Interesting article on direct vs port injections

[ThunderDent]

http://blog.caranddriver.com/explain...mag=cdb&dom=fb

http://blog.caranddriver.com/explain...mag=cdb&dom=fb

[MSq5]

Thank you for the interesting post and link.

Im new to Audi and my direct injection 2017 3.0T Q5. But, I'm not new to direct injection gasoline forced induction engines. My "other car" is an '08 Mazdaspeed 3 with its direct injection turbo 2.3L four. I bought the car new in the spring of '08 and have enjoyed it for 140,000 mostly trouble free miles of very spirited driving. It has been modified with after market intake, exhaust and tune, up about 100 whp over stock. Direct injection forced induction engines respond well to tuning and flow increases. The added cylinder cooling from lower AFR highly atomized high pressure direct injection permits higher timing advance at the same boost level. That means more power at high rpm high load conditions.

My issue with direct injection is the build up of hard carbon on the back of the intake valves. This is common to DI engines. I knew this when getting the 3.0T. The only current solution is repeat access to the intake cylinder head ports for chemical or walnut cleaning or equivalent.

This is because no fuel reaches the back of the valves to clean them, as fuel in injected only into the cylinder. The EGR system belches unburned exhaust gasses, high in carbon, back into the intake manifold to try to reburn it. This gunk collects on the back of the valves. Combustion heat is transferred through the valve from cylinder side to intake side and bakes that carbonized gunk onto the back of the valve. Hard as rock. Fuel additives don't come through the intake, so stuff designed to clean valves never touch it. Chemicals injected through vacuum lines that do reach the valves (Seafoam etc.) are not there long enough to touch it.

The carbon builds up until it obstructs air flow, power decreases, and other adverse effects occur.

I've manually cleaned the intake valves three times on the Mazda and it is due again. You can see the decline in g/s air mass flow on data logs.

What excites me is that a secondary port injector for part throttle operation could spray fuel that would, indeed, reach and clean the back side of those valves, something I didn't see C&D mention. That would be a huge benefit.

But wait . . . then Audi could not charge an arm and leg to clean our valves if we don't want to pull the supercharger to get to them ourselves.

[agautohaus]

There's another solution... Run W/M and balllll the fuck out on intake air temps and powaaaa (and clean valves)

(w/m is not necessarily port injected, though it can be for big power applications, but it is injected prior to cylinder which cleans the valves)

[bloodstar57]

Thank you for the interesting post and link.

Im new to Audi and my direct injection 2017 3.0T Q5. But, I'm not new to direct injection gasoline forced induction engines. My "other car" is an '08 Mazdaspeed 3 with its direct injection turbo 2.3L four. I bought the car new in the spring of '08 and have enjoyed it for 140,000 mostly trouble free miles of very spirited driving. It has been modified with after market intake, exhaust and tune, up about 100 whp over stock. Direct injection forced induction engines respond well to tuning and flow increases. The added cylinder cooling from lower AFR highly atomized high pressure direct injection permits higher timing advance at the same boost level. That means more power at high rpm high load conditions.

My issue with direct injection is the build up of hard carbon on the back of the intake valves. This is common to DI engines. I knew this when getting the 3.0T. The only current solution is repeat access to the intake cylinder head ports for chemical or walnut cleaning or equivalent.

This is because no fuel reaches the back of the valves to clean them, as fuel in injected only into the cylinder. The EGR system belches unburned exhaust gasses, high in carbon, back into the intake manifold to try to reburn it. This gunk collects on the back of the valves. Combustion heat is transferred through the valve from cylinder side to intake side and bakes that carbonized gunk onto the back of the valve. Hard as rock. Fuel additives don't come through the intake, so stuff designed to clean valves never touch it. Chemicals injected through vacuum lines that do reach the valves (Seafoam etc.) are not there long enough to touch it.

The carbon builds up until it obstructs air flow, power decreases, and other adverse effects occur.

I've manually cleaned the intake valves three times on the Mazda and it is due again. You can see the decline in g/s air mass flow on data logs.

