Author Topic: Coil test results - Orange spark?? (Read 5054 times)

carl6405 · « **on:** June 07, 2009, 06:33:53 PM »

This evening, I completed a coil test on my M42 engine. I left the spark plugs in the engine. I connected a brand new spark plug to each coil with the engine running. Cylinder # 4(closest to the firewall) had the strongest spark. Cylinder #1(closest to the radiator) had the weakest spark. I used one of the bolts to the strut tower for the ground. All of them had an orange colored spark. Cylinder #4, had some blue in the spark. The engine is running a bit sluggish. I was told by a member here, that the color should be blue. What do you guys think? These coils arnt cheap.

DesktopDave · « **Reply #1 on:** June 07, 2009, 07:00:12 PM »

Probably a bad ground - the plugs never look right when I test them. The coils seem to last longer on the fender than the small COPs do in the engine. I'd guess that they're OK. You have to test them electrically anyway...

What symptoms does the motor have that it's sluggish? Might be the O2 sensor, AFM worn or a vacuum leak instead. Make sure you get the codes too, let us know what they are. Check other stuff before condemning the coils.

carl6405 · « **Reply #2 on:** June 07, 2009, 07:22:43 PM »

DD- Ive already replaced many sensors and other parts on the car, pursuing another problem(stalling issue) 02, ICV, coolant sensor, plugs, TPS, MAF. This is like the last issue that I have with this car. For some reason, my stomp test isnt working any more, so I cant read the DME now. You helped me on my last post and mentioned the coils and to check for a blue spark. One thing I did in trying to resolve the last issue, was shuffle my coils around and created a new ground. By the way, what is the best ground for this coil pack? Currently, the coil pack is grounded to the fender.
I think that these are the original coils and have 156K miles on them. I see someone selling new coils on Ebay for $23/each. Definately, not OEM, but the price is right. Its tempting.

quinn11m20 · « **Reply #3 on:** June 07, 2009, 08:51:29 PM »

Hey Carl If you can't do the stomp test, my manual told me that the Throttle Position Sensor is bad OR the Check Engine light bulb is out. So check the bulb. Good luck.

DesktopDave · « **Reply #4 on:** June 07, 2009, 10:23:49 PM »

You should see the check engine bulb light up every time you start the car. But while you're in there, you should check the other bulbs too. I never heard that a bad TPS could prevent the CE light, but it wouldn't surprise me. That'd definitely impact how well the car runs. You swapped it out anyway.

Any good ground should be OK for the coils, but the engine strap is critical for the plugs. I took a look at mine yesterday and it's falling apart (like the rest of the car). I'll have to re-do that one of these days. Definintely test the coils electrically with a meter. The spark test is only to see if they're working well, there are too many variables to effectively 'read' the plugs. It's easy to jump current across open air; in the engine with high compression, oil residue & heat it's a different story.

quinn11m20 · « **Reply #5 on:** June 07, 2009, 11:07:52 PM »

Yeah. Dave its suprising to me too. I read that in my Chiltons manual. I ran into a similar problem when trying to check codes. My manual says that if codes are unreadable its either the TPS and or the Check Engine light itself. So I removed my instrument cluster to replace the bulb because not even a month prior I had changed the TPS . There is a Online Friend in this web site having a similar start problem Blip is there name. Hope you get it working Carl.

carl6405 · « **Reply #6 on:** June 07, 2009, 11:14:30 PM »

The check engine light comes on when I turn on the ignition. I just cant get it to start blinking codes any more. Last week, I was stomp testing like a champ. Now.. no go. The TPS that I put in there came out of a 95 318is. Not new. I did test it and it passes all ohm test, 1k to 3.87k. According to my Bentley manual, that's good.

quinn11m20 · « **Reply #7 on:** June 07, 2009, 11:19:18 PM »

Ok. I would suggest to try putting the actual tps that goes with your car reguardless if it has the same resistance. The stomp test completly opens and closes the switch. The one you replaced could have a longer sweep than that of an part OE for you car. Hopefully that made sense.

DesktopDave · « **Reply #8 on:** June 08, 2009, 06:49:46 AM »

I do have trouble getting my stomp test to work sometimes. It's very particular about the pattern of stomping. Sometimes I have to stomp six or seven times :rolleyes:! I haven't figured out the timing exactly.

The TPS is good, passed all tests. Is there a year-to-year incompatibility that we don't know about? I think they're all pretty much the same for M42s. The M20 is have looks the same but it's only a WOT sensor. No variable resistance that I'm aware of. Maybe someone else who knows better than me will chime in?

carl6405 · « **Reply #9 on:** June 08, 2009, 10:09:51 AM »

The stomp test, from what I have read, you have to stomp 5 times with in 5 seconds. All the way to the floor and all the way out. Im not getting any check engine light issues. I may go ahead and buy a couple of the $24 coils. I would think that a weak spark will produce these symptoms. In the back of my mind, Im wondering about my DME as well.

Here is the coils on Ebay for $23. http://cgi.ebay.com/ebaymotors/New-BMW-Ignition-Coils-E36-E34-E31-E38-E30-95-96-97-98_W0QQcmdZViewItemQQ_trkparmsZalgoQ3dSIQ26itsQ3dIQ252BCQ26ituQ3dFICSQ252BUAQ252BUCIQ26otnQ3d15Q26poQ3dLVIQ26psQ3d54QQ_trksidZp3907Q2em263QQcategoryZ33689QQitemZ250345432041

DesktopDave · « **Reply #10 on:** June 08, 2009, 10:29:42 AM »

I know that you have to stomp five times, but getting the timing right is pretty finicky on my car. (everything is sorta finicky...

)

I wasn't sure if you had an e36 or not, my e30 has the coils mounted on the inner fender.

BMW's stock COP coils do seem to have some problems, maybe from vibration or engine heat. I heard somewhere that there were two or three major types. One was an update for the older Bosch type. This was for an S52/M52 anyway, so I'm not sure if it's the same for our little 4-pot.

So if you're sure that it's coils, I'd try switching them around. I'd also avoid the cheap EBay ones unless you can verify that they're decent quality. This post quotes $26.60 in response #4:
http://m3forum.net/m3forum/showthread.php?t=235199

There is a lot of misinformation out there about coils, that's for sure!

carl6405 · « **Reply #11 on:** June 08, 2009, 12:16:31 PM »

DD- I have a 93 318i. Yeah, my coils are mounted on the fender well too. Right next to the bolts for the strut. To me, the COP's seem like a bad idea. Heat has a bad effect on electrical components. Especially on softer metals, such as copper. A coil is essentially a copper wound transformer. I dont understand the reasoning behind COP's. I did go ahead and order 2 coils from FCP. After shipping the total is $57. I will replace the two coils with the weakest spark and see if it makes a difference. Right now, the car isnt running terrible, just feels a bit sluggish, especially when the engine is cold.

DesktopDave · « **Reply #12 on:** June 08, 2009, 01:07:42 PM »

You replaced the coolant sensor too. Seems like it shouldn't be doing this...mine's sluggish when it's really cold, but it heats up quickly.