My wife's 2002 325i was fine when she came home last night. This morning, it starts readily, but surges between 500 and 1500 rpm every two seconds or so for about thirty seconds, and then settles down to surging slightly around 1000 rpm. It will not rev any higher, and makes no useful power. The "check engine soon" and "ECN" lights are on.
Has anyone seen this behavior?
It has been flat-towed to the dealer, but they're so backed up that we won't get it back this week. I'm interested in anyone's relevant experience to use as a cross-check on whatever diagnosis they give us. TIA.
Sorry to have to tell you this (it happened to me as well) its the engine management module, or whatever it's technical term is, ie the computer and the unit needs to be replace. I was lucky and got it paid for on the warranty. Can't recall the cost but it was hundreds of pounds.
Don't be so hasty; it could be a number of things other than the ECU. For instance, it could be the crankshaft position sensor. It could be a plugged catalytic converter. It could be a cracked intake hose. It could be a new mouse nest in the air intake.
It could be that the battery needs to be unplugged for a few hours to completely reset the ECU and anything else needing battery power. Give that a try and see if it works. Couldn't hurt and may save some money.
Remember reading that a UK independant who supplies re-condition ECUs purely on an exchange basis found the *majority* of them had no faults found when tested.
Seems to have - when the one on my E39 failed the engine still ran which would be impossible if it was the sole means of timing the spark. Perhaps the cam position sensor takes over?
I always thought that this was an urban myth until I left my 320i garaged over winter and when I opened the bonnet to check the oil etc I found a little nest and pile of seeds between the suspension turret and the fuse box :-)
Oh no. Far from any sort of myth, but more likely rural rather than urban, don't you think?
I get problems from the wee rodents all the time, even on vehicles that don't sit more than a couple of days between uses. Watch for telltale signs in the blanket they put up over the engine on the hood (bonnet) for sound proofing. The rascals seem to really be keen on burrowing up in there first. Maybe while the engine is still warm?
In fact, here's a funny story. I have a '98 Honda VFR800 that I picked up used last summer for a song. It had only ~12k miles and ran like a dream. Nary a problem. I decided that since the bike had unknown maintenance performed by unknown prior owners and unknown storage conditions, I would do everything that should have been done in the first 12k miles and start my maintenance schedule afresh.
When I pulled off the air box cover to put in a new filter the upper part of the box was jam packed with all sorts of mousey detritus. Empty acorn shells, hay, mouse poop, you name it... The best news was that even though the rascal(s) had also been ingesting the paper from the filter, they has not breached it entirely and so none of the nestings had been ingested by my engine (yet). Phew...
In my powerboat, I put several old cigar boxes full of mothballs in the boat before I seal it up tight with shrink wrap for the winter. I've never had a single sign of mouse activity in there after 5 years of winters. In fact the boat smells of the balls well into the summer.
Well, got the diagnosis today, *one week* after having it towed in: electronic throttle failure, to the tune of $1511.00 US.
The service agent said the fail-safe mode of the electronic throttle allows revving up to 2K, but if you try to go over 2k, it shuts the engine down -- which is not the behavior I was seeing.
Then the advisor tells me the car needs level one service (done two weeks ago), and new wiper blades. Of course, I put brand new PIAA silcones on there about three weeks ago, so that's a clue as to how straight this supposedly top-notch BMW dealer is. 8;)
This is a 2002 325i with 34,000 miles on it. Has anyone heard of electronic throttle failure on a like car, or of any attempts to get BMW to eat some or all of it out of warranty?
OMG. They could have told you that for a few minutes and an OBD2 diag machine. My BS flag would have gone off at that point. Just a guess, but this is not a good showing for the shop it went to. (sprinkle in some choice colorful metaphors!)
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