Microsquirt ecu project

[JamesO]

Project update:-

My car is now running pretty much running fine on its standalone ecu

After much playing with different diodes, some research and some pikey tin foil shielding my lux now revs freely without loosing the flywheel synch!
The rev counter wasn't working as the output from the ecu was too high, this was fixed with a small circuit found on a vw forum.
Due to farnell/RS minimum orders I now have enough diodes and assorted electronical bits to open a shop!

 

[Diver944]

Good news James []

Do you have any more fine tuning to do now or is that it? How does it feel in comaprison to the old setup - more refined, more powerful, more economical?

 

[944 man]

Are you mapping part throttle yourself using a wideband lambda? I presume that you are and I wondered what youre reading the output with? Im tempted to use a multimeter to read the output voltages direct...

Simon

 

[JamesO]

Still lots to do, its not tuned so drives poorly at the moment.
I have a Vems wideband/controller and gauge, the wideband is connected to the microsquirt (0v to 5v output).
I drilled a hole in the exhaust, braised a steel bung to the exhaust with a mapp gas torch from b&q, it looks like a bird has cr@pped on the exhaust but it doesn't leak so thats fine.
I logged the dme for a while and one thing I noticed was it is very rich on startup.

 

[barks944]

Its probably rich on startup to compensate for a cold engine.

Would you do a write up of what you have done, the problems you had etc? id be really interested to know what you have found.

tom

 

[JamesO]

I will do once I am sure I have it working correctly and reliably.
Yes the cold start is the reason for rich running but the standard dme is really rich on cold start. (10.1 AFR)

 

[944 man]

Thats something that Id be extremely interested to read too. James, when youve got it running properly will you be altering anyhting else? Im thinking particularly about the camshaft, which as standard is only about a 225Û«° duration, I believe; and something closer to 275° would be a good deal brisker, but not too lumpy...

 

[barks944]

ive been looking at cams too. sounds like it might be expensive to get hold of one. I spoke to the american tuner, cant recall his name now but i think it was about 900 and was going up due to exchange rate. I wonder if we could get blanks and get somone in the uk to profile them.

 

[tr7v8]

I'm sure someone like David Newman could re profile the original one.Cam duration is only relevant if you know the testing criteria.

 

[944 man]

http://www.jmengines.com/camshafts.htm

US $650 for camshafts, from this fellow. Im tempted, but theres little point until I know that I can fuel it.

 

[Diver944]

ORIGINAL: JamesO
Yes the cold start is the reason for rich running but the standard dme is really rich on cold start. (10.1 AFR)

I found that with my Turbo when it was still running the airflowmeter and standard DME, it would start around 10:1 and then slowly rise to 14.5:1 over a few minutes as it warmed up

 

[JamesO]

Had a play today and have found that with timing set up reasonably I am running out of dwell at higher revs, I think I have the trigger offset wrong.
I'm led to believe that the stud on the flywheel is at 58.6 degrees BTDC, but not sure if the VR sensor is offset from TDC which would throw things out.
Have ordered a timing light to check.
Unless anybody here knows?

 

[333pg333]

ORIGINAL: JamesO

Still lots to do, its not tuned so drives poorly at the moment.
I have a Vems wideband/controller and gauge, the wideband is connected to the microsquirt (0v to 5v output).
I drilled a hole in the exhaust, braised a steel bung to the exhaust with a mapp gas torch from b&q, it looks like a bird has cr@pped on the exhaust but it doesn't leak so thats fine.
I logged the dme for a while and one thing I noticed was it is very rich on startup.

When you say you put the bung in the exhaust for your wideband sensor, where abouts are you talking? Do you have a Cat and therefore is it pre or post this? You will get quite different readings so be careful. With turbo models the general idea is to put them on the downpipe about 12-18" away from the turbo. Not sure on the n/a. but when you go to some dynos they put the 'sniffer' up the exhaust pipe and this also gives quite a different afr reading.

 

[Fen]

I had to move the location of my wideband sensor further down the exhaust from the stock position. It ended up pretty much where the exhaust levels out to horizontal just under the bottom of the bulkhead. The original position was too hot for the sensor. That was on a Turbo (without a cat).

 

[JamesO]

Dwell issue fixed! I was getting my next tach pulse too soon not allowing time for the coil to charge. Car pulls like a train, would like to say it was down to me but I had help on that one.
All that leaves is the idle valve, the car runs o.k without it but I want it to work to make cold idle better. Another bag of resistors e.c.t to order when I only want one, hindsight is a wonderful thing.
It is nice to be able to see all your sensors displayed on the laptop should make future faultfinding easier, I had planned on maybe a cam, rolling road tune etc but in my garage lurks a 968 engine that needs a home.

 

[pauly]

ORIGINAL: JamesO
in my garage lurks a 968 engine that needs a home.

Want me to take that old 2.7 engine away for you [].

 

[Diver944]

ORIGINAL: pauly

Want me to take that old 2.7 engine away for you [].

2.7's are very valuable and desirable as a basis for a 3.0L (or even 3.2L) conversion []

 

[barks944]

what is dwell and what is the vr sensor you are reffering too. Was the problem you were having to do with timing the ignition correctly, the problem being somthing to do with the rpm sensor on the engine?

 

[JamesO]

Dwell is the time the coil is charged for, too long you burn out the coil, too short means weak/no spark.
The "VR" sensors (Variable Reluctance) are the crank speed/reference sensors the one that "reads" the starter ring gear generates 100vac and above which did overload a diode on the ecu until a higher rated diode was fitted.
The other problem was I had the trigger point set at the wrong part of the stroke.

Won't be changing the engine until the summer, will be checking over/refurbing the 968 engine first. All being well I'll then flog the 2.7

 

[Fen]

I had very little success with getting the ISV working with my Autronic. Everything worked much better without it than I could ever get after messing for ages with the huge array of settings for it. It fell squarely in the "not worth the effort" bucket for me.