Small MS issues

[740 Turbo Brick]

I have this posted on 2GNT, but since this site seems to have more traffic Ill try here too.

Im having a few issues that are making the daily drivability of my car difficult. For the most part, it drives great, Id say better than with the stock ECU.

First, when the car is cold I can crank it and it will start and idle on its own. When the car is hot, it will crank, but not start. I have to give it a little gas to get it to fire. Is this a cranking pulsewidth problem?

Im using the IAC control on my MS. Using Corbins settings, the car idles pretty damn good. The only problem Im having is sometime the car will start oscillating. It will sit at ~1000 and all the sudden drop to 500, up to 1300, and repeat. I have the "Idle advance" feature set so that if it falls below a certain RPM it pulls timing in an effort to keep the car idleing. It wont stop hunting until I tap the throttle to steady it out.

Lastly, I think I may need some advice with the accel enrichment. When the car is just started, even a tap of the throttle (2% TPS or less) the AFR goes dead lean, the engine hesitates and then revs up. This is making leaving stop lights a bi***, because the car wants to buck when I give it gas to let out the clutch. This seems to lessen as the car warms up, but I was just guessing on the A.E. settings so Im sure they are not perfect.


Any help would be greatly appreciated. Im getting the hang of tuning/daily driving on Megasquirt, but I could use all the advice anyone is willing to give!

 

[96TurboGS]

I was thinking about doing an extensive write up to go here on tuners some time ago, but got bombarded with other projects.

There are primarily three things you need to consider.


1.Fuel (includes stable pulsewidth and AFR, but will be tricky to implement with EGO correction on at idle)

2.Ignition timing. (needs to be stable)

3.PID settings (mainly adjusting the 'I' and 'P')

The IAC closed loop code is very touchy when you have a high P or an overly aggressive I, leave D as 0 as it doesn't have much of an impact as the other two. As I've said before if you want all the latest bug fixes, the 3.0.3s or 3.0.3t will do you fine. t just has several fixes for sequential than s, but has the latest fixes that is recommended from the developers. To prevent oscillation you must tune P so that it doesn't jump around and the oscillation isn't a problem; you want to test this when it is lean. The reason why you test it when it's lean is because the engine wants to move up the map where there is a richer pulsewidth and a higher ignition advance to prevent it from dying and this causes the IAC to oscillate from lean to rich due to the aggressive PID settings. With a low 'P' it will reduce this and 'I' will control how quick it returns to your rpm target.

The value 50 for 'P' is slightly high and will cause you to have these problems until you lower it. You can slightly raise 'I' though. You want to adjust it so that the IAC will return to its target slowly once within 500 rpm. With ignition you want to keep a solid advance, to do this make the points around your idle area the same; the same could be said for VE table. By doing this you will help against oscillation and the fuel will be burned evenly.

Having the correct opening steps and the right pulse width/low cranking advance will also help you start to a fast stable idle. I and many others found that having a long ASE taper but slightly low ASE also helps hot starts. If you have your IAT on the IM you will experience heat soak when you shut down the car. <-- This effects start up. You either need to relocate your IAT to the intake pipe with a heat resistant material or adjust your MAT curves to account for heat soak. (This is more important on a turbo car, but isn't a must for an n/t but will result to solid results every time) Get your IAT curves right at all temps before attempting to adjust AE, having an overly compensated AE will produce poor throttle response. The point is to have close to a 0% correction throughout the entire fuel map so you don't have to adjust your VE map to compensate for oscillation. I did this and haven't had to touch my VE map for 4 months.

Lastly but not least idle advance isn't needed, it just adds more variables you have to tune around.

Be sure to check this out: 2 Idle Control

It's for MS3 but the concept is the same as allot of the work from MS3 is back ported to MS2.

Always remember that every engine is different per application and there is no "one setting" that is correct. When configured correctly it will produce great results.

 

[740 Turbo Brick]

Thanks for the advice, Ill look into my settings when I get my car back. Currently its on a lift getting an alignment..

 

[740 Turbo Brick]

Id like to say thanks for the info you posted in here. I modified the P and I settings and the car idles tons better. I also turned the idle advance off, that smooted it out even more. My car seems to like 10* of timing around idle.

 

[96TurboGS]

Glad I could help. If there is by chance you updated your firmware to 3.0.3s or 't' you would want to update it to 'u'. One of the developers made a page several bytes bigger causing odd behavior when burning or reading a MSQ. The .ini would be the same as 's' and 't' so you don't have to redo your current MSQ.

 

[740 Turbo Brick]

I read more into that idle control page and tuning the PID parameters became even easier. I tuned I, then P, and I have an almost perfectly reliable Idle. The only problem Im having now is an uncontrollable oscillation when I turn the AC on. When the radiator fans turn on I can recover, but when the AC turns on it will oscillate no matter what. I also have an aluminum UDP and stage 2 cams, would that make idleing with a load like that near impossible?

