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92 deville poor mpg o2 sensor E44

8003 Views 19 Replies 6 Participants Last post by  Ranger
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

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many thanks Rnager, i forgot to say that i had already changed the EGR as well but i will rod the tubes again can you please tell me what you mean by "TB"?
thanks al
Hi guys,

i have been looking at the throttle body and i have noticed that there are couple of perished rubber parts. in particular the small rubber hose from the fuel pressure regualator to the TB and the even smaller hose that goes to the transaxle modulator. i have just found out that neither rubber part is available for sale. if i buy a new fuel regualtor it does not come with that rubber hose:

1) does anyone know where i can buy there parts?

2) does anyone know what the transaxle modulator actually does?

i have concluded that the fuel pressure REG is the reason why i have poor MPG, if you disagree pls let me know


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