[dzenno]

Before I take my car to a mechanic tomorrow for an overnighter I thought why not use the BT Tool to see what it can tell me about the car while the car is running. Never really tried to look at the Actual Values while the car was running at length. Some of you may know, the car's had cold start misfire issues on cylinders 1,2,3 (so bank 1 cylinders) and it was initially mis-diagnosed by the dealer as a headgasket issue. I'm sure my mechanic will be able to diagnose the car properly for the cause but out of curiosity I plugged the BT tool to see if there was any obvious things that would tell me if O2 sensors were causing issues, maybe, possibly...so, have the tool, plugged in, had a friend drive the car while I browsed actual values for anything related to bank 1 vs bank 2, mostly around any values mentioning lambda and cats..If you look at all the actual values that exist, there's quite a few of them mentioning lambda and cats and they always have bank 1 and bank 2 values...in all cases the values for bank 1 followed those in bank 2, with one single exception and its the "adaptation multiplication lambda bank 1" vs "adaptation multiplication lambda bank 2"...Attached is a screenshot...

Notice bank 1 is at over 90% while bank 2 is below 2%...during driving as well as idling, these values stayed up near 98% on bank 1 and down near 2% for bank 2...is this any indication of an O2 problem? What do these values represent and why are they so different?

[Ilma]

Wow....good catch.

Wonder if it's what Shiv suggested in another thread about faulty O2 sensors?

Wouldn't that make the dealership look silly!

[dzenno]

He suggested resetting lambda adaptation, I did that but didn't help..dealership was a waste of both money and time..I just put a new tank of gas and a bottle of STP fuel injector cleaner..seafoam looks to be better but this is all I found at a store tonight..car is going into a shop tomorrow for an overnight scan..

[joec500]

did you also log the Voltage values of bank 1 and bank 2? I had some misfires and my voltage on the misfiring bank was waaaay off.... The funny thing is it only happened when my procede was installed....After I reset lamda adaptation, all was good in the hood.

[dzenno]

I'm pretty sure sure they were close to each other as the ones above were the only ones I noticed..I'll have a look again..how off were they?

[scalbert]

Not the easiet test, but try swapping the O2 sensors and connectors and see if the problem moves banks.

[dzenno]

let's say it really was one of the o2 sensors, would the problem only ever manifest itself on cold start (i.e. cold start meaning car sitting turned off for more than 5 hours, then turned on, no long cranks) and then go away completely after the first 60-90 seconds?

[scalbert]

Originally Posted by dzenno

let's say it really was one of the o2 sensors, would the problem only ever manifest itself on cold start (i.e. cold start meaning car sitting turned off for more than 5 hours, then turned on, no long cranks) and then go away completely after the first 60-90 seconds?

Possibly as they have to heat up. But it could be something affecting them.

That high of an lambda adaptation value would suggest it running lean on those banks. That appears to be a significant difference. Do you have access to an OBDII scanner? I am curious what the LTFT and STFT after and how they compare to the Lambda adaptation values. These OBDII values are normally limited to about +/- 25% so I would like to see a comparison as a reference.

[Ilma]

You know this makes me wonder.......

I have noticed some funny readings on a cold start.

My intake temp is always around 15F higher than the oil and coolant temp sensor readings on a overnight cold start.....I even bought a new sensor and it didn't change a thing

Just this morning I uploaded some new maps to the procede and when I fired up the engine, the coolant temp was reading 100F with an ambient of 44F.

Does that seem odd?

[scalbert]

Originally Posted by Ilma

You know this makes me wonder.......

I have noticed some funny readings on a cold start.

My intake temp is always around 15F higher than the oil and coolant temp sensor readings on a overnight cold start.....I even bought a new sensor and it didn't change a thing

Just this morning I uploaded some new maps to the procede and when I fired up the engine, the coolant temp was reading 100F with an ambient of 44F.

Does that seem odd?

The engine holds heat pretty well and it takes some time to transfer all of it. There is quite a bit of thermal inertia in there.

[joec500]

Originally Posted by dzenno

I'm pretty sure sure they were close to each other as the ones above were the only ones I noticed..I'll have a look again..how off were they?

one hovered around 2volts, the other was reading upwards of 5-7 volts.

[dzenno]

Originally Posted by scalbert

Possibly as they have to heat up. But it could be something affecting them.

That high of an lambda adaptation value would suggest it running lean on those banks. That appears to be a significant difference. Do you have access to an OBDII scanner? I am curious what the LTFT and STFT after and how they compare to the Lambda adaptation values. These OBDII values are normally limited to about +/- 25% so I would like to see a comparison as a reference.

sorry, LTFT and STFT stand for?

Oh, one thing, these 2 values (percentages I've shown) aren't the same values that show up for lambda adaptation values. Is that what I should be looking at? There's a about 5-6 bank 1 vs. bank 2 values in there to do with lambda and I'm not sure which one to be looking at...is this the right one?

[scalbert]

Originally Posted by dzenno

sorry, LTFT and STFT stand for?

Oh, one thing, these 2 values (percentages I've shown) aren't the same values that show up for lambda adaptation values. Is that what I should be looking at? There's a about 5-6 bank 1 vs. bank 2 values in there to do with lambda and I'm not sure which one to be looking at...is this the right one?

Long Term Fuel Trim and Short Term Fuel Trim. They are federally required based ont eh OBDII mandates.

