setting up my throtle pots
Discussion
i got five mins free to reset my throtle pots and bits N bobs this afternoon.
in the process it was the first time i connected my ecu to the laptop.
when i was finished setting things up as per the workshop manual. i ended with one adaptive showing between 28 and 34!!! and one around 5-16 all positive figures.
the book says should be 0- -10 ish. and that any big diffrence indicates a fault els where.
i think 34 is a BIG diffrence from -10.
so what do we think why so far off??
i did also notice that one lamba sensors was fluctuiating nicley but the other just had a reading of 0.00 all the time. so i think thats f***ed. could this be the cause?
also i had fault codes for AFR bad both banks (air fuel ratio?) again lamba sensors??
any help much apricated
p.s runns muc nicer now i have made a few adjustments.
in the process it was the first time i connected my ecu to the laptop.
when i was finished setting things up as per the workshop manual. i ended with one adaptive showing between 28 and 34!!! and one around 5-16 all positive figures.
the book says should be 0- -10 ish. and that any big diffrence indicates a fault els where.
i think 34 is a BIG diffrence from -10.
so what do we think why so far off??
i did also notice that one lamba sensors was fluctuiating nicley but the other just had a reading of 0.00 all the time. so i think thats f***ed. could this be the cause?
also i had fault codes for AFR bad both banks (air fuel ratio?) again lamba sensors??
any help much apricated
p.s runns muc nicer now i have made a few adjustments.
Apologies for the war and peace epic - killing time on a train 
The AFR faults don't necessarily mean a Lambda fault. They are reporting that the adaptive adjustment has reached the limit set in the ECU. This could be because too much/too little air is flowing and the ECU has enriched/weakened the mixture as much as it is allowed to. An unvarying Lambda reading may be because the mixture on the bank is way too rich or way too weak.
But as you have said its also the classic sign of a duff lambda sensor.
Don't follow the instructions in the manual. They won't get you to a decent setup. Just tweak the link rod, throttle pots and idle screw to get equal TPot readings and equal adaptives on both banks as close to zero as possible with suitable idle rpm (950 to 1000)
This is the text from the Cerbera manual (on Faisal's site?) that was copied from a Trackcar post (nee Joospeed)
"If the banks are balanced, then the adaptives should be equal. It really is that easy.
The garage should have an airmass meter ... it comes supplied in the cerbera kit that every dealer got along with their computer / software / cam timing gear. I very rarely use the meter and just balance it from the values on the screen which is much quicker, but if you had a SP6 then I'd be worrying...that engine has individually adjustable butterflies for each cylinder and you cannot balance this without the meter.
The basis for setting the V8 is to firstly slacken the linkrod between the banks, then by interpreting the adaptive value relative to the throttle pot value bank to bank you can deduce which bank is sucking more air (assuming equal t-pot values this is the bank with the higher adaptive value) there is no other way of interpreting the values .. it's as simple as that. You just adjust the link / throttle pots and idle screw to get the adaptives equal, but also AS CLOSE TO ZERO AS POSSIBLE! If one bank of your engine has adaptives of around 30% then this is running about on the rich limit ... it won't enrich any more than that. So this means your engine needs a good tune up.
It's also wrong to say that the ECU throws up spurious fault codes in the garage such as the AFR error ... there's a logged fault because there IS a fault ... it's the difference in airflow that's causing it. The imbalance is more noticeable at small throttles / light cruise conditions and getting it right can give much better town driving - there's also a Joospeed mod for the 4.2 version to cut out the slop in the cross link that gives a lot of poor running at part throttle."
Here is the process I use: -
Note that the 4.2 suffers from slop in the linkage. So check the adjustments for % adaptives with the throttle very slightly open and thus any slop in the linkage already taken up.
Get the engine properly warmed up so there is no ECU fuel/ignition compensation for cold temp
Go to the logging page and record a minute of idle and occasional throttle opened a bit for a few seconds (nothing wild, 2kish is is fine)
Examine the throttle pot readings to see if there is any spiking of the readings. If there is then replace the offending throttle pot.
Examine the lambda readings - they should be varying. If not then it may be wild adjustment or duff lambda.
I also capture the adaptive maps just for interest so I can compare with the results after adjustment.
