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Do these logs confirm that i have a faulty o2 sensor or could there be something else causing the lambda v to be erratic?
The AFR gauge holds a nice steady 14.5-14.9.
Recently when coming off throttle(not all the time,but becoming more frequent)
The AFR gauge goes from fully lean which i would expect to really rich(11's)
this is happening at all revs so it's not injector re-injection/overrun,the injectors are set to come back in at 1500rpm.
The car bucks as the fuel is been thrown in then shut off,it's more noticeable when coasting down a hill with the throttle off and constantly goes lean,rich,lean,rich,lean,rich etc...(i don't have any logs with this happening)
Car idles perfect,cruise and WOT are good but one other thing i do notice is,when im on light throttle at 14.7 and gently put a little more throttle on then the car goes rich low to mid 12's.
I never thought until now that i should have switched off closed loop and tested it but the cars on the drive in bits at the moment so can't test just yet.
is this the reading from the stock front o2 or from your wideband mr? from my experience if the sensor is dead you get no readings from it or it will stick on one value. As your on light throttle there I would assume the change in voltage is closed loop control doing it's thing.
If you can log with a wideband once it's back together that will show if the afr is actually changing or not which will help clue you in on whats happening.
This log is from the oem narrowband sensor,I've not rigged up the wideband in ESL.
I was eyeballing the gauge and held a steady 14.7 and as you say closed loop compensation would change the lamda v but would it go all the way fro 0.06 to 0.70 ?
I can log from my wideband separately but I'm having bother with my serial to usb cable.
I will see if I can get the innovate logging for me and try and line up the data with ESL logs.
Will also take some logs and see how it drives with closed loop switched off.
Range is ok should switch between low n high v
the Bosch lsu2 sensor I use is quicker than ur log
Cool,oem one might be ok then.
My wideband uses the lsu2 but as I say I've not rigged it up to ESL so just use it as a standalone for the gauge.
And ideas why the car keeps throwing fuel in intermittently when I'm coasting off throttle? Could it be sticky injectors? Or something simple like a vac pipe leak?
aye if it's the narrowband sensor it only really reads on or off so will usually be switching between the two even when stoich. TPS could be a good one if it's not reading you off the throttle then your not really in overrun so the car thinks your tapping the throttle?
if you want to share a log/view easily datazap is pretty good: http://datazap.me
you can fiddle around online/share the log with the public etc. and you can overlay the individual item traces which can sometimes make things a bit easier to see. Some new features too like log playback with little charts on the side showing individual paramters. Worth a play with plus free
Yes my tps logs between 16 and 86 but has always been like this,I thought the overrun on ESL goes by RPM so tps shouldn't come into play?
I do hear you tho,if the tps thinks I'm blipping the throttle then this would explain why it keeps chucking fuel in.(Maybe faulty tps?)
I will do some logs and catch what's going on when I'm coasting off throttle
Cheers
Cars back together now so will go for a little drive tomorrow if I get chance.
if the tps is not showing the correct voltage for off throttle then the ecu with think your still on the throttle, and wont activate the over run fuel cut, on idle i think my tps is around 8%.
also check that the throttle cable is not adjusted too tight
Last edited by sean turbo2000; 12 February 2016 at 07:50 PM.
yeh if the ECU isn't seeing the throttle closed then it doesn't trigger overrun fuel cut - the RPM your at no longer matters as far as the ECU's concerned your still touching the pedal. should be able to log the TPS or poke it with the multimeter before you set off just to make sure it's idle (and that it resets to idle after a few pumps incase it's sticky).
Have a read through my thread about fuel trims - I know you commented on some bits, but you may have missed my comments about the TPS - and the useful adjustment technique (post 57)!
When my TPS was only dropping to around 9% it was enough for the ECU to not realise it should be in 'idle' mode and my boost control solenoid wasn't behaving itself.
Ok so I adjusted the TPS.
Got it adjusted down to 8.6% and all was fine until my journey home this morning.
Had the laptop plugged in and logging,after a quick WOT and fully coming off throttle the car started with the problem again,this time I caught it on the logs.
When coasting in gear the TPS goes from 8.6 upto 9 so I assume the ecu thinks I'm blipping the throttle! There are no error codes for the TPS and at over £200 from icp I'm praying it's not faulty!
I will give the throttle body a clean and spray the connector but am I right in thinking the sensor is a sealed unit so can't be cleaned?
Is there anything else to look at that might cause this?
I'd bring it down lower if you can. When mine was showing at 9% it was still at the threshold where the car got a bit confused whether it was on/off throttle. Now that it's down at about 5% I haven't had that problem since.
Ok cheers Ben I will try and get it a bit lower.
I just find it strange that on the logs when this happens(it doesn't happen all the time) that the TPS shows a change from 8.6 to 9 and back to 8.6 constantly,and while it does this I can feel and see it chucking fuel in.
11 February 2016 | 02:49 PM
Does this short log show a faulty o2 sensor?
