Well, we had a look at this today.
A couple of fault codes stored (none were "present"):
P0195 Malfunction code 1:
Coolant temperature is greater than 80 °C (176 °F)
Engine oil temperature is less than 70 °C (158 °F)
Note:
Engine-oil temperature and coolant temperature have no comparable characteristic curve.
P0400 Malfunction code 2:
Actual exhaust gas recirculation quantity is too low
Coolant temperature between 40 °C (104 °F) and 100 °C (212 °F)
Intake air temperature between -5 °C (23 °F) and 45 °C (113 °F)
Atmospheric pressure between 900 hPa ( 0.9 bar ) and 1100 hPa ( 1.1 bar )
Above conditions must be fulfilled for at least 10 s .
Effect:
Maximum performance will be reduced.
Exhaust gas recirculation valve is switched off
P1125 Malfunction code 1:
Ignition ON
Coolant temperature between 40 °C (104 °F) and 100 °C (212 °F)
The air mass calculated from the boost pressure is implausible with the measured air mass
Above condition must be fulfilled for at least 4.5 s .
Effect:
Maximum performance will be reduced.
Exhaust gas recirculation valve is switched off
Boost pressure control is not longer possible.
The above were cleared and did not return during a lengthy test drive during which time it performed with all the urgency of a slug on its' way to receive root canal treatment! It will apparently occasionally take off normally but, unfortunately, we were unable to persuade it to do so while watching the live data.
All vacuum actuators and corresponding valves were checked IAW TIS and performed correctly. MAF response to the EGR actuation was as specified as was boost pressure commanded by the boost pressure control actuator with the engine held at 3000 rpm. Swirl valve actuator could be observed operating correctly.
Coolant, oil and fuel temperature appeared plausible and responding to driving conditions although oil temperature remained 8 or 9 degrees C below reported coolant temperature and coolant temp as indicated by the engine was a good bit higher than reported by the instrument panel (100 deg. C from engine ECU with <90C at the panel). Curious that oil temp was lower than coolant but it was hardly being stretched. It was hardly performing at all, in fact.
During a test drive boost pressure was present whenever the engine was under load and probably about normal (bearing in mind I have no real experience of the live data to expect from this engine). It followed about 0.1-0.2 BAR below target boost pressure throughout and was making just under 2 BAR under full throttle. Throttle position was correctly reported in live data.
Injection start and quantity were following the desired values. Engine and pump speed looked correct. High pressure diagnosis sat at 0 throughout.
The MAF was reading around 400-430 at idle and only peaked to around 560 while driving. This struck me as strange, but, as said, I'm not that familiar with the ways of the tractor.
Induction system was free of any obvious leaks and rubber intake hoses swelled when boost was present.
Power delivery was completely flat. No evidence of any boost-related power delivery whatsoever despite the fact that boost was there.
Engine started, idled and drove perfectly, just without significant power delivery.
So, conclusions?
Hmm <rubs chin>
Vacuum system is all working fine. We have boost pressure controllable by the actuator on the turbo, so suspect that's fine too. EGR is doing what it should, at idle, at least. If it were coming open under boost, I'd expect boost pressure to be bled away.
We have a code related to oil temperature and coolant temperature being inconsistent and this looks plausible given that the oil is consistently being reported cooler than oil. The code didn't return during a test drive, however.
We have a couple of codes suggesting a MAF issue - not plausible with boost pressure and the EGR quantity (which is presumably based on MAF response to EGR). MAF was reading as expected at idle and responded to EGR actuation, but surely if it's reading 430 ish at 800 RPM, it shouldn't top out at 560 at 3000 RPM with a BAR of boost? Codes didn't return during a run, so assume it hadn't gone into a deliberate limp at this stage
MAF has previously been replaced with a new genuine GM sensor to no avail.
No leaks in the induction system that could bypass the MAF.
Nevertheless, could a MAF issue be reducing the injection quantity, and thus limiting the power output despite the fact that the correct boost pressure is present?
I have a data log from the test drive.
I have a feeling that this is "something simple" but have no real experience with the dti, so little sense of what live data from a properly functioning example looks like, unfortunately.
Anyone got any ideas?
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Topic: No Boost on my 2.2DTi (Read 23401 times)