Please Help! No spark...

[Nay]

We had the car starting earlier, and when i dropped the throttle back to idle the engine just cut. Since then it hasn't been sparking... we think!

New spark plugs, Ht leads just stopped sparking we think and are now rather confused.

Any ideas?

[ross_jsy]

How you testing it Nathan?

[Nay]

taking out the spark plugs and keep them connecred, turning the engine to see if they spark.

What do u recommend doing? and shouldn't u be working!

[ross_jsy]

You have to ground them out for them to spark.

I am working......

[Nay]

meaning placing them onto metal whilst turning the engine? well, thats what we were doing....

[SteSE]

If your not getting a spark at the actual plugs take the lead from the coil to the dizzy of at the dizzy end and see if your getting a spark there.

Coil, ECU and i think crank sensor can cause loss of spark.

Very unlikely that all plugs and leads would fail at same time tbh mate. Must be something else, maybe you've knocked something?

[Nay]

its rather strange.

Thinking we may have got something we shoudn't have got wet, whilst sorting out coolant. The coil is dry tthough, which is good!

[SteSE]

Are you getting a spark from the coil lead?

ETA Watch it don't belt ya too

[Nay]

i will double check, but how do i properly check?

Is the crank sensor the little lead that sits at the top of the crank pulley?

[dickster]

i will double check, but how do i properly check?

Is the crank sensor the little lead that sits at the top of the crank pulley?

On the later ones it is but I thought you had the earlier engine and box or did they keep the original later gearbox/TDC sensor on the crank pulley and just fit the earlier block/head and cooling system?

Check for a spark then report back.

[SteSE]

Just follow the lead from the coil to the dizzy, pull out the lead at the dizzy end and rest it somewhere in the bay. Get someone to crank the engine and see if it's sparking.

Not sure where the crank sensor is as my car is the oldder style with pulse sender. i think it works off a trigger wheel but where this is located i'm not sure - not near any of the cars to check. You should also have an extra HT style lead and i think goes to the coil to dizzy lead.
That might also cause this issue but i'm not sure what it does - would be interested to know.

As you've replaced all HT leads and plugs, if you've still got the old ones it might be worth trying them again just incase.

[SteSE]

i will double check, but how do i properly check?

Is the crank sensor the little lead that sits at the top of the crank pulley?

On the later ones it is but I thought you had the earlier engine and box or did they keep the original later gearbox/TDC sensor on the crank pulley and just fit the earlier block/head and cooling system?

Check for a spark then report back.

I thought he had later engine what type of engine do you have Nay?

[Nay]

As you've replaced all HT leads and plugs, if you've still got the old ones it might be worth trying them again just incase.

I haven't replaced the leads.... but I can nab any of them from my 320i to test if that is needed. Providing they're compatible, which I'd think they are.

I thought he had later engine what type of engine do you have Nay?

Urm, difficult to say really. It was bought as a project car from day one, and the guy I bought it from said it had the earlier HC engine, in a facelift shell. The cooling system is from the earlier type and after that, I can't tell the difference.

I want to fit the later Motronic at some point, and the later cooling system.

[biggee]

OK, daft question but where is the battery located?

[Nay]

@biggee - boot mate. 325i tintop.

Right, tested with the coil and ht lead from my 320i to no provail. could it be a fried ecu? hhhheeeeellllppp!!!!!!!!!!!!!!!!!!

[ross_jsy]

Try testing the crank sensor? I am sure mr moore will be able to help with that.

What codes your ecu? I shall have a look at what mine is, you never know. Yours may have the later injection system all there.

[Nay]

ok, will need more info on the crank sensor.

ecu box says motronic (stamped into it), and has a bosch sticker on it. the codes on the sticker are:

0 261 200 073
1 289 786.9
there is also a circled number saying 078

[zaust]

First thing you need to check is the DME relay. Most likley stuck in one position. Located under the cover by the AFM. The orange one is the fuel so leave alone.

