2ZR Turbo Yaris

[06YarisRS]

Stuttering/ bucking at low boost

I've been doing some research on my bucking issue at moderate throttle between 1 and 3 psi. I compared the tuner's map and the basemap for TK. The fuel cell values in that area of the maps are identical, so not sure what's causing that since it started doing it after my tune. The tuner recommends adding some fuel in those cells. I"ll test drive, replicating the stuttering and monitor my AFRs. If lean, I'll add some fuel. The research I did suggests a couple possibilities. 1) radical changes in adjacent cells can cause bucking at certain loads, or 2) I need to wire in parallel a 2.2K ohm resistor between the crank mag wires. Apparently several turboed Scion cars have this issue. Boomslang started adding these resistors to there PnP harnesses around 2007. I have a 2008 Scion ECU.

[CrankyOldMan]

Oh man, I can hardly wait to see what happens when you've got it all sorted out! I remember the change from the stock 1.5 to the supercharger and also to the 1.8 being some next level stuff. Going from the stock 1.8 to boost will be insane, even at 160-170 whp.

[06YarisRS]

Originally Posted by CrankyOldMan

Oh man, I can hardly wait to see what happens when you've got it all sorted out! I remember the change from the stock 1.5 to the supercharger and also to the 1.8 being some next level stuff. Going from the stock 1.8 to boost will be insane, even at 160-170 whp.

Thanks Sam. I'll tell you right now that this car is already insane even at 4 psi. I was out today data logging and adjusting fueling to combat the studder I'm getting at part throttle. Check out my next post for some new info.

[06YarisRS]

More updates...

So, I was out datalogging today. I'll review those in a bit.

I have almost erradicated my stumble at part throttle at around 3100 rpm. I have been adding fuel to the cells which are highlighted when the car bucks. I still have one small buck to eliminate. Fortunately we have a good stretch of highway with hills, but it's still a challenge to drive, hold rpm and edit the table simultaneously. I don't really have anyone that could either drive - the way I need the car driven - or that could make the changes in the software. I'm going out again this afternoon, to kill - I hope - once and for all, the last stumble. It is a tricky process as when you make a change in one cell, the stumble might suddenly shift to the area represented by another cell (aka, different rpm and load). My fuel table looks crazy with fuel added and in many cells and radical shifts from once cell to the adjacent ones, so I'll be closely monitoring my AFRs to be sure I don't have any dangerous lean spots. I don't expect to as all I've been doing is adding fuel. AFRs where I've made the changes look good. That said, I'm going to confirm this with turbokits and my tuner before I go blasting around in boost.

The best news...I think...

For the first time today, I was driving around with my window open. As I enter boost, I can hear air hissing from the driver's side quarter panel. As the boost increases (and maxes at around 4 psi), the hissing gets louder, then my BOV releases when I come off the throttle. I HAVE ANOTHER BOOST LEAK! I think, or a vacuum line leak that's not keeping the BOV fully shut under boost. This is looking very promising. If I get this fixed (I'm still in the process of adding clamps to vacuum lines and will recheck all my T-clamps, I expect I'll see my full boost.

I will say that the car is positively nasty already at 4 psi. It pulls very hard and the wheel(s) (just one as I have no LSD) wants to spin at speeds over 30 - 40, km/h when it downshifts in boost, and I'm on a hill for example. I did, for the first time enter moderate boost (maybe 3 psi, moderate given my current max boost) in 2nd gear and it chirped the tires shifting to 3rd. I was really surprised. Honestly, I'm quite afraid of what this car will be capable of at 8 psi.

[CrankyOldMan]

Originally Posted by 06YarisRS

More updates...I will say that the car is positively nasty already at 4 psi. It pulls very hard and the wheel(s) (just one as I have no LSD) wants to spin at speeds over 30 - 40, km/h when it downshifts in boost, and I'm on a hill for example. I did, for the first time enter moderate boost (maybe 3 psi, moderate given my current max boost) in 2nd gear and it chirped the tires shifting to 3rd. I was really surprised. Honestly, I quite afraid of what this car will be capable of at 8 psi.

