2ZR Turbo Yaris

[heeroyuy01195]

Can you describe the idle issues and the bucking a bit more? Glad you found the source of the leak! I would definitely invest in boost gauge to keep an eye on things.

[06YarisRS]

Originally Posted by heeroyuy01195

Can you describe the idle issues and the bucking a bit more? Glad you found the source of the leak! I would definitely invest in boost gauge to keep an eye on things.

Sure can.

Idle:

Idle is perfect and smooth (around 750 rpm) when the car is below operating temps. It is always hard to start. It takes a few cranks and often requires messaging the throttle in the first few seconds to keep it running. Usually two or three light shots of gas will get it over this hump. My suspicion is that it's very rich at startup - but I could be wrong. Then it settles out into a nice idle. Once it's up to operating temps at idle in neutral or "D", it will intermittently feel like it is going to stall (rpms drop quickly but only for a fraction of a second), then immediately recovers. This intermittent stumbling only happens at idle and occurs every minute or two and sometimes every few minutes. By this time the idle is around 550 - 600 rpm (a bit slow). If I turn my A/C on at this point and put it in drive, it may stall, but not always. Under these conditions it has stalled in reverse as I believe that puts more load on the engine. Before I installed the 440cc injectors, I had no idle issues whatsoever, and it literally ran like stock at idle. I really need to get this issue resolved because it's dangerous at intersections etc in the city as the car might stall when approaching or stopped at a stop sign/light. Then, of course I lose power steering assist and possibly some braking.

Bucking (this did not happen at all before my tune):

If I am driving on the highway at around 110 - 120 km/h under light throttle and encounter a slight grade, the car will start to buck a bit (seems like misfire, which would corroborate the P0303 code). If I apply even the slightest extra throttle when the 'misfire' is occuring, it will completely stop the hesitation and run perfectly.

I plan to do some data logging with the F/IC software. I'll also monitor the fuel cell data while I recreate the 'misfiring'. My tuner said that I would probably have to add some fuel at those points.

Rich AFR:

90% of the time the car runs at, or close to stoich - except of course in boost when the AFR richens purposefully. When I am decelating (basically with my foot just resting on the pedal at low speeds - or to maintain low speeds speed - say coming down from 60 km/h), the AFRs may jump up as high as the high 12s, but most often something like 13.4 - 13.8. Under these conditions, there is no difference in how the engine performs, sounds or feels. If I just tap and release the throttle under this light deceleration, the AFRs will drop to the expected 18.12.

Overall, the car must be running rich as I have black soot in the tail pipe. And, maybe my misfire is related to plug fouling, but not sure about that as the misfiring occurs only under very specific conditions as mentioned in the first paragraph.

A local parts store has a vacuum gauge that can go up to +10 psi. I'm grabbing that today, plumbing into my vacuum lines, running the tubing through my window and will see what it tells me.

MAF:

I can monitor MAF voltages in the F/IC software. It will you show you MAF input and MAF output voltages. It does look like the F/IC is adjusting the voltages as there are subtle differences between the input and out voltages. I am wating to hear back from AEM as to whether the F/IC seeing the voltages indicates that the MAF wiring is hooked up properly. My tuner does think that the MAF may be messing somewhat with my boost/contributing to my idle issues.

Finally, I have a B1S2 (rear O2 sensor) code (P0137), I believe. I am basically catless as the cat is after the rear O2 sensor. I had them weld the cat in as a 'resonator' of sorts. I've fixed this issue before by adding sparkplug defoulers to get the O2 sensor back out of the exhaust stream a bit. This did not work for this car. Although voltages generally fluctuate between 0.1V and 1.0V, it will occasionally spike above that, which I believe is setting the code. I did read that the rear O2 sensor does influence AFR in this car, so maybe it's related to my issues too. In Torque I can data log, so I'll figure out how to get it to monitor O2 sensor voltage and a couple other paramters at the same time. Maybe it will give me some insight into what's going on. I did fiddle with the fuel map, taking out some fuel at the rich points and it did appropriately affect the AFR, leaning it a bit. But, I'm not sure how this would affect AFRs in the opposite direction - aka, accelerating.

I have asked my tuner if we can do a street tune and he's up for that.