What is the difference between 1.8k ohm and 1.0 ohm plug boots?

[byrona8]

I have been chasing a rough idle and bought a new boot from the dealer. But he gave me one that's 1.8k ohm. The ones in my car were 1.0 k ohm. Did the PO have the wrong coils in there? Anyways I swapped out my coils with ones from an e39 M5 because that's what was on my previous engine (2.8). Don't know why they were on there but I didn't have any idling problems. They had the 1.8 k ohm boots. My coils that came with the engine were 1.0 k ohm. And just in case you are wondering what car it's a 332ic. Thanks

[Balthazarr]

I have been chasing a rough idle and bought a new boot from the dealer. But he gave me one that's 1.8k ohm. The ones in my car were 1.0 k ohm. Did the PO have the wrong coils in there? Anyways I swapped out my coils with ones from an e39 M5 because that's what was on my previous engine (2.8). Don't know why they were on there but I didn't have any idling problems. They had the 1.8 k ohm boots. My coils that came with the engine were 1.0 k ohm. And just in case you are wondering what car it's a 332ic. Thanks

Did you clean the ICV or check to see the nipple is secure on the mani?
Buy some Ventil Sauber and put in your tank to blow out the carbon on the back side of the valves.

To answer the question about the boot, extra resistance can make a difference, but I would put the original back in and test the coils after the VS treatment, if it doesn't smooth out.

[byrona8]

Thanks. I am trying to figure out which ones are the original coils now. Realoem says the 1.8k ohms are original. But I had 1.0 k ohm boots. Can anyone tell me which ones belong where? I also changed the temperature sending unit on the radiator and my CEL is now staying off. But I never got a code that said that it was bad. I read about it in the rough idle CEL thread. Whoever said to change the temp sender Thanks!!!

[e30'd much?]

if you dont know for sure use the Realoem information, better than guessing

[byrona8]

I have used realoem. The coil number does not cross reference on one of the coils. That is how I found out one set was from an e39 M5. Well, the rough idle and running came back in the morning. It only happens in the morning and not when warmed and driven for 10 mins.

[bmwpowere36m3]

Well the two OE suppliers of the ignition coil plug boots have different resistance values. Bosch and Bremi, one is 1k and the other is around 1.8k IIRC. The Bosch ones were OE on the vehicle and are only available from the dealer. You’ll get Bremi ones if you order them from anyone else. I’d think it be best to have the same ones on all six coils.

[Xiphos]

Well the two OE suppliers of the ignition coil plug boots have different resistance values. Bosch and Bremi, one is 1k and the other is around 1.8k IIRC. The Bosch ones were OE on the vehicle and are only available from the dealer. You’ll get Bremi ones if you order them from anyone else. I’d think it be best to have the same ones on all six coils.

My dealership sells Bremi for what its worth. I think you should be fine either way you go.

[lesl]

A 1 ohm boot will allow more current to flow over the 1.8 ohm boot. But, the output of the coil is high voltage, low current. A resistor in series will not limit voltage. The output of a coil is greater than 1K volts. But, even at 1K volts, a 1 ohm resistor would allow 1K amps, a 1.8 ohm resistor, 550 amps to flow, which would essentially melt the boot. So any current way below that will flow easily.

The 1.8 ohm boot is probably better because it will reduce the static generated by the ignition system, on your radio.

[Balthazarr]

A 1 ohm boot will allow more current to flow over the 1.8 ohm boot. But, the output of the coil is high voltage, low current. A resistor in series will not limit voltage. The output of a coil is greater than 1K volts. But, even at 1K volts, a 1 ohm resistor would allow 1K amps, a 1.8 ohm resistor, 550 amps to flow, which would essentially melt the boot. So any current way below that will flow easily.

The 1.8 ohm boot is probably better because it will reduce the static on your radio.

kilohms

[byrona8]

I bought the boot from the dealer it is a Bremi 1.8k ohm. I will say my car seems to run better. I don't know if it is because of the bad Bosch boot set or that these coils have more output. They look just like the TMS high performance ones minus the trick paint job.