BT50 being shifty
during starting is closed loop.
In my viewvie it’s taking too long before injection startssta – 1.3 seconds just does not seemse right, thatth t i is aboutb t fi five revolutionsl ti or so.
Injection on a common rail diesel engine starts only when the rail pressure is high enough and when a proper cam and crank sensor signal is received by the ECU.
The rail pressure seems to be there in the beginning of the pattern, but we’re not sure if it was enough. I asked the diagnostician to up the rail pressure sensor’s voltage with the ATS 500XM’s signal generator. He added up to 0.3V, which made no difference in the startability of the BT50.
We had to concentrate on the crankshaft sensor signal. We have had a number of real nasty experiences with BT50 and Ranger starter motors, where a good sounding starter motor was upsetting the crankshaft sensor signal just enough to stop the engine from firing up. After rebuilding that starter motor by an auto electrician the vehicle would still not start.
In those cases replacing the starter motor with an aftermarket one still had the exact same result, no start, or very hard to start.
This is where anyone seriously starts to doubt their skills, but after a lot of further diagnosing, replacing the starter motor with a genuine starter motor solved the issue on those vehicles.
The diagnostician was aware of the starter motor issues. He rebuilt the starter motor, but no improvement
I told him that it was better to analyse the crankshaft pattern first, as the starter motor leaves a very small mark on the crank pattern, before he should purchase a brand new genuine starter motor. The diagnostician made the decision to replace the starter motor without measuring the crankshaft sensor as it is in a bad place. Also this case had every symptom of the common starter motor issues. Result: no improvement! Because I wanted to know if there was a crankshaft sensor issue I asked the diagnostician to measure the crankshaft sensor (voltage over current). I wondered if the ECU in those BTs was responding to