145km (90 miles) From A Full Tank & Shaking- case study
This is a case study illustrating what I did to cure the shaking of the engine and reduce fuel consumption from 145km (90 miles) per tank to 315 kms (186 miles)per tank.
I bought another GTV 3.0 litre last August for a song. It sounded like a bag of nails when running. It had sat for a year before I had bought it. And it had done 145 000 klm (90 000 miles) prior.
She was using a lot of petrol. She sounded terrible and was shaking on idle when cold and also in traffic once warm. It was embarrassing but also made me laugh. Actually it was really embarrassing. When sitting inside the car I was being shaken it was that pronounced. It did not sound like an Alfa.
Initially a full tank of petrol (Ron 95) gave me only 145kms (90 miles) travel. Terrible and very expensive.
I changed the oil and and three weeks later it was doing 175kms (109 miles) per full tank. I used 10w 60 Penrite and Nulon oil flush. I drove it like this for two months hoping for better fuel consumption however not much had changed. As it still only returned approximately 175kms (109 miles) per tank of petrol and shaking was only slightly better.
Next the water pump broke and spewed coolant so I decided to change the thermostat whilst the cam belt and water pump were done with new coolant and Nulon coolant flush. Who new when the coolant was last changed?
Next I put a bottle of injector cleaner into the car with a full tank of (Ron 95) petrol. This did very little. So on the next full tank of petrol I put another bottle of injector cleaner in again. This returned 210km(130 miles). Some improvement.
So I did this three more times with injector cleaner over the next month and a bit, each time with a full tank of petrol (Ron 95). On the last time with injector cleaner in the fuel she returned 300 km (186 miles).
After this without injector cleaner she was returning approximately 285km (177 miles) per full tank.
Next I changed the air filter which rose it to 315kms (196 miles) per full tank(ron95).
Shaking has gone. She sounds like a purring cat on idle. And she is not costing so much to run.
During the fuel consumption testing phase I drove like an old man so as to try to maintain consistency. Not reving the engine higher than 4000 revs. All driving was stop start, short 5km to 10km trips, city style driving.
Since then I have slowly begun to rev it higher and higher each trip, hoping to clean her internal oil ways out. I initially did not do this as I wanted to break her in. I worried that the previous owner had driven her slowly all its life and a lip may have developed on the piston sleeves. I did not want to rev her all of a sudden and do potential minor damage to the piston rings.
I still think she has a little more to give in terms of better fuel consumption. I hope this helps.