Author Topic: The importance of going back to basics.  (Read 707 times)

Offline Tony Smith

  • Posts: 2274
  • Graduate, Wallace and Gromit School of Engineering
The importance of going back to basics.
« on: June 28, 2019, 01:24:04 AM »
I have what ?I think is an interesting ignition saga that others might find interesting. 

Part of it is rooted in my refusal over a number of years to take my own advice - "check the basics first stupid before throwing expensive parts at the problem".


My R65 has been a frequent hard starter. Perplexingly sometimes it would start almost as soon as the button was pressed, but on other occasions I'd crank the bloody thing till the battery was near flat before it would start.

Way back in 2013 when I first reassembled the thing I chased what I thought was a simple corrosion problem and cleaned all the terminals - and it looked like it worked as for a while it would start up pretty much immediately, but slowly it got hard to start again.

Then the original ICU died due mainly to not having any thermal paste left and after fitting a generic Bosch compatible module (remember this bit, it get relevant later) it went back to moderately easy starting, which got slowly worse over time.

Annoyingly I could never isolate the problem, it just seemed that breaking and making all the connectors, loosening and retightening the earths, and a few choice swear words (I swear fluently in three languages) would always get the old tart running.

Then I fitted the 860 kit and decided to update to the late model ICU, over time I'd accumulated several of them, so you can imagine my surprise and annoyance when only one of them would fire a spark - a very generic module of Polish manufacture (again another clue if I'd been smart enough to spot it).

In the last week I decided to take the r65 to the combined restorers meeting, but, it wouldn't start.

I did the basic tests and it was a no-go, then I had a look at the beancan (which tested just fine with the stand=alone tester) and condemned it due to chaffed wiring, stuffed adv/retard and worn bushes. After a bit of a think I decided to buy an Emerald Isle unit and put the days of worn out BMW ignition cans behind me.

Today I fitted my nice new system and was rewarded with zero spark.

Gritting my teeth I tested the EI bean can with the stand alone tester and it was just fine. Next I tried the EME tester plugged in place of the ICU - NADA.

A penny dropped and I decided to go back to first principles.

First I checked the ATU connector under the front cover - it had +12 volts on the correct pin and a strong ground on the other outside pin.

I knew the bean can was capable of working and it was getting power, so what the hell was going on?

I briefly refitted the Polish ICU and was rewarded with a spark. I reconnected the EI ICU and had nothing. For testing purposes I put the Polis ICU back on, but still no spark.

I then partially removed the ICU so that I could carefully prise the boot off the bottom of the connector.

There it was, staring me in the face - one connector was standing 3mm proud of all the others. Quickly removing the ICU and looking into the connector quickly established that there was bugger all chance that it was contacting the pin on the ICU.

Counting across I determined that the pin with no connectivity was Pin 6, and a quick consult with the wiring diagram provided by Snowbum established that the open circuit was the trigger signal from the ATU.

That'll do it I thought....

I took steps to stop that connector from ever backing out again and reassembled - the bike fired perfectly and did so with every ICU I have.

So, here's the thing, my generic 1st generation ICU and the later Polish clone ICU differ from the genuine article by having pins about 2mm longer than standard.

Which kind of explained why they worked and the others did not!

Five years I've been chasing that! And it was so simple.

Doh!

Oh, and by the way the EI ignition system is fantastic.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline Tony Smith

  • Posts: 2274
  • Graduate, Wallace and Gromit School of Engineering
Re: The importance of going back to basics.
« Reply #1 on: June 28, 2019, 01:42:23 AM »
And, in case anyone is interested, here are the pin IDs and connectiosn between the ICU and the ATU.

First the basics......

The 3-pin ATU connector is "sexed" by having two raised ridges on one side and only one ridge on the other, thus making it impossible for all but the most determiend idiot to connect it the wrong way round.

[ +  ||  -  ]    and  [ - ||     || + ]

The centre pin that I have not shown is the signal from the bean can to the ICU to fire the coil


The 7 Pin connector at the ICU is likewise "sexed" having two ridges on one side and three on the other.

