M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Electrical => Topic started by: silence on May 27, 2009, 08:58:28 PM
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Hey guys, I changed my oil today after work, changed my spark plugs, and spark plug wires with some lightly used wires from the Junkyard. I put everything back together in the correct order, and the car won't start, it just stumbles and pops. I put the original wires back on and it still does the same thing. I put the original plugs back in and it still wont start. I have tried looking for the correct firing order, but there seems to be a lot of misinformation based on the e30 and e36 versions of the m42. Can anyone tell me with all certainty that the firing order really is: 1-3-4-2
thanks!
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Absolutely 1-3-4-2. No. 1 is at the radiator. I was unaware of any differences between these engines, mostly every inline 4-cyl is this way.
I was cleaning up my engine and noted that the plug wires kind of twist around in an unusual way. Are the wires plugged into the right coils? Coil pack secondary plugs tight?
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DesktopDave, I have them in the correct order and the car still will not start. It misses and backfires super loud when i try to start it. Next I plan on checking the spark. Let me kow if there is anything else i can check. thanks
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I would really make sure that the wires are in the correct order. The wires could be bad, though 1 bad wire would still allow the car to start it would just run like crap and chug along. First, I would make sure that all four plugs are firing, then I would turn the car over for a few seconds and check the plugs for differences. If all you pulled was the wires and plugs then it goes without saying that your problem is likely in the reinstallation of the plugs and wires.
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THanks for your help guys, I cleaned and gapped all the old plugs at .025, i'm getting spark on all 4. The car cranks, but will not start. I have them 1-3-4-2 starting at the radiator. WHat else could this be?
*edit* Im going to re-gap them at .030 tomorrow.
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The plug wires have to also be 1-2-3-4 from the radiator, matching the cylinders. The computer and coils determine plug firing. Don't put the wires on according to firing order...the engine will never start!
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The plug wires have to also be 1-2-3-4 from the radiator, matching the cylinders. The computer and coils determine plug firing. Don't put the wires on according to firing order...the engine will never start!
Hi Dave, that contradicts what you said in your earlier post. Which is it? 1-2-3-4 or 1-3-4-2?
BTW, today i gapped all the plugs at .030, and it still wont start at 1-3-4-2.
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I'm not contradicting my earlier post. The wires, coils and cylinders all have to match. The firing order, 1-3-4-2, is controlled by the computer. It fires them automatically. What you've done if I understand correctly, is install the plug wires on the wrong plugs. It'll never start that way. The #1 coil runs to the #1 wire which goes to cylinder #1 on the front of the motor.
Pull those wires, match them up 1-2-3-4 and it'll fire right up. I'll take a pic of mine if you need to see what it looks like.
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Hi Dave, I appreciate your help. I'd love a pic, and i'm going to try it in that order tomorrow.
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I forgot my photobucket password, so I'll just describe it until I can get pics posted. If you're looking over the pass side fender, my coils are numbered like this:
3 4
2 1
The wires had to be in the right order to fit into the little rail that goes into the head. Wire #1, from Coil #1, was first in the little rail and runs to Cyl #1 in front. Wire #2 runs from Coil #2 to Cyl #2 next. #3 & #4 were a little different. They still run 3 to 3 to 3 and 4 to 4 to 4, but IIRC #4 looped around 3 and then to #4 cyl. It's just to make the wire fit under the cover, I didn't see any particular reason for it.
So, unless the coil secondary plugs from the engine's wiring harness are swapped, it's a straight match. I didn't pull them to see if they were keyed, but you didn't mention anything about them so I'll leave them out for now.
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Its alive!!!!!!
Desktop dave, I want to thank you for your help and persistence. Yur description was just what i needed, I went out side, swapped them to 1-2-3-4, and made sure the coils were correct. It still wouldnt start...but i remembered a friend of a friend saying to hold the gas down, so i cranked again with WOT and viola, SHE STARTED AFTER ABOUT 10 SECONDS!!!
THanks again!
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You're very welcome. Pass it forward.
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i'll be happy to.
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Good shit.