have 20-25 logs on the variations above. I now have SUPER SMOOTH boost control, hits 20 psi by 3100 +/- 100 depending on variables and .5 psi or so variation. Its CRAZY how different the car is. I will dyno sometime in the next few months. I am not sure if I will play with the tables anymore.

I am not stating that my settings will work for others. I am stating, if you have oscillating boost control issues with MHD or JB4/BEF and cannot tune it out you should play with vanos settings. I am suggesting you will likely have more luck with IN(warm) then with the EX(warm) tables.

[Payam @ BMS]

Very technical, this is going to be for the people who flash and actually know what they're talking about.

This is where I exit LOL

[jturboawd]

@payam

I don’t think so.... lol

I only have a light grasp on this and just want to provide my own data. Will take someone more competent to consider better advise for the masses

[jturboawd]

Also for 2 days I’ve been on the aforementioned #1 and so far so good.

[Payam @ BMS]

Originally Posted by jturboawd

@payam

I don’t think so.... lol

I only have a light grasp on this and just want to provide my own data. Will take someone more competent to consider better advise for the masses

Haha, I'm sure more will follow and reply if they can. I just honestly have no idea what to say or recommend LOL. Reading and learning more things is what I like to do, so I will follow.