GDI engines suffer dirty intake valves?

[user removed]

We used to buy the 1963-66 Plymouth Valiants (slant 6s) with plugged up PCV valves cheap, since the POs thought the motor was gone when they used a quart of oil in less than 400 Miles. Unplug or replace the hose and clean the valve out with gasoline and oil consumption went to 1500 miles a quart or higher. A lot of the grunge was due to parrafin based oils and poor oil change habits from people who were just stupid.

I am hoping the wifes GDI Sorento does not give us problems, but if so the intake manifold is fairly easy to get to for a valve cleaning, but we would probably just get rid of the car. I have been trying to get her into something more economical, but she thinks the height of her seating position gives her an advantage in accident avoidance, and she is paying for her gas, but most of the time she just rides with me in the Fiesta when we go somewhere together.

I did notice the oil in her Sorento gets a lot more dirty than the oil in my Fiesta. I might drop the change intervals to 5k instead of 7.5k.

regards
Mech

[LeanBurn]

Direct injection oil issues are frequent topic of conversation at BITOG. GM even adjusted their oil life monitors on DI engine cars to try to compensate for the issue. Whether it works remains to be seen.

[some_other_dave]

Originally Posted by Old Mechanic

I would suspect based on experience that PCV by itself might not be a problem as long as there is no recirculation of EGR. ...
Maybe the fuel injectors spraying onto the intake valves kept that area clean versus DI that would not.

The latter is the consensus view among MINI owners, at least. And it makes sense--gasoline is a pretty decent solvent, so having a nearly constant supply sprayed into the intake ports would tend to wash away any stuff that would try to build up. DI engines have no such cleaning spray. (Though as may have been mentioned, there are setups that also inject fuel into the manifold in part to help with the buildup!)

Rumor has it that other makers of DI engines are going to larger and more elaborate PCV systems to help separate out oil vapors, due to the carbon build-up problem.

-soD

[cRiPpLe_rOoStEr]

Originally Posted by some_other_dave

Rumor has it that other makers of DI engines are going to larger and more elaborate PCV systems to help separate out oil vapors, due to the carbon build-up problem.

With an EGR delete, the oil vapors are the lesser problem. But the EGR fumes stick into them, so it acts like a binder.

[user removed]

Yep, the first EFI Z cars (1975-76 federal) did not have EGR valves. The intake manifolds were super clean. When they added EGR everything inside the manifold downstream of the egr entrance was covered with a tar like residue, except the intake valve stems where the injectors sprayed fuel.

regards
Mech

[cRiPpLe_rOoStEr]

Water+meth injection decreases the incidence of that tar deposits in the manifold.

[rmay635703]

Originally Posted by cRiPpLe_rOoStEr

Water+meth injection decreases the incidence of that tar deposits in the manifold.

Fed law should read, GDI must be lean burn only with water injection to eliminate NOX, increase fuel economy and clean the intake.

Problem solved. No further research required.

[niky]

That's assuming buyers are smart enough to refill the water tanks. GM ditched water injection because they weren't.

Unlike urea, where you can have a big enough tank to last till the next oil change, you'll need to refill a water tank often... Unless you have a big reservoir, several times per fuel tank. And it needs to be distilled to keep from clogging nozzles... which will add to cost.

(I love water injection, mind you...)

[RobertISaar]

the diesels that use urea limit maximum speed when the tank is empty, correct? i could see that being quite an effective incentive for people to keep the tank full.

but...... everything other than distilled water WILL be used by a lot of people. gasoline, diesel, rainwater, old oil, urine, stale beer, flat soda, etc. how to design a system that will compensate for that, i don't know.

i would also expect quite a few to put in diesel exhaust fluid by accident, if history is anything to be used to anticipate the future.

[niky]

Have cars use pure water coolant and refrigerant (for the AC) from the same tank as the injection system.

Run out, you overheat, in more ways than one.

Big incentive to pay attention.