If this is not the cause then, The 073 ecu's suffer with dry joint's. Either try a known working one or open yours up and look for the yellow brown bit's round some of the joint's on the tracks and resolder.

If it is your crank sensors(yes 2) are located near the starter motor and the go into the gearbox to read off of the fly wheel. If these are down they are about 90 each

[Nay]

zaust, whats this dme thing?

[daimlerman]

Are the plugs getting wet when you crank the engine?

[zaust]

The Digital Motor Electronics (DME) relay unit is a double-relay-in-one box. The main relay is used to fire the DME control unit (ECU), while the second relay gives power to the fuel pump. Failure in the injection system is usually down to the DME relay. So Change it first. Either blue or white and located under the cover next to the Air flow meter.

[dickster]

I think first of all you need to find out exactly what you have i.e whether whoever fitted the earlier engine fitted the earlier injection system or not, if it has the later system then you're laughing because certain bits like the crank sensor will be the same as your 320i so you can swap stuff to test it but if its the earlier system then it'll be different, obviously the ECU is different but I wouldn't jump to conclusions yet.

Again are you getting a spark or not? you say you've swapped the leads and coil but not actually said if you're getting a spark or not and thats quite important.

[ross_jsy]

Anyone know if you can swap the ecu out with a facelift even with preface electrics?

[Nay]

Are the plugs getting wet when you crank the engine?

Urm, I noticed bubbling in the one on the coil (although the coil has always been bone dry...), and I really should check them all. What does this mean? I thought that could have been water damage, so tried other leads to no provail.

I think first of all you need to find out exactly what you have

So true. By the looks of it, plenty is different from the 320i, so assuming that almost all of it is prefacelift.

Again are you getting a spark or not?

I dont think I am. Can't physically see anything, but the coil did electrocute my dad (through a spark plug we were trying to test) as I turned the ignition off. So electricity is lurking around. Spark, not too sure, but I think not.

[Nay]

Anyone got anymore ideas?

[Nay]

The Digital Motor Electronics (DME) relay unit is a double-relay-in-one box. The main relay is used to fire the DME control unit (ECU), while the second relay gives power to the fuel pump. Failure in the injection system is usually down to the DME relay. So Change it first. Either blue or white and located under the cover next to the Air flow meter.

I have this thing that has two blue cubes (look like the cubes found in the fuse box), right near the AFM. Is that the DME as I have no idea. There isn't anything like an orange one.... oh and would I pull the little bluish cover off the cube to check the connections?

[biggee]

Nay, I went through all this S**T recently, have you checked to see if there is an inline fuse on the thin wire coming off the + battery lead in the boot, its about 18" along under a plastic sheath, its a 50 amp fuse, my had a very fine break in it which caused intermitent starting and cutting out, even if it looks fine it might be an idea to bridge it and crank it over. Let me know how it goes.

[Nay]

Bridge it? as in bypass the fuse for a test? I'll try when I get to the garage in a bit.

[biggee]

Yes, there are two little holes either side of the fuse so a reasonalble bit of thick wire will slot in them.

[Nay]

Fuse is fine.
Relays (all are fine).


After a check, 100% not sparking. Only thing I can think of is the ECU itself... or the crank sensors, but I wouldn't know how to check them!

As I said, its not the coil, the HT leads, or the fuses/relays...

Any more suggestions?

Whats the compatibility between pre and post facelift ECUs? I take it none.

Whats involved in swapping round the whole management system, if need be...

[zaust]

There is no compatibility between them, To check the sensors you will need a meter and see what ohm's they are reading. Post your findings.(not in an envelope)

[Nay]

If we have a meter then I'll test it and uppy the results. Where would I put the meter to test?

[zaust]

If you unplug the sensor, you will see the pin's that you need to prod. It should read 500-600 ohms iirc.

[Nay]

I'll have a gander. Is it the two things near the back/middle of the crank case on the passenger side?

A fellow zoner has kindly offered to send me an ECU. If it works, send him a postcard! So, next week sometime, we can try that.

[biggee]

When you get your meter check the power at the far side of that fuse.