Strange lambda behaviour
Discussion
Hi all - during setup, i realised there was no trace for the odd bank lambda. I had recently installed a pair of NTK lambda’s (maybe 200 miles ago) because although one was good, I suspected the other one.
So, just replaced it with one of the old ones that I knew was still working and still no trace.
Weird.
Swapped the connectors over, and although I didn’t get the classic rapid transitions, I finally did get a reading (trace) on Lambda 1, with nothing on 2 (as expected).
So, I swap in the second lambda, no joy.
Third, still no joy and the same with the fourth.
Not sure what else might be going on.
But I can’t believe all 4 lambda’s were duff - 1 was new 200 miles ago, another one was new about 1200 miles ago and the other two were the original factory supplied parts.
All the lambda’s are NTK’s and show 4-6 ohms on the heater terminals (red and white wires).
Any help would be hugely appreciated.
Last of the summer weather, and this is the third weekend I haven’t been anywhere (been replacing fuel pump/filter, plugs, leads, coils and throttle pots… )
So, just replaced it with one of the old ones that I knew was still working and still no trace.
Weird.
Swapped the connectors over, and although I didn’t get the classic rapid transitions, I finally did get a reading (trace) on Lambda 1, with nothing on 2 (as expected).
So, I swap in the second lambda, no joy.
Third, still no joy and the same with the fourth.
Not sure what else might be going on.
But I can’t believe all 4 lambda’s were duff - 1 was new 200 miles ago, another one was new about 1200 miles ago and the other two were the original factory supplied parts.
All the lambda’s are NTK’s and show 4-6 ohms on the heater terminals (red and white wires).
Any help would be hugely appreciated.
Last of the summer weather, and this is the third weekend I haven’t been anywhere (been replacing fuel pump/filter, plugs, leads, coils and throttle pots… )
Edited by Imran999 on Saturday 18th September 21:44
If I've understood your problem correctly you have new lambdas but no lambda trace from the odd bank (left hand bank if you're sat in the car). If you swap the connectors over the ECU now shows voltage fluctuations on Lambda 1, with Lambda 2 now dead as you'd expect. That's sort of good news as it suggests the ECU works and the wiring to the ECU for both Lambda 1 and 2 is good. Low voltage is a rich condition so how are the adaptives doing for the odd Bank, and have you got the throttles set to flow 4-5kg/hr or whatever the unit is on a carb synchrometer?
Thanks for the response Will.
After 4 different lambda’s not working, I decided to remove the good lambda from the even bank and install it on the odd bank.
I took the newest of the apparently failed ones and installed it on the even bank.
As soon as I started the car, the even bank lambda trace was working as it should.
Still nothing on the odd bank.
But now with a known good lambda (and the knowledge that the previous odd bank lambda was working well), I suspected the issue might be fuelling. Turned up the odd side TP and hey presto, the lambda started doing its thing.
It was a hard lesson, in how narrow-band lambda’s work. They only report a ‘voltage high’ when the AFR hits stoichiometric. But if the TP is set so low (relative to the airflow), that the max fuel trim (+30%) still isn’t enough to get the right AFR, then the lambda won’t report anything.
This was a rare circumstance, as I had changed the throttle pots and so the engine was not setup at all and the TP’s were set to 15% with throttles closed etc.
My arms now look like I’ve been sword fighting in short sleeves (and losing).
But I’ve learned how to change lambda’s without removing any of the exhaust (de-cat pipes help).
I swear, the location of the lambda plugs was devised by some little devil who is chuckling in hell somewhere.
Hopefully, that’s the end of all the work I need to on it now.
Until the next time of course!
After 4 different lambda’s not working, I decided to remove the good lambda from the even bank and install it on the odd bank.
I took the newest of the apparently failed ones and installed it on the even bank.
As soon as I started the car, the even bank lambda trace was working as it should.
Still nothing on the odd bank.
But now with a known good lambda (and the knowledge that the previous odd bank lambda was working well), I suspected the issue might be fuelling. Turned up the odd side TP and hey presto, the lambda started doing its thing.
It was a hard lesson, in how narrow-band lambda’s work. They only report a ‘voltage high’ when the AFR hits stoichiometric. But if the TP is set so low (relative to the airflow), that the max fuel trim (+30%) still isn’t enough to get the right AFR, then the lambda won’t report anything.
This was a rare circumstance, as I had changed the throttle pots and so the engine was not setup at all and the TP’s were set to 15% with throttles closed etc.
My arms now look like I’ve been sword fighting in short sleeves (and losing).
