fault log says lambda 1
Discussion
Symptoms: start engine, MIL light stays on. Car seems to run ok though. If it's of any relevance, the car had just spent a week sitting outside, with heavy rain on one or two days, so I thoght maybe it was water ingress. I've had the car on charge in the garage for a week, so it's now dry and charged.
Still same problem today. So I connected up the laptop, checked the fault log. It has a logged fault in Lambda 1. The adaptives on 2468 were all over the place (minus 25% or so at some points).
So: reset fault codes, didn't reset adaptives, start car up (from cold - it hadn't been warmed up)
Immediately registers fault in lambda 1 again, and AFR on 2468 is logged as "bad".
A look at the live data shows that lambda 1 is at a steady 1.8 volts, lambda 2 is cycling between zero and 0.9 volts. TP readings at idle are 18% and 18.4%.
Leave the car to warm up, but lambda 1 and AFR on 2468 are both "bad".
So that points me to either lambda1 or its connection, right? I'd welcome an experienced confirmation that I've got this right.
Does lambda 1 control 2468 directly (ie it's in the right hand exhaust) - I can see how, if it failed, that would cause the adaptives to be all over the place. But I can also see how, if lambda 1 controlled the other side (ie 1357 the left hand side), and it failed, it could be that lambda 2 is moving the right side adaptives about to keep them right, while no adaptives are being applied to the other side because the lambda isn't working. I've tied my brain in a knot - I think I have one fault, but it might be 2!
So the question is - which side is lambda 1 and which is lambda 2? I was going to replace it and see what the effect on adaptives is.
Still same problem today. So I connected up the laptop, checked the fault log. It has a logged fault in Lambda 1. The adaptives on 2468 were all over the place (minus 25% or so at some points).
So: reset fault codes, didn't reset adaptives, start car up (from cold - it hadn't been warmed up)
Immediately registers fault in lambda 1 again, and AFR on 2468 is logged as "bad".
A look at the live data shows that lambda 1 is at a steady 1.8 volts, lambda 2 is cycling between zero and 0.9 volts. TP readings at idle are 18% and 18.4%.
Leave the car to warm up, but lambda 1 and AFR on 2468 are both "bad".
So that points me to either lambda1 or its connection, right? I'd welcome an experienced confirmation that I've got this right.
Does lambda 1 control 2468 directly (ie it's in the right hand exhaust) - I can see how, if it failed, that would cause the adaptives to be all over the place. But I can also see how, if lambda 1 controlled the other side (ie 1357 the left hand side), and it failed, it could be that lambda 2 is moving the right side adaptives about to keep them right, while no adaptives are being applied to the other side because the lambda isn't working. I've tied my brain in a knot - I think I have one fault, but it might be 2!
So the question is - which side is lambda 1 and which is lambda 2? I was going to replace it and see what the effect on adaptives is.
Its either lambda 1 or its connection or (and possibly more likeley) a misfire that is pumping sufficient unburnt fuel down past the lambda sensor to max it out (thereby logging a fault and skewing the adaptives). Does the tail pipe smell more of fuel than usual?
I would check plug leads and coils before changing lambda sensors. Mine has a nasty habit of doing this after being washed. Once it has all dried out it is fine again.
The lambda sensors control the cylinder bank on the side that they are attached to. So bank 1357 and lambda 1 are on the nearside, bank 2468 and lambda 2 on the offside
I would check plug leads and coils before changing lambda sensors. Mine has a nasty habit of doing this after being washed. Once it has all dried out it is fine again.
The lambda sensors control the cylinder bank on the side that they are attached to. So bank 1357 and lambda 1 are on the nearside, bank 2468 and lambda 2 on the offside
Edited by Tanguero on Thursday 30th June 16:54
It's not stinking of unburnt fuel - just the usual exhaust gas.
I was going to change the lambda (once I figure out which one to change) to eliminate that as a possibility.
I'm pretty certain it's to do with water ingress though - either to the sensors themselves or wiring and connectors above the bellhousing. The car's in a garage 4 miles from the house though - I need to get it home where all my stuff is so I can diagnose further or work on it.
I was going to change the lambda (once I figure out which one to change) to eliminate that as a possibility.
I'm pretty certain it's to do with water ingress though - either to the sensors themselves or wiring and connectors above the bellhousing. The car's in a garage 4 miles from the house though - I need to get it home where all my stuff is so I can diagnose further or work on it.
Have you had a look at the ECU area of the car?
I'm currently chasing a sensor problem which I believe is the result of moisture getting into this area.
My car leaks like a sieve through the passenger door seals and most of this is getting into the footwell.
We think the issue is the result of corrosion within the female part of the main ECU connector.
I'm currently chasing a sensor problem which I believe is the result of moisture getting into this area.
My car leaks like a sieve through the passenger door seals and most of this is getting into the footwell.
We think the issue is the result of corrosion within the female part of the main ECU connector.
Thanks all for the advice so far. I got along to the car for a wee while today, removed the ECU, checked the connections, removed the cover and checked inside, everything is as dry as a bone.
Another go with the diagnostic software and a different old laptop (the one I was using on Wednesday died half way through and isn't up for resurrection!) and it's definitely the lambda for 1357 - so that's definitely the nearside.
I had a look at the two connectors above the gearbox, but I couldn't get them apart - I couldn't reach yhem even with the throttle linkage removed, and I didn't have anything to cut the cable tie to pull them up a bit (that's the downside of having a garage 4 miles from all your tools) - but the connectors didn't look to be in great condition, so I think that's the next port of call. I'm going to bring the car to my "workshop" garage here first though, and take the S along there after the club meeting tomorrow.
I've also managed to borrow 2 spare lambdas - presumably they are easy to change once you've removed the cats for access?
Another go with the diagnostic software and a different old laptop (the one I was using on Wednesday died half way through and isn't up for resurrection!) and it's definitely the lambda for 1357 - so that's definitely the nearside.
I had a look at the two connectors above the gearbox, but I couldn't get them apart - I couldn't reach yhem even with the throttle linkage removed, and I didn't have anything to cut the cable tie to pull them up a bit (that's the downside of having a garage 4 miles from all your tools) - but the connectors didn't look to be in great condition, so I think that's the next port of call. I'm going to bring the car to my "workshop" garage here first though, and take the S along there after the club meeting tomorrow.
I've also managed to borrow 2 spare lambdas - presumably they are easy to change once you've removed the cats for access?
I was going to say swap the lambda connections around and see if the fault still pops up on the same connection that way you will know if it is the lambda sensor itself or if the problem is else where.
You may need to clear the fault log before powering back up again.
I would do this first before bring anything else in to the equation.
You may need to clear the fault log before powering back up again.
I would do this first before bring anything else in to the equation.
Just an update - it turned out to be a connector, probably water ingress as I thought.
Here's the two lamda connectors:
The one on the left (lamda2, RHS) was fine - note the use of dielectric water-excluding grease!
The one on the right (lamda1, LHS) was the one giving the fault. You can just about see the ocidisation inside the terminals. Once I'd cleaned them with contact cleaner, applied some grease, and put it all back together, then plugged it up and cleared the fault log and reset the adaptives, it was fine!
Here's the two lamda connectors:
The one on the left (lamda2, RHS) was fine - note the use of dielectric water-excluding grease!
The one on the right (lamda1, LHS) was the one giving the fault. You can just about see the ocidisation inside the terminals. Once I'd cleaned them with contact cleaner, applied some grease, and put it all back together, then plugged it up and cleared the fault log and reset the adaptives, it was fine!
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