Throttle pot wiring Megasquirt
Discussion
spitfire4v8 said:
Update your min tps setting in MS with the value shown when the engine is ticking over.
I'm guessing what's happening is that the throttle spindle is moving due to play in the shaft/plenum. You've presumably set the min value with engine off, but that changes when there is vacuum against the back side of the butterfly.
Makes sense, thanks that’s great advice.I'm guessing what's happening is that the throttle spindle is moving due to play in the shaft/plenum. You've presumably set the min value with engine off, but that changes when there is vacuum against the back side of the butterfly.
spitfire4v8 said:
Update your min tps setting in MS with the value shown when the engine is ticking over.
I'm guessing what's happening is that the throttle spindle is moving due to play in the shaft/plenum. You've presumably set the min value with engine off, but that changes when there is vacuum against the back side of the butterfly.
Never had to resort to this when calibrating TPS in Tunerstudio I'm guessing what's happening is that the throttle spindle is moving due to play in the shaft/plenum. You've presumably set the min value with engine off, but that changes when there is vacuum against the back side of the butterfly.
but maybe the cars I have seen have a little more cranked throttle whilst against the stop, you can only see 0 when connected on my stim 
anyway that figure is irrelevant in this case 
and Jools sees far more ECU traffic than I ever will 
Belle427 said:
I have an enlarged 72 mm plenum which may exaggerate the problem, the throttle stop screw has never really been adjusted from when I received it but the throttle disc is as closed as it will go.
No need to fill the bore with the disc have it cracked open a tad (a few thou will suffice) otherwise you can start getting a sticky initial pedal travel where the butterfly binds 
I stopped using the Lucas stepper ICV years back but the settings are under idle control section (dont use these figures however) you will have to have a play to get it working as intended be patient , sure I have a base tune file/msq for the RV8 with all generic settings somewhere to get you started with the stepper base settings 
While not on a RV8, i did install Megasquirt on an MX5 recently, purchasing a pre built unit as a Plug n Play set up so that all existing engine sensors could be used, including the mazda VTPS. We found a number of issues with the VTPS and megasquirt.
Firstly the ECU was built wrong and this did take a bit of time to work out, so while we would rightly assume it was correct, this was wrong.
Secondly we too had some wobble on VTPS readings at idle, ours was also worn spindle seals allowing some movement that the VTPS saw as spindle rotation.
Having fixed all of that we then had massive air leeks that also caused issues resulting in a fundamental re-engineering of the ITB's because we have converted a set of old twin 40 cabs as a cheap home brew idea.......
Firstly the ECU was built wrong and this did take a bit of time to work out, so while we would rightly assume it was correct, this was wrong.
Secondly we too had some wobble on VTPS readings at idle, ours was also worn spindle seals allowing some movement that the VTPS saw as spindle rotation.
Having fixed all of that we then had massive air leeks that also caused issues resulting in a fundamental re-engineering of the ITB's because we have converted a set of old twin 40 cabs as a cheap home brew idea.......
Belle427 said:
Be interested to know if anyone has used the ve analyze live part of tunerstudio.
Seems a good idea to fine tune a known good map but it gets mixed feedback.
Yes I have used tune analyse live. It works pretty well but you must set your AFR targets up properly i.e. understand what numbers you should be aiming for (these are not necessarily stoich; depends on your engine and what fuel it 'likes'. You must also have a good understanding of the lag in your o2 reading, which varies based on both load and RPM. There is a small table to set up that it uses to better estimate the VE changes needed.Seems a good idea to fine tune a known good map but it gets mixed feedback.
It doesn't work very well on idle; that is best tuned by hand.
One useful feature is the ability to lock out cells you don't want to be affected (idle range for example, or areas you have already tuned). And it will give you a heat map of which cells have been visited most often and how much they were changed. This can be useful if you're trying to hit a particular area of the map while out driving it.
It will obviously only do fuel, as you no doubt know, ignition and fuel are interrelated so changing one will often mean the other can benefit from a tweak and it is only doing one half of the equation, so there's a limit to what you can achieve with it in terms of best torque.
The other thing is that it's hard to hit all the areas of a map without a dyno so there are just some areas it can't hit.