Reset the adaptives to clear any existing values before starting any adjustments. You may find this affects the idle and you may need to open the stop to get a reasonable idle.
If I think its all wildly out I remove the airboxes and use the air mass meter to check the banks are pulling about the same air flow. You can also compare what each inlet is flowing. If on a bank the air flow is significantly different across the 4 inlets the only way to adjust it is to get some drilled screws. You replace the screws that clamp the butterfly to the throttle rod with a drilled screw to increase airflow down that inlet.
Otherwise I leave the air boxes on and don't clamp the purge line.
Get the TPot readings even first - adjust idle if necessary.
Highest adaptive reading is the bank flowing too much air - so close that bank down a bit. if its the odd bank (near side) then use the link rod to do it and then adjust the TPot back to same reading as the even bank
If its the even bank thats flowing too much air then note the odd bank tpot reading and close down the idle stop a bit and then adjust the link rod to get the odd bank back to the tpot reading you noted. then adjust the even bank tpot to the same as the even bank.
Its a lot easier to do than describe but you should be able to get towards zero on the adaptives with the tpots reading about 16.8% and idle at 950ish.
If you can't get anywhere near zero adaptives and you have checked both banks with a mass meter then the unvarying lambda is most likely goosed. Cheapest way to check is to unplug and remove the lambdas from the manifolds and swap them over. If the unvarying reading moves the lambda is duff. If the same bank shows the unvarying reading then its something else - possibly wiring but definitely not the lambda.
Other things to make it easier
Replace the TPot screws with cap heads and use a T handled allen key to slacken/tighten
Replace the link rod ball joints with rod ends from Ondrive
Fit a second throttle stop on the odd bank and use that for idle adjustment - that way the slop in the linkages doesn't have any effect - the even bank is always under tension being pulled back by its return spring.
The AFR faults don't necessarily mean a Lambda fault. They are reporting that the adaptive adjustment has reached the limit set in the ECU. This could be because too much/too little air is flowing and the ECU has enriched/weakened the mixture as much as it is allowed to. An unvarying Lambda reading may be because the mixture on the bank is way too rich or way too weak.
But as you have said its also the classic sign of a duff lambda sensor.
Don't follow the instructions in the manual. They won't get you to a decent setup. Just tweak the link rod, throttle pots and idle screw to get equal TPot readings and equal adaptives on both banks as close to zero as possible with suitable idle rpm (950 to 1000)
This is the text from the Cerbera manual (on Faisal's site?) that was copied from a Trackcar post (nee Joospeed)
"If the banks are balanced, then the adaptives should be equal. It really is that easy.
The garage should have an airmass meter ... it comes supplied in the cerbera kit that every dealer got along with their computer / software / cam timing gear. I very rarely use the meter and just balance it from the values on the screen which is much quicker, but if you had a SP6 then I'd be worrying...that engine has individually adjustable butterflies for each cylinder and you cannot balance this without the meter.
The basis for setting the V8 is to firstly slacken the linkrod between the banks, then by interpreting the adaptive value relative to the throttle pot value bank to bank you can deduce which bank is sucking more air (assuming equal t-pot values this is the bank with the higher adaptive value) there is no other way of interpreting the values .. it's as simple as that. You just adjust the link / throttle pots and idle screw to get the adaptives equal, but also AS CLOSE TO ZERO AS POSSIBLE! If one bank of your engine has adaptives of around 30% then this is running about on the rich limit ... it won't enrich any more than that. So this means your engine needs a good tune up.
It's also wrong to say that the ECU throws up spurious fault codes in the garage such as the AFR error ... there's a logged fault because there IS a fault ... it's the difference in airflow that's causing it. The imbalance is more noticeable at small throttles / light cruise conditions and getting it right can give much better town driving - there's also a Joospeed mod for the 4.2 version to cut out the slop in the cross link that gives a lot of poor running at part throttle."
Here is the process I use: -
Note that the 4.2 suffers from slop in the linkage. So check the adjustments for % adaptives with the throttle very slightly open and thus any slop in the linkage already taken up.
Get the engine properly warmed up so there is no ECU fuel/ignition compensation for cold temp
Go to the logging page and record a minute of idle and occasional throttle opened a bit for a few seconds (nothing wild, 2kish is is fine)
Examine the throttle pot readings to see if there is any spiking of the readings. If there is then replace the offending throttle pot.
