Programmable ignition gave me 44mpg (+10%)

[syncro_user]

A bit of a lurker on here, me. Have read an awful lot though, and planning to do a fair few bits to my car.

Most encouraged by recent results from fitting a Microsquirt ECU to control the ignition on my mk2 Golf. Previous best ever mileage with the current engine, with mechanical distributor set to optimum, without pinking on 98octane petrol, was 40mpg. Motorway only, at 65mph.

The first proper drive with the new system, with a basic safe map (not yet rolling road optimised), same air temps (although with higher tyre pressures - I'm running at 40psi), 44mpg imperial! Not even all motorway driving, but about 50% country roads.

Just goes to show how far off the old systems can be, and how much of a diffference timing can make. I am now very enthusiastic about using the ECU to do many other things. Hopefully I'll get the fuel injection electronic this summer (still on K-jetronic/CIS for now), and then hopefully a hot air intake sorted before the winter as my FE takes a major dive in the cold weather without one..

[cfg83]

syncro_user -

Yeah, if you got the skillzz then you can make an older car humm. I've heard of Megasquirt but not Microsquirt.

CarloSW2

[Christ]

Carlos -

Microsquirt is the small version of the MS system. From what I understand, not as "open" and doesn't have quite as many features, but can be used easily for EFI on motorcycles.

[syncro_user]

It is much smaller, but was the only thing I could find ready-made at the time which didn't need shipping from the USA. Soldering up a PCB is a little beyond my skills atm. It lacks an onboard MAP sensor, and prefers external coil drivers I believe, but should still be up to the job.

[cfg83]

Christ -

Originally Posted by Christ

Carlos -

Microsquirt is the small version of the MS system. From what I understand, not as "open" and doesn't have quite as many features, but can be used easily for EFI on motorcycles.

Ok, that makes sense. They should make nanosquirt for R/C cars, .

CarloSW2

[orangustang]

I have found that I generally get better mileage on country roads at 40-55 MPH than on the freeway running 65, as many on here will likely agree. Microsquirt might have helped some, but I would add some caution to your optimism about a 10% improvement. Most of that was probably from tire pressure and the change in your driving route.

Good luck getting it tuned up for even better mileage, though. I have always wanted to be able to play around with fuel and ignition maps on all of my cars. It seems they're always set from the factory to run safely on the worst garbage fuel in the world, so tuning to the good gas in your area should give you some improvement in performance and efficiency.

[syncro_user]

Yes, I see your point. I suppose a motorway-only test run would give me a good reference point new vs old. I'm also (hopefully) fitting an undertray this week, so should probably get a before and after test run done today.

Power is definitely up with the Microsquirt though, and noticeably smoother to drive and idle. Just a small noise-related miss to sort out, and I'm on to fitting injectors (with a kill switch) and the HAI.

[vrmilionzx]

Always glad to see people playing with tuning, as it's an area of interest to me (I know just about nothing about it, outside of where your A/F should be to stay "safe").

If you don't mind my asking, what values did you change and at what points in the fuel/timing map?

[syncro_user]

Basically I was starting with a clean slate, as the original ignition timing was taken care of by a mechanical distributor ('optimised' for the original 1.8l engine). I started out with a safe table of values based on generic timing for such an engine, with similar bore size, compression, combustion chamber shape etc.

From that point on, I'm trying to find the advance values which give the best power for a given amount of fuel burned, and I can get close on the road (avoiding knocking being the most important aspect so far). I have a knock sensor to plug into the stereo when I find a suitable amplifier. After this, I have a half-baked idea of integrating a load cell into an engine mount in order get it just so. Not sure how this will pan out.

Max advance is about the same as the old distributor, at about 33 degrees btdc, but static timing is higher (from 5deg previously to 10deg now), and the load-related advance is actually much gentler now, which is avoiding some of the early pinking I had with the original set-up. I haven't even begun setting the inlet air temp and coolant temp advance/retard features yet, which should give some decent FE gains during warm-up, and in the wintertime especially.

Getting the fuelling set up correctly will, I imagine, be a completely different kettle of fish. I want an EGT sensor fitted before I even think about tuning for an HAI.

[syncro_user]

Went to see a property this afternoon, with a view to buy. 44.8mpg, mostly highway, with a bit of P&G! Getting there!