overheating, fuel cutout issues?

[mojoyaris]

Does anybody have any overheating or fuel cutout issues?

[Tamago]

can you be more specific ?

[supmet]

Does it overheat and then the fuel cuts off, or do they happen completely separate of one another.

[anonymous user]

I'm guessing separate events? Explain more of the fuel cutoff issue, or were you asking a Q. in general?

[toyota]

yeah be a little more specific
so we can help...

[mojoyaris]

Been away for awhile.
The car runs between 4500 rpm and 6700 rpm constantly at the track.
With the stock thermostat it over heats after a 15 minute hard run on the track and since the car runs lean, it seems to not get enough fuel.

I installed the TRD thermostat and better radiator cap for pressure and although it doesn't overheat, it will cut out when running the car hard, turning the car hard etc.
Basically if I run it 8/10's to 9/10 speed this way it will cut off the fuel or there is fuel starvation.
When I let off the throttle and drive it slowly, it will go back to normal and I can run again, but not for long. I basically have to give it a cool down lap before running hard, but this can be a problem when I'm timing a lap or something.

On day to day driving there is no problem. Only when driving at a Solo 1, time attack or track day. Especially on smaller tighter courses where I'm doing hard 2 to 3rd gear shifts.


I've got a few months to figure this out before I decide to enter the car in the Targa or not.

I'm thinking about getting bigger fuel pump. redo the air fuel management mapping
and bigger/better injectors.

[Biggie™]

I've done several(8-10) track days in my Yaris, some were on hot summer 103º days with track temps in the 130s... And I've never overheated the Yaris, nor had any fueling issues.

The overheating might be causing the ECU to go into limp mode, cutting power and giving the appearance of "fuel cut". Have you ever had your "fuel cut" problem when the car wasn't over heating?

I'd suggest replacing your aftermarket bumper with the stock unit and run another hard track day, there is a good possibility that the ducting/airflow is not as efficient as the OEM bumper. If less air is going through the radiator less heat will get whisked away.

And if that doesn't help, I've had good success cooling down overheating race cars with the addition of a well placed oil cooler.

[Tamago]

Been away for awhile.
The car runs between 4500 rpm and 6700 rpm constantly at the track.
With the stock thermostat it over heats after a 15 minute hard run on the track and since the car runs lean, it seems to not get enough fuel.

I installed the TRD thermostat and better radiator cap for pressure and although it doesn't overheat, it will cut out when running the car hard, turning the car hard etc.
Basically if I run it 8/10's to 9/10 speed this way it will cut off the fuel or there is fuel starvation.
When I let off the throttle and drive it slowly, it will go back to normal and I can run again, but not for long. I basically have to give it a cool down lap before running hard, but this can be a problem when I'm timing a lap or something.

On day to day driving there is no problem. Only when driving at a Solo 1, time attack or track day. Especially on smaller tighter courses where I'm doing hard 2 to 3rd gear shifts.


I've got a few months to figure this out before I decide to enter the car in the Targa or not.

I'm thinking about getting bigger fuel pump. redo the air fuel management mapping
and bigger/better injectors.

you don't need any of that stuff.

buy a MAF translator and just tweak the MAF signal to trick the ECU into giving you a few percents more fuel at your target RPM.

http://www.horsepowerfreaks.com/partdetails/Full_Throttle/Electronics/MAF_Translators/Gen_2/15418

[Biggie™]

buy a MAF translator and just tweak the MAF signal to trick the ECU into giving you a few percents more fuel at your target RPM.

Too bad the Yaris ECU will learn around that in about 5 minutes and render it useless...

[Tamago]

Too bad the Yaris ECU will learn around that in about 5 minutes and render it useless...

.. not if you know what you're doing ;)

[Biggie™]

.. not if you know what you're doing ;)
Um, no... More to the point that fuel is obviously not his problem, but whatever.

[Loren]

It is stated that the car is overheating. How do you know that? What is the actual temperature? Is the ECU storing any fault codes?

The only time I got any behavior of that sort from my car, it was due to a bad spark plug causing misfires at very high revs. (banging the rev limiter in 3rd coming out of turn 17 at Sebring) In my case, it would sometimes toss a misfire code, and a couple times it must have been so bad that the ECU just shut down and went into limp mode until I restarted the engine.

A new set of standard (non-unobtanium) NGK plugs fixed that problem.

So, be certain of what you're dealing with. If the car IS overheating, then fixing the fuel system surely isn't going to cure THAT problem.

You didn't mention what mods you have on the car. It seams reasonable to assume that you're turbo or supercharged with the way you're talking about fuel management... but I think some people here are assuming that you're stock.

What are your mods? What are your ACTUAL engine temperatures? What else do you know about this problem that you're having? Approach it logically and you'll find your solution.

[Biggie™]

What are your mods?

Good question, I was just going off the information in your Yaris World garage. Is that current?

[Tamago]

Um, no... More to the point that fuel is obviously not his problem, but whatever.

he asked how to add fuel, i told him. i never said THAT's why it's overheating..

