Hi guys
Iam having some trouble with my honda civic drag car running a s6 with a ntk lambda sensor the car has been fine in the past and ran times of 8.7 @169mph but we are now having a problem with afr readings.
We put a second lambda sensor (aem with gauge which we know is good) in the exhaust very close to the syvecs ntk one on idle we were seeing around a 13.8 but the aem was seeing around 16 to 17 afr.
Does anyone have any ideas on this?
Any questions just ask please
Lambda reading problems
Re: Lambda reading problems
What fuel?
An absolute AFR value is not helpful unless you know the fuel (mostly whether there's alcohol involved), and I wonder if the AEM has settings for the fuel type so it can translate the measured lambda to an AFR value?
An absolute AFR value is not helpful unless you know the fuel (mostly whether there's alcohol involved), and I wonder if the AEM has settings for the fuel type so it can translate the measured lambda to an AFR value?
Re: Lambda reading problems
Good point tim
Well the car runs e85 at the track but we have tested with both e85 and v power.
We are getting the same difference
My friend has the same setup as me syvecs s6 ntk sensor so we did the same test on his car both sensors reading the same value at idle 14afr
Well the car runs e85 at the track but we have tested with both e85 and v power.
We are getting the same difference
My friend has the same setup as me syvecs s6 ntk sensor so we did the same test on his car both sensors reading the same value at idle 14afr
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stevieturbo
- Posts: 1376
- Joined: Sun Dec 07, 2008 2:04 pm
Re: Lambda reading problems
Fuel is largely irrelevant, as it's fair to assume both are using the normal petrol scale, so normal AFR numbers are valid.
More importantly...is there an actual running problem or change you're trying to resolve ?
Which reading do you suspect to be wrong ?
If you feel the NTK AFR's have changed over time....is this with the same injector pulse widths and running conditions ? ie the AFR numbers should not have changed because no fuel/airflow changes have occurred ?
Is the difference in readings at all loads, or only at idle ?
How far are the sensors from fresh air ? How old is your NTK sensor ? has either sensor ever had any trauma ? ie physical damage, water passing etc from say a HG letting go ?
More importantly...is there an actual running problem or change you're trying to resolve ?
Which reading do you suspect to be wrong ?
If you feel the NTK AFR's have changed over time....is this with the same injector pulse widths and running conditions ? ie the AFR numbers should not have changed because no fuel/airflow changes have occurred ?
Is the difference in readings at all loads, or only at idle ?
How far are the sensors from fresh air ? How old is your NTK sensor ? has either sensor ever had any trauma ? ie physical damage, water passing etc from say a HG letting go ?
Re: Lambda reading problems
Hi steviestevieturbo wrote:Fuel is largely irrelevant, as it's fair to assume both are using the normal petrol scale, so normal AFR numbers are valid.
More importantly...is there an actual running problem or change you're trying to resolve ?
Which reading do you suspect to be wrong ?
If you feel the NTK AFR's have changed over time....is this with the same injector pulse widths and running conditions ? ie the AFR numbers should not have changed because no fuel/airflow changes have occurred ?
Is the difference in readings at all loads, or only at idle ?
How far are the sensors from fresh air ? How old is your NTK sensor ? has either sensor ever had any trauma ? ie physical damage, water passing etc from say a HG letting go ?
we were having isses with boost at an event and we couldn't find any problem, when we put the car on the dyno this turned out to the the AFR reading wrong on the syvecs compared to the one on the dyno. So we tuned the car to the dyno lambda meter and all was fine clean pulls on the dyno making boost no problem.
