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Thread: Ignition issue

  1. #26
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    Quote Originally Posted by rogbmw View Post
    I do not understand why people make the comments about the Bosch plugs. The Bosch f8 LCR plugs were what was installed by BMW as OEM plugs. There is nothing the matter with them.
    It's because Bosch F8LCR is a 10k OHM resistor plug, if your ignition system is 100% top notch condition it will run (still not as well as it should) but if your ignition system is old and tired, old coils and so on 10k ohms will be too much to handle and the car will run like crap. OEM Bosch plugs were rated at 1k ohm, the only plug that is similar to this is NGK BKR6EK.

  2. #27
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    Quote Originally Posted by dragon850 View Post
    It's because Bosch F8LCR is a 10k OHM resistor plug, if your ignition system is 100% top notch condition it will run (still not as well as it should) but if your ignition system is old and tired, old coils and so on 10k ohms will be too much to handle and the car will run like crap. OEM Bosch plugs were rated at 1k ohm, the only plug that is similar to this is NGK BKR6EK.
    4k 5k 6k 10k, nobody knows how much they actually resist but we do know they tend to make cars run like garbage.

    Had a guy replace his plugs because of oil burning from the VCV, old ones were NGK BKR6EKs, new ones are the 7959s. Ran smooth for a little while and now it's decided to go rough again so I've told him to clean the old ones up and check. These NGKs do make the difference, it should be a sticky.

    New coils and leads? Do whatever you want.
    Last edited by XAlt; 07-27-2017 at 12:23 PM.
    Quote Originally Posted by WBAD530i View Post
    M62 is an uncontrolled substance, and when abused can cause severe side effects. Do your drugs in moderation kids.

  3. #28
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    Correction the F8LCR are 6k OHM which is still too high unless you are running MSD blasters.

  4. #29
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    I beg to differ. Original Bosch F8LCR plugs are 1K ohm (just bench tested), Replacement Bosch FR8LC plugs are 6K ohm. At least up here in the frozen North! 8-)
    91 850 (Panzer), 2012 Mini Cooper Countryman (WifeMobile) www.wuffer.ca

  5. #30
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    FR8LC+\7959 is the supposed replacement to the F8LCR that came with our V12s.

    The twin electrode F8LDCR (notice the D) has resistance similar to the NGK BKR6EK at around 1.5k ohms, and is a more suitable replacement than the 7959. However, that has been more recently replaced by the 7404\FLR8LDCU with around 4-5k resistance values.

    In other words, Bosch no longer offers a direct replacement for what they put into our cars.
    Last edited by XAlt; 07-27-2017 at 12:49 PM.
    Quote Originally Posted by WBAD530i View Post
    M62 is an uncontrolled substance, and when abused can cause severe side effects. Do your drugs in moderation kids.

  6. #31
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    Quote Originally Posted by Wuffer View Post
    I beg to differ. Original Bosch F8LCR plugs are 1K ohm (just bench tested), Replacement Bosch FR8LC plugs are 6K ohm. At least up here in the frozen North! 8-)
    Correct, I meant the FR8LC at 6k ohm, sorry no coffee yet lol. The F8LCR are no longer available.

  7. #32
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    The F8LCR are no longer available.
    True, but the dilligent surfer can locate new old stock on occasion. I have 3 such sets on my shelf as well as a set of NGK BKR6EKs...OCD methinks!
    91 850 (Panzer), 2012 Mini Cooper Countryman (WifeMobile) www.wuffer.ca

  8. #33
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    o.k., back to his problem, last info was: "After replacing caps, rotors, leads and plugs everything was working beautifully for a couple of days. Now the misfire is back. It's like a little burp every 2-3 seconds. Feels like ignition miss but I've replaced everything in the last few thousand kms"

    It was mentioned to replace or swop the ignition coils. But if it is a problem of the ignition coil, why only a little burp every 2-3 seconds? There is only one lead between ignition coil and distributor, distributors+ rotors are new, leads are new, plugs are new...

    On the other hand wuffer and other members suggest to change old ignition coils anyway as preventive maintenance, before they destroy more https://www.bimmerforums.com/forum/s...=ignition+coil
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  9. #34
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    Quote Originally Posted by rogbmw View Post
    I do not understand why people make the comments about the Bosch plugs. The Bosch f8 LCR plugs were what was installed by BMW as OEM plugs. There is nothing the matter with them.
    That's what I thought. Bit of an (expensive) minefield sorting fact from BS sometimes on the forums!! Thanks for your feedback. Now I have a spare set of perfectly good plugs!!

    - - - Updated - - -

    Quote Originally Posted by shogun View Post
    o.k., back to his problem, last info was: "After replacing caps, rotors, leads and plugs everything was working beautifully for a couple of days. Now the misfire is back. It's like a little burp every 2-3 seconds. Feels like ignition miss but I've replaced everything in the last few thousand kms"

    It was mentioned to replace or swop the ignition coils. But if it is a problem of the ignition coil, why only a little burp every 2-3 seconds? There is only one lead between ignition coil and distributor, distributors+ rotors are new, leads are new, plugs are new...

    On the other hand wuffer and other members suggest to change old ignition coils anyway as preventive maintenance, before they destroy more https://www.bimmerforums.com/forum/s...=ignition+coil
    Yes, I thought failing coils would have a different effect but they are the only part I've yet to replace. Going to pull the plugs again this weekend and see if there is any oil, etc on any of them. Perhaps a worn valve seal is fouling the plugs. Recently serviced all the injectors so I'm confident they are all okay.

    Unfortunately, just haven't had the time recently to properly investigate and doing it in dribs and drabs is not a very effective way of diagnosing the problem.

  10. #35
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    Followed MIKYZZ4's advice. Ran her in low light, mist tested, etc but nothing out of the ordinary. Pulled the plugs and they all look normal. No sign of oil, etc. Drove her today and she was perfect. I'm stumped. The only difference is today was a stunning (cold) day, on the last few drives it's been wet and, although she's kept undercover it's not always completely dry as it's a carport not a garage. Guess a bit of moisture could be getting in somewhere but, if so, I had hoped the mist test would reveal where.

  11. #36
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    I was confident that the mist test would have revealed the failed component.
    It seems I am stumped as well.
    Btw, check for condensation moisture under cap when symptoms appear again.
    "Choosing the correct shop is as important as the correct diagnosis

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  12. #37
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    Quote Originally Posted by MIKYZZ4 View Post
    I was confident that the mist test would have revealed the failed component.
    It seems I am stumped as well.
    Btw, check for condensation moisture under cap when symptoms appear again.
    Yes, good idea!

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