Hodor
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| posted on 21/5/15 at 10:52 PM |
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megasquirt TPS vs MAP
So got round to a rolling road to do some tuning on my c20xe on throttle bodies. The tuner guy is clearly not an ms guru and the car has clearly been
frigged to run using a couple of tricks, prior to it's sale to me.
Took a bit of figuring out, but the way it was running was it wasn't using the full fuel vs load map, just a 2 dimensional line really with no
variation in fueling with load, load wasn't being registered. The vacuum line to the MAP sensor was cut and MS was using Alpha-N.
So the only way the guy at the dyno could get the car to behave and be remotely tunable was to connect up the MAP sensor and run in speed density
mode, but as far as I can tell, for throttle bodies, I should be only using the tps for fuel and load. But when Alpha-N is selected ( which I believe
is how you make that happen) the car randomly wants to dump a load of fuel as the load and revs increase. It would appear that even in Alpha-N mode,
the load info is being taken from the MAP and is getting screwed up along the way, hence why the guy who sold it probably cut the MAP vacuum line.
So, question is, what am I missing and how do I configure mstuner to ignore the MAP and take all its into from the TPS?
Apologies for any missing info, that was my mstuner cherry broken today, in still taking it all in, so to speak.
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coyoteboy
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| posted on 21/5/15 at 11:09 PM |
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No reason you can't run MAP on throttles if it performs well, people just often find limited map range available and pulsing signal. I found TPS
difficult on some TBs.
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big-vee-twin
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| posted on 22/5/15 at 06:10 AM |
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You should be using alpha-n with throttle bodies.
Then you need to create a VE map in MS that has lots of bins at low TPS% I.e. 0,3,5,7,9,10,12 etc because as soon as the TB opens there is a massive
influx of air.
Lots of reading on the MS forums needed and a RR session with someone who knows MS like baileyperformance on here recommended.
The TBs need balancing also which is quite time consuming and frustrating.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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Jenko
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| posted on 22/5/15 at 07:01 AM |
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Alpha n for TB's.
First question, is the TPS connected up correctly, and also is it calibrated?. Without this you will not get anywhere with the mapping.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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coyoteboy
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| posted on 22/5/15 at 07:29 AM |
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Everyone says alpha-N for TBs but I really didn't find it that troublesome to map with MAP alone and I know a number of folk who're
running MAP on ITBs. I wonder if some engine combinations are a less fun to work with.
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SPYDER
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| posted on 22/5/15 at 11:32 AM |
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I'll echo most of the above. I would recommend that you purchase the full, registered version of Tunerstudio if you're not already using
it.
It gives you live "on the road" tuning ability called VEAnalyzeLive, assuming that you have a Wideband Lambda sensor.
I had excellent results with it.
What version of Megasquirt are you running?
Make sure TPS is calibrated.
Make sure Alpha N is selected correctly. In Tunerstudio it is selected in "Constants" and in "Project Properties".
Make sure "closed loop operation" is disabled.
Make sure that your particular Lambda sensor is correctly selected.
Check that the "required fuel" figure is correct. ( There is a web calculator for this)
Do the temperature gauges give correct readings?
As stated above, the VE table for Alpha N will be very different to when using MAP, particularly with respect to the "load" values running
up the left hand side.
If you select Alpha N then open the throttle fully ( with engine stopped ) does this show up on the VE table?
Will the car tick over on Alpha N?
Many web threads suggest getting it to tick over correctly first.
Regarding the VE table you are using, has it been tuned or is it simply a software generated one?
I would suggest generating a new one. ( After saving the old one)
Try to get the car to tick over at a suitable AFR by tweaking the "required fuel" figure.
Once this is achieved you should re-scale the VE table by the same ratio that you had to alter the required fuel figure then put the required fuel
figure back where it was.
At this point I used VEAnalyze live to further tune the table.
Using MAP ( speed density) may make sense, particularly if your TB's are on the small side but I had better results on Alpha N.
Lots of good info here...
CLICK HERE
[Edited on 22/5/15 by SPYDER]
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mark chandler
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| posted on 22/5/15 at 02:11 PM |
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Map was fine for me, just do not have linear values on the XY axis but group around most used values
As an example for RPM you really drive in the first 1/3 so have it more granular where you need it, as an example
750, 1000, 1250, 1500, 2000, 2500, 3000, 3500, 4000, 5000, 6000, 7000
I logged my car for a 20 minute drive in most conditions, plugged the RPM results into excel and built around the most used values, if you do the same
for MAP you can get it very good as megasquirt will join the dots and estimate.