We bought a brand new L2H2 sensor which was the same as we used beforecar before it failed and we thought all would be sorted, closed loop lambda was turned back on as we have to tune at the track. we then started getting problems again.
we then looked into the AFR again when we got the car back, this is when we tested the AEM lambda in the car to compare against the reading on the syvecs. so we now suspect that the AFR reading on the ECU is wrong coming from the new sensor. unfortunately we have only tested this at idle but throught the rev range will be the next test.
as we tune at the track the fueling and boost constantly change after every run but it seems we are tuning to an incorrect AFR, the car has a 4" up pipe exhaust so i would say it is around 12" from fresh air and we had the other sensor around the same place.
hopefully all of that makes sense and ive given some more background of the problem
thanks
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stevieturbo
- Posts: 1376
- Joined: Sun Dec 07, 2008 2:04 pm
Re: Lambda reading problems
There are some on here who will say each and every sensor needs its own calibration ( que Rice Racing 
) and they no doubt have their evidence to support that. So maybe that might be an option for you to to have your sensor given a test and calibration chart to use.
I've only done a few cars, but never had any issue that caused me any concern. I did also try a couple of sensors in the same exhaust pipe when I changed to the S8 and could do so and again saw nothing that gave me any concerns about them reading different.
Obviously each and every case may be different. As you have the AEM fitted to the car, wire it's output into one of the analogue inputs on the ecu so you can log it too, at least then you can see what both are doing on the same graph. You could even choose to use that as your sensor for any corrections to be applied.
Might also be worth trying with closed loop off too.
I use the LZA09-E1 on my own car and others and is what I tested. I also tried an original L1H1 for a short period too, and it read pretty much the same, with the same linearization as the LZA ( both supplied graphs were the same anyway )
I have a PLX wideband, LSU4.9 on one of my exhaust pipes as well as the Syvecs, purely as I've always had a separate wideband display in the car anyway, but I log this on the Plex dash as well as the Syvecs from both pipes.
Again, other than minor differences at times which is to be expected, it will always give similar readings.
None of the above a great help....although around idle with only 12" from fresh air, not sure I'd be expecting to get honest readings from any sensor, so maybe one is just more sensitive to this than the others.
On power once sufficient volume of gas is moving, it should probably be ok though.
Although if this fuel issue is also affecting boost, it must really be huge AFR differences ?
) and they no doubt have their evidence to support that. So maybe that might be an option for you to to have your sensor given a test and calibration chart to use.I've only done a few cars, but never had any issue that caused me any concern. I did also try a couple of sensors in the same exhaust pipe when I changed to the S8 and could do so and again saw nothing that gave me any concerns about them reading different.
Obviously each and every case may be different. As you have the AEM fitted to the car, wire it's output into one of the analogue inputs on the ecu so you can log it too, at least then you can see what both are doing on the same graph. You could even choose to use that as your sensor for any corrections to be applied.
Might also be worth trying with closed loop off too.
I use the LZA09-E1 on my own car and others and is what I tested. I also tried an original L1H1 for a short period too, and it read pretty much the same, with the same linearization as the LZA ( both supplied graphs were the same anyway )
I have a PLX wideband, LSU4.9 on one of my exhaust pipes as well as the Syvecs, purely as I've always had a separate wideband display in the car anyway, but I log this on the Plex dash as well as the Syvecs from both pipes.
Again, other than minor differences at times which is to be expected, it will always give similar readings.
None of the above a great help....although around idle with only 12" from fresh air, not sure I'd be expecting to get honest readings from any sensor, so maybe one is just more sensitive to this than the others.
On power once sufficient volume of gas is moving, it should probably be ok though.
Although if this fuel issue is also affecting boost, it must really be huge AFR differences ?
Re: Lambda reading problems
The thing is we have tested on another car with the same setup and that reads perfect! It's bugging me so much now as we can't find anything wrong
Re: Lambda reading problems
Dodgy lambda cable?
Re: Lambda reading problems
Iv just took the lambda loom out and fully checked it and refitted exactly the same!
Re: Lambda reading problems
We took the syvecs lambda sensor out of the bung today and placed it down the exhaust like the aem and reads perfect put it back in and now we have the offset this is only 6 inches max from each other
I think it's been mentioned that we might not be getting a true reading with how the exhaust is
I think it's been mentioned that we might not be getting a true reading with how the exhaust is