Megasquirt Calibration - Newbie Questions

As the other MS Newbie thread is getting a bit big, I thought I'd start a 2nd thread. This one is to deal with any issues you have when trying to set up and optimise your megasquirt ECU, AFTER it's built and you've got the car started. Anything before the car has actually run should go in the other Newbie thread, or feel free to start your own thread if you think you've got a lot to discuss.


Anyway... here goes.

I've got the car started - it starts pretty reliably, until it gets to full operating temp.

The coolant temp seems about right for how the ECU is set. The air intake temp is not correct (reading 56 deg F when ambient temp around it is about 75), so I've got to sort that out by taking some readings at different temps (my multimeter has a temperature probe, which should be close enough).

I've used the engine constants function to generate a new VE table, and the engine starts and runs fine, until it gets to about normal operating temp - 190*F (88*C), then it runs rough and cuts out. I'll get the wideband meter out to look at that, but before I do that, I've got an issue on the ignition that I need to sort out.

Ignition Issues
I've set the dizzy to zero degrees (using the fixed angle function in spark settings), and timed it to the TDC mark on the flywheel. That's clamped in place now.

1. Because the engine is higher compression than normal, I've backed off the cranking advance to 5* BTDC, because it was struggling to turn over before on 15*, especially when warm. What are other people using on their cars for a cranking setting?

2. I've checked through all the settings I can think of, but I can't find the source of the next one. The spark table says I should be running at about 23-26 degrees btdc, when idling at about 1300 rpm. However, the megatune display says I'm running about 10* more advance than that. Where's this controlled from?

I've set the idle advance to -10 (use the map) for now.

My coolant temp spark offsets are set like this:

- Add 1 degree advance for every 18 deg F below 149.
As the engine is still advanced from the map after the temp is well above this, I can't see how this is the cause.
Max advance from the map is set at 7*

It's also set to 1* retard every 7*F over an IAT of 72.0
- IAT has been registering in the 50s*F so it's not in use either.

Any ideas where my extra advance is coming from? I'm pretty sure I've burned the new map to the ECU correctly.




3. I

 

the other issue I've noticed is that the TPS doesn't seem to be wired in correctly. On the 'real time display' menu, the throttle is sat at 16% normally (would this generate extra advance?) and if I floor the throttle (engine off, but ignition on) the throttle reading goes to 0%

I'll play with the wiring in the morning, but it looks like I've got that wired in wrongly.

 

Is there a reason you are using degrees F ? Have you calibrated the tps yet?

 

You can switch it to use degrees C, which is better for those of us on this side of the pond from the USA!

Are you using the VW coil TCI unit? If so I could grab all of my settings for you, as that's my setup. Might be of some help.

 

It's got the standard TCI Unit that's original to the car, and a digifant dizzy. I think the ECU was already set up for a VAG TPS, but I've probably wired it in wrongly. The starter map was a copy of the map from Eddie's 2.0 8v, so I'm assuming it's something I've done, rather than a problem in the ECU setup.

Where's the temp unit setting? I can work in either, but my thermometer works in *C.


EDIT: Just found the TPS settings. What do I do with those then?

 

You change to C in MT config settings. This is for the GUI.
The ECU software is already config'd to work with your setup. You are now ready to get on with building a base fuel and ignition map. If you never mapped anything before then this will take a very long time to get right. If you tinkered with carbs and understood those, then imagine programable EFI as a carb that can be tinkered for every throttle angle and engine speed. That would be a good basis to start from if you attempting yourself.

 

You can use the calibrate TPS function from the drop down menus.

It's also worth referring to this for setup inquiries as it does cover a lot.

http://www.msextra.com/doc/ms1extra/MS_Extra_Manual_Index.htm


Gurds

 

@ Eddie - Found the *C setting. Thanks! It seems to convert some of the values existing in the calibration, and not others. I'll have to go through and check they all make sense. I appreciate that the ECU is set up for my install, and it's saved me loads of time already, but the TPS isn't right, so I need to reset that.

@ Gurds - thanks for that. I'll try to look in there before asking too many dumb questions. I'm normally allergic to reading manuals, but I'll give it a go. I found the TPS validation instructions.

 

Yes the TPS counts would be wrong on yours as my 8v uses and different throttle valve.
Pretty easy anyway once you read the instructions.

 

Turns out the TPS was dud, and I broke the spare trying to adapt it to fit - d'oh!

Anyone got a spare 3-pin TPS handy?

 

Get to scrapyard first thing tomorrow!

 

That's the plan. West Drayton didn't have any when you were there last week - did they? I think I'll head up to Bloxham. Most of the bigger places down here are closed on Sundays.

 

Right... got a TPS off a volvo that fits the TB shaft, and made a bracket to fit it, as the bolt holes didn't line up.

I did the Megatune calibration again. The results seem to be a bit more credible, but it still says it's 25% open when throttle is closed.

I think I also found why it's advancing the spark 10* more than the spark table says. There was a trim value of 10 degrees set.

 

Excellente!!

 

No Nonsense Mike - brilliant!

 

Whilst doing some mapping recently. It was observed that when looking at the realtime display. The Throttle position % doesn't show throttle position on a linear scale. I goes from 0 to 100% and nothing in between. Unsure why this happens but car still drives ok.

 

Have you tested the resistance of the TPS with a multimeter. The first one I had went from infinite resistance to continuity, with nothing in between. The current one - bosch 3 pin from a volvo 740(?) turbo - goes from about 500 ohms to about 1900, from memory, but in a nice smooth progression, rather than in one jump.


Question: Does the TPS Accel function advance the timing, or just chuck more fuel in as you open the throttle? I can't find any settings that control advance related to the TPS position.

 

Injector capacity question:

My injectors are rated at 200cc/min at 3 bar, but I'm running a 4 bar FPR.

I found a calculator on the net that reckons that makes them about 230cc/min. Does that sound about right to the wise folks on here.

*dashes off to check if there's an FAQ for this*

 

http://www.megamanual.com/index.html

Look at injectors and fuel supply. There is a calculator for new fuel pressure.

 

when i was with toyotec last he fitted my 4 bar fpr due to the engine having issues and it didnt arf make it run rich i had to lean it out miles so guessing that increased the cc of my injectors which is all good