Messages

1

Engine management / Unable to rev past 3k...

« on: January 07, 2013, 07:37:23 AM »

Well guys- I can't say w/ 100% certainty that it was any one thing, but something I did last night fixed my rev problem.  As I believe I'd mentioned before, my harmonic balancer had a slight crack in the rubber which caused it to "wobble" as it rotated.  Well, last night I installed another balancer from a junkyard car and cleaned the crank position sensor and wallah!  No more rev problems

I discovered, once I removed the old balancer, that it appeared as though perhaps (somehow) the balancer had shifted from center.  I'm not sure how this could happen because the woodruff key was intact, and I don't recall having to put any effort at all into installing it when I had it off the first time.  Perhaps torquing it down with the crank bolt caused it to rotate??  Still doesn't make sense, though, if the key wasn't broken.  So I don't know, but I'm just happy to report that it appears to be back to normal.

Thanks for all the head scratching guys- if not for you guys, I probably would have spent countless hours and money replacing things that didn't need replacing.

2

Engine management / Unable to rev past 3k...

« on: December 17, 2012, 12:15:37 PM »

Got a bit of an update; I was able to pin down a buddy of mine who works at an indy Benz shop, but they had a scanner for BMW's so we hooked it up and were able to see a few things the stomp test didn't reveal.  The only fault code stored was for the No. 2 knock sensor (replaced both knock sensors w/ new Bosch units earlier this past year, while chasing another issue which turned out to be a dead injector), were able to see the intake temperature reading and it seemed reasonable considering the ambient temperature and the fact that the engine was hot when we scanned it.  Coolant temperature readout seemed right as well.  Wish I'd written the exact numbers down, but the scanner honestly wasn't the best one around so I was really just looking for a major red flag here.

He reset the knock sensor code, and we need to scan it again now that I've driven it a while to see if it came back.  My thoughts at this point are:

-something's causing it to knock when cold (failing plug/wire/coil/fuel injector) and the DME is retarding/advancing timing to try to fix the knock, hence in effect "limiting" the revs

OR

-the knock is due to the "misfire" triggered by the DME when the engine is being "limited"

Since I know the knock sensors are new and I in no way touched them (or anything to do with them) while repairing the seals I mentioned earlier, I'm operating under the assumption that they're working correctly.  To me, it's a question of which came first- the knock or the DME reacting to the knock..if that makes sense.

In regards to my first suspicion about a failing component, the plugs have probably less than 10k miles on them, although they aren't the copper plugs I've read so many places that our engines seem to prefer; they're Bosch dual-tipped platinums, whichever ones are outlined in the owner's manual.  I checked resistance on the coils back this summer (when the plugs were replaced) and they all checked out just fine, and one injector has been rebuilt; no. 3 I believe.

3

Engine management / Unable to rev past 3k...

« on: December 13, 2012, 07:41:10 AM »

All good advice keflaman; and to answer your question, I toyed around with mine a little when I was leaving work yesterday and it did its' usual cut-out at around 2250 in gear, but to my surprise, when clutched it would run up to ~3000 before hitting the cut.  But, again, the longer I drove, the better it got.  Even hit the actual limiter on the interstate once it was up to temp.  So I don't know!

I've got a week off coming up so hopefully I'll get in and poke around some more.

4

Engine management / Unable to rev past 3k...

« on: December 12, 2012, 07:34:24 AM »

No, although I did have the battery disconnected for a few days while I was replacing the seals I mentioned before...but I don't understand how a problem like what I'm experiencing would have anything to do w/ a ground strap?

5

Engine management / Unable to rev past 3k...

« on: December 11, 2012, 12:18:23 PM »

Greetings, all-first time posting here, but long time member over on Bimmerforums.  I've been having a similar problem w/ my car (95 318i m/t, 215k and counting) for going on a month now.  I've just been living with it until I find a solution I can bite my teeth into, but I wanted to share my experience because it's a little different from what's being described here and maybe it'll shine some light on what could fix either or both of our problems...

Similar to what Hunsbergring is describing, my car won't rev past a certain RPM, but where my problem seems to differ from Huns' is that mine is seemingly completely temperature related. I.E., from a cold start (on a cold morning, say 30* ambient), it usually will top out at 2500RPM; however, as the engine warms up, the rev cut will gradually rise until it finally will rev all the way to ~6300 when the engine is at normal temperature, and that will remain the case until the engine cools off again.  As w/ Hunsbergring, the "cut" feels very precise and computer-controlled; the engine runs strong all the way up to whatever RPM it cuts out.  Other than this, I've noticed absolutely nothing out of the ordinary as far as performance is concerned.  The stomp test is clean, haven't ever had a CEL, so I'm kinda stumped...

It all started after I decided to replace my front main seal and the gaskets on the oil filter housing.  During that process, I (unfortunately) had to replace my alternator due to one of the studs breaking off my original one.  Other than this, every part I put on the car came off the car, and I've triple checked my handiwork and can find no loose ends there.  The only thing I can knowingly say may have something to do with this is the fact that I noticed while it was removed that my harmonic balancer is slightly out-of-round due to a crack in the rubber at its' base.  I have another balancer out of a junkyard car that appears to be in good shape, but I need to order another crank bolt before I can replace this.  My thought there is perhaps the CPS is getting a bad reading due to the balancer wobbling, but I don't understand how this could be anything temperature-related :confused: Unless it's something as crazy far-fetched as the wiring continuity changing w/ engine compartment temperature, or the rubber on the crank pulley becoming more pliable and it wobbling less once the engine is warm.  But both of those seem to be so far-out in my mind...I can't imagine the tolerances are close enough for either of those theories to have any merit...

As with this thread, people on Bimmerforums suggested O2 sensors, IT sensor, MAF sensor, fuel issues, etc. etc.  But seeing what all Hunsbergring has tried, I'm hesitant to just start throwing money at some pretty expensive sensors.  Granted, I haven't changed anything since this problem started and it's been consistent for over a month now.

Any suggestions are appreciated.