No Spark

[Chris_Mi 6]

Hi all,

 

Hoping to tap your wealth of knowledge, because I am really pulling my hair out!

 

My car is a 1.9 Mi16 (3 row Motronic ECU)

 

Problem:

For the last few months, when I turn the car off, occasionally (i.e. once every 4 weeks) it will not start (no spark). Previously, I assumed it was the HT leads, so I would get out, give them a wiggle, jump back in and after two or three turns, it always fired into life. However, at the weekend, I had to abandon it at my parents’ house in Burnley. The car will turn over (i.e. definitely not started motor), but just will not spark. There is no spark from the coil (I know this as I connected a new king lead to the coil and earthed a spark plug). The strange thing is, it started once and ran once, so I turned it off without disturbing anything, then tried it again, and guess what???? No spark!!!!!

 

After reading loads on here, I tried loads of things, but still with no success:

 

Tests I did:

Tried earthing the ignition module from 2 to an earth on the body, and tried starting. No spark.

Connected light bulb to pin 4, and earthed. Bulb receives current when ignition was on (2nd stage if I remember correctly). Wouldn’t spark.

Connected light bulb to live on coil (can’t remember which), and earthed. Bulb receives current (I think again on 2nd stage ignition). Wouldn’t spark

Tried replacing king lead (coil to dizzy), to ensure that this wasn’t broken (unlikely I think). Still no spark.

 

Also, what is the dizzy signal cable (presumably the king lead?)?

 

So I bought a brand new coil (so assuming this is working) and fitted.

I also bought a brand new Intermoto ignition module (I am aware of the issues, but will assume that this is working) and fitted. Still no spark.

 

Does number 1 pin on ignition module go straight to the fuel pump relay? Because I also have some additional thoughts:

 

Some other things – fuel pump related:

I have never heard/noticed the fuel pump priming on either ignition stage 1 or ignition stage 2 (that is not to say it has never done it, just I have never heard it). Should the pump prime on either ignition stage, as it is definitely not doing this now?

 

Could this be related to my no spark problems? Therefore, does the fuel (tachometric) relay in any way serve the fuel pump AND the sparking side of things (coil, ignition module)? Although, one time when the car did decide to fire up, the fuel pump was definitely working (I could hear it).

 

What I tried:

When I connect 12v live to the pump, it pumps fuel, so pump is ok.

In a black plastic box (near driver side front light cluster), I have two relays. They are labelled “injector relay” and “fuel pump relay”. These are in addition to a green relay near the cooler bottle.

I tried connecting a 12v live to a terminal on either with the following results:

the fuel pump relay clicked, and the fuel pump came on.

When I did the same to the injector relay, there was a faint click, and also the ignition relay(?) on the passenger side rear of engine bay (near cooling bottle) also clicked.

 

But the bloody thing still won't spark.

Arrrggghhh. Any ideas????

 

Apologies for the very long message!

Edited August 3, 2009 by Chris_Mi

[pug_ham 244 3 Cars]

From a quick look at my copy of the 405 haynes manual I can't see any wires between the ignition module & fuel pump relay but the injection relay & fuel pump relay have a wire that runs between them controlled by the ignition swict usually. Depending on how your car has been wired up but the fuel pump shouldn't prime on the first click.

 

Have you tried a different CAS (crank angle sensor) in the gearbox or check its bolted down.

 

HT leads are the end of the line & I doubt they'd all fail together, have you tried a spark plug directly into the king lead to the dizzy from the coil?

 

If thats sparking rapidly, what condition are your dizzy cap & rotor arm in?

 

Theres a guide for the two row ecu in this topic but it might still give some tips to check on your loom.

 

Graham.

[Chris_Mi 6]

Many thanks Graham, CAPS seems pretty useful!

 

The Crank Angle Sensor (CAS), when operating, causes the ECU to earth a pin in the ECU, creating live circuit to the fuel pump.

 

However, does anyone know whether the CAS operates under ignition starting (i.e. starter motor cranking), or does the engine have to be running for the CAS to start the fuel pump?

 

With regard to no spark, are there any relays that may fail in the ignition amp, coil, dizzy loop?

Can anyone explain the ignition circuit to me in simple terms?

 

I cannot make head or tail of the Pug wiring diagrams!