What excites me is that a secondary port injector for part throttle operation could spray fuel that would, indeed, reach and clean the back side of those valves, something I didn't see C&D mention. That would be a huge benefit.

But wait . . . then Audi could not charge an arm and leg to clean our valves if we don't want to pull the supercharger to get to them ourselves.

I thoughtToyota incorporated another series of injector to stop the build but I could be wrong. I posted a thread on here years ago when i did the BG cleaning on the B7 A4; i had before and after pictures. The cleaning system works for sure. If kept on a scheduled cycle, carbon build up should not be an issue, if you don't run a WM system.

There's another solution... Run W/M and balllll the fuck out on intake air temps and powaaaa (and clean valves)

(w/m is not necessarily port injected, though it can be for big power applications, but it is injected prior to cylinder which cleans the valves)

I was running WM before the cleaning and it did not remove present carbon build-up. However, after the cleaning WM kept the carbon build up accumulating.

[Audibot]

Some of the newer Audis also have port injection as well as direct injection. I believe the new A4/5 do, based on their Miller Cycle (or whatever they are using now). It helps with the valves as well as some instances when direct injection is not optimal.

[BierJager]

Thank you for the interesting post and link.

Im new to Audi and my direct injection 2017 3.0T Q5. But, I'm not new to direct injection gasoline forced induction engines. My "other car" is an '08 Mazdaspeed 3 with its direct injection turbo 2.3L four. I bought the car new in the spring of '08 and have enjoyed it for 140,000 mostly trouble free miles of very spirited driving. It has been modified with after market intake, exhaust and tune, up about 100 whp over stock. Direct injection forced induction engines respond well to tuning and flow increases. The added cylinder cooling from lower AFR highly atomized high pressure direct injection permits higher timing advance at the same boost level. That means more power at high rpm high load conditions.

My issue with direct injection is the build up of hard carbon on the back of the intake valves. This is common to DI engines. I knew this when getting the 3.0T. The only current solution is repeat access to the intake cylinder head ports for chemical or walnut cleaning or equivalent.

This is because no fuel reaches the back of the valves to clean them, as fuel in injected only into the cylinder. The EGR system belches unburned exhaust gasses, high in carbon, back into the intake manifold to try to reburn it. This gunk collects on the back of the valves. Combustion heat is transferred through the valve from cylinder side to intake side and bakes that carbonized gunk onto the back of the valve. Hard as rock. Fuel additives don't come through the intake, so stuff designed to clean valves never touch it. Chemicals injected through vacuum lines that do reach the valves (Seafoam etc.) are not there long enough to touch it.

The carbon builds up until it obstructs air flow, power decreases, and other adverse effects occur.

I've manually cleaned the intake valves three times on the Mazda and it is due again. You can see the decline in g/s air mass flow on data logs.

What excites me is that a secondary port injector for part throttle operation could spray fuel that would, indeed, reach and clean the back side of those valves, something I didn't see C&D mention. That would be a huge benefit.

But wait . . . then Audi could not charge an arm and leg to clean our valves if we don't want to pull the supercharger to get to them ourselves.

Funny I'm new to Audi as well having just bought a 2016 Q5 3.0T and I also had a 2009 MS3. We both understand the dilemma with direct injection and carbon buildup particularly on turbo applications. Performance impacts aside, a primary I issue I have read about with Ford Ecoboost in particular is cold, low speed drivability . An induction service can clean the valves and correct it but the resulting heat that creates in the turbochargers often destroys them. Fords solution is replace the cylinder head(s)!
The MS3 was subject to the same risk, unburned fuel overheating the little K04.

I figure since my 2016 is supercharged it may be possible to get an induction service to clean up carbon deposits on the backs of the valves without having to tear the motor down. Can any other forum members corroborate that idea?
And I'm fairly certain ( I'm a NEWB here ) the 2017 3.0T is turbo and not supercharged yes?

I have a number of other questions I will post in another thread but I really like our Q5 and it was interesting to hear about this concern coming from another former owner of a MS3.