Vivaro 1.9 DTI F9Q760 no power/boost below 2.5k rpm.
Discussion
Not the most PH of vehicles I know, but I do use it for carrying my motorbikes around!
I'm not a terribly good technician, completed two years of a three year NVQ apprenticeship in garages some while back which has given me enough skills to get by, but I'm starting to dabble more in diagnostics and hoping there's some more knowledgeable folks out there than I that might be able to give me a few pointers.
Using a cheap copy of Op-Com and an old laptop.
So the van is very slow to rev up to 2.5k with low boost readings, then at 2.5k everything comes in at once and it takes off. Though from 2.5k to the 4.2k redline it still surges in and out. Makes little difference when hot and cold, though it doesn't run brilliantly for the first 30 seconds when cold I think that may be a separate issue, just want to sort them one at a time. Few things I've checked already:
No DTCs present.
Fuel filter, air filter and exhaust are all clean and clear.
Compression is an even 300psi+ across all cylinders.
Glow plug circuit is all working properly, plugs are 12 month old Beru items.
Cam timing is spot on.
Injector leak back test was approx 30ml after a few minutes of idling and varying revs, the same on all injectors.
Vacuum pump is pulling a strong 30in/hg+ from idle. (maxes out my gauge anyway and the brakes work fine)
Bypassing the boost solenoid by plugging the vac pipe from the pump straight to the turbo OR activating it manually with a mit-e-vac has the same result, the boost above 2.5k pulls a lot harder but still no change up to 2.5k. This tells me above 2.5k the boost solenoid is responsible for my boost surging in and out, but whether it's the solenoid at fault (it's also a 12 month old genuine part) or it's getting a surging command from the PCM I'm not sure.
Turbo wastegate is free to move, it closes right up once started at idle.
Have done various wiring repairs around the engine and underneath the ECU, blue multiplug has been binned and all connections remade.
Into the live data, and this is where I'm struggling somewhat.
Both throttle pedal positions read perfectly. Cam/crank synch OK, fuel rail pressures OK. Boost pressure as expected hovers at less than 100 kpa and stays flat until 2.5k when it jumps up, even though the wastegate is shut all this time. MAF figures are ok too I think, about 14 g/sec at idle and rising substantially with the revs so I don't think that's my fault.
OPCom is slow to update it's live data, there's a few seconds lag so it's hard to pinpoint exactly what is happening in those few seconds while the engine is labouring its way round to 2.5k rpm. Much harder still when out on the road where it's more noticeable especially if trying to navigate a hill. Does anyone have any suggestions as to what I should be looking at next? I don't have any desired values to compare my actual readings too which is making things harder.I can also only choose from about 8 different options at the same time, it won't let me have the whole screen of data up which is annoying.
I'm at my wits end with this van so desperately hoping someone has got any suggestions!
I'm not a terribly good technician, completed two years of a three year NVQ apprenticeship in garages some while back which has given me enough skills to get by, but I'm starting to dabble more in diagnostics and hoping there's some more knowledgeable folks out there than I that might be able to give me a few pointers.
Using a cheap copy of Op-Com and an old laptop.
So the van is very slow to rev up to 2.5k with low boost readings, then at 2.5k everything comes in at once and it takes off. Though from 2.5k to the 4.2k redline it still surges in and out. Makes little difference when hot and cold, though it doesn't run brilliantly for the first 30 seconds when cold I think that may be a separate issue, just want to sort them one at a time. Few things I've checked already:
No DTCs present.
Fuel filter, air filter and exhaust are all clean and clear.
Compression is an even 300psi+ across all cylinders.
Glow plug circuit is all working properly, plugs are 12 month old Beru items.
Cam timing is spot on.
Injector leak back test was approx 30ml after a few minutes of idling and varying revs, the same on all injectors.
Vacuum pump is pulling a strong 30in/hg+ from idle. (maxes out my gauge anyway and the brakes work fine)
Bypassing the boost solenoid by plugging the vac pipe from the pump straight to the turbo OR activating it manually with a mit-e-vac has the same result, the boost above 2.5k pulls a lot harder but still no change up to 2.5k. This tells me above 2.5k the boost solenoid is responsible for my boost surging in and out, but whether it's the solenoid at fault (it's also a 12 month old genuine part) or it's getting a surging command from the PCM I'm not sure.
Turbo wastegate is free to move, it closes right up once started at idle.
Have done various wiring repairs around the engine and underneath the ECU, blue multiplug has been binned and all connections remade.
Into the live data, and this is where I'm struggling somewhat.
Both throttle pedal positions read perfectly. Cam/crank synch OK, fuel rail pressures OK. Boost pressure as expected hovers at less than 100 kpa and stays flat until 2.5k when it jumps up, even though the wastegate is shut all this time. MAF figures are ok too I think, about 14 g/sec at idle and rising substantially with the revs so I don't think that's my fault.
OPCom is slow to update it's live data, there's a few seconds lag so it's hard to pinpoint exactly what is happening in those few seconds while the engine is labouring its way round to 2.5k rpm. Much harder still when out on the road where it's more noticeable especially if trying to navigate a hill. Does anyone have any suggestions as to what I should be looking at next? I don't have any desired values to compare my actual readings too which is making things harder.I can also only choose from about 8 different options at the same time, it won't let me have the whole screen of data up which is annoying.
I'm at my wits end with this van so desperately hoping someone has got any suggestions!
lpinset said:
hello mate, did you find a solution for this problem? im having the same problem with my renault traffic F9Q engine.
thanks
The flatness up to 2.5k rpm was cured with a new (genuine) MAF. Van drove a hundred times better after that but the slight surging persisted until I sold it, never did find out what that was.thanks
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