Having driven 200 miles in the TTiD this evening I had 30 miles to go when the car lost all power from the engine.
I dipped the clutch, revs dropped to zero, letting the clutch out the revs picked up, but that was wheels driving the engine. It was as though I had just run out of fuel, with 1/3 of a tank left
Cranking the engine it seemed to fire for 1/2 second, before falling back to pure cranking
Suspecting fuel I cracked open one of the pipes to an injector and cranked the engine, there was no sign of fuel.
There were no error codes either, including from immobilisor (CIM module). Regardless I disconnected the battery for 10 seconds
I decided to see if a fuse to the fuel pump had blown, found that, all OK, but i couldn't locate the fuel pump relay.
WIS has instructions for diagnosing a no start, first was to look at was engine cranking speed. I saw a stable 190 rpm, which confirmed the CPS was working properly
Next was to use the "diagnostic tool" (VXdiag) to trigger the fuel pump relay on and off. I could hear some noise so assumed that had a feed to the relay coils and was being triggered correctly
While I was in the area I saw fuel pressure was one of the values that could be examined, so that seemed a worthwhile effort.
I cranked the engine and after holding at 0.5 kPa, the pressure started to build and rapidy went from 1.7kPa to 3.5kPa at which point it started and I was able to complete my journey without further issue.
I don't have a great deal of experience with diesel engines & it's obvious that this type of failure means I really need to identify what the problem was, before embarking on another 500 miles next week
Any thoughts or suggestions?
Is this a problem with fuel transfer from one side of the saddle tank to the other? One third full would be just about right for the fuel to be below the hump in the middle.
Assuming that the tank is humped, of course. I haven't looked anything up yet...
The NG XWD tank is very similar to 9-3, from what I have seen.
I haven't seen any problem with fuel transfer before. For various reasons I ran very low on fuel at the start of this week, to the point that is stopped giving a DTE number. Filled up and did 230 miles, ran around for a couple of days and then 200 miles back home.
This morning I started the car and it started as normal. A bit slower than I think it should, but no different to before
I now have a P0122 error code, low voltage, which is related to the throttle body. I went looking around for TB and pedal voltages, before realising that it's probably a mechanical throttle. Each time I clear it, it comes back.
I haven't had chance to look at the car yet, but when I started it this morning, the TB position sensor seemed to be reading correctly, fuel pressure was moving up and down according to accelerator pedal request.
Maybe the P0122 is because I disturbed something and unrelated to the original fault. Locating & cleaning would seem to be step one.
Further investigations;
Electrically, the TB is giving 3.6 ohms from terminal 3 to earth, and terminal 1 shows 5.1 volts for the reference voltage. All OK
Next test was to measure the voltage for the intake air flow valve (AKA throttle body ??). The reader shows 0.16v against a test of no more than 0.3v, so checks out.
However I spotted that the TB position is showing 100%.
Having removed the TB I noted that the TB is in the wide open throttle position, due to a spring force. This seems to be a failsafe position, from which engine speed is controlled simply by the amount of fuel injected
Reconnecting the TB electrically (but not on the car intake manifold) demonstrates that the butterfly does not move with the engine running. Physically moving the butterfly does not change the intake air flow valve reading with the scan tool, or the voltage.
Slightly confused, but this does look like a failure of the throttle body electronics / motor :-\
it does look like a TB problem, but beware of testing flows through valves. I only have proper experience of water valves, but a 10% open valve can pass over 90% of max flow.
Looks like I lost an earlier post: here's the gist:
Managed to source a s/h throttle body from a local breaker, for the grand sum of £10
Having electrically fitted the TB, the DTC has cleared, but now I have to find the 4mm hex bit that I lost down the back of the engine, that'll be the most difficult task
The butterfly somewhat strangely stayed in the WOT position, but the voltage was 0.92v, rather than 0.16 so I misunderstood the diagnostic approach and the scan tool was still showing the throttle position at 100%
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Well, 2 hours looking for the 4mm bit. I should have been more carefull, or just use an allen key in the first place, like I did to reassemble
The car is back on the road with no errors. I still don't understand why the butterfly stays in the WOT position with ignition on but engine not started. That doesn't seem right.
I might spend some time watching the induction data stream tomorrow
Question is, with this occurring within minutes of getting the car restarted, was this the original cause (maybe pivoting to the 0% position?), or just an awful coincidence.
The fuel tank readings did look uneven, again something else to look into
This morning I removed the 5 screws that held the plastic cover on the end of the throttle body.
It looks like it's physical motor controlled, with a position sensor operating against the white geared pivot that has the butterfly shaft at the centre of it.
Interestingly, there is evidence of what looks to be water in there, but no signs of ingress & it doesn't smell like water and doesn't behave like oil, maybe it's the electronics I can smell
Actually remarkably simple internally
Yesterday I looked at the fuel level sensors and they showed 2.00v and 1.96v, so far more similar than when I looked a couple of days ago. Perhaps the tank had drained from the right hand (pumped) side ??
Just going to bring this thread to a sort of conclusion
Ever since changing the throttle body I have been suffering from P0299 and P2282 DTC's, suggesting problems with the MAF and low boost
I looked at the manifold absolute pressure request on idle and saw 1.2 bar, while the actual was 1.0
At higher throttle settings, I could see say 2.6 request and 2.2 actual, this would chuck the error code and a limp mode of varying duration (say 2-20 seconds)
Having checked the electrical connections to the MAF and the rest of the pipelines I conclued it must be something I had done and looked at the TB again.
It was, the green rubber gasket between the TB and the inlet manifold sits in a recess and because I fitted the two upper bolts for locating purposes first, the gasket was slipping when I fitted the lower, blind one, resulting in the seal not being effective & allowing some leakage
The car is now picking up better and meeting a demand of 2.9 bar, so 1.9 bar of boost.
Anybody know if this is a "good" value as I can't see anything in WIS :)
... after an apparently happy ending, I had another issue yesterday, new thread, NG 9-3 owners will be on familiar territory ::)