Megasquirters: Thermister settings?

[JohnJL]

I got her running fairly easily a few weeks ago but when I got her back from the suspension shop she just doesn't seem to want to run.

Firstly I discovered my 1-3 top plugs were loose (I remember now leaving them loose to facilitate turning the engine over.)

Ignition is definately working, I get a spark from a plug while cranking. I'm sure the timing isnt perfect though.

I can spell fuel in the exhaust so I know I am getting squirt. I suspect I am flooding it and getting....wait for it....MEGA squirt and therefore flooding. Smell of fuel is apparent.

Here are my symptoms...

RPM reads fine on the tach but sometime reads correctly on Megatune, sometimes jumps to 17500. I am running MSD and have the tach adapter installed.

TPS reads correct (even though I'm not using it.)

Coolant Temp reads 180C. I know that's not correct.

Air temp reads 70degF. That's correct.

Map is correct.

I can't get her to run. I've played with the thermister calibration table but with no success or change in the realtime display of the coolant temp. I am using the stock coolant temp sensor.

I've played with the pulsewidth in hte Warmup wizard with no success.

Since I know the temp is off I thought I'd try and tackle that. Anyone have the 3 points of temp-and-resistance for the stock coolant sensor to calibrate the sensor?

All other hints, tips and jokes accepted too,.

john

[Zendalar]

I did not use any original stuff, just NTC resistors which were about 2k at room temperature.

You could try to use my files. They are definitevely not the latest ones, but car starts with those ok.

I have tuned settings somewhere, at least on the car, but you could give it a try.

Check if the car is really cranking when you try to start. You can see it from megatune realtime display screen for example.

[Zendalar]

here is the link to my old settings.

In case somebody is interested, Megasquirt settings for 2.4T are here


And, yes, there seems to be something wrong with your tacho readings. I recall that I took the tacho information directly from the minus pole of the coil.

I "calibrated" my thermistors by reading the resistance in room temperature, in my freezer (-18 celsius) and in boiling water. I used to use one thermistor from some ford, but the values did not change enough throughout the temperature range.
(This all was with a help of 5$ temperature gauge.)

[911Mac]

John,
Were your sensors behaving normally last week before the suspension work was done? You need to get both the RPM and temp signals stable before you can do any meaningful tuning with Megasquirt. I'm assuming you're building your own megasquirt setup yourself, ie you're not using someone's kit like Tbitz. What are you using as a temperature sensor? Mine uses a short piece of wire whos resistance varies with the temperature. Nothing fancy or complex, but it works. I did have to make sure the connnections at either end of the wire were good although the symptoms of a bad connection were a very cold temperature reading.

Mac

[JohnJL]

My sensors were actually in worse condition last week...my AFR wouldn't move at all and the rpm was dead. I cleaned up a bunch of the wiring (though it is all new) and now the tach is behaving at least some of the time.

Yes, I built the MS2v3, only driving fuel for now. My temp never worked. I think it was warmer when I started it so maybe that helped get it going.

My AAV isn't hooked up but that shouldnt matter as it is in the open position when cold.

I'm off to freeze, thaw and boil my temp sensor. I'm using the stock sensor in the stock position. ANyone have readings on that?


thanks all

[quaz]

Before you pull your hair out, pull a couple of plugs out and see if they are fouled. You may have layed enough gas on them at this point it may not start.

[Zendalar]

Remember to put the thermistors and thermometer in a plastic bag that can handle the boiling water temperature.

[JohnJL]

Back again, I got...

18.5 C = 2.8K ohms
3.0 C = 6K ohms
100 C = 60 ohms

I'll set that up, anyone know what the "Bias Resistor Value" is on the thermister table generator is?

thanks

[hobieboy]

What MS version do you have? I think the "standard" is 2450ohm. You can use Easytherm to create any custom sensors you like.

If your car won't even start, I doubt thermister will do the trick. You can set all your WUE and ASE bins to same value to take out the thermistor effect and see if you can start her up.

[JohnJL]

I have an MS2v3 with Megatune 631.

I really do think I'm flooding it so i suspect that, along with a wrong temp sensor, I was giving it too much fuel.

Will give a shot in the morining..

[hobieboy]

If you floor the accelerator during cranking, MS will stop squirting ( ) to help "fix" flooded scenario. Its TPS reading dependent. You may want to try that + take the plugs out tonight & hope that everything would be dry by the morning.

Good luck.

[JohnJL]

I've used the "floor it" technique to clear flooding in a carb, how can I confirm MS isn't squirting in WOT? I would think it would be squirting at 100% duty cycle at WOT, making it worse?

I've seen people comment they've "turned off fuel" for a few cycles. How is that done?

[hobieboy]

Check out the "Getting Engine started & idling" section.
It describes the floor clear mode.

[EDIT] oops - here's the link: http://www.megamanual.com/index.html

[911Mac]

Simply unplugging the megasquirt ecu will guarantee no more fuel is being injected.

Mac

[mppickett]

Actually, the best way is to be absolutely sure is to unplug the fuel pump relay. That way you continue to get spark, but can be sure there's no fuel.

I used the default bias and these F* values for the stock oil sensor:
32* f - 8450 ohms
69* f – 2760 ohms
201* f – 210 ohms


Here's a thread with a sample MSQ file for a V3 MSII board that should get you started. Change the ignition settings to match your setup.

[911Mac]

He's only controling fuel with MS for now so he should still get spark when he cranks the engine.

[JohnJL]

Awesome guys, thanks.
My thermometer seems to be reading correctly now and after a little playing with the timing I can get her to run for a few seconds but then she dies...Lance on MSEFI has suggested a vacuum port problem, which I have posted here for help:

I'll start doing a compare/contrast with your file Mike, thanks!

Also bought a compression tester and various other bits today to diagnose. My timing light isn't bright enough for daylight use, I'll try it tonight...

thanks again everyonevacuum port on sc throttle body

[JohnJL]

Oops Mike, I noticed you're boosted and have a quite different setup. Anyone have a fully tuned MSQ file for a 3-litre with 26lb injectors, high compression, MS2v3?