Na6 running rich ??

[lowwn]

Having a bit of trouble with my na6. When I changed the oil the other day for the first time since I've owned it (about 2 weeks) I did an engine flush and the oil that came out was black and smelt like fuel. For fuel economy, I get about 400kms out of a full tank hardly ever driving with a heavy foot but mainly driving to and from work where the traffic is pretty bad. On cold starts, it starts a little rough and idles at about 650 - 700rpm untill it warms up then idles at 800 - 1000 and sometimes there is a bit of hesitation low when driving it a bit too cold. Could it just be running a little rich ? If it is running rich, would that cause the oil to smell like fuel ?

I'm probably going to change o2 sensors, clean afm, change plugs and leads and have a look at the injectors on the weekend but any help or advice would be greatly appreciated. Cheers

[speed]

I've never had oil smell like fuel so can't help you there.
Na6's run rich from factory.
When you start, your engine should initially idle round 1,500 rpm then settle down to 850 rpm once ward up.
400 per tank is awesome.



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[Purfler]

On my NA, dríven in traffic everyday (I live in Sydney, there's no choice but to drive in traffic), I get 10l per 100Km on e-10 95.

FWIW.

Tim

[PhilM]

My oil always is clear even when the engine has been running rich. 450kms is all I got out of a highway tank full on std engine unless really trying for economy.
Check your air filter then maybe coolant temp sensor (on rear of head)
If running richer than normal you will have a black deposit on the bumper around exhaust.
Get a tuner with a clamp in the exhaust tip wide band o2 sensor with an A/F readout, to take it for a test then you can see if the O2 sensor is ok, although they are narrow band standard.

[hks_kansei]

Oil smelling like fuel is usually a sign the piston rings are stuffed (fuel/oil gets past the rings, mixes etc)

however...

Since you said you did an oil flush, did you put the flush in with the oil? or empty the sump, then pour it through?
Oil flush is usually just diesel or a similar form of substance. And it smells similar to fuel.
So, if the oil smelled of fuel after using the oil flush stuff, that will be the smell.


Oil coming out black is pretty normal for an older car, carbon etc builds up and discolours the oil. it's nothing to worry about.




400km from a tank in traffic is pretty normal too.

[lowwn]

Thanks heaps for the help. Yeah I put the flush in with the oil so that was probably the smell and why it came out black. I have a pod filter on that came on the car at the moment, might replace it with a stock airbox and see if it makes any difference, just gotta fix the cold start issue.

[Mr Morlock]

if the oil is black and it smells then the motor may be well worn. Oils don't come out black unless it has not been changed regularly. How many KMs and any checks done on the car like compression. I think I am safe in saying that flushing oils should also not be necessary if the maintenance has been regular. You can get 500KM out of a tank without too much problem or put it another way- 8l/100KM depending on whether the traffic is really heavy. 10l/100km as an example is a car in early heavy traffic changing down and braking every 500 metres or less or its being dríven with a frozen ankle.

[hks_kansei]

if the oil is black and it smells then the motor may be well worn. Oils don't come out black unless it has not been changed regularly. How many KMs and any checks done on the car like compression. I think I am safe in saying that flushing oils should also not be necessary if the maintenance has been regular. You can get 500KM out of a tank without too much problem or put it another way- 8l/100KM depending on whether the traffic is really heavy. 10l/100km as an example is a car in early heavy traffic changing down and braking every 500 metres or less or its being dríven with a frozen ankle.

Bear in mind Mr Morlock, with the 500km from a tank, that the NB tank is larger than the NA. So if you're going from your own car it may not apply to an NA.

You are correct on the petrol smelling fuel, however Lowwn mentioned that it smelled after he poured in the oil flush, which would account for the smell. (I agree with you that the flush isn't really necessary)


As for black oil, even the last NA6 models made are over 20 years old, so I would expect the oil to be blackish (unless they have had a very fastidious owner who changes oil much more often than Mazda recommend)

[lowwn]

Only has 160***kms and the previous owner said that he changed the oil regularly and that it had just been changed but I think he could have been lying as the oil that came out had definitely not just been changed.