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Mercedes E500 M113 fuel related single cylinder misfire

  • Shortie
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11 Mar 2018 06:42 #18815 by Shortie
bought car with rod knock , used motor installed / old motor spun bearing and block damage / vehicle runs just misfire on one cylinder on new used engine cylinder #5 misfires , all other cylinders are working fine, new dealer oem plugs,coils , and wires/ water pump, ect , everything relating to new engine install . P0305 code after install a mass air flow sensor code was present installed new oem MAF ,swapped injectors/ coil / wires/ and plug from 5 cyl. to cyl 1, noid light result on cylinder 5 steady lit bright light with ignition on, no blink or pulse when cranking or running steady bright noid light / all others pulse on cranking of the engine and when engine runs , checked for short to ground from injector - plug to ecm no short (i physically took apart wire harness to inspect wires) injectors, coil are within ohm spec. i condemn ecm , sent computer out had it rebuilt new fuel drivers installed and board cleaned /got ecm back now no light on noid light , no blink no pulse on cylinder 5 all others fine . 12 v on 1 +wire of injector connector -10 mili amps on negative side on dvom . i cant figure this out, since ecm came back codes present p0305 misfire cyl5 / p0155 o2 heater circuit bank 2 sensor 1, would this be an intentional injector shut down by ecm?

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11 Mar 2018 11:41 #18834 by juergen.scholl
Replied by juergen.scholl on topic Mercedes E500 M113 fuel related single cylinder misfire
With the P0305 cleared the ecm should pulse - at least initially for a couple of seconds - the injector. You may want to disconnect an injector/coil on another cyinder in order to verify the pcm's strategy in this case...
Chances are that your pcm still is bad if the involved components and the wiring proof good.

An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.

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11 Mar 2018 13:11 - 11 Mar 2018 13:21 #18838 by Shortie

juergen.scholl wrote: With the P0305 cleared the ecm should pulse - at least initially for a couple of seconds - the injector. You may want to disconnect an injector/coil on another cyinder in order to verify the pcm's strategy in this case...
Chances are that your pcm still is bad if the involved components and the wiring proof good.

I leaning towards ecm still bad as well , this is what I'm getting from the wire corrosponding with the ground side of the injector from ecm. Yes I cut the wire, so that is the gray-yellow wire from ecm pin 28 on the schematics , this ecm is vin coded , so I can't just swap ecm in this case. And I am getting running voltage on the other side of injector plug. Just double checked. Other injector and coils as. Quick Compression test 150 psi, didn't do leak down test though. well.

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Last edit: 11 Mar 2018 13:21 by Shortie.

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11 Mar 2018 13:21 #18840 by bruce.oliver
Volt meter isn't a very good choice to check an injector circuit. It is not any where near fast enough.

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11 Mar 2018 13:30 #18843 by Shortie

bruce.oliver wrote: Volt meter isn't a very good choice to check an injector circuit. It is not any where near fast enough.

I'm home it's Sunday, i ran out side just now and did a quick double check, on other coils and wires , can check with my scanner at the shop this week.

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11 Mar 2018 13:53 #18846 by juergen.scholl
Replied by juergen.scholl on topic Mercedes E500 M113 fuel related single cylinder misfire
A quick glance at the schematic invites to check the other wire from injector terminal 2 to pcm terminal 21 as well.....

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11 Mar 2018 14:00 #18850 by Shortie

juergen.scholl wrote: A quick glance at the schematic invites to check the other wire from injector terminal 2 to pcm terminal 21 as well.....

This diagram on my phone is for v6 and v8 engine U50 is for the v6 u51 is for the v8 versions, i double checked that on all data , pin 28 on plug #3 of the ecm is it. For v8

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16 Apr 2019 18:54 #28759 by Shortie
Problem solved, new computer shop, bad inector driver on main board.

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