Put a posting on this site a few weeks back and got some great response (cheers). My E30 316i Lux occasionally cuts out (no spluttering) just like someone has turned the key off - car rolls to a stop, stearing heavy, engine won't start. My old man somehow found out how to start the thing, by pulling off the rubber cover on the ignition coil, disconnecting the HT lead, attaching a piece of wire, making it spark off the car body by turning over the engine, replacing all this, and the car starts again first time.
I suspect that it is a faulty coil, as I am told these things can go. Does anyone have any other suggestions that would make replacing the coil a stupid idea?
Any help - yes please...
Could someone confirm - ignition coil
Moderator: martauto
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Martinaston
- E30 Zone Addict
- Posts: 3749
- Joined: Mon Mar 14, 2005 11:00 pm
- Location: London
Could be the ignition relays. (2or3)
Should be under the cover that sits between the engine and windscreen.
Should be under the cover that sits between the engine and windscreen.
There is NO nucleus.
Test your ignition coil for shorts or opens. Grab an Ohmeter (multimeter) and connect it to the positive and negative +12V terminals on either side of the coil.
The resistance should be extremely small, but just there, at about 0.5 Ohms on an M40 engine, or 0.8 Ohms on an M10 engine.
Then take the resistance between the HT terminal on the coil to the negative 12V point. On an M10, it should be 8250 Ohms, on an M40, it should be about 5000-6000 Ohms.
I know this because I had the exact same issue with my 318i (M10 engine), and recently disconnected the coil and checked it. I should be getting 8250Ohms on the secondary, and I was getting only 5200Ohms, which means there is a major short in it.
Here is where the trick begins though. The best price I can get on a coil for a 318i M10 is $330 at a local parts dealer, else it is $420 from my BMW parts dealer. This is australian money.
I can buy an entire M10 engine second hand for $290, take the coil off it, and throw it away.
Work that out.
Hopefully you have an M40 mate.
Tell me what happens so I can compare notes, I am interested in this arcing it to the chasis and then starting it thing.
The resistance should be extremely small, but just there, at about 0.5 Ohms on an M40 engine, or 0.8 Ohms on an M10 engine.
Then take the resistance between the HT terminal on the coil to the negative 12V point. On an M10, it should be 8250 Ohms, on an M40, it should be about 5000-6000 Ohms.
I know this because I had the exact same issue with my 318i (M10 engine), and recently disconnected the coil and checked it. I should be getting 8250Ohms on the secondary, and I was getting only 5200Ohms, which means there is a major short in it.
Here is where the trick begins though. The best price I can get on a coil for a 318i M10 is $330 at a local parts dealer, else it is $420 from my BMW parts dealer. This is australian money.
I can buy an entire M10 engine second hand for $290, take the coil off it, and throw it away.
Work that out.
Hopefully you have an M40 mate.
Tell me what happens so I can compare notes, I am interested in this arcing it to the chasis and then starting it thing.
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JasparRivers
- E30 Zone Newbie
- Posts: 16
- Joined: Sun Jul 24, 2005 11:00 pm
Thanks for the quick reply. I'll do the tests that you suggested first - the decision isnt so bad over here dsio, as you can get almost identical parts from GSF Car Parts: https://secure.gsfcarparts.com/shop/results.asp
and a coil comes to around Ԛ£40. you could get your parts from them and have them shipped over as it is still probably going to be cheaper...?
Alternatively I just go to a breakers yard where the parts are normally ok for much less. As its an electrical problem I'll go with GSF just to make sure the problem will be solved...
Anyway - thanks, will keep you updated.
Jaspar
and a coil comes to around Ԛ£40. you could get your parts from them and have them shipped over as it is still probably going to be cheaper...?
Alternatively I just go to a breakers yard where the parts are normally ok for much less. As its an electrical problem I'll go with GSF just to make sure the problem will be solved...
Anyway - thanks, will keep you updated.
Jaspar
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Danny_boy_a
- E30 Zone Newbie
- Posts: 4
- Joined: Wed Aug 17, 2005 11:00 pm
Hi there. I have just bought an e30 316i and mine sometimes cuts out too. It also cuts out and jerks back to life at speed. The other day it ground to a hault altogether. When I started it, it was fine
Not a huge electronics expert. My old man thinks its the CPU. Does it have one? Could it be anything else? Anyone had these problems?
Cheers
Dan (distressed BMW driver)
Not a huge electronics expert. My old man thinks its the CPU. Does it have one? Could it be anything else? Anyone had these problems?
Cheers
Dan (distressed BMW driver)
i had all the same problems and it went on for ages i couldnt find what it was ...aa were a waste of space .....then i changed the white relay (dme)and all was sorted never troubled me since .....i thought i sorted it only to find the relay is hidden as the previous message says on the bulkhead under the long plastic trim ...sits with 2 other relays (not in the fuse box)
if you take the relay out ...look at the metal prongs nearest to the plastic if it has been overheating you will see it has blued with the heat ...a big give away.....good luck
if you take the relay out ...look at the metal prongs nearest to the plastic if it has been overheating you will see it has blued with the heat ...a big give away.....good luck
The symptoms sound like a coil, but usually with a failed coil, it won't start again until it's all cooled down. You turn it over and over and it just won't go.
then after an hour it'll start, but after a few minutes it cuts out again. Even if you hold a plug to the block, there will be a spark, because it isn't under much load. Best way is to borrow someone elses's coil.
Make sure it is earthed properly. Take it off, clean up the mountings with a wire brush and reassemble with vaseline.
Can you turn it over easily once the car stops, or is it sluggish?
then after an hour it'll start, but after a few minutes it cuts out again. Even if you hold a plug to the block, there will be a spark, because it isn't under much load. Best way is to borrow someone elses's coil.
Make sure it is earthed properly. Take it off, clean up the mountings with a wire brush and reassemble with vaseline.
Can you turn it over easily once the car stops, or is it sluggish?
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JasparRivers
- E30 Zone Newbie
- Posts: 16
- Joined: Sun Jul 24, 2005 11:00 pm
I replaced the coil this weekend just to see if it was the problem.
The original problem was a total cut out - which required earthing the coil to the car body once the HT lead was removed using some wire. Once this was done the engine started first time, and would work fine either for 100s of miles or for 1 mile and then have the same problem. If the coil was not earthed the engine would just turnover and over and would not fire at all (you could do this for 10 mins with no luck).
After replacing the coil the problem I then had was a spluttering jerking feeling with loss of power but not in such a 'on/off' way, as before it felt like someone had flicked a switch. Now it is more irratic and then engine can continue running if you wressle with it - ie change to a lower gear (higher revs) etc. It also did not need the 'wire trick' to get it working, rather it just started fine again immediately afterwards but then suffered the same problem much more quickly (0.5km down the road).
Might investigate the DME relay.....
The original problem was a total cut out - which required earthing the coil to the car body once the HT lead was removed using some wire. Once this was done the engine started first time, and would work fine either for 100s of miles or for 1 mile and then have the same problem. If the coil was not earthed the engine would just turnover and over and would not fire at all (you could do this for 10 mins with no luck).
After replacing the coil the problem I then had was a spluttering jerking feeling with loss of power but not in such a 'on/off' way, as before it felt like someone had flicked a switch. Now it is more irratic and then engine can continue running if you wressle with it - ie change to a lower gear (higher revs) etc. It also did not need the 'wire trick' to get it working, rather it just started fine again immediately afterwards but then suffered the same problem much more quickly (0.5km down the road).
Might investigate the DME relay.....