Spark Plug Replacement

my325is · 01-21-2006, 07:08 PM

Hey everyone, I'm new to this thread and I am new to fixing cars. I own a 1993 325is and I am about to do my own spark plug replacement. I did read the instructions on performing this task on this website. However, I remember reading something that stated that I will not need to purchase sparkplug wires because of coils. Does this mean all I have to do is replace my sparkplugs and nothing else; meaning I do not need to replace the coils during this process. Any help would be much appreciated. Thanks.

yob · 01-22-2006, 11:00 AM

no don't replace the coils unless one of them is not working. Replacing all the coils is a relatively expensive task.

my325is · 01-22-2006, 03:45 PM

Hey thanks. Just curious, how do I know when I have to replace the coils. Also, do I need to replace the wires while I replace my spark plugs?

yob · 01-22-2006, 06:35 PM

no you don't necessarily have to replace the wires but if they look bad then do it. Easiest way i can think of to check your coils is if you put your new plugs in and the engine sounds like its misfiring that means one of your coils may be bad. If it does sound like its misfiring you can leave the car running and check by pulling one wire out at a time and replacing it and if there is a change in the sound of the engine while the wire is out then you know that that cylinder is firing and its ok. No change in sound means that that cylinder is not firing and it could be your coil.

my325is · 01-22-2006, 07:09 PM

Thanks yob, but how do I know if one or more of my plugs are misfiring? Is there a certain sound to listen to?

yob · 01-22-2006, 09:28 PM

you will hear it, engine will not run well, idle will be rough. if there is more than one not firing it will probably be even rougher and possibly stall out. Actually you could probably feel it better than hear.

Jeron · Jeron's Garage

It is important to get the correct plugs and I strongly suggest a torque wrench when installing them. I would not have tightened my plug nearly enough if i had done it solely by hand because there was a significant resistance at least a half turn before I hit the proper torque.

my325is · 01-23-2006, 12:19 PM

I installed the right plugs, but unfortunately I didn't use a torque wrench though. Everything seems to be running just fine. So I'm not sure if I should worry about the right amount of torque used. Also, if the plugs are misfiring, will it show up on the computer as a check engine light?

Jeron · Jeron's Garage

I know that on OBDii you get a CEL on a missfire. Yours is OBDi but it probably would give a CEL too.

Back yo your original question:
You don't have plug wires to replace, don't replace the coils until you have a problem. The down tube on the coil is a separate part and is the most equivalent to the plug wire. If it ain't broke....

my325is · 01-23-2006, 03:36 PM

Kool, thanks alot guys for the info.

mr.mike36 · 01-31-2006, 07:59 PM

What plug did you replace with? I was given two types of Bosch Platinum II plugs (9003 & 9006) but was recommened an NGK Platinum equivalent to the factory plug. Sorry, but Bosch is the only name I understand...NGK was what I used in my rotary RX-7 right before they blew the apex cumbustion chambers went bad so I have been anti ever since. Any help would be nice.

Jeron · Jeron's Garage

I prefer NGK over Bosch. My E36 M3 had Bosch +4 and I replaced with the same. My E46 had NGK BRK6EQUIP and I replaced with the same. The NGK's actually had both NGK and BMW on the plug.

The stock plug is probably platinum so I would stick with that over the newer iridium.

If it was me I might switch to NGK but I would make sure what ever plug I bought had the same number of grounds (prob 2 in your case) and the same type of electrode (prob plat in your case.)

Both NGK and Bosch have informative websites.

mr.mike36 · 01-31-2006, 10:38 PM

Okay, I will run the Bosch this time but will use the referred NGK plug on my next change in 10k...I need a Fuel/Air Meter to monitor my performance but I will track my mileage and oil quality over the next 10k.

I appreciate the info, I know something isn't right as my car is surging and loading at certain times. I know this can potentially be numerous items but I am starting cheap and working my way up, I figure at 200k, the car could use some fresh parts to give it a little boost. I cant afford a rebuild right now, which I dont think is necessary but at the same time I cant afford the electronic troubleshooting procedures I am going through to fix each aspect. I will break out my multimeter and test everything as I go through it this weekend. I wish everyone tended to their car as I try and do, maintenance is key but when you get the car from a spoiled rich college kid you quickly realise all the issues that happen from neglect....it makes me love my old 318 'hoopty' more and more everyday

Jeron · Jeron's Garage

You dont need to change your plugs every 10k, 50k is often enough with a platinum plug.

AbelBMW328iC · 02-16-2006, 02:27 PM

Jeron..

So for a 96 328ic... which spark plugs should I get?

Jeron · Jeron's Garage

My E36 M3 had Bosch Platinum 4-ground and I replaced with the same plug but I dont have the part number.

I prefer NGK which is OEM on my E46.

I've heard recomendations from BMW mechanics not to change electrode types (platinum, iridium etc)

Check out the NGK and Bosch websites, they should give you the correct part numbers and they have good information.

mr.mike36 · 02-17-2006, 06:00 AM

Read your manual, I would get whatever is recommended...a lot of people use Platinum +4 plugs but I think the best replacement is what was originally used depending on mileage and system wear. Watch your mileage with the replacements and if it is worse then I would replace with Platinum +2's. Plat 4's have a very hot burn and are good for high compression motors but be careful running fuel treatments or lower quality/octane fuel. Your goal is to have full fuel aspiration with the lowest temp possible...length of burn is essential.