Examine the lambda readings - they should be varying. If not then it may be wild adjustment or duff lambda.
I also capture the adaptive maps just for interest so I can compare with the results after adjustment.
Reset the adaptives to clear any existing values before starting any adjustments. You may find this affects the idle and you may need to open the stop to get a reasonable idle.
If I think its all wildly out I remove the airboxes and use the air mass meter to check the banks are pulling about the same air flow. You can also compare what each inlet is flowing. If on a bank the air flow is significantly different across the 4 inlets the only way to adjust it is to get some drilled screws. You replace the screws that clamp the butterfly to the throttle rod with a drilled screw to increase airflow down that inlet.
Otherwise I leave the air boxes on and don't clamp the purge line.
Get the TPot readings even first - adjust idle if necessary.
Highest adaptive reading is the bank flowing too much air - so close that bank down a bit. if its the odd bank (near side) then use the link rod to do it and then adjust the TPot back to same reading as the even bank
If its the even bank thats flowing too much air then note the odd bank tpot reading and close down the idle stop a bit and then adjust the link rod to get the odd bank back to the tpot reading you noted. then adjust the even bank tpot to the same as the even bank.
Its a lot easier to do than describe but you should be able to get towards zero on the adaptives with the tpots reading about 16.8% and idle at 950ish.
If you can't get anywhere near zero adaptives and you have checked both banks with a mass meter then the unvarying lambda is most likely goosed. Cheapest way to check is to unplug and remove the lambdas from the manifolds and swap them over. If the unvarying reading moves the lambda is duff. If the same bank shows the unvarying reading then its something else - possibly wiring but definitely not the lambda.
Other things to make it easier
Replace the TPot screws with cap heads and use a T handled allen key to slacken/tighten
Replace the link rod ball joints with rod ends from Ondrive
Fit a second throttle stop on the odd bank and use that for idle adjustment - that way the slop in the linkages doesn't have any effect - the even bank is always under tension being pulled back by its return spring.
Edited by mikesr on Monday 15th December 21:52
Edited by mikesr on Saturday 16th May 18:43
I second the advice of fitting a second throttle stop on the nearside bank - this will give a much more consistent idle. I simply used a small jubilee clip over the boss on the intake manifolds. I've also fitted a second (linear) return spring as I found the standard return springs provide little return force around the idle position which means the throttles tend to hang very slightly open which again raises the idle. Don't forget too that as the engine bay heats up, the aluminium rod expands and extends which again makes accurate setup even more difficult. It's all fun, but keep trying and don't expect to get it perfect - it will always be a bit out. My adaptives are roughly +/- 5 to +/-10 and the engine is happy enough.
caduceus said:
Hi Mike 
How has the Cerb been since the refurb work? Any niggles needed ironing out?
Done any more since?
Sory for the highjack :
Hi Caduceus How has the Cerb been since the refurb work? Any niggles needed ironing out?
Done any more since?
Sory for the highjack :
Its been fine.
The only issue I had was when I nearly lost a hose off the thermostat on a track day at Keevil. Fortunately the guy behind me spotted the dripping coolant. Tightened it up and topped up the coolant and off I went.
I suspect the hose clip hadn't been tightened up enough but it only started leaking after a major spin (the spin was deliberate. The instructors were trying to get us to learn the limits of the car - great fun!)
ok i had another look today and found that the dogy lamba sensor was now working all be it not as good as the other side. and the adaptive had come down.
thinking this was prop caused by that bank drawing too much air i checked the banks for balance and found that it was drwaing more on the bad side despite showing fine the other day.????
adjusted and reset the adaptive maps and t pots.
however the car did not like it and stalled. so reset idle and took for a spin and idle was a bit high so adjusted down stalled long and short no matter what if i get the car ro tick over around 900 rpm then go for a spin the ecu seems to adjust it back up some how.
will be checking again tomorrow after a good run tonight with some fuel system cleaner in it to see if i can rescue the sensor some more.
thinking this was prop caused by that bank drawing too much air i checked the banks for balance and found that it was drwaing more on the bad side despite showing fine the other day.????
adjusted and reset the adaptive maps and t pots.
