277rwkw for E3 GTS with VCM OTR and Mafless Tune - But there's more to this story

[crackelaktor]

Hi Folks,

Its been a while since I've posted on this forum as for some reason it hasn't been working from my Tapatalk Iphone app for some time now. I'll look into that later. The reason for my post is to thank Dale the Master Tuner from "Castle Hill Performance" for a great job he did on my E3 GTS (aka Storm Trooper) this morning, giving it a nice "Touch up" tune. The short story is my car this morning went from 245rwkw to 277rwkw (up 32rwkw) after Dale worked his magic on it :)

So why did I take it in for a Touch up tune? I bought the E3 GTS manual brand new in July 2011. I had a VCM OTR installed and took it to Castle Hill Performance for a Mafless Tune in Oct 2011 (with the factory MAF still installed but disabled). The car went from 227.6rwkw to 268.8rwkw (up 41rwkw). The car at the time only had a few 1000 kms on it (around 5,000 I think but cannot remember now). I then drove it for a while and decided that I would remove the stock MAF and replace it with the VCM Rubber boot and Temp Sensor, which fits nicely into the bottom of the rubber VCM boot (sitting exactly where the MAF was). A few months later, I did the Bi-Modal switch modification so I could leave the Bi-Modal open all the time and switch back to the stock settings as well (which are controlled from the EDI). This was great as I no longer had to put up with the opening and closing of the Bi-Modal flaps, and my wife could have it nice and quiet if she wanted to. Loved this mod.

The VCM rubber boot is so much less restrictive from an airflow perspective than the factory MAF (you just need to look at them both side by side and you'll see what I mean) that the engine would have most likely been getting more air than it was tuned for, hence running on the lean side of things.

I then called Dale at Castle Hill Performance and asked him whether my car would benefit from a "Touch Up Tune" given I had changed part of the intake plumbing from stock MAF to VCM rubber boot, and the Bi-Modal mod as well. He suggested it was worth doing as the car would have loosened up a little since new, and the tune could benefit from the small physical adjustments I had made. The car now has 24,000kms on the clock, and only has VCM OTR intake, Mafless Tune, and the Bi-Modal exhaust bypass switch.

I took it in this morning.....

On first run, the car made 245rwkw (down 23.3rwkw from the 268.8rwkw from Oct 2011 or 1 year & 9 months ago) and was running very lean. Dale did several tweaks to the tune, and the result was a healthy 277.5rwkw (up 32rwkw on the day, and up 8.7rwkw from Oct 2011 tune). I couldn't believe how much extra power I had lost from the Oct 2011 tune, just by changing the inlet.

Dale suggested that when these cars run lean, they lose power, so he got the air/fuel mixture spot on, and I was back up to where it should have been. The difference in the car is amazing.

The lessons I learnt from this experience:

1. Even such a small change to the Intake or Exhaust can make a big difference to the cars power output (in my case on the negative side), especially when the car is custom tuned and expects a certain AF ratio.
2. If you have a custom tune, and you decide to make any changes, take it back for a touch up to ensure the tune is optimal for the changes you've made
3. Get to know your local tune shop and put your trust into their knowledge and expertise

Thanks Dale and Dave from Castle Hill Performance for giving my baby a little extra bite. It is bloody noticable :)

[team illucid]

nice work and good numbers on a stock exhaust I presume?

[crackelaktor]

nice work and good numbers on a stock exhaust I presume?
Stock GTS Bi-Modal Exhaust

[team illucid]

Stock GTS Bi-Modal Exhaust

Excellent numbers then.

[crackelaktor]

Excellent numbers then.

I am just stoked with the way the car feels and responds. Especially given its issue of running lean and being down on power. You live and learn :)

[tacka007]

What do they do to bypass bi-model. Do they do through edi or manual switch with the vacum line. Nice ride by the way :):):)

[crackelaktor]

What do they do to bypass bi-model. Do they do through edi or manual switch with the vacum line. Nice ride by the way :):):)

Thanks. I did the Bi-Modal bypass mod myself using some great instructions posted up by another forum member (will try to find post). Many people I chat with on the forums have also done the mod and it works a treat. Once I locate post I will share it.

[crackelaktor]

What do they do to bypass bi-model. Do they do through edi or manual switch with the vacum line. Nice ride by the way :):):)

To answer your question, it is a manual switch I've installed into the glove box which plugs into an orange wire of the cars EDI computer and allows you to run the Bi-Modal system as normal via the EDI, or with a flick of the switch, ignores what the EDI setting is and opens up the Bimodal to full open.

[crackelaktor]

Thanks. I did the Bi-Modal bypass mod myself using some great instructions posted up by another forum member (will try to find post). Many people I chat with on the forums have also done the mod and it works a treat. Once I locate post I will share it.

http://my.hsv.com.au/myHSV/forum/topics.aspx?ID=301

Here is the link to the instructions I followed for this BiModal mod. It was posted on the HSV forums as well.

[tacka007]

Thanks heaps

[shucks]

Good numbers, and interesting results. Looks like removing the maf from the airpath is worth about 8 kw, maybe less cause the engine has loosened up a bit, and the maf would need to be recalibrated for the OTR anyway if you got a maf tune, which takes a little extra time. On the plus side once the maf is dialed in you can play around with exhausts without worrying about changes in VE throwing off the air fuel ratios, because the maf just reads the extra airflow and compensates. And you can run the tune closer to the edge because the airflow model is more stable and doesn't swing lean if the IAT false heatsoaks. Food for thought.

[calais190]

I'm not a professional mechanic or tuner, but I understood the leaner it was the more power it gained at the expense of possibly heating the engine internals to cause damage?

[Gmfan]

I would have thought less fuel means possible pinging/knock meaning computer pulls timing and then less power?