Edited August 4, 2009 by Chris_Mi

[pug_ham 244 3 Cars]

I thought the crank angle sensor also determined the piston location for the ignition system as well so it fires at tdc.

 

There aren't any relays in the ignition system.

 

Graham.

[philfingers 5]

Not sure where you are in Brum' but my Mi is on two row management and is up and running. If you need a hand drop me a PM. Have you got the car back here now?

The pump only runs on cranking on Mi's, certainly on mine anyway. 8v's prime on ign coming on

Phil

Halesowen

 

ps also I couldn't recommend enough you get a copy of Autodata 3.18 software. You can download it using lots of methods but I used www.getmiro.com this is the software garages use for diagnositics, very useful, covers most cars and commercials from 1959 to 2007

Edited August 4, 2009 by philfingers

[sub205 5]

the fuelpump on motronic systems does not prime. it will only run when the cas is giving signals!

 

when the cas is working correctly, you can hear the fuelpump run for about one second after the engine is standing still.

 

btw: you can check if the fuel pump gets power while cranking. if not, maybe the ecu gets no power.

 

does your ecu-light go on on stage 2 ignition?

[Chris_Mi 6]

I thought the crank angle sensor also determined the piston location for the ignition system as well so it fires at tdc.

 

Thanks Graham, that may help me chase the problem somewhat, my only issue is that my Haynes wiring does not show how CAS relates to the wiring on the ignition side (or I certainly don't understand it properly!!) - any chance you could clarify further please? ie. where on the ignition side does the CAS feed to/from?

 

when the cas is working correctly, you can hear the fuelpump run for about one second after the engine is standing still.

Phil, I'm in Smelly Oak, but haven't managed to get the car back from Burnley

 

Yep, I heard the fuel pump running/priming when car did start the once. So suggests to me that it may be that the fuel side of things are ok then (I was just expecting priming on second stage ignition, but I feel happy now that shouldn't happen).

If the CAS also operates the spark as Graham suggests then this is pointing to something along the preCAS-CAS-postCAS line being at fault then (having replaced the amp, coil etc).

Do you have a spare known working CAS sensor & ignition amp that I could borrow for a weekend per chance? A few beer tokens in it

 

btw: you can check if the fuel pump gets power while cranking. if not, maybe the ecu gets no power.

does your ecu-light go on on stage 2 ignition?

I will check the power to pump under cranking - not done that yet, but I am pretty sure that it is not priming on cranking! Also no ecu-light on stage 2 ignition.

 

 

Thanks guys

Edited August 5, 2009 by Chris_Mi

[pug_ham 244 3 Cars]

where on the ignition side does the CAS feed to/from?

I could be wrong about this but I think its via the ecu receiving the signal as the CAS passes the cut out in the flywheel.

 

Graham.

[Chris_Mi 6]

Thanks all,

 

Got it sorted now.

The real give away had to be no spark PLUS no pump live (on cranking). Thanks to Graham (and others), who initially pointed to one of two components, and one (or more) of three possibilities:

1) The ECU

2) The CAS

3) The wiring in the circuit between the two

 

Tried a known working CAS, and guess what. Problem solved and case closed !

 

 

Cheers once again

 

Chris

[Chris_Mi 6]

Phil

Halesowen

 

ps also I couldn't recommend enough you get a copy of Autodata 3.18 software. You can download it using lots of methods but I used www.getmiro.com this is the software garages use for diagnositics, very useful, covers most cars and commercials from 1959 to 2007

 

 

Thanks Phil,

 

No need for the ignition amp now, but thanks all the same. I am currently hunting autodata.

If you fancy meeting up at some point I'm often frequenting the many pubs in town/Moseley/Selly Oak!!!!

[philfingers 5]

wouldn't mind trying to organise a local meet, there are a few folk about this area, SPGTi for one.

Week night suit or weekend better?

 

Phil

[philfingers 5]

How about this Chris?

http://forum.205gtidrivers.com/index.php?showtopic=108433

[welshpug 1,657]

have a look at the diagrams on this page, I've got the Autodata pinout lists too

 

http://forum.205gtidrivers.com/index.php?s...0&start=100

 

 

check that you get power down wire 2 to the ignition amplifier on ignition switch, if you do then move on to checking the ecu, i.e is it getting TDC signal.

Edited August 9, 2009 by welshpug