MKIV Supra VVTI now working

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SteveR
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Joined: Thu Dec 18, 2008 12:13 pm

Re: MKIV Supra VVTI now working

Post by SteveR » Thu Jan 29, 2009 11:34 pm

Wez wrote:Mine doesnt do that, how do I get it like that :D

Something to do with launch control maybe, at what revs do you get it?
Just tiny blips that raise the revs to maybe 1500rpm. I think it's the still needs final honing drive-by-wire throttle bits that are causing it and the way the Solaris is currently set up to control the idle as a minor workaround. I might be talking complete bobbins though - Pat! Ryan! ? :D

Ryan.g
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Re: MKIV Supra VVTI now working

Post by Ryan.g » Thu Jan 29, 2009 11:59 pm

SteveR wrote:Actually there is one weird thing happening; once I set off, if I drop into neutral or dip the clutch (e.g. coming up to a junction/set of lights on red) the car idles at 1600rpm until I drop below approx 3mph. What's that all about? As soon as I stop it drops to 1000rpm and stays there. I assume this is intentional but wasn't sure why?

Also once it is warmed up, if I blip the throttle at idle I get make it backfire slightly. I'll stop doing that! ;)
Hi Steve

Glad you are home safely and happy with the car mate :)

Ok answer to your first question Steve, Basically when driving around the engine is working of the Ignition table but when in idle mode the ignition timing is controlled via the closed loop idle control which alters the timing and throttle angle with dbw cars until the target idle is met. Now their are certain parameters which need to be met before the car enters Idle mode. First that the TPS is closed or under a set amount and second that the speed is also under a set amount. Now i found on your car that to keep it smooth around the slow moving speeds it was best to keep it out of idle mode as much as possible to stop the car from sudden jerking when entering idle mode and the ecu suddenly tries to pull the rpm down to 1000rpm.

I can change this but i normally find people perfer the way the cars like this and that in slow moving traffic is helps that no throttle needs to be applied at times. If you dont like though chap i can change for you to suit your driving which needs to be done anyway as you were not around at the mapping session.

The second question sounds like the Throttle enrichement clamp or gain is out and causing either too much fuel or too little fuel to be required when a sudden change in airflow is applied when stabing the throttle. Easily sorted also :)

Ryan

SteveR
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Re: MKIV Supra VVTI now working

Post by SteveR » Fri Jan 30, 2009 8:25 am

Ryan.g wrote:...Now i found on your car that to keep it smooth around the slow moving speeds it was best to keep it out of idle mode as much as possible to stop the car from sudden jerking when entering idle mode and the ecu suddenly tries to pull the rpm down to 1000rpm.
Aha that makes sense. Through trial & error I worked out it was deliberate, but couldn't twig why.
Ryan.g wrote:I can change this but i normally find people perfer the way the cars like this and that in slow moving traffic is helps that no throttle needs to be applied at times. If you dont like though chap i can change for you to suit your driving which needs to be done anyway as you were not around at the mapping session.
Let me see if I get used to it, I don't really see a problem, it was more just a query. :)
Ryan.g wrote:The second question sounds like the Throttle enrichement clamp or gain is out and causing either too much fuel or too little fuel to be required when a sudden change in airflow is applied when stabing the throttle. Easily sorted also :)
Ah I get it - Pat talked about this with me in the morning. Cool. Thanks for the insightful answers as always Ryan.

pat
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Re: MKIV Supra VVTI now working

Post by pat » Fri Jan 30, 2009 8:03 pm

Steve,

Are you finding that the pop near idle is happening when you remove your foot from the accelerator again ?

I have a gut feeling that it's to do with the idle ignition timing. There is SO MUCH air available at idle without driving the DBW to close the throttle a little (which we cannot do at the moment due to the faulty sensor I told you about) that the only way to keep the idle low enough is to run with very little timing. There are two ignition control strategies at idle :
  • There is a closed loop base idle ignition adder; this is applied whenever the ECU enters closed loop idle. It is a function of coolant temperature and engine run time. For warm idle there will be a large correction, I don't recall the numbers off the top of my head, but I'de say somewhere around 20 degrees. It is this correction that gives you the primary drop in idle RPM below 3 MPH....
  • There is also proportional ignition adder, which will advance or retard the ignition based on how far away from the desired idle RPM you are. If the idle is too high, the timing is retarded, if it's too low the timing is advanced.
What you may be observing is the idle strategy retarding beyond the base adder, into the territory that would be classified as Anti Lag ignition timing; it is so retarded that it causes explosions in the exhaust. Imagine the idle is at 1600 RPM and it needs to be at 1000, then at the very instant the closed loop kicks in it has a 600 RPM error, which is "huge", so it reacts to it quite aggressively (yet also effectively, because it DOES reduce the engine torque to bring the idle down to 1000). If we could control the idle air then the base offset may only be 5 or 10 degrees, which means when the proportional correction is applied, the timing does still get retarded further, but not out of the realm of "normal" running and into the realm of Anti Lag...

Hope that makes sense,

Pat.

SteveR
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Re: MKIV Supra VVTI now working

Post by SteveR » Fri Jan 30, 2009 9:53 pm

pat wrote:Steve,

Are you finding that the pop near idle is happening when you remove your foot from the accelerator again ?
Yes that's when it happens; if I blip the throttle at a standstill when the engine is idling (I should have included that important point) it's on the run-down when the pops occur. I only did it literally 2~3 times as I didn't want to damage anything!
pat wrote:...Hope that makes sense
It does! I had to think really hard but I understand what your'e saying. Like I said yesterday at SC, I am keen to keep an eye out for a reasonably priced TPS sensor to replace the knackered one. Remind me, was it the primary or the secondary? I might get on to Jezz the breaker.

BTW I've ordered a (slightly used) Bosch044 fuel pump after taking advice from Ryan. Should I be considering anything before/after fitting or can I simply 'carry on'! :)

jerry
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Joined: Mon Jul 05, 2010 3:11 pm

Re: MKIV Supra VVTI now working

Post by jerry » Tue Jul 06, 2010 8:07 am

Hi that is my first post so hello to all :D

I would like to confirm that it controll stock toyota drive by wire system?
or you use mechanical throttle body?
thanks
Jerry

Snowtigger
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Re: MKIV Supra VVTI now working

Post by Snowtigger » Mon Apr 16, 2012 1:01 am

will this system work on the 2gr motor with its vvti as thats the only thing i really need as well as dbw, dont get me wrong though we are trying to retro fit abs sensors to the mr2 mk1 so we can get some form of traction control going.

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