TUNING

ENGINE PERFORMANCE PROBLEMS? - IT COULD BE THE FUEL.

The performance can be affected in various ways and on a tuned engine where more fuel is required, the symptoms can be magnified. Every week we take calls and emails from motorists with standard and tuned engines where their garage is having difficulty in diagnosing the cause of one or more of the following symptoms: -

MISFIRING, HESITATION, BAD STARTING, POOR PERFORMANCE, FLAT SPOTS, SURGING, CUTTING OUT.

The problem is far more widespread and common than most drivers are aware of, and the motor trade is only just 'waking up' to this.

There appear to be two factors at work:

i) Biodiesel is a more aggressive solvent of the gunge that coats the fuel tank and lines. Clearly, the older the vehicle the bigger the deposit.

The gunge finds its way through the filter and can clog or partially clog the injectors, injection pump and fuel pressure sensor & regulator.

Recently the allowable biodiesel content of pump derv has been increased to 15%. Some major brands* claiming improved fuel saving or extra 'green' or clean credentials probably have the higher levels as do some supermarket brands. In France and some other countries diesel with a much higher biodiesel content is normal and so we often hear from drivers who have problems after filling up abroad. The locals don't of course have a problem because they have been using it for several years.

This is the fuel filter on our '57 reg Vectra after just 5000miles. When we started to experience rough running we removed it and were shocked to find it was almost as black as an oil filter. (the Vectra has a paper element not a cartridge type so its condition is easily visible.)

Its no wonder then that commercial fleet operators are much more aware of this problem and have to replace fuel filters much more frequently.

ii) The biodiesel also encourages the growth of the 'diesel bug' and you can read more about it on oil & fuel treatment manufacturers, MIllers Oils website (click on fuel treatments) here

Look at their photo opposite of a FUEL filter that looks like a very old oil filter. Sister company Energy Tuning is now an authorised Millers stockist and can supply Eclipse and EcoMax. Eclipse is not normally available to the public, being a commercial product but we can supply it to callers. ECLIPSE PDF ECLIPSE SHOCK DOSE PDF

The symptoms are similar to those you get if you have refilled up with contaminated fuel.

In fact the contamination will undoubtedly already be present in the fuel you are filling up with unless the filling station has its tanks cleaned and treated regularly and the 2 or 3 filters between storage tank and pump are changed frequently.

Millers also highlights engine damage caused by oil dilution and we wonder if the problems that Vauxhall have had with the Corsa diesel engine's main bearing is due to this as well as dpf issues. (being a town car, the dpf does not get a chance to complete a regeneration and the extra fuel used when this starts, ends up in the sump is their theory)

The solution:

1) CHANGE THE FUEL FILTER AT THE FIRST SIGN OF ENGINE PROBLEMS.

2) ADD INJECTOR CLEANER TO THE FUEL BETWEEN FILTER CHANGES, ECLIPSE IS RECOMMENDED, AS A SHOCK DOSE AND THEN REGULARLY.

3) ADD ECLIPSE OR SOME OTHER BIOCIDE AND KEEP THE FUEL TANK BRIMMEDIF YOUR VEHICLE IS NOT USED REGULARLY. eg MOTORHOMES & boats.

*I have heard it first hand from a Shell tanker driver & a fleet operator that they have had to change the fuel filters on the tankers at weekly intervals and some have had to have a new injection pump.