[thepoche]

I had the fuel cut off or ECU in limp mode thing happen to me on a track day. The car would not accelerate at all, either coast or slow down and then the check engine light came on. I pulled off the track and waited for the session to be over and everything was fine afterward.

I checked the Error codes after and had two new ones.
I don't remember the actual codes but the description was along the line of "Camshaft position sensor out of range" and another one for O2 sensor temperature.

I cleared them and they never came back. I never saw the Coolant temp light, so I assume the engine was not overheated.

I'm not sure what caused this but I know I was pushing the Yaris really hard trying to follow a WRX :biggrin:

[Tamago]

sad that the yaris is so VW'y

[mojoyaris]

I'm back after another test run getting it prepped for the Targa.

On long fast runs it's ok. But on short tracks with lots of 2nd to 3rd shiift it's another story.

Stock Thermostat it ran 225 degrees plus. Red line is 210 degrees.
With the new thermostat the water temp stays @ 210, so this is good.
Oil temp is @ 210 and stays pretty cool. So no need at all for oil cooler.

MAF sensor issues etc not really a problem. But what I think it is is the ECU runs the car lean and at VVTI it's not putting in enough fuel after an extended period of driving.

The front end actually gives me alot of air and vents it out through the top of the hood and below. Lots of cold air to the brakes (never had overheating brake issues--- compared to the stock bumper).

Stock bumper will most likely go back on for the Targa with new suspension setup.

Engine has no SC or Turbo, but this may be changed in time for the Targa and hopefully get some more testing in before then. By that time, injectors, and ECU etc will be modified for distance running so the car won't be running in fuel economy mode anymore.
(Piggybacks will also be added).
This may also include getting rid of the Drive by Wire system as well :)

but then again, if Toyota Canada can get me the ride with a stock Yaris, I'll use that instead :)

Geez, motorsports sure isn't cheap.
Some of the guys in Japan have proposed I use the ECU from Japan for the turbo model.
I'm not sure about this, but they'll be sending me info later. We'll have to see what happens.

Thanks for all the input.
If you guys ever come to Japan, check out the Vitz challenge series.

[kurokoma-kun]

Basically if I run it 8/10's to 9/10 speed this way it will cut off the fuel or there is fuel starvation.
When I let off the throttle and drive it slowly, it will go back to normal and I can run again, but not for long.

The only time I got any behavior of that sort from my car, it was due to a bad spark plug causing misfires at very high revs. (banging the rev limiter in 3rd coming out of turn 17 at Sebring) In my case, it would sometimes toss a misfire code, and a couple times it must have been so bad that the ECU just shut down and went into limp mode until I restarted the engine.


I had the fuel cut off or ECU in limp mode thing happen to me on a track day. The car would not accelerate at all, either coast or slow down and then the check engine light came on. I pulled off the track and waited for the session to be over and everything was fine afterward.

I got this the other week, when I was absolutely hammering it on a long uphill straightaway in 3rd gear and overboosted a bit (to about 9 psi) :tongue:. At that point I got a flashing CEL and no acceleration that lasted as long as it flashed, maybe 15 sec. No codes though, no overheating, no other issues. So... this is a misfire, you think?

[mojoyaris]

The engine is setup to run lean. I think it's the ECU doing it's bit.
after running the car hard, it just runs out of fuel. Kinda like vapour lock.
The car comes back to life. It's like the ECU and the fuel pump is not able to keep up with the flow that is needed when running at VVTI all the time.

[jkuchta]

Try water-wetter....I have it in mine, and I've done trackdays WFO in 2nd-4th gears with no problems...I've never seen water temps go above 190 in the track, even after a 25 min. session at the streets of willow spent almost entirely above 5,000rpm.

[CpKi1g3]

Been away for awhile.
The car runs between 4500 rpm and 6700 rpm constantly at the track.
With the stock thermostat it over heats after a 15 minute hard run on the track and since the car runs lean, it seems to not get enough fuel.

I installed the TRD thermostat and better radiator cap for pressure and although it doesn't overheat, it will cut out when running the car hard, turning the car hard etc.
Basically if I run it 8/10's to 9/10 speed this way it will cut off the fuel or there is fuel starvation.
When I let off the throttle and drive it slowly, it will go back to normal and I can run again, but not for long. I basically have to give it a cool down lap before running hard, but this can be a problem when I'm timing a lap or something.

On day to day driving there is no problem. Only when driving at a Solo 1, time attack or track day. Especially on smaller tighter courses where I'm doing hard 2 to 3rd gear shifts.


I've got a few months to figure this out before I decide to enter the car in the Targa or not.

I'm thinking about getting bigger fuel pump. redo the air fuel management mapping
and bigger/better injectors.

just take off the thermostat my friend did it on his supra and ran much cooler.

[mojoyaris]

just take off the thermostat my friend did it on his supra and ran much cooler.
Overheating is not the issue anymore. Not with the TRD thermostat.
It's the fuel cutout. This should be fixed later on.

Thanks everyone for their input.