however the car did not like it and stalled. so reset idle and took for a spin and idle was a bit high so adjusted down stalled long and short no matter what if i get the car ro tick over around 900 rpm then go for a spin the ecu seems to adjust it back up some how.
will be checking again tomorrow after a good run tonight with some fuel system cleaner in it to see if i can rescue the sensor some more.
longbow said:
I second the advice of fitting a second throttle stop on the nearside bank - this will give a much more consistent idle. I simply used a small jubilee clip over the boss on the intake manifolds. I've also fitted a second (linear) return spring as I found the standard return springs provide little return force around the idle position which means the throttles tend to hang very slightly open which again raises the idle. Don't forget too that as the engine bay heats up, the aluminium rod expands and extends which again makes accurate setup even more difficult. It's all fun, but keep trying and don't expect to get it perfect - it will always be a bit out. My adaptives are roughly +/- 5 to +/-10 and the engine is happy enough.
not sure I understand the 2nd throttle stop, any pictures of it?Im going to be bringing this thread back to the future a bit as I can see i'm going to get teething problems when I first start the engine.
when you mention T pot adjusting how is this done?
The Tpot is bolted to the end of the inlet manifold with 2 bolts either side, the holes aren't enlongated so how are they adjusted?
Is it done electonically via the laptop or am I missing something.
when you mention T pot adjusting how is this done?
The Tpot is bolted to the end of the inlet manifold with 2 bolts either side, the holes aren't enlongated so how are they adjusted?
Is it done electonically via the laptop or am I missing something.
I set about tweaking (and then replacing) the pots the other week and noticed the same. The holes are not elongated so they can't be moved more than a mm or so. Although a small movement did produce a big change in engine running. I was not too scientific about it as I was just experimenting with the old MBE ECU, it runs on an Emerald day to day which only uses one throttle pot and no lambda. That's my one criticism of the otherwise excellent K3, I would like to put 2 widebands on it and measure\correct each bank separately.
Thread resurrection!
Hello,
So, I've setup my car today. Idle is high 1050,was 900, I will lower it later). Adaptive at idle are OK (between 0 and 10) and the same and tpots give the same reading-ish.
While driving, when I out the pedal down, adaptive remain low. But they go crazy (up to 20) on liftoff. Should I be concerned?
Last question, when adaptatives are the same, but high, what should I do : decrease or increase the tpots value?
Thanks for your answers!
Julien
Hello,
So, I've setup my car today. Idle is high 1050,was 900, I will lower it later). Adaptive at idle are OK (between 0 and 10) and the same and tpots give the same reading-ish.
While driving, when I out the pedal down, adaptive remain low. But they go crazy (up to 20) on liftoff. Should I be concerned?
Last question, when adaptatives are the same, but high, what should I do : decrease or increase the tpots value?
Thanks for your answers!
Julien
It took me a while to get my head around how it works, but it really helps if you get hands on; it may then help to re-write it (someone else's explanation) in your own terminology and file it.
Here's how I see it, simplified, and assuming all sensors are working properly:
For each bank, the ECU receives the TP value and looks in its maps for the amount of fuel for that throttle opening (amount of air). This is purely theoretical, set by the ECU programmer, and is only adjustable by 're-mapping'.
The Lambdas then analyse the exhaust gases (this is empirical, actual) and, on that info, the ECU then corrects ('adapts') the fueling; positive = adds fuel, negative = subtracts fuel, until the Lambdas are happy with what they're sniffing.
(This is how it shows up if one bank is flowing more air than the other; if the TPs are equal but one bank's adaptive is higher than the other, it is because the higher side is sucking more air than the other and therefore needing more +ve correction; the solution is to reduce the throttle opening on the higher bank.)
But if both adaptives are high, the ECU is having to add fuel to both banks to satisfy the Lambdas, which means that the engine is actually flowing more air than it thinks it is, ie the TPs are under-reading compared to the reality. So the solution is to increase both the TP values, bringing them into line with the actual air flow. (Your situation may have simply been caused by setting the TPs to their ideal idle values while the engine was actually at 1050rpm...)
The TP is in effect working like the old 'mixture screw', it makes the ECU provide more or less fuel for that given airflow. And the adaptive value is like a 'plug-chop' looking at the plug colour (or a 'Colortune', remember them?!), showing you if you've got it right.
