Ecumate and Lambda Sensors......

Ecumate and Lambda Sensors......

Author
Discussion

Hedgehopper

Original Poster:

1,537 posts

243 months

Thursday 30th July 2015
quotequote all
My 500 is suffering from massive surging and shunting, much worse than the usual. It happens at all rpm but is slightly less noticeable from 3-4000onwards. Ignition has been thoroughly checked and seems OK.

Ecumate shows fault code 44, Left near side lambda sensor faulty.

The actual reading is Lambda A OK 128x and Lambda B Lean Ox

I thought that the suffix 'x' was in itself a fault showing the lambda wasn't oscillating or was in open loop mode?

Should I therefore change both Sensors?

Anyone any suggestions where to buy? Intermotor seem cheaper than usual dealers...any experiences?

PS, In an old Pistonheads thread Blitz refers to fault code 44 as being the offside Lambda...which is correct?

Help will be appreciated.

ukdj

1,004 posts

183 months

Thursday 30th July 2015
quotequote all
rovergauge has recently been updated v0.72 to v0.74, the changelog indicates that fixes were to correct lambda identification.

not sure if ecumate has the same issues with identification ?

blitzracing

6,387 posts

219 months

Friday 31st July 2015
quotequote all
The ECUmate lambda readings try to work out if you have a general rich or lean condition- but its not that easy as the old 14CUX swings the mixture about a fair way even when its working correctly- but that aside I think the 128 reading is your mid point out of a total available of 256 available trim values between rich or lean, so the important thing is to see if the value is constantly moving with the engine running to show the probe is working. Id take the ECUmate display as being correct with left or right bank- but if you want to double check, simply unplug each probe one at a time, and see which readings change.

Hedgehopper

Original Poster:

1,537 posts

243 months

Sunday 2nd August 2015
quotequote all
Thanks for those helpful replies. I have decided to replace both sensors so the handing won't be an issue.

By the way....do the left and right lambda sensors control the left and right banks of injectors or does the ECU average the readings out and supply the same mixture to both?

I ask this because in spite of a lambda fault on one side all the plugs are the same colour.

stevesprint

1,114 posts

178 months

Sunday 2nd August 2015
quotequote all
Hedgehopper said:
By the way....do the left and right lambda sensors control the left and right banks of injectors or does the ECU average the readings out and supply the same mixture to both?
The left lambda controls the left bank and the right lambda controls the right bank so you must get them the right way around, if not you'll soon know about it especially if you check with your Ecumate.

Hedgehopper

Original Poster:

1,537 posts

243 months

Sunday 2nd August 2015
quotequote all
OK, thanks Steve. With one lambda showing a fault I was expecting one bank of plugs to be a different colour.

ChimpOnGas

9,637 posts

178 months

Sunday 2nd August 2015
quotequote all
blitzracing said:
The ECUmate lambda readings try to work out if you have a general rich or lean condition- but its not that easy as the old 14CUX swings the mixture about a fair way even when its working correctly- but that aside I think the 128 reading is your mid point out of a total available of 256 available trim values between rich or lean, so the important thing is to see if the value is constantly moving with the engine running to show the probe is working. Id take the ECUmate display as being correct with left or right bank- but if you want to double check, simply unplug each probe one at a time, and see which readings change.
Surely it would be infinitely better to forget all this lurching rich/lean ancient narrow band nonsense and fit a proper wide band lambda system that will immediately display the true AFRs in real time?

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

You can buy such wide band systems for around £150 these days, to my mind if there's one diagnostic tool to use on your 14CUX TVR it's a wide band system and it'll certainly be the best £150 you spend on diagnostic equipment.

http://www.ebay.co.uk/itm/New-AEM-Digital-Wideband...

Then buy a miltimeter and a decent advance strobe and you're good to go wink

It's just a real shame the 14CUX is such a biatch to map and you're still stuck with the ancient centrifugal advancing distributor based ignition system, that at the end of the day is no more sophisticated than a steam engine governor with a whiff of vacuum for economy thrown in as it's best nod towards 3D spark management.

