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poor mpg 92 deville


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Hi guys,

i have a 1992 sedan deville 4.9L with about 250,000 miles on the clock. i have nearly finished restoring it as it was due for the scrap heap. Anyway the exhaust had like 9 holes running down it so i replaced the entire exhaust including catalytic converter and silincer and the O2 sensor as well.

Now it runs like a dream but the MPG is down to 10MPG from 15MPG that is just crazy. the DTC that comes up is E44 O2 sensor running lean. i do maninly highway miles and if you turn on cruise control the mpg meter goes slight erractic then the code comes up.

just so you know i have changed the following in the last 2 years:

spark plugs, ISC motor, genrator, Vbelt, idler, battery, HT leads, airfilter, water pump all are AC Delco

many thanks

ahmad jumaili

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First try free fix. Remove battery and and remnove O2 sensor and start the car for 2 min. Then switch off remove battery again and refix 02 sensor and drive for 1 - 2 days and see any change.

If no improvement, also change new crankshaft sensor, very imp for fuel handling. This shud solve problem. Try fuel line cleaner additive on highway miles in half tank, they also actually work.

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many thanks james,

where s the crankshaft sensor exactly or is called something else. i have the service manual for the car but could not locate it.

Also imported this car myself last year what is your view on the engine oil grade. A lot of mechanics in Dubai say that i should go with 20-50 oil due to the heat and not the 10W-30 oil as recommended. Bearing in mind it is a old engine i went with 20-50 for now but i am interested in your opinion on this matter.

thanks you again Ahmad

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Use 20w40 or 20w50 and change oil frequently in older engine. Oil is cheap here.

Secondly never ever clean the engine with engine oil additives as you will have vibrating and pinking engine, as it will clean lot of old carbon with acid.

ABT CKPS here is instructions that i searched for you to help:

Its on the side of the block firewall side

REMOVAL

Disconnect the wiring harness (1) from the Crankshaft Position (CKP) sensor pigtail (1).

Securely attach a scrap piece of wire about 36 inches long to the CKP sensor pigtail. Later, this piece will be used as a pull wire to guide the new sensor pigtail back through the same routing.

Raise and support the vehicle.

Remove the oil filter and capture any lost engine oil in a container.

Loosen the oil cooler lines at the engine block. Back out the fittings far enough in order to gain sufficient clearance for the sensor pigtail connector to pass between the oil cooler lines and the side of the engine block.

Remove the fastening bolt for the CKP sensor.

Remove the CKP sensor and the O-ring seal from the engine block.

Remove the CKP sensor pigtail. Observe the routing of the pigtail. Gently pull the CKP sensor pigtail down through the routing path and out. Guide the pigtail connector along the top of the oil cooler lines around to the side of the engine block. Pass the connector between the lines and the block at the point of the widest gap. Stop when the pull wire is exposed at both ends of the routing path.

Disconnect the sensor from the pull wire.

INSTALLATION

Securely attach the CKP sensor pigtail to the lower end of the pull wire.

Pass the pigtail connector between the oil cooler lines and the engine block.

Using the pull wire as a guide, pull the sensor pigtail along the top of the oil cooler lines and around to the rear of the engine. Use the pull wire to pull the pigtail into position.

Disconnect the pull wire from the sensor pigtail.

Connect the sensor pigtail to the harness connector.

Thoroughly clean the mating surfaces of the CKP sensor and the engine block.

Install the CKP sensor with a new O-ring seal into the engine block.

Install the fastening bolt (1) for the CKP sensor.

Check the harness for proper routing. Make sure that the wiring cannot come in contact with the exhaust manifold.

Tighten the oil cooler lines at the engine block.

Install the oil filter.

Lower the vehicle.

Recheck the engine oil level.

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