Testing HT Leads and Spark (325i rough idle)

[German-Whips]

I have a rough idle and a slight misfire on the cab.

I was wondering if there is a way to check the HT leads and spark to see whether there is a spark.

Also, one of the HT leads, the number 6, is damaged and has black insulation tape around it. The rubber end is stuck to the spark plug. Could this be a possible cause for the misfire?





Would it be best to buy new HT leads from ECP or GSF, or would good second hand leads from someone breaking on here be a suitable option? I read 2nd hand OEM leads are generally fine as long they are not physically damaged?

[Speedtouch]

Best way to test them is to stick a spark plug in and rest it on the rocker cover then crank the engine over with the fuel pump relay removed.

You could also measure the leads resistance - they should all be under 10 kilohms.

[German-Whips]

Best way to test them is to stick a spark plug in and rest it on the rocker cover then crank the engine over with the fuel pump relay removed.

You could also measure the leads resistance - they should all be under 10 kilohms.

How do I remove the fuel pump relay/where is it?

Also, how do I measure their resistance?

Never done this sort of thing before, so not really clued up on it.

[Speedtouch]

FPR is the orange one in the middle of the relay box on the nearside bulkhead (usually under a black plastic cover):

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

Use a multimeter set to 10k or 20k resistance range to measure the HT leads - use a probe at each end of the lead.