differences between 323i and 320i Ignition COils

[g323]

The part numbers are different on RealOem.

Are they the same thing?

I have a 323i coil that has bosch part number:
022122319
(050)
93

what's the number for a 320i?

[Layne]

The only possible differences are 1) is it made to use a ballast resistor or not and 2) the type of connectors on it. Other than that all coils are the same regardless of the car they fit.

[epmedia]

May also run into different diameters as well, ie: clamp area. I have an original '78 coil that is longer and a tad fatter, and an aftermarket coil for "electronc ignition" that is smaller diameter so it does not clamp properly, it works with points though (however a tad weaker spark). So, since they both have different part numbers, there is something different between them.

[GDAus]

Hi ....

The number you are quoting is the Bosch Part # ..... the number in the RealOEM lists is the BMW Part #.

The question is ... which type of electronic ignition control unit do you have ?

The early model, "big boxy one" with the 2 part ballast resistor ... or the later "small sexy looking one" ie the same one fitted to the post face lift 320i models. The early boxy ICUs' use a different part number coil for use with the 2 part ballast resistor ... Don't use this coil with the later smaller ICU ! . . it has a primary coil resistance of 0.4 Ώ If you have the earlier boxy ICU .. this is the one you are stuck with (coil with a higher primary resistance can be used .. but you'd get a reduced High Voltage output).

Checking the parts list shows that the coil for the sexy ICU is the same for 323i & 320i ....
ie BMW Part # 12 12 1 273 216 ... this coil for the later icu has a primary coil resistance of 0.7 Ώ. (ok .. the Swedish models have a different coil ... possibly something to do with their different anti-pollution laws ???) ... (according to the BMW manual).

Of course, pretty much any coil designed for use with a distributor based electronic ignition system should work, as long as the primary coil resistance is 0.7 Ώ or a bit above. Bosch do an aftermarket modern "transformer" type coil for both conventional and electronic ignitions, so if you are in the market for a new coil, I would seriously consider one of these.

I was on the point of buying one of these for my car when I came across something on eBay that I thought would work. It was only $5

The one I got was a more modern "transformer" type coil off a late '80's VL Holden Commodore, (a local GM product), which had a Nissan 6 cylinder engine in it and used a 1.5 mm (~ .060") spark plug gap! This coil has an identical primary coil resistance as my original OEM coil (I measured it at 0.8 Ώ).

At the moment I'm running 1.0 mm (~ .040") plug gaps which has given me a bit more torque with no problems, without changing anything else. I have experimented with 1.5 mm ... it gave a marked improvement in torque across the rev range with better 5th gear acceleration above 100 km/hr ... but there was a bit of bucking at low RPM in certain circumstances. Once I get around to checking my control pressures and know that the FI system is all ok, then I'll do some experimenting with the ignition timing which should fix the bucking problem so I can go back to the 1.5 mm gaps.

Cheers


This is the sort I'm talking about, this one is fully encapsulated, but some brands have some of the core laminations exposed at the base. Basically the big laminated core provides a more efficient magnetic circuit, so they typically can produce higher secondary voltages with less primary current.

[msiert]

The question is ... which type of electronic ignition control unit do you have ?

The early model, "big boxy one" with the 2 part ballast resistor ... or the later "small sexy looking one" ie the same one fitted to the post face lift 320i models. The early boxy ICUs' use a different part number coil for use with the 2 part ballast resistor ... Don't use this coil with the later smaller ICU ! . . it has a primary coil resistance of 0.4 Ώ If you have the earlier boxy ICU .. this is the one you are stuck with (coil with a higher primary resistance can be used .. but you'd get a reduced High Voltage output).

Checking the parts list shows that the coil for the sexy ICU is the same for 323i & 320i ....
ie BMW Part # 12 12 1 273 216 ... this coil for the later icu has a primary coil resistance of 0.7 Ώ. (ok .. the Swedish models have a different coil ... possibly something to do with their different anti-pollution laws ???) ... (according to the BMW manual).

I'm sorry for waking up the dead!

This comment in bold print scared me after I realized that I have been.

"Don't use this coil with the later smaller ICU,"

What will happen if you do?

I have a 1983 E21 that has a bone stock ignition system.

Been working on a fuel delivery problem that seems to be tied to a possible intermittent missing pulse trigger from the #1 (-) terminal on the coil. I ran across this thread and now know that the E21 had two different coils spec. durning it's run.