Regards Mark
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G-sport
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| posted on 22/5/15 at 07:00 PM |
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On throttle bodies Alpha N is the only way to go IMO, I tune Skylines (Rb26) for a living which are multi throttle turbo cars and while you can tune
them on MAP I have found the resolution of the tune to be better when TPS is the main load axis.
But in reality it's what ever works best for the person tuning it !
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BaileyPerformance
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| posted on 23/5/15 at 05:22 AM |
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quote:
Originally posted by G-sport
On throttle bodies Alpha N is the only way to go IMO, I tune Skylines (Rb26) for a living which are multi throttle turbo cars and while you can tune
them on MAP I have found the resolution of the tune to be better when TPS is the main load axis.
But in reality it's what ever works best for the person tuning it !
You tune a turbo car on Alpha N? I assume with MAP as well to add fuel with boost and regard the timing?
ITBs are best tuned Alpha N, you can connect MAP as well if required (not normally if NA) but you need to connect all throttles together to give a
common stable vac signal.
www.facebook.com/baileyperformance
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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G-sport
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| posted on 23/5/15 at 07:00 AM |
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quote:
Originally posted by BaileyPerformance
quote:
Originally posted by G-sport
On throttle bodies Alpha N is the only way to go IMO, I tune Skylines (Rb26) for a living which are multi throttle turbo cars and while you can tune
them on MAP I have found the resolution of the tune to be better when TPS is the main load axis.
But in reality it's what ever works best for the person tuning it !
You tune a turbo car on Alpha N? I assume with MAP as well to add fuel with boost and regard the timing?
ITBs are best tuned Alpha N, you can connect MAP as well if required (not normally if NA) but you need to connect all throttles together to give a
common stable vac signal.
www.facebook.com/baileyperformance
Yes, Multi dimensional fuel table with gauge pressure as secondary load and then manifold pressure for ign load axis. Been doing it that way for
years.
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BaileyPerformance
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| posted on 23/5/15 at 08:12 AM |
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quote:
Originally posted by G-sport
quote:
Originally posted by BaileyPerformance
quote:
Originally posted by G-sport
On throttle bodies Alpha N is the only way to go IMO, I tune Skylines (Rb26) for a living which are multi throttle turbo cars and while you can tune
them on MAP I have found the resolution of the tune to be better when TPS is the main load axis.
But in reality it's what ever works best for the person tuning it !
You tune a turbo car on Alpha N? I assume with MAP as well to add fuel with boost and regard the timing?
ITBs are best tuned Alpha N, you can connect MAP as well if required (not normally if NA) but you need to connect all throttles together to give a
common stable vac signal.
www.facebook.com/baileyperformance
Yes, Multi dimensional fuel table with gauge pressure as secondary load and then manifold pressure for ign load axis. Been doing it that way for
years.
That the way we do it with megasquirt, we map off boost first (alpha N), then second table (MAP) for extra fuel on boost.
Ignition MAP only. We find this method gives best throttle response
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Hodor
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| posted on 23/5/15 at 08:17 AM |
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quote:
Originally posted by BaileyPerformance
quote:
Originally posted by G-sport
On throttle bodies Alpha N is the only way to go IMO, I tune Skylines (Rb26) for a living which are multi throttle turbo cars and while you can tune
them on MAP I have found the resolution of the tune to be better when TPS is the main load axis.
But in reality it's what ever works best for the person tuning it !
You tune a turbo car on Alpha N? I assume with MAP as well to add fuel with boost and regard the timing?
ITBs are best tuned Alpha N, you can connect MAP as well if required (not normally if NA) but you need to connect all throttles together to give a
common stable vac signal.
www.facebook.com/baileyperformance
This is where we ran into trouble, the tuner wanted to go to tps for fuel and load, but with alpha-n selected, the car just didn't behave. Only
with speed density did the car settle down and was tunable. He said exactly what others have said, that alpha-n will give better resolution,
it's that it simply didn't work in this mode
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MikeRJ
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| posted on 23/5/15 at 09:08 AM |
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This is probably a simple configuration problem, MS can be very obtuse in this way. Although you may have chosen Alpha-N as the control Algorithm,
it's possible that the secondary load parameters have been set to MAP, so both TPS and MAP will be used. For pure Alpha-N you need to set
secondary fuel control to disabled.
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