I have the AJ16 engine and I added an oil catch can a few years back. It has kept everything in front of the throttle body butterfly plate clean as a whistle, however, there is still quite the collection of soot on the engine side of the butterfly.

What is causing that? I always thought the throttle body got dirty from the camcover breather hose. Looks like the oil catch can doesn't really eliminate the need for occasional removal and cleaning?

 

The EGR will always introduce CARBON into the intake.

 

Have you also disconnected the thin hose on the intake manifold just behind the throttle body?

 

No, that remains. My hose routing tees from the camcover breather to the thin hose you pointed out one way and the oil catch can the other.

 

I also disconnected the small hose on both AJ16 4.0 blocks. With one I have an oil cats can and with the other a dipstick modification. This one with the oil cats can still be clean after fifteen years, but it has no EGR. The other one, with EGR, is also reasonably clean after five years.

 

My engine has the EGR.

The EGR feeds gases into the exhaust manifold, right?

If I plug up the "small hose"...I don't think there should be any effect to the engine, right?

 

The EGR feeds exhaust gases to the intake manifold.

Disconnecting the small hose has no effect on the engine running.

 

Thanks for that. I guess that’s why they call it a Exhaust Gas Recirculator. Duh.

If I disconnect the small hose, I guess all breathing occurs through the catch can then? I have to say that the can has not been catching a ton of oil, perhaps it’s been going towards this small hose and into the intake manifold.

Thanks again.

 

It is not only oil but also a lot of condensation water that enters the tank. Bit dependent on car use, but empty every 5000km.

Original is the small hose for oil and condensation to be drained behind the gas valve and the thicker hose for the air outlet in front of the gas valve.

If you connect the outlet of your cats can back to your inlet, the condensed water will still go into your inlet before the gas valve, so even worse than original.

 

Thank you Keesh, I have disconnected the small hose and blocked it off.

Everything seems to be running fine. I replaced the tee with an elbow and all is well!

One last question. Where did you vent your oil catch can? Did you send it back to the intake elbow, or is it just vented to the open air?

 

It is just vented to the open air. Not legal according to MOT, but inspectors have never seen or noticed it in 15 years.

 

That's what I did too! just attached a hose to it and ran it down so it vents somewhere under the car.