BMW Forums : BimmerForums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Driving along the motorway, car was running as normal. There was a slight 'splutter' when driving along at 70mph, but then returned to normal.

15 minutes later, after cruising along at 80mph, it was as though the accelerator pedal became unresponsive. There were no warning lights, everything else was running fine, no strange noises, the rev counter went to 0 and the accelerator pedal wasn't getting any power to the engine. I switched down gears (engine braking was fine) and the accelerator pedal was still not responding. Car was behaving as though I had just lifted off the accelerator and carried on decelerating.

I pulled over and switched off the engine. Tried to switch it back on, it would crank but not come back on. The DTC warning came on briefly and it has not been able to start since.

Mechanic plugged it into diagnostics and said it showed up random error codes. He said the fuel pump and fuel filter were fine and referred the car to a specialist. The specialist just sent off the ECU to be examined.... has anyone had the same problem? or have an idea what may be wrong with the car?

The plastic casing the ECU sits in had no water ingress.
 

·
Registered
Joined
·
166 Posts
Crank sensor could be a culprit, as the sensor fails, the rev counter cuts out to zero as it's not getting an engine speed from the sensor. It usually doesn't throw an error code, because as far as the ecu is concerned, the engine has stalled which is why it won't accelerate, or start up (as it cant see the engine being turned over).

You might find it will start when the engine is cold, as 90% of cases of this sensor failing happens when the engine is at operating temperature.

I had the same symptoms with my last car and this was the fault. Replaced the crank sensor and all was well.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #3
Well the ECU was inspected and was found to be fine. Upon reconnecting the ECU, the car started up first time with no problem. The car was running fine for an hour before it cut out again at speed, when I took it for a test drive. Exactly like the first time, cut out and decelerated until I pulled over and switched off the engine. Tried starting, haven't been able to get it started.

So why was it that when I reconnected the ECU, it started up first time?
 

·
Registered
Joined
·
125 Posts
What year is your car ?

Depending on year it could be the Fusebox power connection issue which causes the car to cut out....

Dean
 

·
Registered
Joined
·
166 Posts
Well the ECU was inspected and was found to be fine. Upon reconnecting the ECU, the car started up first time with no problem. The car was running fine for an hour before it cut out again at speed, when I took it for a test drive. Exactly like the first time, cut out and decelerated until I pulled over and switched off the engine. Tried starting, haven't been able to get it started.

So why was it that when I reconnected the ECU, it started up first time?
Re-read my post.

When a crank sensor fails, it throws no codes. It will be fine when you start an engine from cold, but once warmed up, the sensor internals fail.

A replacement costs between £30-50, worth doing that before looking at the expensive stuff like wiring or ecu issues.
 
1 - 5 of 5 Posts
Top