In testing my primary resistance in my coil I bought last year and it was 3.56 ohms k, it looks like I have the one that was meant for the earlier ignitions. I still had the old coil that it replaced and its primary resistance was 4.58 ohm k, so I been running the wrong coil for 34,000 miles.

On Pelican Parts they have the ohms listed on their coils, 3 ohms and 6 ohms. I take it for a 1983 E21 you want to buy the 6 ohm coil? Is this correct? It doesn't matter if I pick the 3 ohm or the 6 ohm coil and run the check if it will work in my 1983 BMW it says yes to both.

This is the picture of the coil that I removed from the car, bought it on Amazon, it's ad does not list the ohms, but says it fits my 1983 E21.

[GDAus]

I'm sorry for waking up the dead!

This comment in bold print scared me after I realized that I have been.

"Don't use this coil with the later smaller ICU,"

What will happen if you do?

I have a 1983 E21 that has a bone stock ignition system.

Been working on a fuel delivery problem that seems to be tied to a possible intermittent missing pulse trigger from the #1 (-) terminal on the coil. I ran across this thread and now know that the E21 had two different coils spec. durning it's run.

In testing my primary resistance in my coil I bought last year and it was 3.56 ohms k, it looks like I have the one that was meant for the earlier ignitions. I still had the old coil that it replaced and its primary resistance was 4.58 ohm k, so I been running the wrong coil for 34,000 miles.

On Pelican Parts they have the ohms listed on their coils, 3 ohms and 6 ohms. I take it for a 1983 E21 you want to buy the 6 ohm coil? Is this correct? It doesn't matter if I pick the 3 ohm or the 6 ohm coil and run the check if it will work in my 1983 BMW it says yes to both.

This is the picture of the coil that I removed from the car, bought it on Amazon, it's ad does not list the ohms, but says it fits my 1983 E21.

Hi ...

this thread was about coils for 323i models with the 2.3 litre M20 motor. The OP didn't say what year his was and the earliest electronic ignition system on the M20's used a coil with a very low primary resistance of 0.4 ohms and a 2 part external ballast resistor. The later type electronic ignitions on the 1.8 litre M10's and later M20's used a coil with a primary resistance of 0.8 ohms.

So the warning was for the OP just in case he had an early coil and a later ICU.

The resistance is there to limit the amount of current flowing through the coil and ICU to stop it overheating and going up in smoke ... so using the 0.4 ohm coil on a later ICU type would result in higher current through the coil and ICU could cause that to happen.

Bosch states the range of acceptable primary resistance is 0.55 to 0.8 ohms for the ICU on 1.8 litre M10's. So the coil in your pic would be fine.

Since this thread I've spent a bit of time digging into coils etc. There's some contradictory info floating around our there about secondary resistance on OEM coils.
What I found was that coils on the North American market cars were fitted with a lower output coil to the euro and rest of the world models.

Both the M10 and M20's out here in the rest of the would have Bosch 0 221 122 319 coils with a Secondary resistance of around 8 K ohms verses the NA models with only about 3.5 K ohm secondary windings.

Just out of curiosity ... what's the Bosch part number on the base of your original coil?

As to your other issue try checking the female connectors in the Fuel Pump Relay socket ...with a bit of wear and tear it is possible for the connectors to get pushed down inside the socket so they don't make a proper contact ... particularly the small connector.

F Pump relay Sock04.JPG The 31b connector is the input from the ignition coil.


Cheers

[msiert]

I'm not sure if this is the original coil, it was on the car when I bought it back in 2012.

When I replaced it, it turned out not to be the problem but I had already ordered a new one and installed it, it has a higher primary resistance then the new one.

In trouble shooting the fuel pump relay, I found the pulse trigger wire loose from the relay socket but after I reconnected it, it still didn't start. Afterwards I did a continuity test between the fuel relay 31b terminal and the (-) side of the coil and to the ICU and rechecked that the pulse wire was still connected to the socket all was good but still no start.

What fixed the non start:
In the wire diagram it looks like the fuel pump relay is feed its ground through the Lamboa relay, after cleaning the Lamboa relay socket the car started, idle till warmed up and handled several blips of the throttle perfectly.

But I don't feel I have seen the last of the problem but I have cleaned all the fuse holders and relay sockets along with the grounds including the engine to frame strap. I will have to take my trusty little fuel pump relay jumper wire with me on my next drive to see.