In summary, it works fairly well within the constraints I've mentioned but it is not a substitute for a dyno day or (in my case) pouring over the logs and tweaking the tables, rinse, repeat, until it is right.
ric355 said:
Yes I have used tune analyse live. It works pretty well but you must set your AFR targets up properly i.e. understand what numbers you should be aiming for (these are not necessarily stoich; depends on your engine and what fuel it 'likes'. You must also have a good understanding of the lag in your o2 reading, which varies based on both load and RPM. There is a small table to set up that it uses to better estimate the VE changes needed.
It doesn't work very well on idle; that is best tuned by hand.
One useful feature is the ability to lock out cells you don't want to be affected (idle range for example, or areas you have already tuned). And it will give you a heat map of which cells have been visited most often and how much they were changed. This can be useful if you're trying to hit a particular area of the map while out driving it.
It will obviously only do fuel, as you no doubt know, ignition and fuel are interrelated so changing one will often mean the other can benefit from a tweak and it is only doing one half of the equation, so there's a limit to what you can achieve with it in terms of best torque.
The other thing is that it's hard to hit all the areas of a map without a dyno so there are just some areas it can't hit.
In summary, it works fairly well within the constraints I've mentioned but it is not a substitute for a dyno day or (in my case) pouring over the logs and tweaking the tables, rinse, repeat, until it is right.
Well said It doesn't work very well on idle; that is best tuned by hand.
One useful feature is the ability to lock out cells you don't want to be affected (idle range for example, or areas you have already tuned). And it will give you a heat map of which cells have been visited most often and how much they were changed. This can be useful if you're trying to hit a particular area of the map while out driving it.
It will obviously only do fuel, as you no doubt know, ignition and fuel are interrelated so changing one will often mean the other can benefit from a tweak and it is only doing one half of the equation, so there's a limit to what you can achieve with it in terms of best torque.
The other thing is that it's hard to hit all the areas of a map without a dyno so there are just some areas it can't hit.
In summary, it works fairly well within the constraints I've mentioned but it is not a substitute for a dyno day or (in my case) pouring over the logs and tweaking the tables, rinse, repeat, until it is right.
my daughter use to be at the TS tuning as a passenger while I drove (good fun and progress) I many years ago after changing fuel pressure and inj's got her to highlight and grab a load of cells to remove a % of fuel she miss heard with the number by mistake and burned it the car fell flat on its face 
lean as hell and I coasted to the curb 
she panicked I laughed she thought she broke my car 
So I tried the suggestion of calibrating with engine running and it’s just as erratic on the colvern style pot.
I’m wondering if because it’s not spring loaded like the original Lucas Tps then the spindle play may be affecting it more.
Going to change it back tomorrow and see what happens.
I’m wondering if because it’s not spring loaded like the original Lucas Tps then the spindle play may be affecting it more.
Going to change it back tomorrow and see what happens.
Its going to be an issue if there is slop in the drive distance piece (I presume this as one) its why many OE solutions have an internal spring to remove any slack in the drive exchange from throttle spindle to TPS didnt know you was using an alternative to the Lucas/Hotwire TPS
didnt know you was using an alternative to the Lucas/Hotwire TPSEdited by Sardonicus on Monday 14th October 13:14
I would only use the spring loaded version .. but if you['re really struggling with the sensor following the shaft, and you feel you've exhausted the opportunities for getting a better plenum/shaft combo on there, you might have to go MAP sensor and just use the throttle signal for large throttle changes for accel enrichment.
The alternative is to have a flange TIG'd onto your plenum to accept an aftermarket throttle body, a well trodden path that gets you access to new position sensors and a new throttle body and shaft that's un-boltable ie replaceable.
The alternative is to have a flange TIG'd onto your plenum to accept an aftermarket throttle body, a well trodden path that gets you access to new position sensors and a new throttle body and shaft that's un-boltable ie replaceable.
Belle427 said:
Why does it go lean (19:1) is it because its moving to the wrong point in the map?
Trailing closed throttle? do you have over-run fuel cut enabled ? if its constant throttle or accelerating (not snap open) then yes you may be hitting small number bins on the VE table get that sorted if so , if its just when your jumping on the throttle for a second then you may need to play with AE acceleration enrichment settings Edited by Sardonicus on Monday 14th October 17:26
Well, if its slow throttle openings either your map is wrong or your change of airflow isn't being acted on, if your throttle sensor is lagging behind the spindle position and hence change of airflow that would explain it.
If on snap open throttle your acceleration enrich settings need a tweak.
If on snap open throttle your acceleration enrich settings need a tweak.
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