Help guys 348 has been running ok until last weekend and then.......... Went on a run (all was well), scraped the belly on a speed bump :-( and then idled in a heavy queue for 30 mins. Parked the car and thought all was ok. Came back to the car and it started ok but didn't sound quite right (not mis-firing as such but different to her normal self) Got home ok and thought i'd have a look around underneath. The fuel tank guard had dislodged and looked like it had interfered with the front crank sensor data cable. I did a system re-learn and upon starting the car it was constantly spitting and banging from the exhausts - so much so that i just shut it down. Front crank sensor problem? Any idea's guys?
It's hard to believe that there could be anything seriously wrong with your car, but I would make sure that the timing belt cover has not been damaged by your impact with the speed bump. If you can see a definite sign of trouble with the wiring to the front crankshaft sensors, then I would correct that first, especially if the problem started directly after you bottomed out. It doesn't look possible to me that you could have flattened the bottom of your muffler, or knocked the thermocouple off the bottom of the exhaust, but it wouldn't hurt to look. The crank sensors have been known to cause problems from broken, loose, or oily wiring connections. Just to be sure, you say that you did a "relearn" on the Motronic system (which was a good thing to check). Are you famiiar with the procedure for this? In particular, you didn't touch the throttle pedal when you restarted the engine after disconnecting and reconnecting the battery? The only other thing that comes to mind is to make sure that the rubber intake boots are properly attached so that there are no vacuum leaks at the throttle position sensors or airflow sensors. Does your UK car have downloadable Motronic fault codes? Please keep us updated on what you find. Good luck.
Militonian, i am following a process of complete logic here - although i may be wrong. Car was running perfectly en-route to this Ferrari meet and had been for many months. The car grounded on the speed bump only a few miles away from the meet, so at best i was doing 3000 rpm between hitting the speed ramp and attending the meet. Inbetween time, the car was idling for 30 mins on the queue into the Fcar meet - no problems. Upon leaving, car didn't sound "right" upon starting but was driveable ok for the 40 mile jouney home. On the way home, the car woul;d drive ok BUT if revved hard in 2nd or 3rd gear would misfire at high revs (7000 rpm +) - commensurate with a front crank sensor issue. Upon getting home car was running rough also on idle and "popping" - not mis-firing, just popping from the exhaust. I disconnected the battery overnight, and did a relearn in the morning. Flicked the key and it started first time as usual and (without touching anything) let her warm up. Car had pronounced popping and banging from exhaust (all items functioned - air valves, rad fans cut in correctly etc), but after re-learn i tried moving the car and it just stalled. Never done this before. I shut her down and upon closer examination of the front crank sensor wiring it looks as though the fuel tank shield has moved backwards, removed the rubber boot from the wiring harness (pushed it back) and compressed one of the wires (3 wires on the connector) going to the crank sensor. I've gently squeezed the compressed wire with some pliers (it's now round again ) and cleaned / reconnected the wiring but haven't started the car since Do you think this may be the problem?
I think if I were in your position, that's the first thing I would try. The wires and pins are rather fragile, as you have seen, so take a good look at that harness to see if the wires may have started to fray. It sounds like you did the re-learn exactly correctly. I'm not sure of the configuration on UK cars, so I ask again - do you have "check engine" lights on your dash and "pigtails" and pushbuttons on the Motronic ECU's so that you can download stored fault codes? The stalling is curious. Again, I'm wondering if maybe the popping and backfiring MAY have blown off one the engine vacuum hoses. Did you check for that? Others please pitch in, let's get this gentleman back on the road ASAP!
No engine check lights on my dash - UK car. 1992 2.7 Motronic. The only other thing that i had changed for this Ferrari meet was the radiator cap for a nice new shiny one but temps were normal and fans cut in correctly and correct Ferrari part was fitted. Logic dictates at the moment that........it's related to front crank sensor cables as these are the only things that got disturbed between the car running fine for months and months, hitting the speed bump and now rough running? I might add that the car starts ok and revs ok but on idle is "popping" loudly from the exhausts.
Update Guys, OK, prior to fitting the new fuel tank guard (that got wrecked on a speed bump), i unplugged the front crank data cables (one of the cables was missing it's spring clip and held on by a cable tie) gave them a thorough cleaning (including the sensors), found a new spring clip and plugged everything back together. Whilst the car was in bits, i renewed all of the domed nuts on the plenums and cam covers and thoroughly cleaned the rear suspension and exhaust manifolds. The exhaust manifolds are now a nice bright silver With fingers crossed, turnt the ignition key and fired her up. She started immediately with absolutely no throttle depression (as she always has done) and i then left her well alone to gone through the re-learn process. Things are looking good, air injection valves running (i love that sound), no misfiring indeed she was purring like a kitten. I allowed the fans to cut in twice before touching anything and all seems well Idles like a purring kitten and growls like a savage beast when revved (decatt X OST) So, hopefully my problem is resolved. It would appear that the front crank sensors / wiring to this part is particularly sensitive so if you have any rough running or mis-firing - this is well worth checking first.
So I take it that we all need to watch ourselves when flying over speed bumps? Glad you got it sorted out.
