s13 problems

[ju5tify]

Hi 2 all. First of all forgive me my poor English.
I have 1989 200sx swapped CA18DE with mechancal tranny and harness from the CA18DET. But ECU is A/T version. Don't ask me why. I dont know :hs:
1) I never had my speedo working. It always shows 260 :hs:. But when i hit smth like 80-100kmph, arrow begins to slowly move in opposite direction. I suppose my speed sensor is broken. The question is which one i need — from automatic or mechanical transmission?
2) I have some serious issues with fuel economy. I'ts around 17-20 liters per 100km. Oxygen sensor is working, spark plugs are replaced, throttle cleaned, but no effect. ECU diagnosis says it's all ok (code 55). What can it be? Fuel pump? Or speed sensor malfunction? Or maybe ECU from A/T?
Thanks in advance.

[rcdad123]

so that`s roughly about 5 gallons for 60 miles of driving. that is 12 miles per gallon. what size tires are you using? is the clutch slipping? how does the spark plugs look like? there are a few things that can cause bad fuel consumption. very small diameter tires, slipping clutch, stop and go driving, etc.

[ju5tify]

R16 tires, no clutch slipping
old spark plugs looked erm..black

[ju5tify]

bump bump