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Bad Lambda Sensor with out MIL indication

skhell

skhell

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Location
Portugal
Car
1.8, 6th gen Accord
Hey guys,

As some of you might know, my car is running on LPG, the car runs great either on LPG and on Petrol. The thing is, I suspect it has a low mpg, it thing it as drinking problem :lol: I say "I think" because when comparing it to other Accords, also with LPG, mine drinks more ;) It's not a problem from the LPG system, as I already went to two LPG installation shops(two of the best in Portugal) and they can't find anything wrong with the LPG system.

I "suspect" it could be something related with the Petrol "system", perhaps the Lambda Sensor is not in its best days. I am not sure of this also, as I don't know the fuel consumption when running on Petrol, since I never drive on Petrol :lol:. For now, I am just wondering what possible causes to this problem.

Now, my question: Is it possible for the Lamda(oxygen) sensor to be not working properly, even if I have don't have a "check engine light" on? If so, is there any way to test it, maybe my self, or in a shop?
 
yes a lambda sensor will fail with no MIL light on one to find out is to get the emissions checked (like they do on an MOT) also plugging into a diagnostic machine to see if the sensor is reading ok
 
Paul said:
yes a lambda sensor will fail with no MIL light on one to find out is to get the emissions checked (like they do on an MOT) also plugging into a diagnostic machine to see if the sensor is reading ok
Click to expand...

It passed the MOT with no problems. Plugging it into a diagnostic machine might be a good idea.

Forgot to say that the car is from 2000(10 years) and has 123000km.
 
Pedro bear in mind that you are constantly carrying the extra weight of your LPG tank and system everywhere you go.. that won't be helping your economy.
 
F6HAD said:
Pedro bear in mind that you are constantly carrying the extra weight of your LPG tank and system everywhere you go.. that won't be helping your economy.
Click to expand...

Yeah, I know that, but still... Driving about 140km/h I get around 11.5/12 litres /100km (running on LPG). I know people with cars like mine and with the 7th gen 2.0 litres that make about 9/10liters /100km, also on LPG...

I will have to make a few kms on Petrol to see what is the consumption.
 
Sorry I misunderstood, you are complaining about the fuel economy on LPG?

When were the filters last changed?

Also, it really depends on how the system has been calibrated as the LPG system should have it's own ECU, and I'm not entirely sure which sensors it will take readings from inc the lambda sensor.
 
i don't know to much about LPG but was the car running on LPG for the MOT as I believe the emissions will be lower with LPG than with petrol so it would still pass even if running slightly rich on LPG (does that make sense?)

so it maybe worth getting the lambda sensor checked by either method that I said above and whilst running on petrol particularly if the LPG system does take a reading from the lambda sensor
 
Kind of, I only have the fuel economy numbers of the LPG, as I don’t use Petrol, but I guess its not cause of the LPG, as the system has already been calibrated by two top LPG experts.

IF, I really have a bad fuel economy, I guess its something not related to the LPG, hence the Lambda Sensor question :lol:

About the LPG system, it really has its own ECU, but its directly connected to the Petrol ECU and read has access to all the sensors of the engine, so, if any of the sensors is not ok, the Petrol ECU will produce bad results, which will be transmitted to the LPG ECU, and then make bad things happen.

Well, before reaching any conclusion, I will make a few kms n Petrol, and then I will now.

But answering my question: I guess really could have a faulty code, even with out the MIL light and passing on MOT...
 
Paul said:
i don't know to much about LPG but was the car running on LPG for the MOT as I believe the emissions will be lower with LPG than with petrol so it would still pass even if running slightly rich on LPG (does that make sense?)

so it maybe worth getting the lambda sensor checked by either method that I said above and whilst running on petrol particularly if the LPG system does take a reading from the lambda sensor
Click to expand...

No, the car was running on Petrol, the MOT has to be done with the car running on Petrol. Ans yes, it makes all sense, LPG has lower emissions :)

I guess I will try that, after checking the fuel consumption running on Petrol.

This has been very helpful, at least I know what will be my next thing to do, test the lambda sensor on workshop :lol:
 
Pedro, lambda sensors never last the life of the engine anyway and even if they're not broken, in my experience after 100k it's normally a good idea to change them.. think of it as a consumable item.

Just change it anyway, it won't hurt things.
 
Found a great article about Lambda Sensors and how to diagnose them:

http://www.picoauto.com/applications/lambda-sensor.html
 
I am getting more and more convinced to buy the Lambda Sensor. I have been looking at its price at Honda and is way too expensive. Does anyone knows what brand and reference of the Lambda Sensor installed on our cars?

I suppose it is a NGK... I found this one on ebay http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=370444032407&ssPageName=STRK:MEWAX:IT, which has a pretty good price. It is a NGK OZA501-H17, and it seems to be compatible with my car.

I have read somewhere that our cars doesn't like compatible Lambda Sensors, only like sensors equal to one that is installed. So, it would be great to know the make and reference of the sensor installed...
 
Hi guys,

Long time I have created this topic B) Bring up this topic, I got access to an oscilloscope and managed to test the lambda sensor and see check its condition. As I suspected, the lambda sensor was not in a great shape. It was producing good values, but it was starting to get too slow.

So, I decided to buy a new one, a NTK NGK from ebay and fit it my self B)

After the first LPG tank, I managed to get a much better fuel economy. I managed to make 510km on a tank when I could only do about 420/430km, which represents a huge gain in economy :wub:

So, my advice, if your car (petrol) is getting poor fuel economy, and if it has a few miles on it and a few years, replace the lambda sensor, you might get a surprise B)

As a side note, mine has 126000km and almost 11 years, but in its first 8 years of its life it did lots of city/traffic...
 
thats good news Pedro bet your well pleased

on a side note it is worth sometimes removing the sensor and giving the sensor a clean they get covered in exhaust soot something like carb cleaner would do
 
Well done Pedro and yes you're right. Sensors like oxygen and airflow are really not designed to last the life of the engine. Best to replace them after 120k miles in my opinion anyway..
 
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