Megasquirt question.... Options

[Joe Bob]

If you are running dual throttle bodies...where can you put a "fifth" injector for cold start enrichment or is there a setting in the software I'm missing? My 2.2 runs like crap until 210F.....which is about 5 miles at cruising speed.

[DNHunt]

Mike

Why would you need a fifth injector unless the injectors are too small? Warmup enrichment should provide longer injection times unless you are bumping up against max openning times. If that's the case, I'm surprised you don't have a melted lump. Are you sure the sensor is calibrated right and warmup enrichment is correct? Start it cold and watch the pulsewidths as it warms up. You should see them start out longer and decrease.

Dave

[Joe Bob]

OK...I'll try that. The injectors are what came with the running motor from a sand rail. I converted it over to a sedan configuration, changed out the turbo and converted to Megasquirt.

What should I be looking for on the pulsewidths? I'll have to check my notes on the injector ratings.....

More info...CB Performance kit, ITB throttle bodies, 2180 Type I, wide band O2....when cold it starts relatively easy.....popping and missing until warm.

At around 200F oil temp is starts to smooth out and has a few pops but nothing major at WOT from 1500rpms up to 5K....EGT, head temps and boost are fine, no noticeable pinging....

[DNHunt]

Mike

Are you familiar with the sreen that has the Warmup Wizzard. If you have the WBO2 running into MS, it will show O2 on a bar graph. After the sensor heats up (~ 20 sec) you should see values for O2. it sounds like you haven't got enough enrichment. Enrichment can be increased in the bins to the left. It is in percent so 100% is no enrichment. On my rig I start at about 150% and taper down. Temp values end at 160 degrees.

Dave

[mightyohm]

5th injectors are for outdated 70s analog fuel injection systems. (IMG:style_emoticons/default/bootyshake.gif)

There is a calculator somewhere on the MS pages that tells you how big to size your injectors for a given horsepower. Assuming your motor runs ok at WOT (injector duty cycles aren't going over about 85%) then you should be able to deliver enough fuel for warmup. There is a table that gives you warmup enrichment % vs. temperature.

What are you using for your "coolant sensor" in Megasquirt? This is the sensor it uses for warmup. I have mine connected to my stock CHT.

[Joe Bob]

Mike

Are you familiar with the sreen that has the Warmup Wizzard. If you have the WBO2 running into MS, it will show O2 on a bar graph. After the sensor heats up (~ 20 sec) you should see values for O2. it sounds like you haven't got enough enrichment. Enrichment can be increased in the bins to the left. It is in percent so 100% is no enrichment. On my rig I start at about 150% and taper down. Temp values end at 160 degrees.

Dave

Wouldn't it be better to have the warmup run off of the oil temp sender? I checked my values...way low, 120% and down as temp goes up....I'll dial in some more enrichment and see how that works.

[crash914]

richen the hell out of it at low temps...head temp reads faster, you just need the extra squirts for cranking and the 30 secods or so after..

no problem starting mine in NH in the low 20 degree area....

[Joe Bob]

No problem on starting....just during engine oil warm up cycle....

[DNHunt]

Mike

I don't think there is a problem using the oil temps. It will just have a longer warmup cycle. Another issue may be the calibration of the sensor. On that warmup wizzard screen watch the temp change vs the oil temp gauge in the car. What MS is seeing may not be what is really happening. Any time the firmware (not the info on the tuning screens) on the chip is changed it wipes out the calibration for the sensors and the tables revert to the defaults which are GM sensors. That's really kind of a pain in the butt cause there isn't any warning. In the case of warmup it would be the values for a GM coolant sensor and something tells me that's not what you are using.

Dave.

[toon1]

MS also has "easy therm" it is a program dedicated to using other air and coolant temps than GM sensors. There is a list for bosch HTS.

[DNHunt]

MS also has "easy therm" it is a program dedicated to using other air and coolant temps than GM sensors. There is a list for bosch HTS.

True enough. The files kick out are then include when the firmware is compiled and then it's burned to the chip. Kind of intimidating the the first time. Or Easytherm will burn it to the chip directly. Much easier. This is for MS I

MS II the calibration is right in Megatune.

Both need to have 3 pairs of Resistance and Temp figures. Some of that's available or you can read resistance with a DVM in ice water, room temp and boiling water.

Dave

[restore2seater]

This may help with calibration.

DIY Auto Tune

[ischmitz]

O.K.,
I will richen up the table for warm-up on Mike's engine. That should take care of the "running like crap at cold" issue. Currently we only do about 120% when at ambient temperatures (60 degrees).

The real question is how to get additional air into the engine while cold. Can you run an idle stabilzer with ITB's and plumb it to all four intake pipes? That would allow to run at lower idle when warm. Currently we start out at 900 - 1100 RPM when cold and end up at 1600 RPM when warn on the 2.2. That is a whee bit high.

Another question for you MS-II guys: Ever noticed that sometimes flashing a new table does not take. I sometimes have to flash at least two or three times until the changes in the ignition or VE table are permanent and retained through a power cycle. That is super-anoying. Any thoughts on that? We are running Megatune 2.25 built Feb. 5 2006 and code variant "Bowling and Grippo MegaSquirt-II"

Cheers,
Ingo

[smdubovsky]

Got ITBs on my 911. No easy way to add air for idle. I've always thought of using one of the stepper motor screw drive type IACs, removing the IAC part, and mounting it so the screw drive pushed on the throttle linkage. Closed loop idle control but its ALOT of work. One valve and 4 tubes would work, but you'd have to balance them. You could also do a 'fast idle' solenoid to push on the linkage.

Easier to add some ign advance below idle. Say your running 10deg at 1000rpm. Put 15deg in the <=900rpm bins. If the motor rpm sags, the extra advance will help out. Of course you need to play w/ the # to find a safe and effective amount.

SMD

[banger]

I thought on some of the 80s chevy cars, they had a solenoid to kich the throttle open a little for idle, but it might have been for opening a little when the A/C was on. Needless to say there was something around to do that. Had an adjustable plunger so you could set how far it would increase the idle.

[messix]

add advance below desired idle is the way to go.

[crash914]

the table burn problem sounds like a communication speed issue...

there are some parameters, like update time that might conflict when you try to burn the table.

There should be some info on this in the FAQ's. I remember seeing it before...I have never had a problem...

to add air, I would just go with a throttle kick. Use a solenoid that kicks up the idle when you turn on the A/C. You will have to fabricate a bracket.

[Aaron Cox]

add advance below desired idle is the way to go.

will that make it harder to crank over?

[Crazyhippy]

Just added 25* to mine, no problem cranking...

Pulled it back out too, cause i dont need it.

BJH

[ischmitz]

I found that too much advance below your target idle speed makes the engine a lot harder to start.

Regarding the burning issue there has been mentioning of similar observations on the MS-II forum but no thread offers final conclusions as to what causes it. Some speculate low battery voltage, others talk about the serial port. I plan to get the latest firmware and the latest 2.25p version of Megatune and see if the issue goes away.