I did buy the .6 ohm coil thinking that it may be what I should be using.

[320iAman]

.7 Ohms for TCI is specifications for 80-1983 320i. I got mine from the 2002 Company in Socal NEW for $25 or so--its the oem Bosch one, ebay purchase. BMW # 12131269637.

Randy

[msiert]

Thank you GDAus and Randy for your help!

[320iAman]

Sure, Since your working on the cleaning of the fuel pump relay and accessories, know that the fuel pump relay is the work horse relay it powers 5 different devices,, Lambda relay, WUR, AAV, and 2 Fuel Pumps.
My Fuel Pump Relay was going out after about a year of use. I then recalled there was a Hella Update to this entire circuit. What the hella relay does is power 2 devices , leaving the Fuel Pump Relay to run only the Fuel Pumps and provide a small 100-250 milliamps @12V to the new inserted Hella 30 Amp Relay and the new lambda Relay reducing its workload by 2 devices WUR and AAV. Here is a diagram I drew of this Circuit, top part is stock, bottom is the Hella update with a few of my own inputs. The new lambda relay( my insert) and the new inserted Hella Relay have diodes in them , they are free wheeling, snubbers, or fly back relays. Most if not all modern cars with relays implement fly back diodes. The fly back diode protects sensitive devices upstream from the huge voltage spikes that occur when coil devices such as relays open there contact points-shut off-the voltage spikes are run back thru the relay coils via the one way valve of the diode to neutralize spikes in relay coils rather that send them upstream where these spikes can ARC across terminated connections and damage upstream devices and contacts.

IMG-page-001.jpgDSCI0003.jpgDSCI0007.jpg



The ground chuse(lower part of the diagram) I used the battery box ground and for the fused wire I used the positive battery terminal. The second picture is the Hella Update, 3rd Picture is Hella Update Installed. The relay holders and female 6.3 mm terminals are available, also the diode relays.lol-----hella update--an added hella relay with diode- powdered blue color. Notice the lambda relay is Bosch with a diode-why they did not diode the stock e21 lambda relay for these cars is a mystery to me. All Numbers of the parts are good to go and wire sizes, ect.

The savings of this update for the fuel pump relay is Amps to run WUR and AAV less New Hella Relay(100-250 milliamps)--its quite large in % terms and quite an upgrade.

Also just because a relay or other electrical device say its rating is 30A ,ect does not mean that is what it can sustain, most relays run efficiently at 60 to 90% of published rating depending on quality of the materials used and the design and the workmanship--higher quality / higher efficiency and closer to published rating.

My fuel relay is not breaking now after 1 yr or so and the 2nd new one I have has years of dust on it.. This upgrade works for DD's, occasional users wont notice the difference, mine is a DD.

Randy

[msiert]

That's a good idea!

Mine is taken out quite frequently for running around for work and pleasure, not a garage queen but not a DD either.

I'm not afraid of working with the car's electrical system, last year I added a relay for the head lamps and starter for the old Alfa without to much fuss. In fact I would like to add a relay for the starter on BMW, not sure if the BMW would benefit like the Alfa did for adding a relay for the head lamps. I'm all in for reducing loads where I can.

I need to study your wiring diagram more to see if I can grasp how to do it.

[GDAus]

Hi again ..

thanks for the pic of your coil .. I've been trying to work out the taxonomy of the differences of the various coils for a while.

Bosch states the range of acceptable primary resistance is 0.55 to 0.8 ohms for the ICU on 1.8 litre M10's. So the coil in your pic would be fine.

I probably should have emphasised this a bit better.




Either of these coils will work for you because their 0.8 ohm primary resistance is within the BMW secs. It's only if it was less than 0.55 ohms that there could be a problem. Of these 2 coils .. the one with the 4.56 k ohms secondary resistance will give you a potentially higher output voltage to the spark plugs. So you don't need to be buying another coil.

