Mark writes:

Sajeev,

I’ve had my 2015 Focus ST for 15 months and 14,000 trouble-free miles so far, and I’m really enjoying the car. The car is still 100 percent stock, but I’ll likely contact Torrie for a tune before long.

As much as I like the car, I’m really alarmed to read about the intake valve “gunk” issues with Ecoboost and other direct-injection engines. It seems as if DI engines have a real problem that the manufacturers really aren’t willing to acknowledge or address (if it even can be addressed).

What’s your opinion on oil separators and/or catch cans? Are they a good preventive measure, or should I just resign myself to funding a cleaning via walnut shells or other similar clean-up tactics when gas mileage starts to dip, power drops, or misfires develop?

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Hi Sajeev & Steve,

“You have not covered extensively the problems encountered by GDI engines, especially Mitsubishi Dion (the engine is 4G63). As the revs go beyond the 2000 rpm, the ‘check engine’ light comes on, then eventually the engine — if forced — cuts off. After a few minutes, the engine can start but it does not take long before it repeats. I was told by a mechanic to buy a new pressure pump. This was fitted but the problem has not gone away. Please help!”

Ummm… we think your mechanic needs to keep away from Runaround Sue.

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Arley writes:

Sajeev,

I have a 2003 Jetta TDI with 178k miles. Runs 100%. My mechanic recommends a carbon cleaning. What are the positives and negatives? To be more succinct, what can go wrong?

You can tune a piano but you can’t tuna fish. (Good to know! – SM)

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Evan writes:

Sajeev,

I have a piston slap question for a friend at work. She drives an ’11 Mazda CX-7 2.3. For over a year she has had an issue with fuel in the oil. Enough that the oil level has been as much as 1″ above the full mark on the dipstick as a result (oil level was checked after service, and frequently between services). This is noticed within weeks of service/oil change. (Read More…)