+ Reply to Thread
Results 1 to 2 of 2
  1. #1
    Registered Member
    Location
    Indianapolis, IN, United States
    Member No: 61621 shjlaw is an unknown quantity at this point shjlaw's Avatar
    Join Date
    Dec 2002
    Posts
    56
    Rep Power
    0


    Yes | No

    Maddening Misfire....

    My í87 325is suffers from an aggravating misfire that I have been unable to diagnose. Iím hoping someone here can help. Iíve owned the car for 7 years. It has been rock solid. It has a total of 258,000 miles. Iíve got to add a qt of oil about every 1k miles. The car starts easily, cold or hot, even through the coldest part of the winter (Iím talking -10 and below), but there is sometimes a miss until the car has run for a few seconds. The idle is then a bit lumpy, but steady and solid, and it revs without hesitation from idle. The misfire occurs only at rpms above 4k and generally only during hard acceleration. Hereís what happens: foot to floor; engine revs and pulls strong and fastÖno hint of a missÖuntil there is a sudden, violent engine failure that feels like a backfire. It feels like a single, instantaneous failure. This usually doesnít happen in first, but happens often, but not always, in second and third. It happens so fast there is no time to lift, and the engine immediately picks up pulling as hard as ever right up to redline, as if nothing happened. This phenomenon is sporadic. While it happens more often than not, there are times the thing runs like newÖnot a hint of a miss. The miss occurs at randomly different rpms. It might happen at 4,300 during one stretch of multiple accelerations and then at 5,500 during another stretch. It is less likely to occur with slow, gradual acceleration through the full range, but sometimes occurs even then. That is as well as I can describe it.

    Today, while driving, I was reminded of another variation from the ďnormalĒ in this abnormal phenomenon. Today, the car pulls strongly to 5,400 rpms when it begins to miss, but it will not accelerate beyond that point. It sticks at 5,400 and wonít go beyond. The failure is not as violent as typical and feels much more like itís hitting the rev limiter. Go figure! This odd, changing, unpredictable behavior is a big part of why I am so stumped.

    This is what Iíve done to analyze: just about everything! O2; crank sensor; AFM (have even swapped it);
    Temp sensor; throttle position sensor; fuel pressureÖ. Compression testing: with a max of two compression strokes per cylinder, all cylinders show 130 +/- 5psi. All cylinders come up to 170 +/- 10psi with five compression strokes.

    Iíve replaced the fuel filter and even the fuel pump. Iíve changed the plugs. A couple of the old ones were fouled black. One had a broken ceramic insulator. I checked the replacements just the other day. Theyíve got maybe 2k on them at most. They have an odd, non-uniform appearance: one side of the plug might look like itís burning just right, while the other side of the same plug shows black deposits. Photos are attached. You will also see that there is oil all over the threads of all the plugs. Can that possibly be coming from inside the cylinder? I guessed it accumulated from a valve cover leak. It seems excessive for that, however. Is my engine entering a dying stage? I can live with that. Iíve got a replacement that I can swap in. Iím just stubborn about squeezing as much as I can out of the original motor. I get a sense of pride driving a 25 year old car with the original engine and 258,000 miles. Plus, I donít want to swap motors only to have the new one suffer from the exact same miss. Thatís a possibility until Iím more confident about the cause of the miss.

    Can anybody help?
    Attached Images
    Reply With Quote Reply With Quote 50.90.145.163


  2. #2
    Registered Member
    Location
    Indianapolis, IN, United States
    Member No: 61621 shjlaw is an unknown quantity at this point shjlaw's Avatar
    Join Date
    Dec 2002
    Posts
    56
    Rep Power
    0


    Yes | No
    Update: I read another thread about a very similar, but not identical, problem. It was on this or another forum. One contributor suggested the crank position sensor (cps) could be the culprit. He argued that the symptoms sounded like an ignition timing problem, which could easily be caused by a poor signal from the cps. He insisted that the cps can malfunction even when it tests okay, which mine does. I pulled the cps off another motor I have just to test the theory. Viola!!! The car pulled to redline without a hitch, which it hasn't done in months. I've only driven maybe 10 miles since the swap, but the difference is like night and day. I'm not ready to claim a complete cure yet because I have had a couple of minor hiccups in the few miles I've drive. Nevertheless, the cps made a dramatic difference. It's like a different car. I am very encouraged and am keeping my fingers crossed. Thanks for reading my post. Best wishes and trouble free driving to all. :-)
    Reply With Quote Reply With Quote 50.90.145.163

+ Reply to Thread


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Similar Threads

  1. Misfire Remedy
    By Tony (UK) in forum BMW 2002 Forum (E10)
    Replies: 0
    Last Post: 05-04-2001, 04:09 AM
  2. Misfire
    By Tony in forum BMW 2002 Forum (E10)
    Replies: 2
    Last Post: 04-27-2001, 06:51 PM
  3. 2000 328i cold misfire first 30sec, no codes
    By 330CI Black/Black Nav Sys in forum BMW 3 Series Forum (E46)
    Replies: 0
    Last Post: 03-25-2001, 12:41 AM
  4. strange misfire issue, your thoughts?
    By Corey Turner in forum BMW 2002 Forum (E10)
    Replies: 5
    Last Post: 06-21-2000, 08:16 AM
  5. 2002 misfire and heavy fuel consumption
    By Tall Paul in forum BMW 2002 Forum (E10)
    Replies: 1
    Last Post: 12-30-1998, 06:03 PM

Bookmarks

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum