bad millage
80

Asked by Luis Jun 11, 2015 at 10:46 PM about the 1999 Mercury Grand Marquis 4 Dr LS Sedan

Question type: Maintenance & Repair

How to reset the ECU to factory settings

4 Answers
143,765

T_S_T answered 8 years ago

Undo the battery for a few minutes,

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143,765

T_S_T answered 8 years ago

But if there is no engine light on in car,it is set.

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143,765

T_S_T answered 8 years ago

If you are getting bad gas mileage ,change plugs,wire,s ,fuel filter,and air filter.

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80

Luis answered 8 years ago

Replaced the intake manifold(recall)Thermostat,wires, coils, plugs,alt, battery, cleaned MAF and throttle body.The car runs and start.Just choke @99 mph.Used to go 110mph.I think my son reprogramed the ECU so I don't get killed,lol,.It botthers me, because my 99 marquis LS used to glide @70-75 mph, without pushing it.Now drops the rpm and have to step on the gas. I think that's the reason for the bad millages.Otherwise have 144,600m and looks, runs like new.Thanks.

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