Fuel additives

LuckyBenski · 18 May 2019 at 11:25

Hi all, first post in Motors as I drive a clown car inherited from work...

I'm looking for recommendations on a good fuel additive for reducing carbon deposits... I think. I've recently had a couple of fault codes stating a misfire. No obvious bangs or lurches though, but I'm now a bit paranoid my engine's running rough.

It's a Smart, 1L 3-cylinder engine. I live in London so do loads of low speed/stop-start driving and very rarely get to high revs. Doesn't help that I try to drive the car in a fuel efficient way

. Other Smart users have suggested the engines are prone to carbon/general buildup at low speeds.

If the engine light comes on a third time I'll take it to the garage for some tests but in the meantime, it's been suggested to use a fuel additive to try and clean things up a bit.

What do you lot like to use?

LuckyBenski · 18 May 2019 at 12:09

smilertoo said:
Petrol or diesel?

Petrol.

LuckyBenski · 18 May 2019 at 13:13

Orionaut said:
Oh, And another thing.

If the engine light is coming on, do you have a fault code?

Misfire on cylinder 3. Apparently Smart don't always use the standard codes though - but this code did lead me to other threads on forums . They mainly had loss of compression issues.

LuckyBenski · 18 May 2019 at 15:52

Orionaut said:
Do you have the actual Pxxxx code?

P0303:

LuckyBenski · 18 May 2019 at 17:22

Thanks, that makes sense. Someone suggested swapping coil packs around to see if one is starting to fail - as the error has always been cylinder 3. Does that make sense?

Annoyingly they're not easy to get to as the engine is tucked in under the boot. Have to take a panel off. But a set of Torx bits should work out cheaper than a garage trip!

LuckyBenski · 18 May 2019 at 20:47

Nasher said:
An Italian tuneup once in a while is a good idea though. Find a stretch of road and rev the crap out of it for a bit

Indeed, I used to rag it pretty hard as it's small and light. Loads of fun until you hit 40+, I just started being "sensible" at some point

LuckyBenski · 24 May 2019 at 13:34

red eye said:
The good old itlalian tune up.
But the smart being a 3 pot it’s always going to feel like it’s missing......because it’s missing a cylinder

It's a straight 3 as well... I really don't think anyone considered noise when designing it!

LuckyBenski · 24 May 2019 at 16:30

Overlag said:
Being in London 50% of his journey will be sitting there with his handbrake on.

Spot on. And it's pretty fast out the lights because a) it's literally made of plastic and b) all its power lives on the 0-20 range.

LuckyBenski · 26 May 2019 at 00:16

andy_mk3 said:
It's half a V6

That's what I tell myself!

Update on the car: no engine lights since posting, have been revving harder and changing later until I get a chance to go out to a motorway. Got some Redex on order as it can't hurt