Bosch M1.5.5

Bosch Motronic etc ECUs and PCMs
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Triangule
Posts: 5
Joined: Sat Sep 05, 2015 6:56 pm
cars: Alfa GTV 2.0 TS from 1999
Bosch M1.5.5

Bosch M1.5.5

Post by Triangule »

Hy guys.

I'm a bit far from all of you, but i found several good informations and a lot of work on your forum that could help me.... and the most important you love alfas !

I own a 1999 GTV with a 2.0 TS (16V engine with VVT) and a Bosch M1.5.5.
There is only 1 ECU model for all these GTV : 350386 0261206061

I have fully modified my engine with longer cams durations, ported head, new exhaust header, hi compression piston, lighter rods and flywheels, remove the balanced shafts, increased oil pump pressure.
As the LCA is very small on the original cams, the ECU was a bit lost with the new set up.
I sent the car to the local dyno shop to get the maps tuned, and this was made greatly, with a nice result.

But I have to made a part of the job myself.
The idle still not working properly, the guy have adjusted the screw on the butterfly but seems not change the target iddle in the ECU.
So the idle control motor try to decrease the engine level ... making thinks unstable sometimes.

The other problem is that the engine stop if the engine speed decrease too fast (this is my thinking) as when you push the cluch pedal.
the engine is running fine when the weather is cold.
The Bosch documentation say that the ecu is slowing down the engine speed before a little bit under 2000 rpm.

The M1.5.5 is not really detailed on the web, probably beceause there is not so many people interested to modify this small alfa.
I have the original bin file and also the modified one.

I woudl like to get some advice, how to find the maps and also some advice about how the idle and "slowing down engine speed function" could work.

Not all the ecu seems managing theses 2 functions in the same way, so as i'm a newbie i need help to go ahead.

I also want now to go for other modifications and I would like to be able to set up myself some stuffs.


Thanks for your advices and answers.

Ps: Hope my english is ok. :)
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festy
Posts: 1039
Joined: Sat Apr 30, 2011 6:27 pm
cars: Alfa Romeos
Location: Narellan, NSW

Re: Bosch M1.5.5

Post by festy »

There should be a map with the desired idle speed x engine temp - that's the main one that controls idle speed.
You are correct in that if you adjust the throttle stop to raise idle speed, the ECU will try to bring it back down by closing up the IAC and/or retarding ignition - and your lightened flywheel is likely making it worse ;)

I think I have a copy of the 350-386 bin file, I'll see if I can find the desired idle map for you when I get some free time.
Triangule
Posts: 5
Joined: Sat Sep 05, 2015 6:56 pm
cars: Alfa GTV 2.0 TS from 1999
Bosch M1.5.5

Re: Bosch M1.5.5

Post by Triangule »

Hi Festy,

thanks for offering your help, it's not hurry, but that's hard to drive the car in town with such problem.

I'm looking your 160S file and XDF to try to get some inspiration.
If you are agree i will have some few questions to understand how bosch is managing some function.

For exemple, when i push the cluch pedal, the rpm decrease, injector are switched off, right ?
the ecu switch on again the injectors when the rpm will be close to the idle or do it by different steps.
I can see on my engine this function have different beaviour with the engine temp.
Witch map is managing that ?
Do you think with the current screw setting i have on the stop butterfly, the ECU is not seeing the throttle as closed ?

thanks
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festy
Posts: 1039
Joined: Sat Apr 30, 2011 6:27 pm
cars: Alfa Romeos
Location: Narellan, NSW

Re: Bosch M1.5.5

Post by festy »

I don't know a great deal about the M1.5.5, it's a bit newer than the ML4.1 that I'm used to but most of the operation modes are pretty standard across ECUs.

When you say push in the clutch and the revs drop, do you mean while stationary and in neutral, or during gear change?

When you lift off the throttle, the injectors are switched off under certain conditions but it's not really related to idle speed usually. This is called deceleration fuel cut-off, or DFCO.
There will probably be at least a pair of maps for this to give a hysteresis and will likely have axis of RPM x engine temp, and the map holds the on/off points for the injector pulse times.

For example, here's the 160S (ML4.1) DFCO maps - injector pulse times are in milliseconds:
DFCO.jpg
DFCO.jpg (50.51 KiB) Viewed 7316 times
So you can see why your car could behave quite differently when it's cold compared to warm.
Motronic ECUs usually use maps like this, Delco ECUs use a different method of working out DFCO in/out points but they achieve the same thing.

Re: throttle stop - the throttle body probably has a microswitch to tell the ECU when the throttle is closed (often called an idle switch) and if your throttle stop is adjusted to the point where that switch isn't closed at idle then it will mean the ECU could be running on the part-throttle maps at idle, and it may also have logged a TPS fault code and be trying to guess when the throttle is actually closed.
Triangule
Posts: 5
Joined: Sat Sep 05, 2015 6:56 pm
cars: Alfa GTV 2.0 TS from 1999
Bosch M1.5.5

Re: Bosch M1.5.5

Post by Triangule »

thanks for explaining this.

The deceleration problem appear when i drive the car and i need to stop it.
Seems that every thing is ok if i drive under 3500 rpm and slowy but hard to find precisely the condition that create the problem.
I just can see the rpm dropping to 0 without any step and even try to idling.

I wonder if the back pressure of the exhaust with the bigger LCA should be the reason of such behaviour.

Is the DFCO related to the RPM negative delta ?

I have to check again, but i don't think there is an iddle switch. Just the TPS. So should have a value limit to considere the butterfly closed.

From my point of view idle and deceleration are 2 differents problems, but i need to understand how these 2 functions work.


From what people told me the M1.5.5 is closed to the M4.3.
Triangule
Posts: 5
Joined: Sat Sep 05, 2015 6:56 pm
cars: Alfa GTV 2.0 TS from 1999
Bosch M1.5.5

Re: Bosch M1.5.5

Post by Triangule »

I've found a lot of maps, and would like to get some help to indentify them.
It's still difficult to find the scales, because nothing look like the traditionnal factors (x40 or x 0.25 or 0.75) nothing work.
Hard also to indentify the idle and DFCO maps.
Triangule
Posts: 5
Joined: Sat Sep 05, 2015 6:56 pm
cars: Alfa GTV 2.0 TS from 1999
Bosch M1.5.5

Re: Bosch M1.5.5

Post by Triangule »

after around 200 hours spent, i'm close to finalize my research.
I have most of the most important maps, and found most of the factors.
Some still need a little bit of research, but most of the job is done.
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