Bigger injectors = same flow???

[praivo]

Hi,

I'm running E85 and wanted to get rid of the piggyback I was using, so I went to eBay and bought a set of 1NZ injectors (23250-21020). As the 1NZ has about 1.5 times the displacement and power but probably about the same fuel pressure (44 to 50 psi for the 1NZ but I haven't found any numbers for the 1SZ, so it's just an assumption), I expected the injectors to also deliver about 1.5 times the amount of fuel which would be just right for E85.

So you can imagine my surprise when I installed them, took the car for a test drive, and saw the MIL come on with P0171 and the long-term fuel trim (after 3 starts) go as high as +40 %!

Does anyone has any idea what the hell is going on here? The only thing I can think of is that the new injectors are not, in fact, what they claim to be, but that doesn't seem too likely to me.

Thanks.

[Jeff Lange]

Based on my research, the 1SZ uses 160 cc/min injectors and the 1NZ uses 210 cc/min injectors. This is approximately 1.3x larger.

That said, there is a range of acceptable flow for both. On the low end of acceptable flow according to Toyota is 188 cc/min for the 1NZ injectors. On the high end of acceptable flow for the 1SZ injectors is 184 cc/min.

Jeff

[praivo]

Well, 30 % more would be enough, but I haven't noticed ANY increase in flow at all. Can't believe *both*¨sets could be right at the threshold... If I sell these things, are there any other injectors guaranteed to fit and flow 30 to 60 % more than the stock ones? 23250-22040 from a Corolla, maybe?

edit: Or should I get an adjustable fuel pressure regulator? That would be a more practical solution (because I would be able to decrease the pressure in order to use regular gasoline if needed), but I'm not sure how well the stock pump would handle the 25-30 % higher pressure.

[Fluxtasy]

don't you need some sort of ECU management for fuel flow?

http://www.yarisworld.com/forums/showthread.php?t=57887

[praivo]

I'm not looking for more power, all I need is hit the right AFR while keeping the engine bay looking as stock as possible. The car needs to pass the state inspection this summer and with these being one of the most common cars here obvious modifications will make it fail as soon as the guy looks at it. And I'd prefer not having to undo any mods and then redo them again after the inspection because I have a ton of other work (front suspension, rear muffler, brakes, and some bodywork) to do...

[Bluevitz-rs]

e85 needs an AFR of 9.8:1. You'll never be able to achieve this with the stock tune in your OE ECU. It is always trying to maintain 14.7:1, so with e85 you'll be running super lean no matter what injectors you're running.

stock 1NZ injectors are only rated at 190cc.

[Jeff Lange]

That's true. The only way you're going to get the stock ECU to not aim for that AFR is to get it stuck in open loop. If it's in closed loop and reading AFR's correctly, it's going to aim for its target AFR no matter the injectors.

Jeff

[praivo]

The ECU does NOT care about the actual AFR - all it wants to do is to reach lambda=1. Lambda is lambda, regardless of fuel. So the only thing I need is to increase the flow so that the ECU can its reach target lambda without having to increase the injector pulse width too much and freaking out, and the least obvious way of doing that is by using bigger injectors that spray more fuel.

[Jeff Lange]

The ECU does NOT care about the actual AFR - all it wants to do is to reach lambda=1. Lambda is lambda, regardless of fuel. So the only thing I need is to increase the flow so that the ECU can its reach target lambda without having to increase the injector pulse width too much and freaking out, and the least obvious way of doing that is by using bigger injectors that spray more fuel.

Is your 1SZ not equipped with a wideband O2 (A/F) sensor?

Jeff

[Bluevitz-rs]

Is your 1SZ not equipped with a wideband O2 (A/F) sensor?

Jeff

Pretty sure a 1SZ from 2000, only has a basic O2 sensor.

[Jeff Lange]

It appears you are correct.

Jeff

[Fluxtasy]

just switch back from E85 to petrol and see if there's a difference.

I swap my 1NZ injectors to 1ZZ injectors and it took about a full tank for ECU to fully calibrate them.