Sounds like you're ready for a MT swap!

[06YarisRS]

Originally Posted by CrankyOldMan

Sounds like you're ready for a MT swap!

I woud love to have Tom's 6-speed, LSD and all the goodies for the swap! Now, wouldn't that spice up my Yaris! Haha.

[06YarisRS]

Bubbles

As I mentioned earlier, I could hear a significant air leak coming from my driver's quarter panel area when I entered boost. It got louder the farther I went into boost. I think I got lucky and stumbled on the right combination of factors: I had my window down and I was test driving on a back road, so sounds were bouncing back off the trees. Otherwise I might not have even heard the leak.

So... I conducted more testing.

Using my mini compressor, I repeated my charge pipe pressure test. As before, it held 20 psi with ease and there were no leaks - the gauge stayed dead at 20. This is with the BOV removed and the port capped off.

Then I tested my vacuum/boost line that runs from the FIC MAP sensor to the BOV and gets its vacuum source from the brake booster line. The vacuum lines held 20 psi, no leaking, gauge didn't move.

So, we've established that there are no vacuum leaks, nor charge pipe leaks.

Finally, I reinstalled the BOV and tee'd off my compressor line so I could pressurize both the vacuum lines and the charge piping - simulating a manifold pressure boost situation. Unless, I'm doing something wrong (highly probable) or am not understanding fully how the system works (again, highly probable), I think my BOV is faulty. With both sides of the BOV pressurized, I have a significant leak with air bleeding from the BOV, until - guess when? - the pressure lowers to a little less than 5 psi and the gauge stays put. Hmmm... ~ 4 psi is the max boost I'm getting. I can't think of anything else, but it does really seem like I'm losing my boost - or not able to get to full boost - due to a leaking BOV. I passed this all by my tuner and he's pretty sure I've diagnosed this correctly. I've emailed the turbokits guys and I'm sure they'll have an answer for me. They are very attentative and bang on when it comes to support.

New testing apparatus



One hose from the compressor, one hose to the BOV and one hose to the F/IC MAP sensor



Lots of gushing air and bubbles with the BOV pressurized from both sides. The air is coming from the holes in the BOV, not my coupler/clamps.



Here's a pic of the schematic of my testing precedure:




On a positive note, I have pretty much erradicated my partial load stumbling at highway speeds. I did this by adding fuel in the active cells of the map where the stumbling occured. I still have one hiccup but could't get to it as my laptop battery died before I could eliminate that one. The changes have made for a pretty funky looking fuel map, but my tuner tells me that it is so vehicle dependent and that tuning it to address driveability issues is what's needed. He launched into a detailed explanation of closed loop vs open loop transitions, kilopascals and all kinds of other stuff that flew over my head. However, he says that many cars he's tuned have maps that are all over the place and that's perfectly fine if that's what the car needs. Of course, I do have to watch AFRs as I make changes, but I'm only adding fuel, not subtracting. Again, I'll bounce this off the turbokits guys as they're the experts.

[CrankyOldMan]

Having done zero research myself, I can't verify how accurate the wikipedia article is but it suggests that the MAF vs blowoff issue is fairly common and can be compensated for by placement of the MAF.

[06YarisRS]

Originally Posted by CrankyOldMan

Having done zero research myself, I can't verify how accurate the wikipedia article is but it suggests that the MAF vs blowoff issue is fairly common and can be compensated for by placement of the MAF.

Thanks Sam. Great read.

My BOV is before the MAF sensor, so a blow through system as opposed to a drwa through system. The kit, I believe, was designed purposefully as a blow through type. I found the SR20DET example interesting in the respect to the necessary relative position of each piece.

