Piston Slap: A Rather Thirsty Escort?

Sajeev Mehta
by Sajeev Mehta
piston slap a rather thirsty escort

TTAC Commentator Weltron writes:

Hi Sajeev!

The car I am writing about today is my winter beater, which is a 1999 Ford Escort SE sedan which says it has a tick over 155,000 miles. The problem I’m having with it is it it getting dreadful gas mileage. My average tank is about 19 miles to the gallon (in comparison that is what my twin turbo straight six Volvo gets around town). Over the winter I replaced both of the o2 sensors and got a marginal improvement (about .4 mpg).

And here’s the kicker: the dumb thing runs perfectly. No error codes or anything. Idles smooth and everything (well as far as Escort refinement goes). When I go on the highway (which is fairly often) I can see upward of 21… If I’m lucky.

Help please! I’m debating on whether to sell it or not due to this gas mileage problem for something bigger (thinking an Oldsmobile Eighty Eight/LSS or if I’m feeling lucky … an Aurora if I do end up replacing the Escort.) Thank you in advance for your help.

P.S. Here’s a list of what has been replaced/cleaned since the fall.

Mass air flow sensor cleaned

New air filter

New spark plugs/ plug wires

New o2 sensors (both upstream and downstream)

New muffler

New tires

Sajeev answers:

It’s funny how well-maintained vehicles occasionally have an obvious problem that’s impossible to diagnose. But going to the beautiful, enjoyable yet expensive and complicated Northstar powered Oldsmobile is the wrong move!

You’ve done the basics, kudos to you. That makes our job easier. Considering your Volvo drives in the same manner (presumably) there’s certainly a minor problem outside of driver error. And I wouldn’t be so adamant if it didn’t happen to me:

Try changing the fuel filter first, then get new/reconditioned fuel injectors.

That’s it. I know you’ve slooooowly been losing power and efficiency. Perhaps you notice a mysterious fuel smell? The injectors are no longer turning on/shutting off correctly. And when you get ’em installed, ZOMG SON, note the instant acceleration improvement and the later MPG lift.

So go ahead and keep it, even if the cylinder head might be a problem in the future.

[Image: Shutterstock user Chill Chillz]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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2 of 86 comments
  • Beerboy12 Beerboy12 on Jul 28, 2014

    I would have suspected a fuel leak in the return lines. Cold weather plus a short commute would definitely return bad MPG to. A faulty thermostat that does not block water from the motor in the warm up faze could add to the problem to. Basically the engine block and oil never get to running temp. so the car is running on it's electronic little "choke" all the time.

  • Chicagoland Chicagoland on Jul 29, 2014

    I had 2000 Scort for a beater and had the thermostat replaced, and that helped mileage. But I also agree with fuel filter and injectors. It's 15 years old, so age wears a motor out also.

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