Jump to content
The mkiv Supra Owners Club

VVTi FBW throttle bypass.. who's done it and what problems did you encounter?

Mike B

By Mike B
in mkiv Technical

 Share

Recommended Posts

Mike B Newbie

Mike B

Posted
Posted

Hi All,

 

Been a while since I've been on the forum, but next spring I want to get my supra back on the road, and I'm sorting all the little niggles before then.

 

Primary thing I need help with is the FBW throttle which after many years of trying to sneak my way around, I'm completely over it and want rid.

 

So...

 

Who's ripped theirs out, installed a cable throttle body and what problems did you have to overcome?

 

I run stand alone fuelling Vpro.. but

 

I expect to deal with;

- stock ecu cabling and feedback will be different and light the dashboard up like a christmas tree

- installation of an ICV

- potential loss of VVTi

 

?

Link to comment
Share on other sites
Chris Wilson Experienced

Chris Wilson

Posted
Posted

A customer of mine changed from VVTi FBW to cabled earlier TT body and pedal. I fitted a two wire idle control valve and wired it into his Syvecs. ICV was trivial, I welded a boss on the pre TB intake pipe to pick up filtered air and drilled and tapped the manifold for a fitting for a hose on the manifold runners themselves.

 

EDIT: I *think* he changed the pedal, not adapted it...

 

Whatever, it's not rocket science and Ibrar has the car now, it ended up in a motorway barrier and was written off. He could tell you if the pedal was changed or just a cable nailed on.

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted

Thanks Chris..

no ecu issues you can remember?

hmm.. wonder how I will get round the icv.. don't really want to call the mapper out again. FBW uses the butterfly to control idle :-S

 

The cable and pedal are standard all the way to the body - solid connection i mean.. the fbw is activated by motors on the other side so it mirrors the physical side, until it decides it knows better.

 

more investigation needed!

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted

Yeah, Ryan mapped the car, no issue on the dyno at all, but on the road FBW and I regularly have a difference of opinion..

 

Why would you want to remove it? Serious question, what's wrong with FBW?

 

hmmm.. well seeing as you asked!

 

More to the point; whats wrong with MY fbw... well actually it works perfectly - but I have a problem elsewhere.

 

There is some noise in the engine that the ecu picks up as det...

 

There is ZERO det on the dyno, and it runs perfectly on a dyno run, but put it on the open road and there is something going on... When you go from gear to gear the first 2 1/2 seconds on the next gear is on 50% throttle. Sometimes it will go through the whole gear at half throttle. I have lived with it for 4-5 years and I have had enough.. it's getting sorted!

 

Ryan mapped the car...

he listened to the engine and he can hear no det under load, infact no det at all (he's only listening on the dyno mind you)

 

I have a 3rd party knock sensor wired in, and we can see no det under load.

 

There is no det during a hard pull on the road.. just like on the dyno, it's mapped perfectly.

 

but drive it through a few gears, get full throttle 2nd, take third and there is a throttle shutdown. Take 3rd and go to 4th.. throttle hesitation again. I thought it may be an extra sensor safety shutdown as I run a T67 single, but every time this happens I look at the peak hold on the knock monitor and sure enough, there it is; a spike.

 

We are sure the spike is not load related, but it's there and i have no idea where it comes from.. and I cannot seem to get rid of it. Occasionally after a long run on the motorway the car will run perfectly, but the next day there is the spike again..

 

Car has had a new flywheel and clutch while I have had it and no difference. The problem has always been there..

 

I thought the answer would be to disable to knock sensors. So to start with I wired a variable resistor into the sensor feed; no difference, until the resistance was so high that the ecu light comes on.

 

Then I screwed the knock sensors off the block, but the ecu light comes on and I'm in safe mode. I then realised that they were earthed through the block, so I wired them to the chassis, but the ecu light is still on 10 seconds after startup, and engine is in limp mode. I will try a stronger earth, but I think the ECU is reading zero noise and as such it's deciding that there is a faulty sensor.

 

either way, the FBW throttle and I are arguing, and it's an argument I intend to win...

 

my only other thought is that I could somehow mount the sensors somewhere less noisy, but I have a feeling that this will also end in frustration...

 

ALL ideas welcome!

 

come spring, I want a ghost free throttle...

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted

Oh dear..

I can see where this is going..

I have a mail on ryan's computer waiting to be answered about this subject already..

surely there must be something sneaky I can do to get round the stock knock sensors...?

they just need a nice quiet spot to keep them out of trouble.

