[C5 X7] Multiple ignition / injection fault codes.

[the-termin8r]

Hi everyone,

I feel like this is potentially the culmination of an issue I've been ignoring for at least a few months. I have a 138 BHP 2L HDI. It started with the revs stuttering or fluctuating (for lack of a better term) for a second or two usually around 2K RPM in 2nd gear with constant throttle input (i.e. I wasn't actively applying more throttle). This was intermittent and happened after any amount of time spent with the engine running (could be 2mins or 2h). It also happens in 1st and 3rd, but rarely. 2nd seemed to be where it was most common. As time progressed I started noticing it under harder (but not extreme) acceleration in 3rd and 4th as well. I can't confirm this as fact, but a couple of times in the past week I think I felt such a stutter in 6th at motorway speeds as well. Though given our world-class motorways, I might have just been feeling motion from the road surface. I thought it might be an injector or maybe a clutch issue. The car is at 91.something K miles off the top of my head, has been in my family for almost 10 years (bought at ~9K), has been run on Shell V-power for most of its life with us. I've been its legal owner for the last 10 months, I think I filled up with the Costco stuff a month in, but have been on V-power exclusively since then.

Anyway, it all came to a head yesterday on the motorway on my way back from work. I don't know if this is related to the stuttering, but it feels like it might be. I was overtaking and jumped from lane 2 to 3 doing about 75 MPH. Next thing I notice is a distant flash of headlights in my rear view and some lunatic flying towards me at at least 100 MPH (still in L3). Not wanting to find out how good his reaction time or brakes were I suddenly put my foot down (near full throttle, but didn't hit the end stop) and got up to about 90 to quickly (and as less-dangerously as possible) dip back into L2. As I was accelerating a warning came up on the speedo saying "Engine management system faulty" and the check engine light came on. The car and engine (to me at least) felt fine. No limp mode, no loss of power, no weird vibrations or noises.

When I got off the motorway and into town, I cut the engine at a set of lights and let it sit for 5-6 secs, turned the ignition on and let it sit for another few secs and then turned the engine over. The error still came up. I drove home normally with no issue. I let it sit overnight and then went to probe it with Diagbox in the morning. Before connecting, I turned the engine over to see if maybe the error had cleared, but no. I did my first scan with the engine off and didn't really get any errors, just a load of communication failures from things like the ignition/injection and ABS. I assumed they just needed the engine running, so I turned it over and ran another scan. This time I got good communication, but the ignition/injection threw up a bunch of codes (attached) that look to be related to each other. I'm also not sure why the engine speed readings differ so much in each image. I wasn't even in the driver's seat when I was running the scan. I re-ran the scan with the engine running still and saw no change. I then ran another scan with the engine off again and it threw up the same communication errors, but this time the BSI also threw up a F5FF error reading "unexpected re-initialisation fault coming from the BSI" it was local and not characterised.

At this point I just took my laptop and VCI back into the house to go and make this post, but just for the sake of it, decided to come back out and fire the engine back up. The error and check engine light didn't come on. To be clear, I did not clear any errors over Diagbox, I just read them. Took it for a 5 min spin around my neighbourhood and although the 2K stuttering was still present in 2nd, the car felt fine. Rather stupidly, I didn't think to then re-scan with diagbox (might do it tomorrow) to see if the codes had cleared.

Am I correct in assuming bad injectors? Would it be worth buying a bottle of cleaner or do I need new injectors? Come to think of it, the car had its glow plugs changed in Dec, but I can't for the life of me remember if I noticed the stuttering before that.

Thanks for any help you can offer.

[RichardW]

If it detects an intermittent fault then it puts the light on, and it stays on 5 engine starts, but the code remains in the memory. All yours are intermittent, but it's not clear which one put the light on - but given the engine speed of the crank sensor one that seems likely. I would go back in clear the codes and then see which come back.

[the-termin8r]

Hi Richard,

Thanks for the reply. How long would you suggest I wait after clearing the codes to check if they've reappeared and do you reckon this is related to the stuttering issue?

[GiveMeABreak]

There's a Technical Issue for this engine where the following fault codes are present. But I agree with Richard - deal with the P0337 fault - Engine Speed Sensor issue first (see bottom fault table) and see if that resolves the issue. But in either case you have the graph and Diagbox to test the signal.

P0088, P1166, P0181, P0183, and you have 3 out of four of them.

"Flat Spot On Acceleration - The Engine Has Stalled - Unstable Engine Idle Speed - Hesitation"

Origin: High pressure fuel pump pressure regulator

Read the fault codes:
In the presence of one or more of the following fault code(s) P0088, P1166, P0181, P0183: Carry out the repair

Check

"A" : Signal conforms.
"B" : Signal does not conform (Significant fluctuation).
Start the engine and let it run at idle.

Check the "Measured fuel pressure" signal using the diagnostic tool:
If the signal fluctuates significantly (Fuel pressure unstable) (Figure "B"): Apply this document
If the signal does not fluctuate significantly (Fuel pressure stable) (Figure "A"): Do not apply this document

Repair:
Replace the high pressure fuel pump pressure regulator.