I've even seen wide band lambda systems used to tune carb engines with good results, so to be totally frank forget all this ECU Mate stuff and fit a wide band sensor plus controller box & gauge (all included in the above £150 kit).

Trust me, it's like all the lights going on at once when you can actually see whats truly going on in the combustion chamber during all driving conditions & engine loads.

blitzracing

6,387 posts

219 months

Sunday 2nd August 2015
quotequote all
The 14CUX works really nicely if you simply go to the green map, and let the ECU do its thing- Ive got wideband as you suggest and its spot on 99% of the time running green tune. Problem is the 14CUX is designed to pass emission laws, and really needs the lambda probes in the top of the exhaust headers, not way down the exhaust tube past the precats- I think adding this extra length and pre-cat simply delays the time between the mixture being trimmed in the combustion camber to when it gets "read" by the lambda probes, which can make the response a little slow when gas velocities are low. I believe this can lead to some overshoot of the trimming, but you cant blame the ECU design for how TVR implemented it. Of course if a modern ECU is running wide band probes it will get a much smoother transition to the ideal lambda 1 point, not the rather crude go -no go switch state of a narrow band probe- but of course the cost goes up considerably on after market when running wideband on both banks, as the probes are not cheap. As for getting it mapped- you have not been keeping up in the back of the class- its now pretty easy now the freeware Tuner pro has the required .xdf files to show where the fuel tables sit in the Eprom. As long as you have some way of blowing a new Eprom (£35 worth of programmer) and can understand Tuner pro its easy enough. This will be no different to mapping a modern ECU- you just need to understand the programming software to make it possible.

stevesprint

1,114 posts

178 months

Sunday 2nd August 2015
quotequote all
ChimpOnGas said:
Surely it would be infinitely better to forget all this lurching rich/lean ancient narrow band nonsense and fit a proper wide band lambda system that will immediately display the true AFRs in real time?
Please don't ask me to explain the following but it seem the "lurching rich/lean" is deliberate to make 3 way cats more efficient.

Mark Adams said:
As it turns out there is nothing crude or slow about the way the 14CUX uses the Oxygen sensors in the exhaust, and you will see exactly the same behaviour on any modern car. The cycling rate increases dramatically with engine speed, so you can see that it is not a limitation of the system.

Taking a step back, you need to look at the reason why the vehicle is run on Lambda 1.0 in the first place, since this is not ideal for economy or power on these engines. It is certainly not for combustion efficiency, but rather more for correct operation of the three-way catalyst.

European legislation requires that all petrol-engined vehicles manufactured after January 1993 be fitted with a catalyst. It goes on to require that if they have a catalyst, they must be operated at Lambda 1.0 for certain parts of their operating cycle which is mostly warm cruise and idle. This same piece of legislation is the one that effectively killed all the promising research into Lean-Burn engines, as they were effectively outlawed. Things have got even tougher since then, but that's another story.

When a three-way catalyst is operating correctly, it will store Oxygen as a normal part of the chemical process. However it can only convert oxides of Nitrogen when the mixture is richer than Lambda 1.0, which is why the cycling of the mixture around Lambda 1.0 is vital. Oxygen is stored all the time in a healthy catalyst, but NOx is only converted in the rich side of the cycle. Since the catalyst effectively averages out the chemistry, the overall result is correct.

ChimpOnGas

9,637 posts

178 months

Sunday 2nd August 2015
quotequote all
stevesprint said:
ChimpOnGas said:
Surely it would be infinitely better to forget all this lurching rich/lean ancient narrow band nonsense and fit a proper wide band lambda system that will immediately display the true AFRs in real time?
Please don't ask me to explain the following but it seem the "lurching rich/lean" is deliberate to make 3 way cats more efficient.

Mark Adams said:
As it turns out there is nothing crude or slow about the way the 14CUX uses the Oxygen sensors in the exhaust, and you will see exactly the same behaviour on any modern car. The cycling rate increases dramatically with engine speed, so you can see that it is not a limitation of the system.

Taking a step back, you need to look at the reason why the vehicle is run on Lambda 1.0 in the first place, since this is not ideal for economy or power on these engines. It is certainly not for combustion efficiency, but rather more for correct operation of the three-way catalyst.