It appears so but am curious what the value differences might be. I'll try and check mine tonight and see what they look like with OBDII and BT interfaces.

[dzenno]

Originally Posted by scalbert

Long Term Fuel Trim and Short Term Fuel Trim. They are federally required based ont eh OBDII mandates.

It appears so but am curious what the value differences might be. I'll try and check mine tonight and see what they look like with OBDII and BT interfaces.

think BT tool has actual values that are reported to OBDII as well as I recall seeing them but don't know if they're lambda related..thanks

[scalbert]

Originally Posted by dzenno

think BT tool has actual values that are reported to OBDII as well as I recall seeing them but don't know if they're lambda related..thanks

I checked with BavTech and they do not read any of the OBDII data. Granted, things like IAT and ECT would be the same. But the true calculated OBDII values may not be available or the same.

[dzenno]

ok...so do we know what Actual Value(s) to look at for bank 1 sensors and if BT tool supports tis? on top of that, how/would we be able to use BT to see which one is/may be faulty? Think in my case with cold starts I'd need to log bt actual values for anything o2 related on bank 1 and just graph pre vs. post cat sensor values?

[scalbert]

Originally Posted by dzenno

ok...so do we know what Actual Value(s) to look at for bank 1 sensors and if BT tool supports tis? on top of that, how/would we be able to use BT to see which one is/may be faulty? Think in my case with cold starts I'd need to log bt actual values for anything o2 related on bank 1 and just graph pre vs. post cat sensor values?

That is why I will check mine tonight for comparison purposes.

[joec500]

Originally Posted by scalbert

That is why I will check mine tonight for comparison purposes.

Hey Scal, can you check your O2 Lambda voltages too?

[scalbert]

Here are the results, and joec500, I included the Lambda Voltages (at least the ones I assumed you wanted), and they stayed right around 2 VDC.

dzenno, I would definitely try swapping those front sensors and connectors. That reading is way off. I suspect the dramatic readings will move with the sensor and you will need to replace that one. Otherwise, those bank one injectors are not up to par which I doubt they would be that bad.

Granted, the below readings are not the same between OBDII and the BT interface, but they are within reason of what I would expect. In watching the readings, and they do move around quickly, in particular the STFT, it almost looks like the BT readings is the sum of the Short and Long Term Fuel Trims for that bank. I realize they don't match here as the values were moving and there is only one OBDII port to hook up to so it is not the same moment in time. But the averages would have been close.

Anyway, dzenno, there is something wrong and is most likely that sensor IMO. Worth an hour or two in swapping them and retesting. Or, just purchase a sensor and try it out. Granted, there is a costy but may also be a cure.

[dzenno]

very interesting find...in my case the adaptation multiplication lambda for bank 1 was above 95% while bank 2 was down to around/below 4% when i was looking...it would for a split second drop suddenly down to 4 (not even half a second, like a spike) and then it'd be back up to over 95%...i'll test this again later on tonight once the car cools down...what's interesting is that the voltages were fine (around 2V DC +/-0.5V) and stayed there for both bank 1 and 2...

i was at RMP tonight to leave my car for an overnight diagnostic to see if a headgasket was leaking (compression test and maybe a fuel system pressure test) but we decided to take a peak at the plugs...pulled all bank 1 plugs and the first 2 bank 2 plugs...all EXCEPT cyl 2 plug were "clean"...these are brand new plugs put in this past Monday..the cyl 2 plug had carbon build up on it..when Rocco pulled the codes he found a misfire on just cylinder 2 not all three bank 1 cylinders which is what I used to find...reason for this is I cleared all the codes before I headed out to his shop as I had misfires before I left...BUT, i didn't clear the codes on the last restart that also felt like the car was misfiring, but it wasn't bad enough so i didn't clear and the car felt fine...

so the fact that all other plugs but cyl 2 plug were clean, and cyl 2 plug had carbon (dirty) on it already (not even 4 days in the car) and the fact that code reader showed a misfire only on cyl 2 (probably because i restarted too soon for the other two bank 1 cylinders to start), we're assuming its the cyl 2 injector so that's what we'll try changing out first...

i'll take a look at the adaptation multiplication lambda on bank 1 using the BT tool tonight/tomorrow morning and see how the percentages compare to bank 2...

Question: If this really turns out to be a leaky injector on cyl 2, could it be causing a discrepancy on this o2 bank 1 sensor? In other words, if I do see this huge discrepancy in the BT tool can I conclude that the front o2 sensor on bank 1 is faulty or could it be that the discrepancy is there because a leaky injector is making bank 1 cyl 2 run rich?

- thanks

[joec500]

If that cycle 2 injector is leaking and/or could be over spraying causing a rich condition, which could create a non-ideal combustion causing the pre-cat o2 to read abnormal conditions thus causing it to send out of spec manipulation values? So it could be possible that your o2 is fine and you may just have a faulty injector. But if you injector is faulty, you need to bring your car to the dealer because they have a specific computer to calibrate those high pressure injectors. Unless your local mechanic as one of those... Also those injectors are pricey, I think around 200-300 each.

Scal, thanks for cheking the voltage, 2v is the norm, when my car was mis-firing the misfiring bank's lamda read 5-7volts, but went back to 2v once I cleared lamda adaptation.

[dzenno]

Tischer (getbmwparts.com) actually has them for 130 now, price went down a lot in the past 10 days...same for o2 sensors, 180...i'll ask him about calibration..is that done once they're mounted or can they be bought pre-calibrated?