How not to clean engines
I own a 2001, 2.5-litre Colt double-cab bakkie. Last time I had it serviced, they washed the engine, and it has been jerking in first and second gear ever since, even though I have done more than 1000km since the service. - Zolile
Zolile, there's a good chance it was brought on by the engine wash.
I know from bitter personal experience that one of the worst things one can do to an engine is let an overly enthusiastic washbay operator loose on it with a high-pressure water/ steam/paraffin gun.
My own experience was some years back and, luckily, involved an engine built before the days of electronic engine management. The car had failed a roadworthy examination because it "needed to have the engine steam-cleaned".
At the nearest service station this job was done by an operator on steroids.
Surprisingly, the engine started afterwards and ran smoothly ... just long enough to take me out of sight of the service station. It refused to start and the next day I dried the distributor and plug caps using rags, a hot-air gun and de-watering fluid. The car then started.
Nowadays, with engine compartments chock full of highly sensitive - and very expensive - electronic devices, the opportunities for wreaking havoc with a water gun are limitless.
Twenty-three years ago BMW, one of the early leaders in the field of auto electronics, first issued a warning against high-pressure engine steam-cleaning on its vehicles.
Instead it recommended "normal, low-pressure degreasing methods". I'm not sure what BMW had in mind, but my own recommendation for cleaning a dirty engine is very simple:
- Get the engine slightly warm, not red hot.
- Use plastic bags, held in place with rubber bands, to cover or shield all electrical components in the area to be cleaned.
- Pour some good-quality engine cleaner into an old jam tin and use a stiff paint brush to work it into the dirty area. Let it soak for a few minutes.
- Use a household squirt bottle with lukewarm water to flush the solvent and dirt from the treated area, aided by brush action if necessary. An old toothbrush works well in tight areas.
- Dab the cleaned area dry with paper towels before starting the engine.
I realise, Zolile, that all this is cold comfort in your case. The best I can suggest is that you systematically go through all the electrical connections, including multiplugs.
Unplug each one, dry it out, using paper towels or a hair dryer (or a hot air gun, but very gently, on lowest setting), spray with electrical contact cleaner, and refit. If the misfire persists, you will have to call an auto-electrician or a mobile diagnostics expert.