Check engine light

[od2000]

Recently, my check engine light came on so I took the car to the mechanic.
He told me there was a misfire mostly likely due to the car being in need
of a tune up. Now two weeks later I get a flashing check engine light
when I am on the highway. at about 50 mph the car seems to stall a bit
until I let off the gas peddle, and then everything is ok. It stops
stalling and check engine light goes off. I am going to take it back to
the mechanic, but wanted to know if anyone had an diea of what may be
going on. Fuel pump??

 

[Zeke]

Recently, my check engine light came on so I took the car to the mechanic.
He told me there was a misfire mostly likely due to the car being in need
of a tune up. Now two weeks later I get a flashing check engine light
when I am on the highway. at about 50 mph the car seems to stall a bit
until I let off the gas peddle, and then everything is ok. It stops
stalling and check engine light goes off. I am going to take it back to
the mechanic, but wanted to know if anyone had an diea of what may be
going on. Fuel pump??

Hiya,

It may be the fuel pump. I hope not. Depending on the year/ model,
etc. the only pumps available may be the Bosche ones. Very pricey, and
probably remanufactured. More likely it is the fuel presure regulator.
Not nearly as pricey, not nearly as involved of a repair. It is
located to the front of the fuel rail, and resembles a micro sized
beer keg, with a vacuum hose attached. To check it, simply draw a
vacuum on one side of the FPR diaphragm, and see if it is gradually
released. More likely still, it may be the O2 sensor. It regulates the
fuel/ air ratio, and if it is not functioning properly, it will place
the ECU in "limp" mode, or cold start mode, which is a full rich
mixture. Which results in generally poor performance, warning lights,
etc. Pretty pricey to fix, but if you haven't replaced it yet, you
will wind up doing so pretty soon anyway. The O2 sensor is pretty much
the fulcrum of the whole engine management system in these cars. To
check it out, warm up the car for a few minutes until it is at
opperating temperature, Then isolate the lead from the O2 sensor
(located in the exhaust stream) and tap it with the positive probe of
a multimeter. Ground the negative probe. If the O2 sensor is
functioning properly, you should recieve a reading of around 200-240
Mv.

Good Luck,
-E-

 

[Mike F]

Recently, my check engine light came on so I took the car to the mechanic.
He told me there was a misfire mostly likely due to the car being in need
of a tune up. Now two weeks later I get a flashing check engine light
when I am on the highway. at about 50 mph the car seems to stall a bit
until I let off the gas peddle, and then everything is ok. It stops
stalling and check engine light goes off. I am going to take it back to
the mechanic, but wanted to know if anyone had an diea of what may be
going on. Fuel pump??

Start by having someone with a scan tool read the codes.

--
Mike F.
Thornhill (near Toronto), Ont.

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