I have a MS3 Xtra on a Honda CBR1100 engine with a twinscrewsupercharger that I run in full sequential mode. The throttle is placed on the superchargers intake side.
The driving range (3000-11000 rpm) runs ok but I have not been able to tune the idle correctly.
The best/lowest I have managed is 2600 rpm at 60kpa with the TPS at about 2.3%. The original Engine idles at 1100rpm.
There is no idle air valve so I adjust the air with the throttle stop.
When trying to tune the idle it is not very sensitive on ve-setting but when I decrease TPS ever so slightly a surging starts that is high in frequency and rapidly increasing in rpm-range until it stops.
While surging the revs goes higher than it could reach while stable in RPM at a slightly higher TPS. The surge is so fast that I cant make any adjustments while its running and have to rely on logfiles to make adjustments. I try to adjust the cells the marker is going towards when the RPM:s drop.
I have read the manual and it all seems so simple but as I have been messing with this for a long time now and have several hundreds of logfiles I thought maybe there is something fundamentally wrong with my setup or the way Im tuning. I would really apreciate if someone could look into my logfile ans msq.
Stefan Larsson
Super-sensitive idle tuning ?
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HovstaSX360
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Re: Super-sensitive idle tuning ?
Take a look at the Idle Advance and Idle RPM Timing Correction functions.
Temporarily shut down - back soon!
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
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QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
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HovstaSX360
- MS/Extra Newbie
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- Joined: Thu Jun 30, 2011 2:54 am
Re: Super-sensitive idle tuning ?
As I understand it the Idle Advance and Idle RPM Timing Correction is like changing to another Ignition advance map under certain defineable conditions. Maybe Im misunderstanding but wouldnt that be just as difficult to tune for idle as the basic ignition map ?
Im sorry if my english maybe is a little confusing. It is not my native language and its a ittle difficult to express myself clearly, but I will do my best.
This is my first Megasquirt installation and I have not done anything like this before so Im a real FI rookie.
Relatively quickly I had the engine running 3000 rpm at 4%tps. I worked my way down by decresing tps 0.1% and adjusting ve until it was stable at the new tps. As the surging was so fast and the engine eventually stopped I made all adjustments when the engine was not running and only made small adjustments each time.
It has been a very slow process and maybe my strategy is totally backwards. Im now down at 260o rpm at 2.3% tps . Progress is now so slow It feels like I with this strategy, will never get this engine to idle anywhere near the stockers 1100 rpm.
This picture show how the marker moves on the VE-map when decreasing throttle from 2.3% to 2.2%. The marker starts at 2600rpm-60kpa. When tuning I have adjusted VE in the cell the marker is heading to, in this case 2000rpm-60kpa and 2000rpm-65kpa.
When looking at the logfiles I dont know how to relate the AFR timewise to what is happening as the surging is so fast and I dont know the timelag between what happends in the engine and what shows in the log.
This picture shows how quickly the surging starts and accelerates when decreasing throttle from 2.3 to 2.2 %. I dont know what to expect. Why does it act like this?
Im sorry if my english maybe is a little confusing. It is not my native language and its a ittle difficult to express myself clearly, but I will do my best.
This is my first Megasquirt installation and I have not done anything like this before so Im a real FI rookie.
Relatively quickly I had the engine running 3000 rpm at 4%tps. I worked my way down by decresing tps 0.1% and adjusting ve until it was stable at the new tps. As the surging was so fast and the engine eventually stopped I made all adjustments when the engine was not running and only made small adjustments each time.
It has been a very slow process and maybe my strategy is totally backwards. Im now down at 260o rpm at 2.3% tps . Progress is now so slow It feels like I with this strategy, will never get this engine to idle anywhere near the stockers 1100 rpm.
This picture show how the marker moves on the VE-map when decreasing throttle from 2.3% to 2.2%. The marker starts at 2600rpm-60kpa. When tuning I have adjusted VE in the cell the marker is heading to, in this case 2000rpm-60kpa and 2000rpm-65kpa.
When looking at the logfiles I dont know how to relate the AFR timewise to what is happening as the surging is so fast and I dont know the timelag between what happends in the engine and what shows in the log.
This picture shows how quickly the surging starts and accelerates when decreasing throttle from 2.3 to 2.2 %. I dont know what to expect. Why does it act like this?
Re: Super-sensitive idle tuning ?
It's funny - most times I see someone apologizing in advance for their English, it's usually far superior to most of the posts out there ...
Right now you're trying to tune for idle by VE without the help of an IACV, which - as you've noticed - isn't easy. The changes in engine power caused by changing the spark advance are more subtle, and less likely to cause surging.
Right now you're trying to tune for idle by VE without the help of an IACV, which - as you've noticed - isn't easy. The changes in engine power caused by changing the spark advance are more subtle, and less likely to cause surging.
Temporarily shut down - back soon!
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
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pit_celica
- Master MS/Extra'er
- Posts: 682
- Joined: Tue Jul 18, 2006 3:12 pm
Re: Super-sensitive idle tuning ?
I would suggest that you flatten your spark table to a single value (let say 20°) everywhere from 0 to 100 kPa and from 0 to 3500 RPM.
Also, based on the log, when it goes from 2600 RPM to 1000-1500 RPM, the AFR is too lean. Try to richen this part of the fuel map. What you want to achieve, is the lowest MAP at your desired RPM idle target. You may need to aim for a slightly richer AFR so that the engine has plenty of fuel. I would aim for 13-13.5 AFR for now.
Do not enable idle control, RPM idle correction or idle timming feature until you can run reliably using only the main spark and fuel tables.
Sam
Also, based on the log, when it goes from 2600 RPM to 1000-1500 RPM, the AFR is too lean. Try to richen this part of the fuel map. What you want to achieve, is the lowest MAP at your desired RPM idle target. You may need to aim for a slightly richer AFR so that the engine has plenty of fuel. I would aim for 13-13.5 AFR for now.
Do not enable idle control, RPM idle correction or idle timming feature until you can run reliably using only the main spark and fuel tables.
Sam