Road tuning VVTi using CLL fuel correction?

Hi all,

I am currently learning to tune my MR2 Roadster (with a 1zz engine) on a Link G4+ Xtreme and have my fuel table dialled in and the car runs well as well as basing some ignition timing advanced from the Link basemap. I have watched a few webinars which actually use the 1zz engine as the test engine so quite handy to work out where I should be aiming for. I have also tuned a Power FC for the 1zz as well as I am able to use some of the learnings from knock and VVTI settings from those maps as a basis for the Link Xtreme.

Anyway, after watching another great webinar with tuning VVTi - where the engine leans out slightly with an increase in VVTi degree owing to improved VE (to a point), I was wondering if I could use my wideband CLL auto fuel correction % to be able to get a handle on how far advanced I can run the VVTI.

I don't have access to a dyno at the moment - its a high mileage engine and I am using it as a test bed to try out/learn the ECU, I currently am currently building a fully forged engine ready for high boost in the near future (which I will be getting tuned on a dyno). Just currently having a bit of fun to see what I can do with the Link before it gets tuned on the dyno - coupled with the fact that I will want to have a decent basemap on the car when I need to drive my car to the dyno with a turbo attached.

Looking at the PFC maps I have (which oddly swap the VVTi values around so 55 degrees is fully retarded), the maximum advance seems to be at around 44 degrees.

I was just wondering if I could use my Link G4+ logging to run the current fueling, adjust the VVTi by say 10 degrees more advanced and see if the engine needs additional fueling to correct to the main AFR table - if it does I can continue increasing the VVTi values until less fueling is needed.

Would also be great if anyone could share what sort of ignition advance the 1zz engine is happy with - aware its not knock limited which is great - current ignition timing is in the mid to high 20s at 100KPa.

Hey David,

Using the fuel mixture as a guide to vvti will get you in the ball park, but will not be optimised. You could end up around within 10-15 degrees +/- from optimised angle.

One thing to remember with the closed loop is it is adjusting the fuel mixture after the event has happened. It might be bette to run the map a little richer so its safe and then see how it is effected. You will find on your first 10-15 degree movement the mixture will change noticeably (maybe 2-4%) then after that the AFR movement wont be as much, making it very tricky/impossible to get the vvti correct.

Assuming the webinars you have watched are the ones below? Maybe also check out the thread below

Have you completed the road tuning course on how to tune ignition timing? I have attached a short video for this to. I only have Supercharged 1zz maps I have done on hand

https://www.hpacademy.com/previous-webinars/113-dual-vvt-tuning-strategies-motec-m1-2/

https://www.hpacademy.com/previous-webinars/081-vvt-cam-tuning-aem-infinity/

https://www.hpacademy.com/previous-webinars/continuously-variable-cam-control-link-g4-plus/

https://www.hpacademy.com/forum/general-tuning-discussion/show/practical-vvti-tuning-questions

[url=https://www.youtube.com/watch?v=Q4CGbaNKB9s]https://www.youtube.com/watch?v=Q4CGbaNKB9s

Thanks for that, yeah I had a look at the Link G4+ webinar which is where I got the idea from, not signed up for the road tuning course as of yet, currently using the current engine as a testbed as its high mileage coupled with the fact that its not knock limited so fairly safe to adjust and learn on.

I know it won't be perfect but will be better than stock - will be logging stock figures on the car as well to see what sort of values are stock - have also seen a few aftermarket VVTi tuners and can see how they adjust the curve slightly so could look to capture the stock values then tweak them using some of the aftermarket plug and play curves.

I think I will also richen the map slightly - say 3%, turn off the CLL and log the data, then tweak it by a bit and check the log to see if its pulled the fueling back to where it was etc.

Being able to log stock cam angle and starting from there will be a big bonus. Most manufactures will aim more for economy over outright power but it will be a really good base.

Using the idea of fueling and seeing how the cam angle effects the fueling will be a great start. Although as mentioned you won't be able to get it bang on.

Being able to see what others have come up with and comparing to what you have will also help.