I have two codes on my 1995 oldsmobile eighty-Eight P1640 P1670 what do they mean.

Answered in this link. Plus pictures on the Parts websites. Follow the fuel line from the tank. It is a small metal cylinder.

https://www.google.com/search?q=1993+oldsmobile+eighty-eight+royale+replace+fuel+filter

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You will probably need to make new lines out of stock tubing and use a flaring tool to install new compression fittings on the ends.

Most likely a harness problem,for injectors and or ecm computer.

I'm assuming that you are refer to the "firing order", so check this...

1995 Oldsmobile Eighty-Eight Royale FWD 3.8 liter V-6 VIN "K"
and
1995 Oldsmobile Eighty-Eight Royale FWD 3.8 liter SC V-6 VIN "1"



1995 Oldsmobile Eighty-Eight Royale FWD 3.8 liter V-6 VIN "L"




Hope helps (remember comment and rated this).

Need to know which 3.8L engine you have, need the 8th digit of your vin number be 1, K or L. after have can email you directions and images of replacing your water pump, in pfd format, if would like reply back with vin letter & email address

You need a new computer

It isn't hard but you will need a three jaw puller to remove the balancer. Also you will need a impact gun and a 15/16 socket to remove the balancer bolt.

3.8 right? Behind the crankshaft pulley (harmonic balancer)

check here
http://www.2carpros.com/car_repair_information/tec_info/1995/oldsmobile/eighty-eight/1995_oldsmobile_eighty-eight_drive_belt_routing_diagram.htm

it means driver 1 input high hope this helps