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted
have you tried a new knock sensor, might but an intermitant fault with it

 

It's possible, but the correlation of the throttle fault with the 3rd party knock monitor spike, means that there is a det frequency noise somewhere, and the stock sensors are picking up something that the other knock system is picking up too..

 

a change in the stock sensors *may* make them less sensitive and help, but if I change them they will still pick up the same noise... and the problem will still remain...

 

I either need to

- get rid of the noise..

- put some ear mufflers on the sensors whilst not upsetting the ECU

- fit a mechanical throttle body

- fit an ecu that will run the fbw and the mapper can program around..

Link to comment
Share on other sites
Chris Wilson Experienced

Chris Wilson

Posted
Posted

When I fitted it I wired it into the Syvecs ecu, but I think this was removed before the car was sold, so I don't know what it has now.

 

http://www.gatesgarth.com/knock.pdf Shows how Motec look at knock frequencies before setting up a *00 series ecu to react to it, you can see what the sensors are seeing from this. It's a complex subjectCan you log anything with the V Pro? Can't you just turn off knock sensing?

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted

That motec link is very interesting, thanks for sharing.. it goes a long way to describing the noise and programming of the data it interprets...

Learned a lot.,

 

The Vpro in my car has a knock link, yet I believe (need to check) that it is locked into the stock sensors. It's possible that the v pro can advance and retard the map, (I can also do this manually through a rotary dial in the glove box!).

 

Yet the problem I have is with the stock ecu..

The stock ecu controls the throttle and VVTi, it is fed data by the stock knock sensors.. hence the shutdown..

 

all fuelling and ignition is controlled by the Vpro.. But throttle is all done with stock ecu.

 

So it's the stock knock sensors feeding data to the stock ecu that is causing the shutdown.

 

I pulled the sensors off the block but the ecu immediately shows the engine warning light, then I realised they need to be earthed, so I rigged something to the body.. But the light is still on..

 

You think the ecu can tell the sensors are not actially on the block??

 

I will earth them to the block directly on the next tinkering session.. I will also pull the fault codes to check exactly why the engine check light is coming on.. It's not been run for a few months.. Perhaps a mouse chewed through a different wire..

 

I know a tuner who could log the Vpro.. I do not have the softwear

 

I use a phormula knock sensor as a stand alone system with a 3rd and stand alone knock sensor on the block, this is where I see the peak hold value between gears. I will research and see if I can log this..

 

Again, any ideas on how to turn off the stock ecu sensors or mask them would be appreciated!!

Link to comment
Share on other sites
Ryan.G Newbie

Ryan.G

Posted
Posted
When I fitted it I wired it into the Syvecs ecu, but I think this was removed before the car was sold, so I don't know what it has now.

 

http://www.gatesgarth.com/knock.pdf Shows how Motec look at knock frequencies before setting up a *00 series ecu to react to it, you can see what the sensors are seeing from this. It's a complex subjectCan you log anything with the V Pro? Can't you just turn off knock sensing?

 

Not seen that document before. I can't see how MoTeC say it's only able to be setup by trained staff. It's on the level of basic knock on the Syvecs/life racing gear. Plus it's free with the Ecu and not hundreds of pounds extra!

 

Does not even do cylinder shutdown

 

Mike stop messing around with having so many box of tricks in the car. 2 x Ecu, external boost controller, knock and lambda amp, valcon cam controller, racelogic traction control.

 

Sell it all and buy a Syvecs S6 which does it all! It even controls the Toyota dbw unit. Do it once and properly.

 

I bet you find you make money also from all the bits you have.

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted
Mike stop messing around with having so many box of tricks in the car. 2 x Ecu, external boost controller, knock and lambda amp, valcon cam controller, racelogic traction control.

 

Sell it all and buy a Syvecs S6 which does it all! It even controls the Toyota dbw unit. Do it once and properly.

 

I bet you find you make money also from all the bits you have.

 

you know..

you are absolutely right :innocent:

 

I'll mail you for a quote.

The car is a real hodge-podge of different tech, and this system I have now is a fudge from the first install IMHO.

 

I think it will be an expensive install though, a lot of work....

Link to comment
Share on other sites
Mike B Newbie

Mike B

Posted
  • Author
Posted

For the sake of the thread and future readers I did test all fault codes held in the vvti ecu, using the thread "how to check the diagnostics codes"

 

There were 2 codes stored;

52 - you've taken the front knock sensor off and I can't hear the crank revolutions

55 - you've taken the rear knock sensor off and I can't hear the crank revolutions

 

they listen all the time, so you cant unscrew them, sneaky devils!

 

:-S

 

edit...

when I catch the piggy bank it will be a syvecs transplant.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.