changing a throttle pot!
Discussion
Hello all!!
well the saga continues! hooked the car up to the laptop today and saw that there was an error on AFR, so reset the adaptives and seemed better, but lo and behold the fault came back
then i acctually opened my eyes and realised that throttle pot 1 was on 15% with the engine of, (lovely) but throttle pot 2 was flickering from 50% up to 70% !!!!
so the adaptives were going -30 etc, hence the bad running!!!
so a new pot has been ordered (a whopping 20 notes), but how on earth do you fit it? and set it up??
can anyone do a guide here on how to install, setup, and get it on 15% like pot 1
many thanks as always everyone!
Grant
well the saga continues! hooked the car up to the laptop today and saw that there was an error on AFR, so reset the adaptives and seemed better, but lo and behold the fault came back
then i acctually opened my eyes and realised that throttle pot 1 was on 15% with the engine of, (lovely) but throttle pot 2 was flickering from 50% up to 70% !!!!
so the adaptives were going -30 etc, hence the bad running!!!
so a new pot has been ordered (a whopping 20 notes), but how on earth do you fit it? and set it up??
can anyone do a guide here on how to install, setup, and get it on 15% like pot 1
many thanks as always everyone!
Grant
To replace is dead easy - simply unplug the pot, undo the two screws that brace the pot with the metal strip and pull it off the throttle spindle. Exact reverse for fitting the new one. To set up make sure the screws are just slack enough so you can twist the pot by hand. Even the slightest movement creates big changes in reading. You will need to be able to see the laptop screen as you do this to see what effect your twisting has on the pot reading. When you have it set as you want, tighten the screws up making sure you don't let the pot move as you tighten. Simple job, if you want to set the car up properly I'd recommend using a synchrometer to ensure you have even airflow through the banks too. Its a bit of an iterative procedure but you'll get there in the end. Ideally you want to get those adaptives as low as possible with balanced airflow.
If you want to just replace the tpot then you need not do anything else. If you want to do the tpot adjustments sorted then yes you have to mess with teh link rod and idle screw.
Pasted below is Trackcars mthod of doing it without the air mass meter.
mikesr
This is the bit here. I guess equal adaptives close to zero, throttle pots reading the same each side and equal injector times for both banks means balanced airflow.
"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 / lightcruise 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."
Pasted below is Trackcars mthod of doing it without the air mass meter.
mikesr
This is the bit here. I guess equal adaptives close to zero, throttle pots reading the same each side and equal injector times for both banks means balanced airflow.
"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 / lightcruise 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."
Yes, Joolz' method works equally well as you are simply using the O2 sensor to indicate rich or lean relative to the throttle pot reading. I'd say for an amateur, the synchro is bullet proof as its simple, you just bung the synchro in the inlet and adjust the link rod until the reading is the same. It also bypasses a potentially misleading O2 sensor issue. Once you have acheived that, then you can set the adaptives equal again by the method I described. After that, if all is well, the adaptive will be low for sure. Have a play with it, you'll soon see what does what!!!
gcpeters said:
Hello all!!
well the saga continues! hooked the car up to the laptop today and saw that there was an error on AFR, so reset the adaptives and seemed better, but lo and behold the fault came back
then i acctually opened my eyes and realised that throttle pot 1 was on 15% with the engine of, (lovely) but throttle pot 2 was flickering from 50% up to 70% !!!!
so the adaptives were going -30 etc, hence the bad running!!!
so a new pot has been ordered (a whopping 20 notes), but how on earth do you fit it? and set it up??
can anyone do a guide here on how to install, setup, and get it on 15% like pot 1
many thanks as always everyone!
Grant
well the saga continues! hooked the car up to the laptop today and saw that there was an error on AFR, so reset the adaptives and seemed better, but lo and behold the fault came back
then i acctually opened my eyes and realised that throttle pot 1 was on 15% with the engine of, (lovely) but throttle pot 2 was flickering from 50% up to 70% !!!!
so the adaptives were going -30 etc, hence the bad running!!!
so a new pot has been ordered (a whopping 20 notes), but how on earth do you fit it? and set it up??
can anyone do a guide here on how to install, setup, and get it on 15% like pot 1
many thanks as always everyone!
Grant
Hi There,
With all due respect are you sure you need a new pot? Have you tried loosening the screws and moving it by hand to show 15 and then tightening back up?
There are lots of great posts on here regarding throttle pots in particular the one above
. Duncan
Gassing Station | Cerbera | Top of Page | What's New | My Stuff