[Jezza86]

Morning guys.
Caught a whiff of my exhaust and it smells like its rich.
Would also explain the fuel im using 14l/100k.
Checking the intake sensor, air filter, and pulling the plugs today.
Anything else I could look at while im at it?

[JrZook]

How old is the o2 sensor? Got any exhaust leaks?

[Jezza86]

O2 sensors are 30k km old. But were switched from the stock exhaust and maifold to the current ss one with extractors.

I have doubts the exhaust has a cat in it. Would lack of a cat make it run rich?

[want33s]

Removing the cat/con won't make any difference to mixtures.
I'd start by looking at the air cleaner and work my way through the airflow meter, temp sender and O2 sensors.

[Jezza86]

filters fine, gave the maf a spray with cq contact cleaner, looked ok. tightened up the bolts on the extractors. none were loose enough but all moved when i cave them a twitch with the long breaker bar.

[alien]

could the choke be blocked causing it to not get enough warm coolant to turn the choke off all the way?

[droverdave]

Removing the cat makes it smell worse than a car with a cat.

Doesn't explain your 14L/100 though.

[want33s]

alien wrote:

could the choke be blocked causing it to not get enough warm coolant to turn the choke off all the way?

M13a...... choke?

[Jezza86]

Stuck my hand over the exhaust tip. Built up enough backpressure to nearly stall it before I couldn't hold my hand there any longer. Think the exhaust system and extractors are fine. O2 sensors still might be a cause not ruling them out. Going to put 26 psi in the wheels. Im avraging 14l/100k and my work is 12k away, and the roads only 80kph top speed. After work I normally go for a wheel through the bush with the dog in tow which I thought was the extra fuel usage as I think im a rally driver. But last week I didnt wheel it at all and got the same numbers which is confusing.

[alien]

want33s wrote:

alien wrote:

could the choke be blocked causing it to not get enough warm coolant to turn the choke off all the way?

M13a...... choke?

Don't they still have a wax stat in the manifold?

[Jezza86]

Iac thingy ZN was talking bout.

[JrZook]

alien wrote:

want33s wrote:

alien wrote:

could the choke be blocked causing it to not get enough warm coolant to turn the choke off all the way?

M13a...... choke?

Don't they still have a wax stat in the manifold?

Modern day EFI. No need for that shizz! However the ECU still relies on a coolant sensor to determine the engine temp and the enrichment of the mixtures when cold. Could also be something to check.

[zukenutter]

If there's no cat the exhaust will smell rich but doesn't mean the engine is running rich.

Still to sort mine and still learning about its full purpose but PCV valve could cause rich running if it's not performing properly. Pull the PCV and look for excess oil build up or milky oil build up, also check the hose it's attached to. When you remove the PCV shake to check for rattle (it should rattle)

[JrZook]

Interesting. Whats the logic behind possibly running rich from a malfunctioning PCV valve? Where does the extra fuel come from?

[zukenutter]

Like I said, still learning about its full purpose. From what I've read the breathing flow of the engine changes based on intake air flow. Just throwing it in as a possible cause, maybe I'm talking total crap and it has nothing to do with it, feel free to educate me.

[zukenutter]

My thinking is, Jezza noticed richness while at idle, if the PCV is blocked, crankcase will not vent during idle causing a higher fuel to air mix.

[Jezza86]

i should just run a supercharger, that will lean it out.

[JrZook]

zukenutter wrote:

My thinking is, Jezza noticed richness while at idle, if the PCV is blocked, crankcase will not vent during idle causing a higher fuel to air mix.

Just to clarify: The crankcase is technically sealed bar the vent. Thus the air/gas coming out of the vent is just pulsed, what ever is displaced is replaced. In other words the vent is not increasing the net air flow to the intake. The only way it could possibly do so is if you have extreme blow-by past the rings.

No CEL Jezza? How accurate is your stated economy of 14L/100km? When did you notice that is was loosing economy, straight after the exhaust mods?

[Jezza86]

Always used lots of fuel, since it came to the NT on a barge really, and Monley reckons mines gutless compared to his.

Could shit fuel block injectors making them overcompensate or something? Might disconnect the duel battery system incase thats working the alternator . I know the 50AH batterys a bit hadit

[zukenutter]

From the M engine swap thread. Like I said, still trying to get my head around possible ramifications and feel free to explain PCV complexities in greater detail.

nordom wrote:

[Jezza86]

this may be the case if so much exhaust gas is entering the intake at idle and WOT that it is actually inhibiting combustion making it smell rich, but would it cause extra fuel to be injected i wonder.

mabie i should get my fuel rail pressure checked too.

[zukenutter]

^^ It's not combustion exhaust, the graphics imply crankcase ventilation exhaust (air that's flowed in via pre-TB breather and then needs to come out

[pete_79]

Seeing as this is in the noob section I'm going to put it out there;
Have you compared your exhaust 'smell' to another Jimny?

I ask because the exhaust fumes from our Jimny are so over powering and 'rich' when compared to my commodore.

Our fuel economy is at or just under 10L/100km, so no issues there. But man it stinks if I leave it running in the carport for a little while.....

[henno]

Does it send out plumes of black smoke out the back when you hit the loud peddle?

Maybe get someone to drive behind you and take a look.

[JrZook]

zukenutter wrote:

^^ It's not combustion exhaust, the graphics imply crankcase ventilation exhaust (air that's flowed in via pre-TB breather and then needs to come out

I see where you are coming from in that scheme. However everything is happening downstream of the mass air flow sensor so any change in air flow past the TB will be sensed.

[royce]

JrZook wrote:

zukenutter wrote:

^^ It's not combustion exhaust, the graphics imply crankcase ventilation exhaust (air that's flowed in via pre-TB breather and then needs to come out

I see where you are coming from in that scheme. However everything is happening downstream of the mass air flow sensor so any change in air flow past the TB will be sensed.

And the amount of gas flow is minimal, any decent amount there means your rings are stuffed and you've got bigger issues

[Jezza86]

just by chance, was walking the dog, and switched from 4H to2H, and heard a noise. i had heard the noise a few mornings ago, and it was constant so the thought crossed my mind about the plastic material coating the outer race of the power steering pump belt tensioner pully insufficient durability recall https://www.recalls.gov.au/content/inde ... mId/987934

turns out it was air getting sucked through the 2wd VSV for the air hubs. luckily there is a in-line filter, but still, if I can hear it at idle over my exhaust... it was sucking a decent amount of air.

I drove home, and sat the car idling. I had a sniff, still smelt rich. i swapped the pipework round so the vsv 1 flows to vsv2 and went and had another sniff
completely different. normal. night and day. and i don't have a headache so i didn't just OD or something...
so i guess next question is what relies on vacuum to lean out the engine. because extra air should have done that....

[royce]

too lean a mixture can still give a really high unburnt hydrocarbon count which is what you would be smelling

[Jezza86]

*head desk* obviously...

should have been asleep at that hour anyway... durp...

thanks Royce

[JrZook]

If you are really concerned and want to recalibrate your sniffer try probing a multimeter into your o2 sensor while running. Provided its a heated type (3or more wires) it will still function at idle and the comp should trim the mixtures to give a reading around 0.5V when the engine is warm. If the reading hits 1V it will be on the richer side of chemically ideal.