The pinout is:

[ 7 6 || 5 4 3 || 2 1 ]


If anyone is ever fitting an aftermarket tacho, Pin 7, which is unused (and in fact may not even be present in the BMW OEM wiring loom) is a TTL output for a tachometer


And now, with no further ado

ATU

+ve   --> Pin 5
sig     --> Pin 6   (and I will never forget this one)
-ve    --> Pin 3

ICU

Pin 1  --> Coil
Pin 2  --> GND -ve
Pin 4  --> +ve


To put it together - the ICU connections are

Pin 1 --> Coil
Pin 2 --> GND -ve
Pin 3 --> -ve ATU connector
Pin 4 --> +ve
Pin 5 --> +ve ATU connector
Pin 6 --> Sig - centre pin ATU connector
Pin 7 --> Tach - unused by BMW


If the above helps anyone out I'm happy.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline skippyc

  • Posts: 339
  • Shouldn't have sold them old bikes.
Re: The importance of going back to basics.
« Reply #2 on: June 28, 2019, 07:20:06 PM »
I would have to admit that the non contacting pin would be the last thing I would look at especially as 1 unit works and another doesn't.
This is good information to know and is what makes this Forum so good.

Offline Tony Smith

  • Posts: 2274
  • Graduate, Wallace and Gromit School of Engineering
Re: The importance of going back to basics.
« Reply #3 on: June 28, 2019, 09:03:56 PM »
Quote
I would have to admit that the non contacting pin would be the last thing I would look at especially as 1 unit works and another doesn't.
 

Well it all but had me beat, especially as the piece of harness that connects the ATU, ICU, power and coil was bought new for GBP40 from Motobins only about 3 years ago as I didn't like the way some of the contacts looked in the original harness. DOH! I should have realized then that the problem was that (at that stage) one of my modules had long pins and was deforming the contacts.

One step I omitted was why I decided to take the boot off. I plugged the EME tester into the ICU socket and bridged +ve to sig on the ATU connector (do not ever do this more than momentarily with a real ICU plugged in). I expected to have the big bright LED on the top of the tester glow its little heart out, but Zip, NADA and dam all. I thought - "that's wrong cause I know I have 12 volts to the +ve pin and I know there is connectivity to the trigger on the ICU". at that stage I'd simply shoved the multimeter probe into the socket and I had not taken any notice of the relative heights of the contacts.

Anyway, I was at the point was dragging out the spare "points" bean can I have, fitting that and swearing off electronic ignitions forever.

Glad I didn't.

Now that the R860 is off the bench it's time to do some long overdue maintenance on the wife's R65/80. Rehab the final drive, fit new rear subframe, new timing chain and crankshaft sprocket and major service for starters.

1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline ged in oz

  • Posts: 148
  • I Love YaBB 2!
Re: The importance of going back to basics.
« Reply #4 on: June 28, 2019, 09:49:11 PM »
Quote

Now that the R860 is off the bench it's time to do some long overdue maintenance on the wife's R65/80. Rehab the final drive, fit new rear subframe, new timing chain and crankshaft sprocket and major service for starters.

Bravo! says the Mrs, Im sure.

Im glad to see youve finally resolved a nagging PITA like that Tony. Your R86 is making me really jealous!

I had a similar(ish) experience when I installed the EME bean can connector recently. Id buttoned everything back up in the timing chest, installed the connectors, crossed my fingers and fired it up. Nuffin.... Never a good look with all the work Id just done replacing the timing chain. I pulled a plug and cranked it, no spark. I pressed the two ends of the connector together and got a fat blue spark, so at least I narrowed it down fairly quickly.

When Id installed the pins into the connector, one of the barbs on the pins had failed to catch on the holder and had then receded when I connected the two sides. They were obviously really close, because it sparked with just a little bit of hand pressure on the two sides, but Im glad that I needed to investigate it because it might have repeated your hard starting experience for the next 5 years!