But I’ve learned how to change lambda’s without removing any of the exhaust (de-cat pipes help).
I swear, the location of the lambda plugs was devised by some little devil who is chuckling in hell somewhere.
Hopefully, that’s the end of all the work I need to on it now.
Until the next time of course!
Imran999 said:
Thank you Matt, I did get it sorted and was out enjoying it - pretty much the first time (since arriving in Can) that it’s felt “right”.
Then of course being a TVR, the throttle cable snapped and I got stuck in a filter-lane.
Oh no how annoying!Then of course being a TVR, the throttle cable snapped and I got stuck in a filter-lane.
Edited by Imran999 on Monday 20th September 02:23
Imran999 said:
Thank you Matt, I did get it sorted and was out enjoying it - pretty much the first time (since arriving in Can) that it’s felt “right”.
Then of course being a TVR, the throttle cable snapped and I got stuck in a filter-lane.
I've just replaced my throttle cable (inner) with a stainless bike brake cable, the advantage being that it's thinner, and less likely to cause friction - and it's stainless.Then of course being a TVR, the throttle cable snapped and I got stuck in a filter-lane.
Edited by Imran999 on Monday 20th September 02:23
Inexpensive @7 quid or so, and an easy enough diy job.
https://www.ebay.co.uk/itm/180977657952
https://www.ebay.co.uk/itm/254113042725
I cut the cable from the top, pulled through into the cabin, then fed the new cable up from the cabin back into the engine bay. I used the nipple and also a hollowed out cable crimp to hold the cable in place. If you're interested, I'll take a few pictures and update tomorrow.
Pedal feels amazing, ita nice modification for anyone to do tbh
Edited by DuncanM on Monday 20th September 21:21
FarmyardPants said:
Both ordered. Thanks for doing the legwork
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2054502.m570.l2632&_nkw=bike+cable+crimps&_sacat=7294I used one of these too, will explain with pictures tomorrow.
It's actually something I read on here years ago, so can't take all the credit
DuncanM said:
FarmyardPants said:
Both ordered. Thanks for doing the legwork
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2054502.m570.l2632&_nkw=bike+cable+crimps&_sacat=7294I used one of these too, will explain with pictures tomorrow.
It's actually something I read on here years ago, so can't take all the credit
My TVR is second only to my mountain bike in terms of service required - but I get the lads at the bike shop to look after the bike.
So I called them today, and they have a suitable cable for me, with a knarp nipple. They were actually quite excited about helping with the Cerb.
I got into the footwell, but the bloody throttle pedal is so far to the right that there’s no way I can get my head AND my arms in there. Neither is it possible to just reach an arm up under the dash to the top of the pedal.
But, I discovered there’s a bit of gap under the AC thermostat dial, that allows easier access - sitting on the floor next to the car, legs stretched out under the open door, I can reach my left arm in through this aperture and easily thread a cable through the nylon bush in the top of the (loud) pedal and then to the right into the existing cable sleeve (in the bulkhead).
I reckon I could probably even do this by the side of the road :-)
On the 4.5, the even bank has a semi-circular disc (double plate) that the cable wraps around, with a little aperture (between the discs) for the 5mm spherical swage-end to sit in. Then one of the discs is bent over to prevent it from popping out - crude but effective.
I will start at the pedal-end, so the engine bay side of the cable will have no swage.
Once in the engine-bay, I’m hoping the knarp will be small enough to sit at the end of the plate, and not foul the vacuum line (to the brake servo) - I’m sure it will be a total bugger to tighten up the nipple, while minimizing any slack in the cable, because (a). the access under the plate is next to zero and (b). because it’s a TVR, so any job, no matter how small, is an absolute bugger.
A well maintained TVR should be notable, by the owner having ‘Mr Tickle’ arms and Trump sized hands.
Would love to see some photos, and will also take some of mine when I do the work.
My plan is to manually open the throttle and unhook the cable from the semicircular bit, then wedge the pedal up, pull on the cable and measure how much cable is exposed. Then after threading the new one through, attach the thingy to make it the same length, trim off the rest and hook it into the semicircle thing. Does that sound like a good approach?
PS thanks Imran for the tip on how to reach the pedal end.
PS thanks Imran for the tip on how to reach the pedal end.
Edited by FarmyardPants on Tuesday 21st September 09:58
FarmyardPants said:
My plan is to manually open the throttle and unhook the cable from the semicircular bit, then wedge the pedal up, pull on the cable and measure how much cable is exposed. Then after threading the new one through, attach the thingy to make it the same length, trim off the rest and hook it into the semicircle thing. Does that sound like a good approach?
