Fuel running rich and spluttering from exhaust

ABS

ABS

Active Member
Premium Member
Hi,

Recently my fuel has been running quite rich and there is a very strong fuel smell coming from the exhaust.

After the car has warmed up for a good five minutes, usually in the mornings I always see specks of fuel spluttering from the exhaust. I assume it's happening whilst I am driving as well. Is this normal? :?:

Do I need to get a fuel injector service done and what does this normally involve?

:?

Just now I managed to record this on video, heres the link: http://youtu.be/cmOXu4GcFMs


Has anyone else experienced this?

Thanks.
 
Are you sure its not fuel but condensation? Because that's a very normal thing. Especially in the cold mornings.
 
smell like strong fuel when cold is richer because the engine is cold and extra fuel is done on purpose by the ecu until the coolant temp is nominal.
also smell like its too rich due to the fact the cat is not working. cats do not work very well at cold temps.
they remove emissions optimally when they are at proper temp

the black stuff is what the man above said.
 
I've noticed a burble, spitting noise thats quite profound from the exhaust when off the throttle that I initially thought might be the 4g69 running rich, but I'm leaning towards thinking it's just an exhaust noise characteristic of the ch.
as for the dripping, my car behaves like a kettle for the first 10 minutes of my drive.
 
ABrouwer said:
Are you sure its not fuel but condensation? Because that's a very normal thing. Especially in the cold mornings.
Click to expand...

+1, the fuel would have vaporised so you wouldn't be seeing it I reckon....
 
Ahh really, so it is normal. hmmm

I'll have to check it again after driving around the block. Will let you know soon.
 
I really don't think it will stop after driving around the block. Mine can do it for quite a long time.
If you really want to check its fuel light it on fire and film that! .... Don't actually probably not very smart hahah
I wouldn't worry about it to much. If your fuel economy is still good I don't think you will be losing so much to the point that its dripping out the end of your exhaust like a tap.
 
My car was chewing fuel and blowing smoke and carrying on when my oxygen sensor was rooted. If its only doing this when cold its pretty normal
 
sladey121 said:
My car was chewing fuel and blowing smoke and carrying on when my oxygen sensor was rooted. If its only doing this when cold its pretty normal
Click to expand...

oh yes! A while ago I had a computer scan done on my car and I got three error codes all relating to the 3 oxygen sensor's.

They read:
Total codes: 003
CODE001: P0136 Oxygen sensor (rear)
CODE002: P0135 Oxygen sensor (front) heater
CODE003: P0141 Oxygen sensor (rear) heater

The auto electrician who did the scan told me I had to leave the car there for a day for them to check each sensor. I didn't have the time so I didn't bother.

On the other hand, my mechanic told me not to worry too much about it unless I notice the dashboard engine light turning on.

:?

I don't know if these error codes have something to do with the fuel burning (i know that faulty sensors can cause fuel to burn rich/lean and obviously decrease fuel economy).
 
if your o2 sensors are fried, my understanding is the ecu compensates with not getting an accurate response from your exhaust gasses by dumping extra fuel and giving you a rich (but safe) mix. It's not cheap, but getting them fixed will save you money at the petrol station.
 
U can try cleaning the O2 sensor. Not recommended but worth a try if ur going to replace it.

Use throttle body cleaner or soak in fuel
 
U can try cleaning the O2 sensor. Not recommended but worth a try if ur going to replace it.

Use throttle body cleaner or soak in fuel
 
Liam said:
if your o2 sensors are fried, my understanding is the ecu compensates with not getting an accurate response from your exhaust gasses by dumping extra fuel and giving you a rich (but safe) mix. It's not cheap, but getting them fixed will save you money at the petrol station.
Click to expand...

Is there a way to check which o2 sensors need replacing?

Or do the above error codes indicate that all 3 need replacing?
 
3 o2 sensors? I might be wrong but I was very sure we just have one? Maybe its only in newer cars
 
ABrouwer said:
3 o2 sensors? I might be wrong but I was very sure we just have one?
Click to expand...