European legislation requires that all petrol-engined vehicles manufactured after January 1993 be fitted with a catalyst. It goes on to require that if they have a catalyst, they must be operated at Lambda 1.0 for certain parts of their operating cycle which is mostly warm cruise and idle. This same piece of legislation is the one that effectively killed all the promising research into Lean-Burn engines, as they were effectively outlawed. Things have got even tougher since then, but that's another story.

When a three-way catalyst is operating correctly, it will store Oxygen as a normal part of the chemical process. However it can only convert oxides of Nitrogen when the mixture is richer than Lambda 1.0, which is why the cycling of the mixture around Lambda 1.0 is vital. Oxygen is stored all the time in a healthy catalyst, but NOx is only converted in the rich side of the cycle. Since the catalyst effectively averages out the chemistry, the overall result is correct.
When I met Mark I quizzed him on why my car was hunting on the good old 14CUX, but he couldn't give me an answer let alone resolve it.

To me it sounded like an exhaust restriction so I asked him if he felt it could be the cats.

Mark dismissed my theory saying the cats used by TVR were very good quality, confused by his answer and following my gut feeling I removed all three cats a few weeks later.

Hey presto, the hunting immediately vanished wink

Question 1: Do modern cars run old narrow band lambdas these days rather than the more advanced wide band sensors?

Question 2: Do modern cars absolutely nail AFRs like the old 14CUX could only dream of?

Question 3: Do cats really need lurching rich/lean mixtures to work properly?

If you've answered no to 1 & 3 but yes to question 2, you're on the right track wink

blitzracing

6,387 posts

219 months

Monday 3rd August 2015
quotequote all
No car locks the AFR at 14.7:1, it must cycle to fist add oxygen to one type of pollutant (the HC's and CO) to burn them, and then remove oxygen to the NOX component, so its called a 3 way catalyst. I dont know how far on each side it has to cycle to get it to work effectively, but as Ive already mentioned I think the slow 14CUX cycling is due to mechanical lag in the TVR exhaust set up- and nothing to do with the probe response times or processor power of the 14CUX. What would be interesting to see is a probe waveform of say a 14CUX v's say a Megasquirt both on narrow band, and see if there where any differences.

stevesprint

1,114 posts

178 months

Monday 3rd August 2015
quotequote all
ChimpOnGas said:
Question 1: Do modern cars run old narrow band lambdas these days rather than the more advanced wide band sensors?

Question 2: Do modern cars absolutely nail AFRs like the old 14CUX could only dream of?

Question 3: Do cats really need lurching rich/lean mixtures to work properly?

If you've answered no to 1 & 3 but yes to question 2, you're on the right track wink
ChimpOnGas
Please rest assure we all acknowledge modern OEM and after market engine management systems with wideband sensors and mappable ignition are far more superior to the 14CUX especially sequential injection systems. As I'm not an engine tuning expert plus a little off topic I'll leave you to discuss the chemistry of the 3 way cat with the tuning expert Mark Adams.

I'm personally more interested in helping 14CUX owners, like myself, that are not in your fortunate position, being able to upgrade to Canems, Vectra injectors or install an AEMX - WiFi AFR gauge.
Cheers, Steve

Hedgehopper - Should you have any further 14CUX questions please do not hesitate to contact me.

Edited by stevesprint on Monday 3rd August 21:31

Hedgehopper

Original Poster:

1,537 posts

243 months

Wednesday 5th August 2015
quotequote all


'Hedgehopper - Should you have any further 14CUX questions please do not hesitate to contact me.'


Thanks for the offer Steve. I have been trying to email you through your profile but Pistonheads shows an error message when I hit SEND.

I am going away until early next week so will try again then.

stevesprint

1,114 posts

178 months

Wednesday 5th August 2015
quotequote all
Hedgehopper said:
Thanks for the offer Steve. I have been trying to email you through your profile but Pistonheads shows an error message when I hit SEND.
Hedgehopper
I've just received the same error message while trying to contact you. My email address is my PH's nick name at gmail.
Cheers, Steve