According to my tuner, we are basically trying to get a economy car to perform in ways that it was obviously not intended to and the hard part is reconciling the piggyback's and the ECU's handling of open loop and closed loop operations. I think I'm getting close to a good tune and I asked him if when we achieved a good tune for this car if it would remain stable. He said, "definitely". It will just take tweaking to make it 'perfect'. I'm still having some minor idling issues and overall the car is running a tad rich, evidenced by a bit of soot in the tailpipe. I do want to get this ironed out because not doing so could potentially result in high EGTs and issues with the cat converter. That said, it seems my car is rich only under vacuum conditions and relatively low power demands, so excess heat may not be an issue. I'll keep tweaking the fuel map.

Thanks again for the article!

[CrankyOldMan]

That's definitely the biggest hurdle--getting a closed-source ECU that will fight tooth and nail to optimize fuel efficiency to instead optimize power output. That's why standalone ECUs are a thing, or in the case of cars intended to be performance vehicles the manufacturer will make the ECU customizable (Ford Mustang, Chevy Camaro, etc.) with aftermarket profiles.

I think if I'm going to do another FI build on a Toyota engine I will go standalone. The MegaSquirt line of products is very well documented and even has native ECU connectors for some older models (Echo, MR2, Paseo, etc.) so I could start with an Echo 1NZ wire harness on a 1NZ and go from there.

I'm amazed at both the amount of effort this has taken and the dedication you've put into it. Most people wouldn't have even started this project and you've climbed some huge obstacles to make it happen. My hat is off to you!

[06YarisRS]

Originally Posted by CrankyOldMan

That's definitely the biggest hurdle--getting a closed-source ECU that will fight tooth and nail to optimize fuel efficiency to instead optimize power output. That's why standalone ECUs are a thing, or in the case of cars intended to be performance vehicles the manufacturer will make the ECU customizable (Ford Mustang, Chevy Camaro, etc.) with aftermarket profiles.

I think if I'm going to do another FI build on a Toyota engine I will go standalone. The MegaSquirt line of products is very well documented and even has native ECU connectors for some older models (Echo, MR2, Paseo, etc.) so I could start with an Echo 1NZ wire harness on a 1NZ and go from there.

I'm amazed at both the amount of effort this has taken and the dedication you've put into it. Most people wouldn't have even started this project and you've climbed some huge obstacles to make it happen. My hat is off to you!

Thanks very much, Sam! I'm compelled to do such things as I thoroughly enjoy tinkering and working at solving problems. It is frustrating at times but infinitely rewarding when things work out. I do hope that once the car is done that it will remain stable (the tune) and my tuner is convinced that this would be the case.

I too would go standalone if I did this again. I did have a great discussion with my tuner about the pros and cons of piggybacks and standalones. I have hockey practice with my son now but will elaborate in a bit.

[ern-diz]

Originally Posted by CrankyOldMan

I'm amazed at both the amount of effort this has taken and the dedication you've put into it. Most people wouldn't have even started this project and you've climbed some huge obstacles to make it happen. My hat is off to you!

+1000000

[06YarisRS]

Originally Posted by ern-diz

+1000000

Thanks ern-diz!

[Leegamer]

I agree, the amount of time, research, work, dedication to this build is outstanding.

This is what project cars are all about, trying new things and having fun.

[tmontague]

I agree with the above sentiments - kudos to you and your determination, it will pay off well in the near future

[06YarisRS]

Thanks Leegamer and Trevor! I appreciate it. I was away to my son's hockey school, but am now back ready to tackle the issues I'm having with my BOV. I repeated my tests again: No leaks in charge piping (holds 20 psi easily) independent test with BOV port capped. No leaks in vacuum source (hold 20 psi easily) with BOV installed. BOV leaks after ~4.5 - 5 psi when charge piping and vacuum line is pressurized simultaneously. I'm thinking I'll remove the BOV and cap the BOV port and vacuum line to the BOV and go for a drive. If I get over 5 psi, I'll pretty much know for sure it's the BOV valve.

Thanks again!

[Leegamer]

Nice detective work!

[06YarisRS]

Originally Posted by Leegamer

Nice detective work!

Haha, thanks. Unfortunately, with the BOV port plugged, I still max out around 4.5 psi and can hear air escaping. This is becoming very frustrating. I am next going to try and test my intake manifold gasket and throttlebody gasket. Ho hum...