I had a 'download' map to my STi V recently, and then a few custom tweaks to it - £750. Not cheap.

Over Xmas I have 5 times hit fuel cut off on overtaking in 5th at high speeds (complete and very violent loss of power for about 0.5" during hard acceleration in top). Not safe during an overtaking manouver - esp as I thought I'd lost a bl@@dy wheel the first time it happened!

Boost is so much slower to build up in 5th ('to avoid over boost' it seems)

Also engine does not lose revs between gears like it used to - sometimes have to wait for revs to drop enough before releasing clutch for the higher gear.

There are clear plus points to the conversion too (least of all that it will run safely on 97 RON) but the bottom line is that I am dissapointed.

What should I do guys, bearing in mind that it is £40 in petrol to get to these guys and back, and that the new software is protected unaccessible to anyone else...

 

All Ecutek dealers AFAIK offer money back guarantee.

Practically, it could be a number of things - a mechanical fault, or more likely the duty cycle is a bit too high in the zone you are overboosting. On occasion, you can find that the point where you drop the maximum duty cycle during spool up can lead to an overboost in 5th gear only and you need to drop it just 100 RPM earlier to stop this, but not harm spool up.

With a 2 port solenoid you have to accept a slight overboost in higher gears to reach target in lower gears, but it sounds like you are getting too much or the fuel cut is not high enough.

Standard STi fuel cut is about 19.6 PSI. What is yours spiking to and at what revs? What does it do in lower gears?

The other option you have is to get a 3 port solenoid - either from a Subaru dealer, BRD or a breakers, and get your dealer to map the boost with that. In this way you get much better boost control.

 

Thanks for the advice John! It was programmed to boost to 20PSi in their 'standard' map... Would seem to explain the prob if the cut off is at 19.6 PSi (is this threshold not ECU tweakable though?)

I'll speak to them after the break as they were very decent & helpful - maybe I could get a refund and get a re-map done to a 3 port solenoid system from a certain person that lives 10 miles away, but is very busy!

Thanks J

D

 

Yes the fuel cut is able to be raised, and would have been as part of the reprogram. However, I would not run a VF28 at 20 PSI target boost personally, I think the turbo is too small and you will just heatsoak the poor little intercooler. Below is a compressor map of the VF23 which uses the same compressor wheel but a larger P20 exhaust housing than your VF28 which has a P18. At Pressure Ratio 2.4 (y axis) the turbo has a 1.4 bar pressure across it. However, yours will probably be running more like 1.45 bar (21 PSI) across it because there is a small pressure drop in your intercooler. The net result is that your turbo is at well under 72% efficiency and spinning at over 160000 RPM, it could be as low as 55-60% with high boost and moderate flow. Personally for this reason I would run a VF24/28/29 at UP TO 19 PSI, and set boost targets to 18 PSI. Just my thoughts, but the VF28 is not a big BHP turbo and at 20 PSI it could overspeed and do stretch its compressor wheel blades. (I did this to a hybrid turbo that was designed for 1.8 bar running at only 1.5 bar). The place this would probably happen is on a track when the overboost would be more marked.



[Edited by john banks - 12/28/2002 4:50:46 PM]