Stuck lambda readings.
Discussion
My Cerbera SP6 year 2000 is running too rich and has failed the emisions test!
On inspection the lambdas and cats were kaput.
New lambdas, cats and spark plugs installed.
Lambdas 3 pin not 4 pin. Presume they are correct as they came from the German TVR importer.
Emissions a bit better but still too high.
Connected the mbe Ecu 941 rev. F to Evo Ollie’s software.
The lambda readings are both stuck at 1,98 on idle (780 rpm) and under load and at an indicated 90 deg engine temp.
When disconnecting one lambda it’s value falls to 0 and the other one drops to 1,96 and vice versa.
Adaptives are both at 0,4
Throttles for both banks are 14,9 and 15,2 at idle and go up to approx 93 under full load.
I am presuming an electrical problem somewhere - any ideas gratefully received.
Cheers
Martin.
On inspection the lambdas and cats were kaput.
New lambdas, cats and spark plugs installed.
Lambdas 3 pin not 4 pin. Presume they are correct as they came from the German TVR importer.
Emissions a bit better but still too high.
Connected the mbe Ecu 941 rev. F to Evo Ollie’s software.
The lambda readings are both stuck at 1,98 on idle (780 rpm) and under load and at an indicated 90 deg engine temp.
When disconnecting one lambda it’s value falls to 0 and the other one drops to 1,96 and vice versa.
Adaptives are both at 0,4
Throttles for both banks are 14,9 and 15,2 at idle and go up to approx 93 under full load.
I am presuming an electrical problem somewhere - any ideas gratefully received.
Cheers
Martin.
Martin,
The 'newer' 4-wire lambdas were offered to address an issue with the fact that the 3-wire lambdas had to earth via the ECU. I never experienced 'funny' lambda values on my Tuscan with the 3-wire probes, but at one service, Str8Six changed them out to the 4-wire lambdas.
Guess this is a roundabout way of saying:
CHECK your earths....(recent post from a guy in France with poor running on a T-car...consensus being clean all the "front" earth points.)
Check that you have correct lambdas....go to the parts wiki on the Speed 6 forum. As with any new electrical components these days, cheap, poor quality copies from China are flooding the market - worth verifying the branding on your recently replaced items.
Nick
The 'newer' 4-wire lambdas were offered to address an issue with the fact that the 3-wire lambdas had to earth via the ECU. I never experienced 'funny' lambda values on my Tuscan with the 3-wire probes, but at one service, Str8Six changed them out to the 4-wire lambdas.
Guess this is a roundabout way of saying:
CHECK your earths....(recent post from a guy in France with poor running on a T-car...consensus being clean all the "front" earth points.)
Check that you have correct lambdas....go to the parts wiki on the Speed 6 forum. As with any new electrical components these days, cheap, poor quality copies from China are flooding the market - worth verifying the branding on your recently replaced items.
Nick
Martin - parts wiki is on Tuscan forum.....Not Sp6 forum apologies!
This link for the 4-wire probes from ebay.
https://www.ebay.co.uk/itm/FOR-LAND-ROVER-DISCOVER...
Nick
This link for the 4-wire probes from ebay.
https://www.ebay.co.uk/itm/FOR-LAND-ROVER-DISCOVER...
Nick
If the lambdas are reading nearly 2v, that's odd for starters...they normally max out at 1.1V. If they both read high, the ECU would be going nuts trying to lean it out, not rich it up. Adaptives of 0.4 mean "untouched"...kinda default state...so its like the ECU is doing nothing (could be because of the 2V...it may conclude this means error)
You could quite easily attach a 1.5V AAA battery in place of a sensor and check you see 1.5V from the ECU...just to verify that wiring etc is ok.
Normally a GND fault causes a volt drop/GND offset and the ECU cant see the 1V signal, so sticks low from the ECU pov and goes mad trying to rich-up. More like what your seeing.
You could quite easily attach a 1.5V AAA battery in place of a sensor and check you see 1.5V from the ECU...just to verify that wiring etc is ok.
Normally a GND fault causes a volt drop/GND offset and the ECU cant see the 1V signal, so sticks low from the ECU pov and goes mad trying to rich-up. More like what your seeing.
nawarne said:
Martin,
The 'newer' 4-wire lambdas were offered to address an issue with the fact that the 3-wire lambdas had to earth via the ECU. I never experienced 'funny' lambda values on my Tuscan with the 3-wire probes, but at one service, Str8Six changed them out to the 4-wire lambdas.
Guess this is a roundabout way of saying:
CHECK your earths....(recent post from a guy in France with poor running on a T-car...consensus being clean all the "front" earth points.)
