Trying to track down rough running after replacing timing chain, 1.6thp

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lime
Posts: 12
Joined: 20 Oct 2019, 04:20

Trying to track down rough running after replacing timing chain, 1.6thp

Post by lime »

So I replaced the timing chain on my 2013 DS5 1.6thp, as far as I know I followed all correct procedures. Initially it was cranking but not firing, so I started troubleshooting that. After swapping in some coils from my BMW it fired up and was running very well (much better than previously when it was rattling etc), but the same pesky code that led to me replacing the chain was still present (P0016).
I took it for a test drive of around 7km, by the end of the test it wasn't running as well.

Since then it will usually start and run very rough when cold, when I try to take it for a drive it will cut out and can then not be restarted when warm. It is throwing codes for misfires as well now where I don't believe it was before the timing chain (P0354 among others). I have replaced plugs and coils, fresh fuel, new camshaft position sensor etc.
At first I thought the timing could be out, but I don't see how that's possible given the car was timed correctly when I replaced the chain. I have heard of the cam sprockets slipping after replacing the chain, but I torqued them to spec which felt very tight.
I've purchased a diagbox interface to give more in-depth diagnostics than what my other equipment can provide. It shows the camshaft dephaser at 36 degrees which I believe is correct?
One interesting thing I found was the injector timings. I'm far from knowledgeable in this area but cylinders 1-3 are showing <2ms while cylinder 4 is flat 0.00ms. Does that indicate a faulty injector or something else?

I would be very grateful for any assistance in analysing these values and figuring out a solution or even just pointing me in the right direction to look. Apologies for the photos, anytime I try to print/save a page from diagbox the program crashes. It may be easier to view them here https://imgur.com/a/67ywP5p
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dfabrici
Donor 2021
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Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by dfabrici »

I'm not an expert in any way, but from what I'm seeing there's definitely an issue with the camshaft sensor. The code P0016 reads as "lack of coherence" between what is given by the crankshaft sensor and what is given by the camshaft one. P1340 and 1336 both refer to anomalies in the signal read by the cam sensor (out of range or something like that). P0354 refers to fault in the ignition coil of cylinder 4. I bet that since it gets faults from the coil (open circuit? short to ground?) it stops the operation of cylinder 4, thus showing 0 ms of injection time. You should try, multimeter at hand, to measure the feed to the cam sensor, it should have +5v, GND, and signal out. With the engine off, the signal wire should have (usually, I don't know your engine) +5v or GND if it's a pull-down or pull-up magnetic sensor, respectively. If all reads out, using a scope you should chech what reads at the signal output of the cam sensor while cranking. You should obtain a squareish wave signal alternating from +vcc and gnd. Measure the ignition coil 4 too, to check for oper circuits or shorts to ground. Inspect the coil visually too, sometimes the insulation gives up and starts shorting on the engine head when sparking.
Don't know if you can see the cam sensor reading from live data in Diagbox, that would tell you if it's reading or not. You can try also actuating the coil 4 with the spark plug on it to see if it's sparking ok.
You already cleared the codes after fitting the new timing chain?

I'm just following a line of thought, might be completely out of track, as I'm not an expert.

Bye
Davide
lime
Posts: 12
Joined: 20 Oct 2019, 04:20

Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by lime »

dfabrici wrote:
19 Apr 2021, 10:45
I'm not an expert in any way, but from what I'm seeing there's definitely an issue with the camshaft sensor. The code P0016 reads as "lack of coherence" between what is given by the crankshaft sensor and what is given by the camshaft one. P1340 and 1336 both refer to anomalies in the signal read by the cam sensor (out of range or something like that). P0354 refers to fault in the ignition coil of cylinder 4. I bet that since it gets faults from the coil (open circuit? short to ground?) it stops the operation of cylinder 4, thus showing 0 ms of injection time. You should try, multimeter at hand, to measure the feed to the cam sensor, it should have +5v, GND, and signal out. With the engine off, the signal wire should have (usually, I don't know your engine) +5v or GND if it's a pull-down or pull-up magnetic sensor, respectively. If all reads out, using a scope you should chech what reads at the signal output of the cam sensor while cranking. You should obtain a squareish wave signal alternating from +vcc and gnd. Measure the ignition coil 4 too, to check for oper circuits or shorts to ground. Inspect the coil visually too, sometimes the insulation gives up and starts shorting on the engine head when sparking.
Don't know if you can see the cam sensor reading from live data in Diagbox, that would tell you if it's reading or not. You can try also actuating the coil 4 with the spark plug on it to see if it's sparking ok.
You already cleared the codes after fitting the new timing chain?

I'm just following a line of thought, might be completely out of track, as I'm not an expert.

