Blinking dash lights and intermittent power loss

Jambo Car Doctor, thank you for your regular insights on moto gari.

 I have a 2013 automatic transmission ex-UK Hilux. When VSC and Slip warning lights intermittently come on there is substantial power-loss. Computer diagnosis was "injector-4 malfunction". Diesel additive treatment seemed to have worked for six months but the menace is back. What could be the problem?  Ndwiga.

From afar without on-the-spot sight or sound…the diagnostic finding, the come-and-go symptoms and apparently positive diesel treatment results suggest your diesel injectors may be dirty or faulty. 

Have these checked and cleaned (not unduly expensive or time-consuming). They may need to be replaced… for a bit more than petty cash.

If power loss is accompanied by clouds of black exhaust smoke, the fuel is not being combusted properly. If there is no smoke during power loss, then not enough fuel is getting to the cylinders. 

Injectors are extremely precise and therefore sensitive to dirt, and particles of grit or rust etc. may be moving in an out of an obstructive position inside them. 

So, the fact that the problem returned after an apparent “cure” warrants both a remedy and an investigation of cause. Where has the dirt come from? If you use fuel stations with good storage and delivery hygiene, there should be no impurities… except from the inside of the car’s own fuel tank. 

And in either case good quality OE filters (in this case Toyota) renewed at regular service intervals should capture any dirt that has got in before fuel reaches the injectors.  

Bear in mind that even one fill at an “iffy” location could have put dirt in the tank. If dirt is confirmed as the problem have the tank checked and perhaps flushed. And use genuine filters renewed at every service. Examine the old filter elements for clues.

The only place dirt can get in “after” the fuel filters is detritus generated inside the injector mechanism itself or ingested through the air filter. Don’t skimp on the quality or renewal of that.

Good garages will be competent to research the issue (on your instruction if not by their own initiative) and there are “specialist” workshops who have high-tech “test benches” to overhaul and re-set an entire injector system. 

Their all-day and every-day experience on this singular issue will give them a “sixth sense” of what has gone wrong and why, and they will have technical competence to put it right.

In general, the quality and condition of filters (fuel, air and oil) may be “out of sight, out of mind” items, but their function is important to performance, fuel economy, wear rates and reliability, so neglecting them won’t do you any favours.

Ideally, use original parts and refuel at stations with quality brand disciplines and high volume turnover in their storage tanks and pumps.

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