Fault Code:	P0337
Description of Fault:	Engine speed signal: Signal not coherent. The number of teeth seen on the target of the engine speed sensor is too low on 1 engine rev The fault is forwarded after 2 engine revolutions.
Conditions for Fault to clear:	Under starter
Downgrade Modes whilst Fault is active:	-
Symptoms:	Starting problem Jerking/stalling
Suspect Areas:	Engine speed sensor target Engine speed sensor Electrical harness Connector

[the-termin8r]

Thanks for the info, Marc. Do I carry the above testing out before or after I clear the fault codes? As I'm still quite new to it, where in Diagbox would I find the live sensor graph? Also I'd like to have a look at the connector, where abouts on the engine would I find it and am I ok to just unplug it with the engine off or do I need to run through some procedure?

Thanks.

[GiveMeABreak]

You need to go into parameters to get live data. Run a Global Test / Diagnostic, then when complete, from the list of ECUs, select the Injection ECU. Confirm, then this will take you to various menus of which one should be 'Parameters'. You should be able to select from the pre-defined tests or choose your own - in which case make sure you include the 'measured fuel pressure' paramter.

When running, you can then check the graphs to see if they conform to either A or B for the fuel pressure regulation.

The Engine Speed Sensor is shown at (4) below, located at the timing end:

[the-termin8r]

I ran the live test during my lunch break today, got some weird results (on the assumption that the reference graphs are X7 specific). Fuel pressure seems to be a lot lower than the image and very erratic, but I also feel like my graph has more data points. Another pair of issues I ran into is that on scanning again today, I had an error P2084 crop up for some reason. And when I tried to clear the fault codes I got an error along the lines of "can't clear fault code." I don't remember the exact phrasing and didn't think to take a screenshot, but after I entered the current milage, it gave the error. I tried clearing two of the four codes and got the same result for both.

[darbuck]

If You're not getting the correct fuel ratio your exhaust temperature is going to be incorrect possibly causing the latest code, however, if the exhaust temperature sensor is out of spec it could be causing the ecu to recalculate the fuel-air mixture causing a poor running condition it could also be a clogged DPF you need to test your sensors to determine which ones are bad if any. Don't be tempted to deploy the parts canon. Methodical testing of parts is the only way to solve this, otherwise, you could find yourself with empty pockets and a badly running car. The Exhaust Temperature sensor connector is located on the bracket beside the high-pressure fuel pump at the gearbox end of the engine, its a brown connector.

[the-termin8r]

I'm not planning on throwing money at it yet, my intention is more to narrow the issue down as much as I can so that I can feed it back to whomever I'll send the car to for fixing. I unfortunately don't have the time or the tools to do anything engine related. Though I want to troubleshoot as much as possible. Is there a specific order / list of sensors I should check? Thanks.

[darbuck]

I would test the crank, cam sensor and exhaust temperature sensor first, then the fuel pressure regulator. They are the two main sensors showing issues.

[darbuck]

All of these can confuse the ECU into thinking there is a fueling problem if there is a problem that's intermittent. But so can the MAF. You will need to graph them and see if you can get a known good for comparison.

[the-termin8r]

Apologies for the very late reply, it's been a busy few weeks and I haven't had much time to troubleshoot.

Either I'm blind or I was looking in the wrong menu (almost certainly PEBKAC), but the only cam/crank sensor I managed to find was a sync one. I also completely forgot to pull up the exhaust temp sensor. I did however probe the fuel temp (one of the errors was complaining about it) and the fuel pressure. Cam and crank stayed in sync the whole time, the fuel held a steady 36? and then jumped to 37 at the end of the graph which seems expected, however I have no context for whether the temp is good or bad.

The fuel pressure is where it gets interesting though. A couple of times you can see it drop for a bit and then recover. I noticed that during the dips, the engine made a subtle 'tapping' / 'clacking' / 'knocking' noise. I took an audio recording that I'll include below. It's between 17 and 30 secs in the clip and captures the double dip in the middle of the graph. I'm leaning more to this being a pressure issue, but I don't know if the cars stuck in it's own feedback loop due to an iffy sensor elsewhere.

For the record I've been driving the car as normal this whole time and besides the occasional 2K RPM, 2nd gear stutter as before, it's been fine. No warning lights or anything. With that being said, with every new scan, I feel like I'm getting that many more errors in the injection / ignition section. I suppose it makes sense, but what concerns me is that I can't seem to clear them. I go into the ECU to clear the faults, it makes me enter the current milage and then throws up an "erase faults failed" error.

I'll try and see if I can find some time in the next couple of days to go back in with Diagbox.

[cit-rotti]

A "permanent" error cannot be deleted.
First the error problem must be eliminated.
Only then is clearing successful.

Greetings Wolfgang

[the-termin8r]

I see, but surely technicians have to be able to clear them somehow? Or are these errors that the car knows will crop up immediately again and just doesn't let you clear them at all unless the part has been changed and another scan run?

[darbuck]

They can't be cleared unless the engine is off. But I think you are missing the point, they can't be cleared because it is a significant permanent fault. If it keeps coming back or won't clear the operational parameters have not been satisfied. You may need to tell the ECU you changed the DPF in your case.The computer is looking for a specific voltage from the faulty system and can see it is not correct, bin simple terms the car knows the problem has not been resolved so you need to determine and fix what is wrong to clear the fault.