Check that you have correct lambdas....go to the parts wiki on the Speed 6 forum. As with any new electrical components these days, cheap, poor quality copies from China are flooding the market - worth verifying the branding on your recently replaced items.
Nick
Hi NickThe 'newer' 4-wire lambdas were offered to address an issue with the fact that the 3-wire lambdas had to earth via the ECU. I never experienced 'funny' lambda values on my Tuscan with the 3-wire probes, but at one service, Str8Six changed them out to the 4-wire lambdas.
Guess this is a roundabout way of saying:
CHECK your earths....(recent post from a guy in France with poor running on a T-car...consensus being clean all the "front" earth points.)
Check that you have correct lambdas....go to the parts wiki on the Speed 6 forum. As with any new electrical components these days, cheap, poor quality copies from China are flooding the market - worth verifying the branding on your recently replaced items.
Nick
Thanks for the advice, lambdas are the right ones, 3 wires not 4 and same make as per the old ones.
Earths seem to be the main thing to check.
Cheers
Martin.
PetrolHeadPete said:
If the lambdas are reading nearly 2v, that's odd for starters...they normally max out at 1.1V. If they both read high, the ECU would be going nuts trying to lean it out, not rich it up. Adaptives of 0.4 mean "untouched"...kinda default state...so its like the ECU is doing nothing (could be because of the 2V...it may conclude this means error)
You could quite easily attach a 1.5V AAA battery in place of a sensor and check you see 1.5V from the ECU...just to verify that wiring etc is ok.
Normally a GND fault causes a volt drop/GND offset and the ECU cant see the 1V signal, so sticks low from the ECU pov and goes mad trying to rich-up. More like what your seeing.
Thanks for the reply - a good tip with the battery - will check that when next at the garage.You could quite easily attach a 1.5V AAA battery in place of a sensor and check you see 1.5V from the ECU...just to verify that wiring etc is ok.
Normally a GND fault causes a volt drop/GND offset and the ECU cant see the 1V signal, so sticks low from the ECU pov and goes mad trying to rich-up. More like what your seeing.
Thank you for your reply.
Cheers
Martin.
Might be the NOVRAM. I have never fully got to grips as to how but I had terrible problems getting the Tuscan to run smoothly and it wasn't behaving or learning, put a new chip in and bingo.
Does sound like an earth though. I sound like the mad Earth Man of Essex, but earth everything properly with crimped and then soldered terminals, use star washers to dig into the metal and spray it all with ACF 50. I have big bird earth cables from battery negative to chassis, from battery negative direct to bell housing, from chassis to engine mounting on the opposite side so there is no poor earthing. The engine harness on the bulkhead gets a hard life, get the detail brush out with acetone on it, then ACF 50 it and wang in and out a dozen times to clean those terminals. The section of the harness where the lambda wires tuck in is heat shrunk, cut that open and check the soldered joint, the wires go green n crusty. Strip back, solder and ACF 50 it then heat shrink it to trap it in there. I know some people advocate an earth to the block at this point but there is already an earth and you don't want to have the ECU with a long earth path, so fix the failure in the original wiring if there is one, best IMHO.
Easy... big soldering iron, heat shrink, fat multi stranded flexible battery cable, bacon banjos and filter coffee.
Does sound like an earth though. I sound like the mad Earth Man of Essex, but earth everything properly with crimped and then soldered terminals, use star washers to dig into the metal and spray it all with ACF 50. I have big bird earth cables from battery negative to chassis, from battery negative direct to bell housing, from chassis to engine mounting on the opposite side so there is no poor earthing. The engine harness on the bulkhead gets a hard life, get the detail brush out with acetone on it, then ACF 50 it and wang in and out a dozen times to clean those terminals. The section of the harness where the lambda wires tuck in is heat shrunk, cut that open and check the soldered joint, the wires go green n crusty. Strip back, solder and ACF 50 it then heat shrink it to trap it in there. I know some people advocate an earth to the block at this point but there is already an earth and you don't want to have the ECU with a long earth path, so fix the failure in the original wiring if there is one, best IMHO.
Easy... big soldering iron, heat shrink, fat multi stranded flexible battery cable, bacon banjos and filter coffee.
Sagi Badger said:
Might be the NOVRAM. I have never fully got to grips as to how but I had terrible problems getting the Tuscan to run smoothly and it wasn't behaving or learning, put a new chip in and bingo.
Easy... big soldering iron, heat shrink, fat multi stranded flexible battery cable, bacon banjos and filter coffee.
When you say the novram do you mean the Dallas chip?Easy... big soldering iron, heat shrink, fat multi stranded flexible battery cable, bacon banjos and filter coffee.
Looks like we need to really check the earths.
Another problem is the filtered coffee - will tea be an adequate replacement?
Thank you for your suggestions and time.
Cheers
Martin.
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