misfiring, popping, spluttering, back firing, E30 320.

[Jimmythelug]

Hi guys, im fairly new to the zone but i was wondering if you guys could help me.

I have a BMW E30 320 and its practically undriveable. when cold it tick over is seriously lumpy and when you try to give it some gas its revs slightly then pops and bangs and if you do get enough revs to let the clutch out as soon as you start to let the clutch out the revs die and it wont pull away.

I was wondering if there is anyone local that could maybe pop round to have a look at her and shine a bit of light. I would be more than happy to pay for your time.

Thanks for your help, James.

[Speedtouch]

Whereabouts are you?!

Check the blue temperature sensor as a first port of call; it should measure approx. 3300 ohms cold, dropping to around 600 ohms hot.

[jmc330i]

Has this problem suddenly appeared or something that's slowly become worse?
I'd be looking at all the hoses and pipes for air leaks, but it could also be an igniton or timing issue.

I've never heard of an air leak or the blue temp sensor issue causing the car to to die enough not to be able to pull away

[Jimmythelug]

Im located in Sunderland, Tyne & Wear. Thanks for the quick response guys. im gonna get under the bonnet now.

[Jimmythelug]

The problem has been there for a while, but started as a intermittent misfire under hard acceleration. It has gradually got worse and now its undrivable.

[Grrrmachine]

Age of the car is important; early 320s have different problems to late 320s.

My car responded in exactly this way when the Air Flow Meter wasn't plugged in.

[Speedtouch]

Also try, with the engine idling, spraying WD40 around the inlet manifold and throttle body gaskets. If it briefly raises the idle speed, then you have a gasket leak.

Grrrmachine, I think his is a 1988 Motronic one.

[Brianmoooore]

Distributor cap been off and checked lately?

[Speedtouch]

According to this, it has:
http://www.e30zone.net/modules.php?name ... highlight=

[Jimmythelug]

Age of the car is important; early 320s have different problems to late 320s.

My car responded in exactly this way when the Air Flow Meter wasn't plugged in.

Its a 1988 320 Saloon.

[Jimmythelug]

Distributor cap been off and checked lately?

Yeah mate not long had a new one.

[Jimmythelug]

According to this, it has:
http://www.e30zone.net/modules.php?name ... highlight=

well spotted mate. i posted this when it first developed the misfire.

[Speedtouch]

Can you confirm it's a Motronic? It will have the dizzy at the front of the engine, on the end of the camshaft, rather than block-mounted.

[Jimmythelug]

Can you confirm it's a Motronic? It will have the dizzy at the front of the engine, on the end of the camshaft, rather than block-mounted.

Dizzy cap is at the very front of the engine so i guess it is.

[Speedtouch]

Test the blue temperature sensor at the ECU socket, to ensure the wiring to the sensor is OK; see the Zone Wiki for details:

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

Also, did the misfire start after you replaced the spark plugs and dizzy cap, or was it doing it prior to this?

If not, ensure the spark plugs are the correct rating and gapped correctly. Also, was a new rotor arm fitted, as these eventually erode away, reducing the spark strength.

[Jimmythelug]

When i remove the blue plug the engine still runs the same, does this mean it could be the sensor?

[Grrrmachine]

Unplugging the sensor won't make any difference if the fault is in the wiring, that's why you need to follow the test outlined in the wiki.

[Jimmythelug]

ok il give it a shot. thanks