 

[96TurboGS]

Currently, the developers for MS3 are working on something called AC idle up. (with promising results) The code will add x number of steps when there is stress on the engine from either lights, fans, PS, AC, ect. via input. MS2 doesn't support it yet, but I believe it eventually will. Reducing your 'P' more and increasing your 'I' may be your best bet for now. You can go as low as 5 for P and still be able to tune I. Remember, P sets the switch point on how fast the IAC will counter react to sudden shifts in RPM. If I were to turn my wheel while idling I would get a small dip in RPM's due to the ECU not knowing the PS pump kicked in, but my idle will never oscillate; same could be said for AC. Upgrading to at least 2.1.1 has the improved map sampling code (which will help with the cams) and numerous bug fixes. The current code (3.0.3u) has all the latest fixes for IAC. Another thing that helps stability is sequential injection.

 

[740 Turbo Brick]

I looked into sequential injection, but Im on a bit of a budget now after spending $600 on my ECU.

I got my car to start quicker also. I opened up the crank steps for the IAC. Instead of 15 steps at 180*, Im doing 55, which takes just BARELY longer than stock to fire after cranking. This puts my RPMs about 1200 after firing, which settles to 975-950. My P setting is currently 45, I is 90. Ramp to target is 6 seconds, I believe. When decelerating coming to a stop light, the RPMs almost always start around 1200 and settle. Sometimes I noticed the steps will go to 1, and when I let out the clutch the car will go to 500 RPM, but then come back up. So I think my settings are going to stick this time. I can actually listen to my CD player without having to worry if my car stalled! Still cant turn AC on at idle, but Im willing to sacrifice just using it while driving to get it to idle. Hell, I may even just delete the whole AC system for weight savings. I just liked the thought of running a 14 all motor and then using the AC on the way home.

 

[96TurboGS]

I opened up the crank steps for the IAC. Instead of 15 steps at 180*, Im doing 55, which takes just BARELY longer than stock to fire after cranking.

Yea, 55 sounds much better than 15.

Ramp to target is 6 seconds, I believe.

I got mine at 2 seconds, drops to a solid idle.

When decelerating coming to a stop light, the RPMs almost always start around 1200 and settle. Sometimes I noticed the steps will go to 1, and when I let out the clutch the car will go to 500 RPM, but then come back up.

On 2gnt I remember you having minimum steps at 3, you only want to have it fully closed to where it won't stall you engine. You usually want to have it around 20-30 or so steps. (or wherever you want your safety net; usually around 600 rpm is the lowest I would allow) Around this time of year your IAC will require little air to keep idle, so make sure your closing steps are low enough where it doesn't cause a high idle. Last saved step was also a problem the 2.1.0 series had.

Hell, I may even just delete the whole AC system for weight savings.

This is on my list for the next tear down.

 

[740 Turbo Brick]

Im going to give this newer firmware a try, because I think I am loosing steps, like the algorithm is getting confused. My idle valve closed steps is 15, and it still will go to 1 or 7 sometimes. Is this where I download it from? Alpha 303t?

Index of /doc/ms2extra/files/alpha

 

[VelocitàPaola]

Is this where I download it from? Alpha 303t?

Index of /doc/ms2extra/files/alpha

Yep.

See what I did there? I let Rafiel answer all the tough questions, then I came in for the easy one.

 

[740 Turbo Brick]

. I ask alot of questions, theres enough to go around.

And speaking of having alot of questions, I have another one. To get this firmware into the ECU, do I go to Tunerstudios, File, Project, project properties, ECU definition, and click Other and find the file titled "megasquirt-ii.ini.ms2extra" in the folder I just downloaded?

 

[96TurboGS]

I let Rafiel answer all the tough questions, then I came in for the easy one.

If there is by chance you updated your firmware to 3.0.3s or 't' you would want to update it to 'u'. One of the developers made a page several bytes bigger causing odd behavior when burning or reading a MSQ. The .ini would be the same as 's' and 't' so you don't have to redo your current MSQ.

That was a big if, but yea you don't want 't' as there was problems with the firmware; 'u' is currently the most stable. You must make a new .msq from scratch as the two .ini's aren't compatible from 2.1.0 to 3.0.3u. However, when you get it loaded its normal to see 3.0.3s instead of 3.0.3u because the ini for 's', 't', and 'u' are the same. When you get everything switched over have TS compare your old .msq to your new one to insure you have switched everything over successfully.

To get this firmware into the ECU, do I go to Tunerstudios, File, Project, project properties, ECU definition, and click Other and find the file titled "megasquirt-ii.ini.ms2extra" in the folder I just downloaded?

You got it. (but make sure you download 'u' and not 's'!)

EDIT: Upgrade Video: http://www.youtube.com/watch?v=A24IUu3_-tI

 

[740 Turbo Brick]

Cool thanks man. I just got done flashing the firmware into my ECU. I was actually able to just open TS and "send TS settings to ECU" from my project and I got all my settings and tables back. The only thing I had to do was recalibrate my tables and sensors. My laptop died just as I got done (Thank God!) so Im going to go out tomarrow and try starting it up.

Also, I was asked by CMD to remove the connectors to my coil before flashing it, or damage would occur. Why is that?

 

[VelocitàPaola]

Also, I was asked by CMD to remove the connectors to my coil before flashing it, or damage would occur. Why is that?

The default settings in your ECU after flashing it with new firmware are such that your ignition coil may be damaged. Specifically, the spark output may be set to "going low," which would saturate and eventually overheat the coil. You should only reconnect the coil after loading your MSQ/settings into the ECU.