Effects of killing one injector - 4 cylinders

[Vman455]

No oil consumption yet, at almost 80,000 miles....

[Fat Charlie]

My Fit lost almost 1/2 quart in a few days last week.

Turns out you need to put the 710 cap back on if you want the stuff to stay inside where it belongs.

[kurzer]

Originally Posted by hayden55

Yeah I'm not one to try it on the Prius. Car is too nice to be doing hanky mods.

and, there is no need to do it on a prius, since it has the best working point managment one can imagin.

[ME_Andy]

A V8 will shake quite a bit if you lose a cylinder.

Originally Posted by hayden55

Considering what most of my American cars have used over 7.5k that's fantastic. 😂

That's funny, my Cruze doesn't burn any oil.

[clarknova]

I had a cylinder misfire in my 1997 Saturn SL with a 1.9 (1.8?) L 4-cylinder engine during a road trip. I disconnected the injector so as not to be dumping raw fuel and drove another 500 km or so. Fuel economy for that leg of the trip was around 6 L/100 Km as I recall, which was typical for that car on 4 cylinders under similar conditions.

[Phantom]

I think you would have three methods for doing it and having the computer play nice.

1. Get a O2 spoofer these are usually are used to make the car think the CAT is still there or used when you do not want to spend the money on the post cat O2 sensor.
Wire up a switch so you can turn on the fake O2 when you turn off an injector. With some work you could possibly use one switch to do both.

2. Depending on how the exhaust is routed move the O2 to read only one bank so it does not see the deactivated injector. This would take more work and would not be able to adjust for unbalanced fueling on half the engine.

3. Depending on how the PCM/ECU operates it might be possible to change the tables it uses by adding a switch. That is only easily possible if it had something like "sport" mode available that already does that. IIRC some GM engines like the 3800 you could move the programming to Speed Density mode by disconnecting the MAF and I believe the system ignored the O2 for fueling and only went on MAP and RPM. The down sides not all PCMs had decent fueling tables in SD mode and you could not get back to standard fueling without turning the car off.

[hayden55]

"Three-cylinder Ecoboost petrol engine gets the ability to run as a twin under light throttle loads, improving fuel economy by up to 6%"

I swear a Ford fiest 1.0 ecoboost swap in an insight or civic crx would be a cool swap. Drop the frontal area about 40-50%. With a stage one tune you could have a 160hp triple and a 50hp twin good for ~55 mpg on the interstate.

[Shaneajanderson]

Originally Posted by Phantom

I think you would have three methods for doing it and having the computer play nice.

1. Get a O2 spoofer these are usually are used to make the car think the CAT is still there or used when you do not want to spend the money on the post cat O2 sensor.
Wire up a switch so you can turn on the fake O2 when you turn off an injector. With some work you could possibly use one switch to do both.

.

I don't think that would work, the O2 sensor in the manifold and the post cat O2 sensors are very different creatures: The post cat only determines if there's a difference fore and aft of the cat, whereas the one in the manifold actually gets a fairly precise stoichiometric reading.

Of course this could have changed on newer cars, I mostly work on pre-2010.

[Angel And The Wolf]

Originally Posted by RedDevil

The 'dead' cylinder would pump fresh air into the exhaust, so the lambda sensor will sense an overage of oxygen and the EFI computer will try to compensate by injecting extra fuel into the other cylinders.
.

Here's a strange thought. Run a pipe from the exhaust manifold to the intake of your chosen dead cylinder. Then, it would pump exhaust gas, just as if it were still firing. Don't forget to pull the wire on that injector, and block the intake air to that cylinder.

[RedDevil]

Originally Posted by Angel And The Wolf

Here's a strange thought. Run a pipe from the exhaust manifold to the intake of your chosen dead cylinder. Then, it would pump exhaust gas, just as if it were still firing. Don't forget to pull the wire on that injector, and block the intake air to that cylinder.

That would require a lot of fabrication on the intake and exhaust manifold.
Also it would compress the exhaust gas on the dead cylinders compression phase, which would entirely wipe out any possible gains.

So much easier to adjust the rocker arms to not open the valves at all, or leave one valve stuck open or even removed.