Well the error codes state there are 3, I've also called up Mitsubishi and they have also said there are 3 (each o2 sensor costs $390) :(

1 on the engine manifold
2 underneath the car (near the catalytic converter - so 1 before and 1 after the converter)
Total = 3

btw my car is a 2007 Lancer CH, as seen in my avatar. :mrgreen:


So I was wondering how to test them? :?:
 
You can test them with basic multimeter. But the problem is, that you have to do it while driving with low RPM. The Lambda sensor doesn't really give any sensible signal on idle. Other problem is, that you would have to connect the meter (preferably analog meter) to your lambdas wiring while it is still connected to ECU. You can try it while standing still and someone keeping the rpm's consistent ~2000-3000rpm, but really only reliable way is to drive flat road on a stable speed.

When driving ~2000-4000rpm on low TPS the engine should be trying to get to stoichiometric AFR. That would be 14,7 on gas and the Lambda value would be 1. But since you don't have access to OBD dataloggin you have to see what voltage the lambda gives. On stoichiometric AFR it should be 0,5V but since lambda does sine wave the voltage should bounce from ~0.1-0.2V to 0.7-0.8V. And the wave should be pretty consistent.

If you find out that the problem is on your 2nd or 3rd lambda, you can fix it cheaply with soldering a lambda simulator between the wiring from lambda to ECU. :thumbup: I have one too, because Mitsu's ECU is really demanding on cat's efficiency. :?

You know what? This would be ridiculously easy job if you had an OpenPort cable. You could datalog your OBD via Evoscan easily. And you could also disable 2nd and 3rd lambda from your ECU easily with EcuFlash, if you had the cable :troll:

On EvoScan, you can, if you like, see a live graph like this on Lambda's values:
11079933.jpg

(this is not live, I just took a little piece of my datalog to show you)

From this picture you can have an idea what voltage readings lambda should give. 1st lambda is yellow and 2nd (with the simulator on) is purple. I lifted the throttle on 37,150-43,150 so thats why you have to drive stable speed with stable TPS.
 
Does anyone know any places (workshops or specialists) in Sydney where I can get someone to check which oxygen sensors are faulty (using datalogger or any method) ?

Thanks..
 
Just go to mitsubishi and have them run a diagnostics scan on it. If you have error codes on your oxygen sensors, then they will need replacing. Don't buy the sensors through mitsubishi, they charge a fortune. Go to bursons or repco or something. They will be much less
 
Well the fault code doesn't really tell you if the sensor is broken or not. It will tell you does it give figures that it should. For an example if it runs too rich and lambda doesn't read values that ECU would be happy about -> fault code.

My 2nd lambda was complaining that my cat's don't work as efficient, as ECU would like. Still it gave fault code "2nd Lambda sensor". Replacing the sensor really doesn't solve that problem. But datalogging it showed me what was the problem.

And by the way OEM sensors seem to last a fortune longer than non-OEM :) At least from my experience. If you get to know who manufactured the OEM, you might get the same one straight on that brand, cheaper.
 
Urran said:
Well the fault code doesn't really tell you if the sensor is broken or not. It will tell you does it give figures that it should. For an example if it runs too rich and lambda doesn't read values that ECU would be happy about -> fault code.

My 2nd lambda was complaining that my cat's don't work as efficient, as ECU would like. Still it gave fault code "2nd Lambda sensor". Replacing the sensor really doesn't solve that problem. But datalogging it showed me what was the problem.

And by the way OEM sensors seem to last a fortune longer than non-OEM :) At least from my experience. If you get to know who manufactured the OEM, you might get the same one straight on that brand, cheaper.
Click to expand...


Can't speak for the CH but the CJ doesn't throw error codes for the sensor if it thinks the readings downstream of the cat aren't correct. Instead it throws a P0420 Catalyst under-efficiency error...

My CJ didn't like my headers and through CELs, ended up fixing it by slapping one of these on it:
New_o2_spacer.JPG

http://www.ebay.com.au/itm/O2-Spacer-Ad ... 2a239dc42a
Given how cheap and non intrusive they are I would recommend trying these before going with a device you have to solder into the wires going to the sensor...

But in reply to the OP, if you're getting normal fuel economy and it's not throwing any check engine lights I really wouldn't worry about it.... If you come to the NSW meet on Friday I can whack my scan tool on it and see what error codes it is actually spitting out before and after the run through the RNP...
 
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