Megasquirt is in!

Yeah, i'm finding that's the case. I decided to take the ISV out now as it'll have to come off when the bodies go on, so I may as well deal with it now rather than have it added to my problems later. The MS does allow for a wide range of warmup enrichments, but there's only so much you can do by chucking in more fuel.

 

On N/A cars the location of the IAT isn't too important, as long as it's in pretty much the same ambient air as the engine is breathing. It's only on turbo cars where the inlet air gets hot quickly as it's compressed where you need a well located fast acting sensor.

 

I think there are actually quite a few of us, but most seem to be keeping quiet. I've heard rumours that there are already a couple of valvers running MS in the UK. And don't forget that the MS'nS-Extra is a British creation

 

ah i see,

when i was thinking about it, i was thinking of a air flow sort of sensor.

 

Nice work! Where did you source the fuel lines/ adaptors for plumbing into the solid k-jet lines? I need a set of these for mine.

 

I got the fuel lines from Think Auto.

 

Cheers!

 

I always thought its was 14.7 for best air fuel ratio, i'll be damned if i can spell the word to describe it though, so lambda 1 will have to do.

 

Stoichiometric?

 

14.7:1 is the stoichiometric ratio and it gives the best compromise between power and economy.

For best power, you want 12.6:1 and for best economy, 15.4:1

Joe

 

To be fair optimum AFR is too engine specific to be that precise about figures. Remember you're only measuring the by-products of a chemical reaction that has already happened with an electrical device. I think a dyno/RR is the only real test.

 

Was about to say...Setup a car on the rollers with the aforementioned AFR's, youd be surprised which one gave best power... As with everything, there are to many varyables to make one statement overally correct..

 

Yeah, there's always a difference between theory and what works in
reality. It's a good guide as a starting point, but at the end of the
day there's no replacement for actually getting it on the rollers and
measuring it.

 

You can actually safely go quite a bit leaner than 15.4:1 in certain
parts of the map, up to about 16/17:1 but you need to be careful where
you're doing that.

 

its looking good,theres nothing better than building something yourself carnt wait for the t/b`s to see the final results

 

Hey I've got a couple questions for you. In the time since the demise of my Mk3... then the demise of my license... then the demise of my Mk1... I managed to get ahold of a good condition Mk2 16v Jetta. (Pics soon to come) I've been trying to decide what to do for power and ITB's have always appealed to me, but the expense of the standalone fuel system has stopped me thus far. This seems like a nice first step before ITBs.

...anyway... more to the point... Don't the sensors you use for this have to be a specific resistance and whatnot? Are you able to use the stock ones or would I need to purchase compatible sensors?

 

You can use any NTC sensor (i.e. it's resistance goes down as temp goes
up). The more linear the relationship between resistance and temp the
better, as it makes it easier for you to calibrate MS to the sensor.
Basically you need to measure the resistance at a few temperatures,
there's a utility that then takes this data and produces lookup tables
and a calibrated firmware for the controller. I've used the standard
16v VDO coolant sensor, and an air temp sensor robbed off a Saab.If you
look on the net there is published data for most Bosch (ie Digifant)
and GM sensors.



Virtually everything you need to know is here

 

What sort of power.tourge increase do you recon your gonna get?

Does the system allow you to have multiple maps that are selectable whiile driving. I.E. have a switch so you can switch between a really economical map and then switch to a really powerful map.

How much has the whole setup cost you?

 

No idea on power gains, TBH anything is good this is a learning project more than anything else.

The MSnS-Extra firmware has dual table support, so yes, I could switch between two maps when I get round to upgrading the firmware. That said, it's not too hard to make yourself a map that has the best of both worlds, good part throttle economy to get the MPG up, and decent WOT power. Dual table really comes into it's own on things like nitrous setups, where you need lots more fuel and retarded timing compared to 'normal'.

If I add up all the things I can remember i've spent about 400, so probably just shy of 500 once you add up all the little bits here and there. The major purchases were the MS itself ($180 shipped for complete kit), and the fuel rail and fuel lines (about 100 in total).

 

Nice work Martyn.


I also have built andfitted megasquirt to my mk1 with a 9a engine, I have upgraded to MSnS extra code. The ign is now controlled by the megasquirt and I have kept the distributor and use the hall sensor for the trigger. The cold idle is handled by a air bypass valve. Email me if you want a copy of my fuel map (you will have to change the manifold pressurevalues as it is for a boosted setup)