Bye
Davide
This is very interesting, thanks for the input. I had suspected the camshaft sensor itself earlier, hence why I replaced it, but you're right that it could be another point in the cam sensor system. I just did a quick test by clearing the codes and then starting the engine with the cam sensor disconnected. Lo and behold no misfire and the engine was running pretty smooth! I was also able to verify that with the cam sensor connected and codes cleared all 4 injectors appear to be fueling correctly initially but then #4 flatlines and the misfire and coherence codes reappear. Next up I will grab my multimeter and see what's going on with the sensor wiring. I also wonder about the Crank sensor and if there is an issue with that could it be triggering a lack of coherence with the Cam signal?
lime
Posts: 12
Joined: 20 Oct 2019, 04:20

Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by lime »

Well I'm even more confused now. After checking with a multimeter I can confirm that the wiring is providing 5v power to the sensor, and I was able to backprobe the signal wire and watch it working when I put a socket near the sensor, 0.1v when the socket was near and close to 5v when it was clear. That would indicate a functional cam sensor to me, but the fact remains that when I start the engine with the sensor disconnected it seems to run very well, but connected it runs poorly and disables one cylinder. Maybe the crank sensor is the next port of call, although RPM info seems accurate?
dfabrici
Donor 2021
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Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by dfabrici »

Guess you made sure the timing was correct, and I mean using the visual markings on the various pulleys/sprockets, not just making sure that the chain was replaced as was before. If that's ok, but I think so, otherwise it wouldn't run smoothly imho with the cam sensor disconnected, I'd start looking at the schematics of the car (which I should have but SEDRE for some reason doesn't want to load properly many schematics), to see how things are connected. If, as I think, the cam sensor and coil have nothing in common with the injectors, it may be the case to take a look at the ECU itself. Looking at the pics I noticed something else, why id the coolant read 38°C the cooling fan was active at full speed? Relays are active for both low and high speed. Was the fan running? That engine has VVT too, does the dephaser work?
lime
Posts: 12
Joined: 20 Oct 2019, 04:20

Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by lime »

dfabrici wrote:
22 Apr 2021, 11:41
Guess you made sure the timing was correct, and I mean using the visual markings on the various pulleys/sprockets, not just making sure that the chain was replaced as was before. If that's ok, but I think so, otherwise it wouldn't run smoothly imho with the cam sensor disconnected, I'd start looking at the schematics of the car (which I should have but SEDRE for some reason doesn't want to load properly many schematics), to see how things are connected. If, as I think, the cam sensor and coil have nothing in common with the injectors, it may be the case to take a look at the ECU itself. Looking at the pics I noticed something else, why id the coolant read 38°C the cooling fan was active at full speed? Relays are active for both low and high speed. Was the fan running? That engine has VVT too, does the dephaser work?
Thanks for the reply. As far as I know the timing was correct. There aren't any markings on the sprocket/VVT gear and from what I understand it doesn't matter how they go on, only that the cams and flywheel are locked correctly, and the tensioner applied while everything is locked which I definitely did.

To my mind something is causing a misfire which the cam sensor detects, which causes the car to shut off cylinder #4 in order to protect the catalytic converter. I believe that's the link between the cam sensor/coil/injectors, and the cooling fan activates when the car detects misfires as far as I know.

I'm not sure how to test the VVT dephaser, was hoping there'd be some live data to monitor. I did however replace the VVT solenoid (what a pita) so theoretically that should be ok.
lime
Posts: 12
Joined: 20 Oct 2019, 04:20

Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by lime »

Just reconnected the cam sensor and the car started up and appeared to be running ok. Strange. I took it for a 15km drive and then brought it back home where it had a few new codes for me. Attached are the reports I managed to get, as well as some live data I recorded while it was running. I'm not sure what to make of it, doesn't appear that the dephaser is doing much. Looks like I can rule out the HPFP as a potential cause.
readings.jpg
p0016.jpg
p0326.jpg
p0327.jpg
p0420.jpg
dfabrici
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Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by dfabrici »

Hmmmmmmm... There's a knock sensor fault, short circuit to ground. Knock sensors are piezo accelerometers, if it's faulty it may well be that it tells the ECU that cylinder 4 is misfiring. You should test it for insulation to ground and values between pins. If I were you, I'd start to check for shorts among wires too. Unfortunately now diagrams would be pretty helpful... Cam dephaser seems to be stuck at 36°, no matter the opening or closing of the inlet valve. I don't know the VANOS system installed in those engines, whether it's continuously variable (maybe with a PWM signal to the solenoid) or discrete (by which I mean off or on). It might be that the ecu won't allow the vanos system to work if it detects misfiring. However that doesn't explain why it continuously reads 36°of dephaser angle (is there a sensor? that might be well worth investigating).

As I'm writing, I'm thinking that if the engine dephaser angle sensor reads 36° continuously, the ecu thinks that the camshaft is actually rotated 36°, but since it is NOT actually dephased, it's tricked in thinking that there's an incoherence between cam and crank sensor, since it expects a signal dephased 36° with respect to the crankshaft signal, while the signal it receives is (correctly) not dephased. That would also explain why the solenoid valve is never operated even at mid rpms (3/4000 as per graph). And it would explain why without the cam sensor the engine ran better, since without the closed loop the ecu doesn't try to adjust parameters to recover from a nonexistent dephasing.
That may be bollocks anyway, it's just something that struck my chain of thoughts as I was thinking on how the system works.
dfabrici
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Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by dfabrici »

Another thinking... it may be that the pulley itself is stuck or stiff so the readings are consequently wrong, since the cams are not dephased anymore even if they're told to. That pulley seems to be a bit finicky and not so reliable.
dfabrici
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Re: Trying to track down rough running after replacing timing chain, 1.6thp

Post by dfabrici »

Just to make sure... are the injectors coded correctly, aren't they? :)