Bosch Injector Servicing

The smart 450 fortwo petrol and Roadster uses Bosch EV6 injectors and like all injectors, they eventually require cleaning. The injectors have replaceable filters that catch anything that the fuel filter lets passed. If you are removing your injectors to clean and replace the filter basket, you may as well replace the seals too.

I bought my kit from eBay but sellers were not reliably keeping them in stock so we decided to stock kit on smartmods. Click here.

In the kit you get a pintle cap, 2x O rings and a filter basket for each injector.

Lever off the rear O ring.

Pop off the pintle cap and the O ring behind it.

Bin the old seals.

Look closely into the back and you’ll notice a copper coloured ring. This is the rim of the filter basket.

You can buy removal tools but a number 10 screw works fine. Screw it in about 10mm.

Wiggle and pull the screw and the filter basket should start to slide out.

Bin the old filter basket. It’s totally shafted after that.

Give the injector a good clean with brake cleaner or isopropyl alcohol.

Grab your wife’s toothbrush quickly and give them a scrub before drying the injector off.

Time to fit the kit. Push on the O rings on each end, followed by the plastic pintle cap.

Look closely at the pintle cap and you’ll see 4 indents. These face forwards.

Just the new filter basket left to fit.

Push the filter basket into the hole…

…and carefully tap it all the way in. I used my forehead but you can use a soft face hammer.

1 done, the other 2 to go.

Ultrasonic Cleaning

If you have an ultrasonic cleaner, throw the disassembled injectors in one of those.

You are supposed to use de-ionised water or special cleaning solutions. Under no circumstances use isopropyl alcohol. This is because it’s incredibly flammable and has a very low flash point.

Needless to say, I used isopropyl alcohol because it’s what I had on hand as I use it to clean 3D prints. If you do use IPA, don’t use the heater, only use full metal units (cheap plastic melts) and use it outside at arms length. Needless to say I used the heater just to see how much of an explosion would occur. I was disappointed.

Back Flow Cleaning

I have seen YouTube channels showing how to clean the injector nozzles by spraying cleaner through them in the same direction as the fuel normally travels. They pulse the injectors using a 12v bench power supply. The problem there is the size of the injector nozzles. They’re tiny.

If they are blocked, spraying cleaner in the same direction won’t clear the build up. It’ll probably make it worse.

If you want to clean them like that, pass the cleaner in through the nozzle and out the back of the injector. That way, any build up of crud is much more likely to dislodge and flow out of the injector body. I’ll try and knock something together to show what I mean at some point.