R33 Rattling Under 2500Rpm, Rich On Fuel And More

[sakuratoge7]

i have an r33 s1 1993 it has done 175xxxkms and i have had no issues until a couple of months ago when i started the car after stopping off at the shops and it sounded more like a wrx and was shaking like a bitch.. i stopped about 50m up the road and looked under the hood and around the car and figured out it sounded like it was coming from underneath, so i let it sit for awhile and turned it back on, issue still there until i messed around with the immobiliser button and then shifted the gearstick (it is auto) from P to 1 a couple of times which seemed to trip the car back to normal... limped home and hoped it was a one off.

After a couple more times of this happening i figured out it would only happen on the 2nd start for the day, and only if i started it after only a short period of time elapsing inbetween starts... also taking note of the fact the shaking would almost completely go away when the car was above 2500rpm

I have only been driving the car when absolutely necessary and have noticed that the car makes a ticking noise on idle and once the car has turned off, sounds similar to the tick a car makes when cooling down, but is more rapid and coming from underneath the car, im assuming it is coming from the cat converter

The car uses fuel like crazy, probably somewhere between 300-350km per tank, but i have only gone through about a tank and a half in this time so i cant get a good average

I have noticed only in the last couple of drives that when i am driving on a flat road or on an incline that the minute i take my foot off the pedal the revs immediately drop to 1000 and then sit on around 1200rpm, it makes the car feel like it is engine braking meaning i have to keep my foot on the pedal to not lose a significant amount of speed almost straight away

i am a beginner when it comes to cars and engine maintenance so i am not sure where to even begin with the issues, i have checked fluids and they all seem normal but that is the extent of what i have done

i would appreciate any advice anyone can give me on what to do!! if it is gonna cost me a heap of money to fix then i will just sell the car and start again, so any advice of this nature will be even more helpful! I have read through page upon page of the forums but i can only seem to find posts that cover bits of my issues and not the whole lot, and also have read lots of different suggestions but i cant seem to find a common enough fix between them all..

thanks!!!

Edited December 24, 2014 by sakuratoge7

[GTRPSI]

Souunds like its running pig rich.

O2 sensor, fuel pressure regulator, airflow meter if your smelling fuel and seeing black smoke out the rear.