Technical Engine tap/ knock

[RobBravo]

Hi,

I was feeling flush the other week and decided to fill up on Esso's 97 RON fuel for to test.. with great results.

Previous best MPG was 41.5 but a tank of Esso 97 got me 43.7 MPG first attempt and I only got 5 miles less than on 95 ron fuel.

I decided from that moment on I would test all of the "premium" fuels and create a little guide for Bravo/ 1.4 T-Jet owners - could be interesting for those who may want to run 95+ RON fuels and want to know what works best with the engine.

The problem is this; the next fuel to test was Tesco's "Momentum 99" and now I'm on the tailend of the test (40 miles range) I'm finding my engine is tapping and starting to sound very diesely. After a brief discussion with my Dad he feels that the only change to the car is the fuel, and perhaps the car is pinging due to the car not being able to take advantage of the 99 RON rating.

Any thoughts? My car has only just turned 19k miles so I wouldn't think anything is seriously wrong..

I will be looking for some V-Power next as I've read on some Vauxhall forums that it helps to clear the injectors and such may stop this noise I'm getting.

Thanks

 

[carlorff]

Bravo can run on 100 octane gasoline without problems.I tested that since we have such fuel.The problems you are describing can be related to fuel as your father said...but it could be some additives in this 99 something that are not good or best for the engine...or that something got into the tank at the gas station. Some dirt or water.
Since "lead" ( tetraethyllead ) was removed from the gasoline as the lubrication agent they are using other lubricants like MMT.Perhaps that is what you are hearing. Usually with higher octane number fuel the engine becomes lively as the fireing of the fuel in the engine is better.The engine should run smooth and accelerate better.

 

[RobBravo]

I am still suffering with the same problem.. any ideas what I could do to solve this issue?

The car sounds like a diesel when stationary whereas before I had to glance at the rev counter to check it was still running!

 

[JayDMistry]

My car is doing the same, when this happened to my Mazda it was due to a lack of oil. I don't know about the fuel, but I'm sure there's something to put in the tank to fix this?