2004 Avensis Black Smoke When Accelerating- No Power Loss

[avensisd4d786]

Hi guys, I'm worried about the black smoke coming out the exhaust and my real mpg is 38mpg but reader says 47/48.

I have already cleaned the egr and throttle body, but I did notice the inlet manifold was gummed up with soot, (could this be the cause). I am hopefully going to clean this in a few days. I have a new gasket on order.

fuel filter and air filter are not that old-about 7,000. genuine parts too.

I have no power loss.

any other suggestions;

if it was a injector wouldn't I incur loss of power and some kind of knock.

[Raistlin]

Black smoke is soot, which is basically because you're running very rich.

[korat102]

If the inlet manifold is partially blocked it'll be restricting the air supply, that could cause a rich mixture and definitely needs sorting out. Youu say you cleaned the EGR, is the valve working properly? Any fault codes stored?

Could be an injector as well though, have you tried running a fuel system cleaning additive through the system? BG244 seems to get good reports from those who have tried it (and dismissed as snake oil by those who haven't).

[avensisd4d786]

after cleaning it- the valve open and closed freely- no codes-what is the best way to test it; its electronic-

I have used bg244 with no sucess-

I will have a go with cleaning inlet- could the maf sensor cause this? or any split pipes?

[korat102]

Could be a MAF sensor but that would affect power delivery as well and you said there was no loss of power. You could try unplugging it and see if it makes any difference. If it runs the same or better with it disconnected, you may well have found your fault. With a MAF sensor that's working properly, unplugging it will result in the engine running 'worse'. If you do this, make sure the ignition is off though, don't connect or disconnect things with the ignition on.

I'd expect a split pipe to be detectable due to the noise the air makes as it escapes. Do you have any whooshes or other strange noises?

Any way to retrieve fault codes?

[avensisd4d786]

I can try another MAF and try other parts. I have access to the same vehicle but with a knackered box so I can swap parts over and trail them if you like- I have a code reader & there are no codes present;

do you think anything could be read if I post up the live data?

[avensisd4d786]

Can I just add it smokes more when using regular diesel than BP ultimate.

[korat102]

Just as a matter of interest, how do you drive this car? Does it only do sedate short journeys around town or does it get to stretch its legs on motorways and dual carriageways. Lots of diesels get badly clogged up when they're used for a purpose which doesn't really suit them...i.e. short journeys at low speed where they never warm up.

With no fault codes stored, assuming it's not clogged up due to journey type (in which case a good long run might clear it all out), I think you're just going to have to check all the hoses, etc. then start start replacing parts.

Having said that, I'd take a look at that air filter first, if the thing is running rich that's the first obvious and cheapest thing to look into. MAP and MAF readings look ok but the engine's idling so that doesn't really tell us a lot about what's happening under load. If the air filter's ok, you might take a look at the MAF sensor wires, see if they're sooted up, if so try cleaning them (CAREFULLY!), use a spray and don't actually touch the wires.

[avensisd4d786]

Thank you Phil, it does mixed driving around town and a roads, I'm going to do a minimum 110 mile trip to Scarborough and back today, that should clear it- I will see if I can get some readings whilst under load- I will clean MAF today with electrical contact cleaner.

I have a bit of a heavy foot sometimes so it does go up 3000 to 3500 revs at times.

[avensisd4d786]

update- I think I may of fixed it; but I don't know which procedure fixed it- I cleaned the MAF with electrical cleaner and changed the fuel filter- no where near as bad but time will tell. I'm still going to clean manifold when I get chance.

[korat102]

Sounds like a good result...potentially :)