Good morning,
I have a problem vehicle at the moment, a couple of weeks ago I was called out to take a look at a 2016 Fiat Doblo Cargo. It is a 1.3 Multijet 90, engine code 263A2.000 with a Marrelli ECU. The garages' complaint was that the van started fine (maybe a little longer than expected cranking time) from cold but as the engine reached normal operating temperature the exhaust emitted white/grey smoke and it caused stinging to the eyes, (basically unburned fuel).
A quick check of dtc's and none recorded save for a glow plug circuit error, a new glow plug will fix this fault.
As white/grey smoke is a sign of unburnt fuel and as the garage had already replaced the injectors, I did a quick relative compression test also with a channel connected to No.1 injector circuit. I have attached a file which clearly shows the injector is firing after TDC. With this information I advised the garage that I suspected an issue with the valve timing.
The garage stripped the timing side of the engine and sure enough the chain was indeed slack and the cause was a faulty chain tensioner. All worn/failed parts were replaced and the engine retimed using the correct locater pins in the cam and crank. (just for info, the chain drives 1 cam at the front of the engine and the other cam is driven by a gear train at the rear of the engine).
Unfortunately this has not altogether fixed the fault; the vehicle still starts, but with a slightly longer cranking time than I would expect and still emits a white/grey smoke when warm. I have checked that the EGR valve is actually closing and done yet a further cranking compression waveform capture; although the injection event is now a little more advanced I still thing it is retarded.
So can anyone please advise the pin location for cam and crank at the ECU as the crank sensor is virtually impossible to back probe and maybe a cam and crank signal capture.
I have attached a cranking compression waveform from a later (2018) vehicle which shows the first injection event is BTDC followed by further injections at TDC and ATDC, whereas the 2016 vehicle the injection events are all ATDC. I have attached a screenshot of an in cylinder waveform of the still faulty vehicle which looks like the intake valve is actually opening 21* ATDC (if the waveform can be relied on as being a fault??) I would really appreciate any comments please.
Many thanks for reading,
Gary
Fiat Doblo Cargo 1.3 Multijet idle quality and more
Fiat Doblo Cargo 1.3 Multijet idle quality and more
- Attachments
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- Fiat_Doblo_2018 known good.psdata
- (837.87 KiB) Downloaded 48 times
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- Fiat_Doblo_2016_Diesel_20230309-0001.psdata
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Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
Нi.
.
Post-injection is not used in this mode.
Two pre-injection and main injection are used.
The timing of the main injection usually coincides with the TDC.
If the injection occurs after TDC, then there is a displacement of the reference point.
The ECU calculates the TDC based precisely on the signals of the crankshaft sensor.
In this example, there is no correspondence between the actual TDC and the calculated TDC.
Just an opinion.
.
Post-injection is not used in this mode.
Two pre-injection and main injection are used.
The timing of the main injection usually coincides with the TDC.
If the injection occurs after TDC, then there is a displacement of the reference point.
The ECU calculates the TDC based precisely on the signals of the crankshaft sensor.
In this example, there is no correspondence between the actual TDC and the calculated TDC.
Just an opinion.
Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
Many thanks for your reply, it can be seen that the 2 pre injections are actually after TDC and the main is very late. I already understood where the injection event should occur. I was hoping for a known good just so I could convince the garage who had carried out the chain replacement that there was an issue with the camshaft to crankshaft placement.
Gary
Gary
Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
I have just spoken with the garage that asked me to take a look at this vehicle and they are adamant that the timing pin locking tools were used correctly, so a known good cam/crank waveform capture would be a great help. I would expect the position hole in the flywheel to be a drilled hole in the actual flywheel and not referenced to the reluctor itself. Just thinking outside the box, if it was referenced to the reluctor and the reluctor had moved its position, then the computer would still be happy with the cam to crank sync and consequently trigger the injector (albeit in the wrong position of the firing stroke). Grrrr.....a known good would still be helpful though.
Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
Pulse generator is attached to the flywheel. If it had this replaced, theoretically could of been wrong mounted. Post your captures 1st,
maybe someone has something? And put photo of ecu wires so someone else can do a capture as well?
maybe someone has something? And put photo of ecu wires so someone else can do a capture as well?
Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
Many thanks for the reply,
Apparently the timing tool for the crankshaft position is inserted through the bell housing into the flywheel, now I have no idea if it inserts into the reluctor or the flywheel itself. It did cross my mind that if the timing pin located into the reluctor and the reluctor for whatever reason had moved then the PCM would be happy and trigger the injector according to the information it had received from cam and crank. Whereas if the timing pin locates into the flywheel and the reluctor had moved I would have expected a cam/crank correlation error.
As already stated there are no error codes. I think it may be time for the garage to remove the gearbox and have a look to check how the crank signal is generated. First though, I have finally managed to get hold of a wiring diagram for the pcm, so I will grab a cam/crank waveform and post here.
regards,
Gary
Apparently the timing tool for the crankshaft position is inserted through the bell housing into the flywheel, now I have no idea if it inserts into the reluctor or the flywheel itself. It did cross my mind that if the timing pin located into the reluctor and the reluctor for whatever reason had moved then the PCM would be happy and trigger the injector according to the information it had received from cam and crank. Whereas if the timing pin locates into the flywheel and the reluctor had moved I would have expected a cam/crank correlation error.
As already stated there are no error codes. I think it may be time for the garage to remove the gearbox and have a look to check how the crank signal is generated. First though, I have finally managed to get hold of a wiring diagram for the pcm, so I will grab a cam/crank waveform and post here.
regards,
Gary
Re: Fiat Doblo Cargo 1.3 Multijet idle quality and more
I’ve never saw an engine having timing check against a fragile pulse generator wheel. That would be crazy.