PS thanks Imran for the tip on how to reach the pedal end.
That's exactly what I did, however you can get away with not trimming the cable until you have the nipple and crimp in place, giving you more accuracy on cable length.PS thanks Imran for the tip on how to reach the pedal end.
Edited by FarmyardPants on Tuesday 21st September 09:58
I hope the pictures attached help, using the crimp was an improvisation, because the nipple didn't quite work as I expected. The end result is pleasing though, as the cable is firmly held in place by the crimp being wedged in.
Imran, you're absolutely right that this is something that can easily be done roadside, I have spare cable/nipple and crimp in the car.
I'll do a separate thread for a wider audience, some reading this might not think they need a new cable, but the standard one gets as sticky, and can cause a high idle when the car warms up (not shutting properly).
Bonus points for removing the play in the plastic cable retainer in the footwell, by slicing a tiny bit of hose, with a cut in it, and wedging it in.
DuncanM said:
FarmyardPants said:
My plan is to manually open the throttle and unhook the cable from the semicircular bit, then wedge the pedal up, pull on the cable and measure how much cable is exposed. Then after threading the new one through, attach the thingy to make it the same length, trim off the rest and hook it into the semicircle thing. Does that sound like a good approach?
PS thanks Imran for the tip on how to reach the pedal end.
That's exactly what I did, however you can get away with not trimming the cable until you have the nipple and crimp in place, giving you more accuracy on cable length.PS thanks Imran for the tip on how to reach the pedal end.
Edited by FarmyardPants on Tuesday 21st September 09:58
I hope the pictures attached help, using the crimp was an improvisation, because the nipple didn't quite work as I expected. The end result is pleasing though, as the cable is firmly held in place by the crimp being wedged in.
Imran, you're absolutely right that this is something that can easily be done roadside, I have spare cable/nipple and crimp in the car.
I'll do a separate thread for a wider audience, some reading this might not think they need a new cable, but the standard one gets as sticky, and can cause a high idle when the car warms up (not shutting properly).
Bonus points for removing the play in the plastic cable retainer in the footwell, by slicing a tiny bit of hose, with a cut in it, and wedging it in.
Interestingly, your throttle pedal and cable location (in the bulkhead) seem to be well aligned, so how/why then did your cable break? Did it fray in that spot?
I think you’re onto something with that crimped collar keeping the cable wedged in between the plates, I’m definitely going to replicate that - neat tip.
Will also measure out the length required and secure the nipple, before trying to hook it around the assembly.
I did wonder if it would just be better to attach the cable (with a suitable adjustable eyebolt type attachment) to the back of the throttle link bar attach-point. This would allow some adjustability and give me greater confidence. But, it will alter the ratio of pedal travel to throttle opening.
Is no one worried that the nipple might let-go eventually?
Imran999 said:
Thanks for posting the photo’s, although how you managed to take the one of the bulkhead is beyond me, I can’t even get a decent image using a borescope in there.
Interestingly, your throttle pedal and cable location (in the bulkhead) seem to be well aligned, so how/why then did your cable break? Did it fray in that spot?
I think you’re onto something with that crimped collar keeping the cable wedged in between the plates, I’m definitely going to replicate that - neat tip.
Will also measure out the length required and secure the nipple, before trying to hook it around the assembly.
I did wonder if it would just be better to attach the cable (with a suitable adjustable eyebolt type attachment) to the back of the throttle link bar attach-point. This would allow some adjustability and give me greater confidence. But, it will alter the ratio of pedal travel to throttle opening.
Is no one worried that the nipple might let-go eventually?
Hello,Interestingly, your throttle pedal and cable location (in the bulkhead) seem to be well aligned, so how/why then did your cable break? Did it fray in that spot?
I think you’re onto something with that crimped collar keeping the cable wedged in between the plates, I’m definitely going to replicate that - neat tip.
Will also measure out the length required and secure the nipple, before trying to hook it around the assembly.
I did wonder if it would just be better to attach the cable (with a suitable adjustable eyebolt type attachment) to the back of the throttle link bar attach-point. This would allow some adjustability and give me greater confidence. But, it will alter the ratio of pedal travel to throttle opening.
Is no one worried that the nipple might let-go eventually?
The photo was relatively easy, phone with light on, angled up and right from the footwell.
My cable was rusting and sticking, rather than frayed, the alignment is as I'd expect all of them to be, offset to the right of the pedal?
