Position of wideband sensor in exhaust??
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Just installed an Innovate Motorsport wideband and took it for a drive. The readings go wild on acceleration so I suspect the sensor is mounted in the wrong place.
The garage has fitted it in the stock O2 bung accessible from the left hand rear wheel arch - is this correct or is it better to put it further away and near the outlet?
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The garage has fitted it in the stock O2 bung accessible from the left hand rear wheel arch - is this correct or is it better to put it further away and near the outlet?
Cheers
#2
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the stock O2 bung is before the turbo, many say the O2 sensor should be after the turbo but not too close to it due to heat. My O2 sensor is also before the turbo but not in the stock location (I have different headers). It works there with no problems since 2 years. The readings are spot on, tested and compared on several dyno pulls (compared with post-turbo dynometer O2 sensor). what AFRs does your gauge show @ idle? what exactly at WOT?
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It is FACT that widebands are affected by the pressure induced by placing before the turbo. My original shop placed it before the turbo. I checked the difference between before and after and was material enough for me to change it. There is plenty of technical documentation on the effect include compensation curves if you choose to leave it before turbo.
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One pluspoint for post-turbo installation is that, if the sensor fails, there is no risk of damaging the turbo.
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As James says, it is important to install a wide band sensor after the turbo due to the backpressure which affects the readings. On some ECUs like MoTeC, you can build a compensation table to compensate for the back pressure and then install it pre turbo, but I don't think that is applicable here.
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As James says, it is important to install a wide band sensor after the turbo due to the backpressure which affects the readings. On some ECUs like MoTeC, you can build a compensation table to compensate for the back pressure and then install it pre turbo, but I don't think that is applicable here.
All 3 dynoplots from my car show the same AFR readings as my in-car pre-turbo AFR gauge (no EFI, CIS typical pig richness (high 10s) in midrange, high 11s from 4000rpm up to max rev @1bar).
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Thanks.. I thought this was the problem but wanted to check before I remove the end pipe and cut/weld etc.
On idle I was getting AFR at about 11-11.5. On hard acceleration it was going to 30 but on gentle acceleration it was about 12. The back pressure must have made it read incorrectly.
On a similar note, the CO mixture 3mm hex can adjust idle mixture but if the AFR is out higher up the rev band what can you do? Do you have to adjust by the adjustable WUR (I have Leask mod with stronger diaphragm).
My mechanic is saying he thinks my fuel distributor needs a refurb as it is still a bit rough on light throttle before the boost picks up and we have changed/cleaned everything else (injectors, WUR, fuel accumalator, filter, cleaned tank etc). What do you guys think as he says the springs and valves in the distributor can get tired and/or clogged over time.
On idle I was getting AFR at about 11-11.5. On hard acceleration it was going to 30 but on gentle acceleration it was about 12. The back pressure must have made it read incorrectly.
On a similar note, the CO mixture 3mm hex can adjust idle mixture but if the AFR is out higher up the rev band what can you do? Do you have to adjust by the adjustable WUR (I have Leask mod with stronger diaphragm).
My mechanic is saying he thinks my fuel distributor needs a refurb as it is still a bit rough on light throttle before the boost picks up and we have changed/cleaned everything else (injectors, WUR, fuel accumalator, filter, cleaned tank etc). What do you guys think as he says the springs and valves in the distributor can get tired and/or clogged over time.
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#8
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My mechanic is saying he thinks my fuel distributor needs a refurb as it is still a bit rough on light throttle before the boost picks up and we have changed/cleaned everything else (injectors, WUR, fuel accumalator, filter, cleaned tank etc). What do you guys think as he says the springs and valves in the distributor can get tired and/or clogged over time.
I'd check the spray patterns of the injectors, check for leaks in the intake track (especially the o-ring on the throttle body/intercooler interface) and have the wur rebuilt before I would crack into the fuel distributor.
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Injectors have been removed and cleaned at Bosch. Vac system also checked and can't find any probs but will recheck the o ring. WUR is rebuilt by Brian. Not sure what else to do as process of elimation.
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Your AFR sensor must be knackered. Find a shop where they can put a O2 sensor inside your right tailpipe, check the readings and adjust the mixture correctly via the 3mm hex. Avoid WOT until you havent done this.
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The mixture was set as normal with the 3mm hex and I am using the wide band to validate I am not too lean. It is brand new. It seems to work fine apart from under strong boost - as it is located before the turbo the back pressure must be affecting it.
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Well, if the mixture is adjusted you are fine. I have no experience with innovate sensors but I would surely try to install it after the turbo if you have problems with the readings. On the other hand the back pressure shouldnt affect the idle AFR readings and it shows far too rich readings @ idle.
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Sounds like the wur can be eliminated.
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My mechanic is saying he thinks my fuel distributor needs a refurb as it is still a bit rough on light throttle before the boost picks up and we have changed/cleaned everything else (injectors, WUR, fuel accumalator, filter, cleaned tank etc). What do you guys think as he says the springs and valves in the distributor can get tired and/or clogged over time.
Some failures that I've heard about are broken diaphragms and rusty plungers. I'm sure there are other failure modes.
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I understand what you are saying, my own experience is that if there is any difference it is very small. It would also be interesting to know if pre-turbo shows richer or leaner compared to after turbo readings.
All 3 dynoplots from my car show the same AFR readings as my in-car pre-turbo AFR gauge (no EFI, CIS typical pig richness (high 10s) in midrange, high 11s from 4000rpm up to max rev @1bar).
All 3 dynoplots from my car show the same AFR readings as my in-car pre-turbo AFR gauge (no EFI, CIS typical pig richness (high 10s) in midrange, high 11s from 4000rpm up to max rev @1bar).
Here are the details for working out the compensation:
A pressure change of the measured gas gives a deviation of the sensor output signal of:
IP(p) = Ip(p0) * p/(k+p) * (k+p0)/p0
The factor k is depending on operation conditions “rich” or “lean” and is for the measuring gas from LSU test bench:
klean gas = 0.47 bar krich gas = 0.39 bar