AS to sticking in extra relays .. the headlights are all ready switched via a low beam and a high beam relay.
A separate starter relay has some merit, there have been some people here who have had trouble with burnt contacts in the ignition switch causing problems.I've toyed with the idea of a start relay and a run relay to take the load of the ignition switch .. I just haven't ever got around to it

As to an extra relay to take about 1 amps worth of load off the fuel pump relay, not worth the effort and it just adds an extra level of complexity. I did a write up on this a couple of years ago .....

https://www.bimmerforums.com/forum/showthread.php?2372302-Fuel-Pump-Relay-Issues&p=29985292#post29985292

The idea that the fuel pump relay is working anywhere near capacity just doesn't hold water. That's based on my 35 years of experience as an electrical engineer. In the early days I worked with a lot of D.C. based relay logic control systems so I do know when you use "diode" relays and when you don't .. as BMW didn't use them on the E21 models

Certainly some of the current aftermarket ones may be a bit dodgy, but the original factory ones are pretty damn reliable. My E21 has 603,194 km (that's
374,807 miles) on the clock without any problems. DD for about 12 years ... for 5 years I was doing a 200 mile round trip commute for work 3 days a week about 80% at motorway speeds above 100km/hr (62mph). When I got mine E21, I did pickup another one off ebay but never needed to use it.

The contacts on the fuel pump fuse are much more likely to cause problems than the relay.

As you've all ready discovered having a "bad" connection at a ground point causes all sorts of problems, So my best advice would be to clean up all the ground points .. the one next to the battery .. chassis to engine ... (for anyone else .. the base of the support bracket for the intake manifold) .. (for North American Models the extra lead at the back of the cylinder head- this is to help the O2 sensor work properly) ... the one on the one under the dash behind the pedals and the one underneath the rear parcel shelf on the left hand side.

This one is very important because it is the ground point for the fuel pumps!
It's a pain to get too because you have to lift the parcel shelf but if this one has a bad connection then the fuel pumps will be drawing more current than normal and cause problems. So if your pumps are a bit noisy... this is good thing to check first!

Cheers

[msiert]

Hi again ..

The contacts on the fuel pump fuse are much more likely to cause problems than the relay.

As you've all ready discovered having a "bad" connection at a ground point causes all sorts of problems, So my best advice would be to clean up all the ground points .. the one next to the battery .. chassis to engine ... (for anyone else .. the base of the support bracket for the intake manifold) .. (for North American Models the extra lead at the back of the cylinder head- this is to help the O2 sensor work properly) ... the one on the one under the dash behind the pedals and the one underneath the rear parcel shelf on the left hand side.

This one is very important because it is the ground point for the fuel pumps!
It's a pain to get too because you have to lift the parcel shelf but if this one has a bad connection then the fuel pumps will be drawing more current than normal and cause problems. So if your pumps are a bit noisy... this is good thing to check first!

Cheers

Thank you for clarifying on the coils! Im going to use the Bosch coil with the 4.56 ohm k, and put the 3.62 ohm k Imtermotor coil on the shelf. Guess I will have a 2nd spare coil when the BMW # 12131269637 Bosch coil comes in next week, but might get lucky and be able to return it?

I found the the fuel pump ground just where you said it would be, it looked like it got hot enough to melt some old insulation, You can see it in the picture below, both before and after cleaning the ground..

The fuel pump fuse showed that it got a little hot too, this is what lead me to first believe it was a bad pump. Maybe it is bad but I'm hoping cleaning up the grounds and relays will take care of it?

I could not find the ground point behind the peddles?

[320iAman]

That's a good idea!

Mine is taken out quite frequently for running around for work and pleasure, not a garage queen but not a DD either.

I'm not afraid of working with the car's electrical system, last year I added a relay for the head lamps and starter for the old Alfa without to much fuss. In fact I would like to add a relay for the starter on BMW, not sure if the BMW would benefit like the Alfa did for adding a relay for the head lamps. I'm all in for reducing loads where I can.

I need to study your wiring diagram more to see if I can grasp how to do it.

The BMW E21 Automatics have a start relay standard not the manual shifts though. I have a start relay installed and its a manual 5 speed it helps in several ways. Murray if you have any questions feel free to ask away, I put that up there for E21 owners to use if they want too. The upgrade works exactly as the original wiring to the WUR and AAV the difference is the amp output from the Fuel Pump Relay has been reduced to milliamps- enough to turn on a relay which now powers the WUR and AAV, so if it was 4 amps from the FPR to power these devices now its been reduced to 100-250 milliamps via a relay put in to power these devices, an upgrade, a Hella Upgrade.

Randy

[msiert]

Randy,

I need to study the diagram more to figure it out, I'll pm you on questions.

Thank you!

[msiert]

Just updating, after a long drive this afternoon I have to say cleaning up my grounds and relay connections fixed the dying problem.