BT50 be­ing shifty

Motor Equipment News - - DIAGNOSTICS -

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

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