Michael's V8Y62

[Plasnart]

During the last week I have taken some datalogs of Pearl and taken a look at them. HP Tuners does support the VK56 engine but there are a few things within VCM Suite (VCM Editor and VCM Scanner) that are not setup correctly and it is taking a bit of time to find the right settings for our V8 engines. There are many parameters in the gauge screen of VCM Scanner that don't function and they don't function because their settings are wrong. I am slowly working through them and will send a message to HP Tuners so they can update the dongles so that scanning, and then tuning, will be easier.

Things I have noticed viewing the datalogs are:
1. Pearl rarely goes over 1600 rpm, with the occasional 3000 rpm foray when overtaking or on cruise control going up a steep hill at 100 kmh (actual not speedo).
2. Timing is set extremely high at cruise speed, 48-51 degrees btdc is not uncommon in the datalogs which makes me think there is not a lot of room to move with timing to gain more performance and economy.
3. On decel timing can go as low as -7 degrees (7 degrees atdc) idle timing is around 15 degrees btdc which is fairly normal for modern engines.
4. STFT runs between 0.2 and 6%. My intent is to try and get it to under 2% across the board.
5. LTFT on VCM Scanner shows 3 digit numbers, 420 comes up often. I reset it to % and it is hovering about 6% which is way to high.
6. The MAF is a voltage based MAF. As a comparison GM use Frequency based MAFs so rescaling the MAF, to get the ST and LT FTs back under 2%, is different to what I am used to. What makes it even more difficult is VCM Suite doesn't seem, atm, to have settings for the voltage based MAF. This is my priority at this time.
7. VCM suite doesn't have many settings for the automatic which I find disappointing. While the auto is great and extremely smooth I am well aware the torque converter locks and unlocks alot. In Toyota 200 series forcing the converter to stay locked for longer and locking earlier saves alot of wear and tear on the trans and helps them to run cooler. While I am not towing it is not much of an issue so I am interested in other peoples experiences when towing.

EDIT: My FB page for my projects https://www.facebook.com/profile.php?id=100089631151497

All very interesting mate, but really this sort of stuff is above my head. Of your points above though, a couple of questions:

Point 1.. I find it hard to believe you drive a VK56 and rarely exceed 1600rpm. The pleasure of hearing that puppy sing at 3-4k rpm is worth the fuel outlay!

Points 4 & 5: So many things can affect the fuel trim (the long term I suppose is more interesting). But what exactly does the percentage indicate? I.e. what is the 6% figure a reflection of? And why is 6% way too high?

Point 6: Adjusting the MAF will obviously have a bearing on your fuel trim. Do you know, or is there a factory standard setting, frequency, voltage or whatever? How do you know the MAF is working per design specs?

Do you have the factory exhaust system still fitted? There are 4 x O2 sensors in the exhaust system. Each side has one located pre-cat and one post-cat. It is my understanding only the pre-cat sensors have the authority to alter fuel trim. The rear sensors are for error coding only. If you have an aftermarket exhaust system installed, and have subsequently altered the O2 sensor offset from the exhaust flow, you could negatively affect the fuel trim via changed sensor configuration from factory design parameters.

Edit: the aftermarket exhaust system comment really only relates to an aftermarket cat replacement, not a cat-back exhaust replacement. I have aftermarket high-flow cats still in the shed until I pluck up the courage to mess with the O2 sensors!

Cheers.