Who changes filters between oil changes

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Has there been a paper on why GDI are causing fuel dilution? Given that the fuel is injected near the top of the compression stroke - and maybe in two shots for a stratified charge. I don't understand the mechanism for sump dilution over a PI fueler.
Does the gas wash on the cylinder walls in a PI engine help create a ring seal that is now missing on the GDI? It's got to be more than just injection pressure issue - the atomization must be better in GDI and the particle KE has to be less given the lower mass, so I don't think it's a "pressure wash past the rings" scenario.

Thoughts?

With a PI engine the fuel has vaporised inside the manifold, before entering the compression chamber. Those engines tended to wet the walls of the intake manifold.

DI engines spray liquid fuel into the compression chamber. If the fuel doesn't vaporise quickly enough, there's liquid fuel reaching the cilinder walls eventually. That mixes with the oil present there, and won't heat up much beyond the cilinder wall temperature. That temperature isn't much higher than the coolant temp.
 
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Yesterday i changed the oil with filter on my car and again there was some soot like material in the filter.
I also checked the VANOS/VVT filters but luckely those where perfectly clean so the oil filter is doing its job.

This car burns about a quart every 2200miles, i am not sure that because of the high oil consumption also means that a lot of combustion soot enters the oil past the pistonsrings? This does not seem possible to me, however with all my oil changes theres soot in the filter.

I have not ever had this with other cars where most of the time the filter came out like new and could indeed also be reused for 2nd oci. (although filters are so cheap i always replace them)

Because the filter is only like 8 euros i will probably change the filter again at 5000 miles.
As i said its located on top of the engine and is changeable within a minute.

Do a leak down test to see how much exhaust gas is getting pas the rings. Maybe a simple compression test can give you a clue aswell
 
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15,873
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N.H, U.S.A.
With a PI engine the fuel has vaporised inside the manifold, before entering the compression chamber. Those engines tended to wet the walls of the intake manifold.

DI engines spray liquid fuel into the compression chamber. If the fuel doesn't vaporise quickly enough, there's liquid fuel reaching the cilinder walls eventually. That mixes with the oil present there, and won't heat up much beyond the cilinder wall temperature. That temperature isn't much higher than the coolant temp.
Thanks for your answer Jet, - but I'm really looking for a white paper from BOSCH engineers or others as this appear to be a deleterious phenomenon and it must have been studied and reported.
This is my take. Pi is (relatively) low pressure nozzle injection during valve opening event and the resulting droplets will be larger than DI - plus the injection is near the valve bowl and is timed so it will get carried by a supersonic air column with various states of the charge modified on the way in. There may be improved atomisation over a valve lip or seat and then maybe condensation at other parts.
Alternatively The Di is injected near the top of a comparatively high compression stroke to cool the now (partial) adiabatic heated charge and vaporise the fuel, with the piston at the top of its travel, there may be a second quick pulse to have a rich stratified charge near the ignition point. This D.I process seems properly efficient and with low fuel wash.
So I'm not seeing the mechanism in the described scenario, but i'm sure i have not describe all injection scenarios applied in practice.
just light-to-med light-throttle cruise operation near stoiciometric. Maybe full enrichment injection has intake event injection
added - though there may be risk of detonation here given high compression / low AKI fuel.
- Ken
 
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15,873
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Actually injection is typically done while the intake valve is closed.
Fuel evaporates off the valve and port area before the valve opens.
I can see it mapped to start early BTDC at High RPM due to time and volume, but not at lower RPM.
With a typical Ex. over lap, that's going to be patially scavenged, Unless VVTi with no over lap at low rpm,
I would not risk agglomeration and condensation of a good atomisation.

Circuitsmith, have you mapped a engine using a piggy back or custom ECU? Just curious about your statement.
 
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5,375
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Thanks for your answer Jet, - but I'm really looking for a white paper from BOSCH engineers or others as this appear to be a deleterious phenomenon and it must have been studied and reported.
This is my take. Pi is (relatively) low pressure nozzle injection during valve opening event and the resulting droplets will be larger than DI - plus the injection is near the valve bowl and is timed so it will get carried by a supersonic air column with various states of the charge modified on the way in. There may be improved atomisation over a valve lip or seat and then maybe condensation at other parts.
Alternatively The Di is injected near the top of a comparatively high compression stroke to cool the now (partial) adiabatic heated charge and vaporise the fuel, with the piston at the top of its travel, there may be a second quick pulse to have a rich stratified charge near the ignition point. This D.I process seems properly efficient and with low fuel wash.
So I'm not seeing the mechanism in the described scenario, but i'm sure i have not describe all injection scenarios applied in practice.
just light-to-med light-throttle cruise operation near stoiciometric. Maybe full enrichment injection has intake event injection
added - though there may be risk of detonation here given high compression / low AKI fuel.
- Ken

PI doesn't have to and often doesn't inject when the intake valve opens. They started PI with batch injection, all injectors fired at the same time. This meant there were 3 injections on a closed intake valve. This fuel has a lot of time to vaporise.

sequential injection fires only once per 2 cycles, but you still don't need to do it with open intake valve. Back in my megasquirt days i remember that not injecting during intake stroke was better for smoothness.
 
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193
Location
Ontario, Canada
I've only done it once as something hit the filter driving down the highway in my Jeep :oops:

jeepoilf.jpg
 
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