Fuel injector change for FE...

[t vago]

Yesterday, I changed out the fuel injectors on the Karen-Mobile. The old injectors were of the 4-hole variety,and were likely the original injectors that have about 235K miles on them. The new ones were more of the 12-hole injectors of the type I already installed into my wife's Durango. Both have the same rated flow rate of 24.0 lbs/hr.

It's certainly possible that my old injectors were misbalanced and dirty to the point where they'd negatively impact fuel economy, so I am not ruling that out, but...

Normally, on my 19 mile drive into work, I would reliably get anywhere between 24.8 and 25.3 MPG. Nice, steady-state conditions (at least once I get out of the Cedar Rapids city limits, anyhow), little traffic, and weather conditions this time of year appear to be fairly steady.

I got 28.2 MPG this morning, with the new injectors. That's a 12.8% increase in fuel economy.

[ar5boosted]

Yeah, good to know this information.

My old mechanic was telling me for a while there that I should upgrade engines because the injectors on the newer engines were better. I was just thinking to upgrade the injectors, like this.

Thanks for putting actual numbers on the upgrade, it's useful.

[t vago]

I think that part of my gain is due to the already-installed coolant-based warm air intake. The fuel fog generated by the new injectors is pushed further toward a gaseous state by the warm air (about 40 F above ambient temperature).

This morning saw a 27.8 MPG trip fuel economy.

[oil pan 4]

I have read that going from first gen single hole, or early multi hole to post 2000s injectors can be good for up to around a 10% boost in fuel economy.
Now I believe it.

[Baltothewolf]

Doesn't surprise me one bit. The more holes, the better the vaporization, the more the fuel gets burnt, the more power you make for the same amount of fuel, thus the less throttle you have to use to make the same HP. All this equates to less fuel overall being used, and a bump in fuel economy. I'll bet your idle is smoother, and your on/off throttle transitions are smoother.

I can feel the hood of the car and feel misfires. When I installed bigger injectors on my insight, that are of a significant bigger size (flow rate) and 12-hole vs the 4 hole that stock is, I felt the smoother idle on the hood.

[t vago]

Originally Posted by Baltothewolf

Doesn't surprise me one bit. The more holes, the better the vaporization, the more the fuel gets burnt, the more power you make for the same amount of fuel, thus the less throttle you have to use to make the same HP. All this equates to less fuel overall being used, and a bump in fuel economy. I'll bet your idle is smoother, and your on/off throttle transitions are smoother.

This.

I also have to blip the throttle a lot less when maneuvering into parking spaces. In fact, this morning, all I had to do was modulate the clutch to back into a spot. It's also pretty neat to be able to accelerate to the parking lot speed limit of 15 MPH on the way home, also without having to touch the gas pedal at all.

Originally Posted by Baltothewolf

I can feel the hood of the car and feel misfires. When I installed bigger injectors on my insight, that are of a significant bigger size (flow rate) and 12-hole vs the 4 hole that stock is, I felt the smoother idle on the hood.

It should be a lot quieter too. The Karen-Mobile idles much more smoothly and quietly. I actually had to check to make sure my engine was still running, when I first stopped at a light while test-driving these new injectors.

[oldtamiyaphile]

Looking at my Proton, it appears to have only two hole injectors

How would I go about finding suitable replacements? Are they all broadly interchangeable?

The stock injectors are 180cc, what would happen if I went to say 200cc? The ECU should be able to compensate, some say it will run rich, but surely that's what the O2 sensor is for?

At around $200 for a set of four, it's a pretty good investment, particularly if there are ancillary benefits.

[oil pan 4]

They are broadly interchangeable.
There were at one point 2 main styles and 2 different resistance values in all kinds of different injection rates.
Could be more out there now.
So you only needed to lean the 3 main parameters of your injectors, the style, resistance and flow rate used on your older vehicle and find a newer generation of that injector with those same specifications and make sure they haven't changed the electrical connector.
As the injector internal design changed and got better the outward foot print and coil resistance stayed the same.
I don't recall the injector style types and improvements they gained over the years, I used to keep track of that stuff but I have shifted back to carburetors.

[cRiPpLe_rOoStEr]

Seems like the spraying pattern and pressure are more important than the amount of holes in an injector nozzle, even though multi-hole nozzles fare better on those matters.

[oil pan 4]

The pressure has maintained a pretty steady 3 atmospheres above manifold pressure for many years, starting in the mid 1980s into at least the late 2000s.
3 bar may still be the standard for non GDI engines.
I just don't follow it like I used to.

You could put on a lower rate injector and turn up the pressure.