The nipple is doing the job it's intended for, and shouldn't be under stress because it hits a throttle stop before being pulled too much. I used the nipple because I couldn't trust anything crimped on in the engine bay.
The hollowed out crimp holds it in place very nicely
I can take more pictures in the footwell if you think it will help, does it look very different to yours?
DuncanM said:
Imran999 said:
Thanks for posting the photo’s, although how you managed to take the one of the bulkhead is beyond me, I can’t even get a decent image using a borescope in there.
Interestingly, your throttle pedal and cable location (in the bulkhead) seem to be well aligned, so how/why then did your cable break? Did it fray in that spot?
I think you’re onto something with that crimped collar keeping the cable wedged in between the plates, I’m definitely going to replicate that - neat tip.
Will also measure out the length required and secure the nipple, before trying to hook it around the assembly.
I did wonder if it would just be better to attach the cable (with a suitable adjustable eyebolt type attachment) to the back of the throttle link bar attach-point. This would allow some adjustability and give me greater confidence. But, it will alter the ratio of pedal travel to throttle opening.
Is no one worried that the nipple might let-go eventually?
Hello,Interestingly, your throttle pedal and cable location (in the bulkhead) seem to be well aligned, so how/why then did your cable break? Did it fray in that spot?
I think you’re onto something with that crimped collar keeping the cable wedged in between the plates, I’m definitely going to replicate that - neat tip.
Will also measure out the length required and secure the nipple, before trying to hook it around the assembly.
I did wonder if it would just be better to attach the cable (with a suitable adjustable eyebolt type attachment) to the back of the throttle link bar attach-point. This would allow some adjustability and give me greater confidence. But, it will alter the ratio of pedal travel to throttle opening.
Is no one worried that the nipple might let-go eventually?
The photo was relatively easy, phone with light on, angled up and right from the footwell.
My cable was rusting and sticking, rather than frayed, the alignment is as I'd expect all of them to be, offset to the right of the pedal?
The nipple is doing the job it's intended for, and shouldn't be under stress because it hits a throttle stop before being pulled too much. I used the nipple because I couldn't trust anything crimped on in the engine bay.
The hollowed out crimp holds it in place very nicely
I can take more pictures in the footwell if you think it will help, does it look very different to yours?
I got a very nice stainless steel extruded cable (quite slick/low friction) and further added a tiny bit of lithium grease to the last 3” at the pedal-end.
I also realized that the pedal-end of the old cable had a somewhat removable ball-swage. So I yanked the rest of the cable out of it and drilled right through it. Threaded the cable through this first and then the nipple - of course, it sits perfectly in the old slot, and now I have a working Cerb again!
The cable was about 2m long, and had a soldered-end. So I was reluctant to cut it, until I was sure everything was good. At some point, it caught the battery terminal and dam near started a fire (plenty of smoke and hot fingers) - “always disconnect the battery” for any and every job!
Will take some photo’s later and post them up.
Quite why anyone would replace the whole cable assembly is beyond me.
Thanks for all your help
Edited by Imran999 on Wednesday 22 September 00:55
The first picture shows the old broken cable and the new one (extruded stainless steel, soldered end) along with the nipple (uses hex keys on both sides)
The next photo shows the cable in the engine bay with the original swage-end loose on the cable and the nipple attached at the end.
The final picture shows the nipple in place, the original swage-end is inside the semi-circular throttle arm and ensures that even if the throttle is opened by hand (instead of via the pedal), the cable doesn’t just pop-out.
The next photo shows the cable in the engine bay with the original swage-end loose on the cable and the nipple attached at the end.
The final picture shows the nipple in place, the original swage-end is inside the semi-circular throttle arm and ensures that even if the throttle is opened by hand (instead of via the pedal), the cable doesn’t just pop-out.
The first picture shows the old broken cable and the new one (1.6mm extruded stainless steel, soldered end) along with the nipple (uses hex keys on both sides)
The next photo shows the cable in the engine bay with the original swage-end loose on the cable and the nipple attached at the end.
The final picture shows the nipple in place, the original swage-end is inside the semi-circular throttle arm and ensures that even if the throttle is opened by hand (instead of via the pedal), the cable doesn’t just pop-out.
The next photo shows the cable in the engine bay with the original swage-end loose on the cable and the nipple attached at the end.
The final picture shows the nipple in place, the original swage-end is inside the semi-circular throttle arm and ensures that even if the throttle is opened by hand (instead of via the pedal), the cable doesn’t just pop-out.
Edited by Imran999 on Wednesday 22 September 05:17
Edited by Imran999 on Thursday 23 September 02:55
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