It's a crude (= early) system and one that requires an incremental approach to adjustment; you keep checking and adjusting everything in (hopefully) ever decreasing circles until you achieve nirvana!
Happy for anyone to flame me if they think any of this is wrong, as I said, it's just my interpretation.
Here's how I see it, simplified, and assuming all sensors are working properly:
For each bank, the ECU receives the TP value and looks in its maps for the amount of fuel for that throttle opening (amount of air). This is purely theoretical, set by the ECU programmer, and is only adjustable by 're-mapping'.
The Lambdas then analyse the exhaust gases (this is empirical, actual) and, on that info, the ECU then corrects ('adapts') the fueling; positive = adds fuel, negative = subtracts fuel, until the Lambdas are happy with what they're sniffing.
(This is how it shows up if one bank is flowing more air than the other; if the TPs are equal but one bank's adaptive is higher than the other, it is because the higher side is sucking more air than the other and therefore needing more +ve correction; the solution is to reduce the throttle opening on the higher bank.)
But if both adaptives are high, the ECU is having to add fuel to both banks to satisfy the Lambdas, which means that the engine is actually flowing more air than it thinks it is, ie the TPs are under-reading compared to the reality. So the solution is to increase both the TP values, bringing them into line with the actual air flow. (Your situation may have simply been caused by setting the TPs to their ideal idle values while the engine was actually at 1050rpm...)
The TP is in effect working like the old 'mixture screw', it makes the ECU provide more or less fuel for that given airflow. And the adaptive value is like a 'plug-chop' looking at the plug colour (or a 'Colortune', remember them?!), showing you if you've got it right.
It's a crude (= early) system and one that requires an incremental approach to adjustment; you keep checking and adjusting everything in (hopefully) ever decreasing circles until you achieve nirvana!
Happy for anyone to flame me if they think any of this is wrong, as I said, it's just my interpretation.
Edited by Twinkam on Monday 12th September 10:45
Edited by Twinkam on Monday 12th September 10:52
Jooles81 said:
So, I've setup my car today. Idle is high 1050,was 900, I will lower it later). Adaptive at idle are OK (between 0 and 10) and the same and tpots give the same reading-ish.
You should aim to get the adaptives between 0 and -10. Best to have the default state slightly rich so the adaptives are trying to remove fuel rather than add.Jooles81 said:
Last question, when adaptatives are the same, but high, what should I do : decrease or increase the tpots value?
A high positive adaptive means (WRT adjusting TPS):- it is adding fuel
- more air than expected
- TPS under reading
- Therefore adjust TPS position so TP reads higher (Rotate opposite direction to that of throttle shaft when it is opening, ie if throttle opens by rotating anti-clockwise then adjust TP by rotating clockwise)
You will need to adjust both sides. If they are already well balanced then that should be all the adjustment you need to do.
Thank you for your clear and thorough explanations.
Both banks are balanced, as both adaptatives are almost equal. That's good. I'll move both pots to get on the rich side, it sounds logical.
So, is it logical that the adaptatives go very high on liftoff? If I get it right, the throttle bodies should close, so no air, but the car thinks it's lean and tries to enrich. Sounds strange or good?
I've read somewhere that the lambdas are not taken into account over 4krpm. Am I right thinking that there is not correction over 4krpm? So if the engine is setup with big adaptatives it will be very off at high rpms?
Thanks!
Julien
Both banks are balanced, as both adaptatives are almost equal. That's good. I'll move both pots to get on the rich side, it sounds logical.
So, is it logical that the adaptatives go very high on liftoff? If I get it right, the throttle bodies should close, so no air, but the car thinks it's lean and tries to enrich. Sounds strange or good?
I've read somewhere that the lambdas are not taken into account over 4krpm. Am I right thinking that there is not correction over 4krpm? So if the engine is setup with big adaptatives it will be very off at high rpms?
Thanks!
Julien
Jooles81 said:
I've read somewhere that the lambdas are not taken into account over 4krpm. Am I right thinking that there is not correction over 4krpm?
Correct - the injection system goes "open loop" over 4k RPM (you can see this on the Adaptive Dials within RS-AJP - they flick to Zero over 4k)The injection duration's aren't positively or negatively trimmed over 4k - it just relies on whatever is in the base fuel map (which is common to both banks)
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