C5 X7 no start (or only runs for fraction of a second)

Unread post by **MattBLancs** » 09 Oct 2022, 16:57

Looks fine

: Vehicle immobilisation information

: Battery voltage recorded appears low but otherwise nothing much here to see

Unread post by **MattBLancs** » 09 Oct 2022, 17:31

Helper available briefly.

Battery voltage with multimeter reads 12.2 Volts = bit low, haven't done massive amount of cranking today, was charged up yesterday afternoon.

Reading between negative and good earth (starter mounting bolt head) under cranking records 0.2 Volts. This doesn't seem excessive drop (given hundreds of amps flowing at the time) so am hopeful means no high resistance bad earth issues present.

Will get car fed with healthy voltage (Coupe is nose to nose with it, bring it forward should get them less than jump lead length apart)

Is there anything in particular I need to do/ not do when jump leading an X7 C5?

Matt

Unread post by **Rp0thejester** » 10 Oct 2022, 19:08

Yes, make sure the fire brigade is in attendance for the electrical fire, just to be on the safe side. I'm in no way saying Citroens have terrible electrical issues....

Unread post by **CitroJim** » 11 Oct 2022, 07:29

Having just read through this entire thread I may have missed any reference to it but has the crank position sensor been checked and is it correctly mounted?

I've only done one cambelt job on an X7 and felt the crank position sensor was very vulnerable and easily damaged during pulley removal/refitting...

Just a thought as everything else seems to have been investigated but as I say, I may have missed that it's been swapped...

Unread post by **MattBLancs** » 11 Oct 2022, 20:43

CitroJim wrote: 11 Oct 2022, 07:29 Having just read through this entire thread I may have missed any reference to it but has the crank position sensor been checked and is it correctly mounted?

I've only done one cambelt job on an X7 and felt the crank position sensor was very vulnerable and easily damaged during pulley removal/refitting...

Just a thought as everything else seems to have been investigated but as I say, I may have missed that it's been swapped...

Hi Jim,

First off - thanks for reading all this long tail!

Crank sensor not specifically checked. Yes is vulnerable, was moved out of the way during the belt change.

Diagbox shows an rpm value during cranking, not sure if this confirms sensor functional or not? But will check, definitely,

Matt

Unread post by **moizeau** » 11 Oct 2022, 20:52

Check on Diag if Cam and Crank are synced

Unread post by **CitroJim** » 12 Oct 2022, 09:56

MattBLancs wrote: 11 Oct 2022, 20:43 Hi Jim,

First off - thanks for reading all this long tail!

I'm reading this thread with great interest Matt and I'm looking forward to seeing a successful conclusion very soon

You have all my best wishes in this and I know we'll all be celebrating once it's sorted

It might be worth swapping the crank sensor for a known good one as it'll be the only thing that's been disturbed in the process... Sometimes they can check out good statically but still be faulty when in use... The fact that it sometimes starts and then immediately stops may reinforce this train of thought...

I'm not saying it is but given it's been moved around and all else has been excluded...

Unread post by **MattBLancs** » 14 Oct 2022, 20:39

moizeau wrote: 11 Oct 2022, 20:52 Check on Diag if Cam and Crank are synced

yes, I have seen that one before, will check it again. Remember it changed from something akin to "not synchronised" to "synchronised" when cranking, but worth double check.

CitroJim wrote: 12 Oct 2022, 09:56
I'm reading this thread with great interest Matt and I'm looking forward to seeing a successful conclusion very soon You have all my best wishes in this and I know we'll all be celebrating once it's sorted

It might be worth swapping the crank sensor for a known good one as it'll be the only thing that's been disturbed in the process... Sometimes they can check out good statically but still be faulty when in use... The fact that it sometimes starts and then immediately stops may reinforce this train of thought...

I'm not saying it is but given it's been moved around and all else has been excluded...

Thanks Jim,

That's a good point about crank sensor, as you say it's vulnerable position (could see a snapping auxiliary belt taking it out potentially too) and has been disturbed to do the belt replacement.

Thank you also for the words of encouragement - very much appreciated!

Matt

Unread post by **Rp0thejester** » 14 Oct 2022, 22:07

My turn for encouragement, Go on Matt.... that's all I have, busy day.......

Unread post by **MattBLancs** » 14 Oct 2022, 22:12

Thanks Ryan, it all helps spur me along!

Forecast is typically terrible, but will see what I can get done tomorrow

Matt

Unread post by **Rp0thejester** » 14 Oct 2022, 22:27

It's either you or the crusher, you can save that old girl, patience is the key.....

Unread post by **MattBLancs** » 15 Oct 2022, 12:58

Ok, rain subsided so fired up my Italian built jump pack

Unread post by **MattBLancs** » 15 Oct 2022, 13:01

moizeau wrote: 11 Oct 2022, 20:52 Check on Diag if Cam and Crank are synced

: Synchronised (when cranking)

Seems ok

Unread post by **MattBLancs** » 15 Oct 2022, 13:05

: Vehicle immobiliser information

: Air intake info

: Air intake info 2

This confused me - airflow shows zero when cranking. Clicking the row says something about EGR so wondering if just a red herring

: Fuel circuit information and a stray finger on the lens

: Fuel circuit information

Can't see anything untoward on any of those.

Easy start trial again after dinner , if weather ok and can borrow a helper again

Matt

Unread post by **MattBLancs** » 30 Oct 2022, 19:33

Blimey, time flies and weekends especially so.

Had chance today at last, and still dodging showers.

Coupe connected up as jump start booster again. Intake hose off, under cranking increasingly large squirts of firstly WD40, then brake cleaner (run out of Easy Start, both these are combustible and I believe should do the trick)

Nothing, not even a cough of life. As mentioned by others earlier in the thread, the above suggests timing.

I can (triple, quadruple?) Check the timing again next weekend but was happy last time it was correct.

As per

viewtopic.php?t=42544&start=15

I'm now looking (locally preferably given the need to draft the damn thing there most likely) for someone (I.E. a garage) to investigate and find whatever it is I'm clearly missing.

Weirdly popped up to say hand brake faulty (then message disappeared again) - suspect low battery voltage behind that.

Matt

French Car Forum

C5 X7 no start (or only runs for fraction of a second)

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Re: C5 X7 no start (or only runs for fraction of a second)

Re: C5 X7 no start (or only runs for fraction of a second)

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Re: C5 X7 no start (or only runs for fraction of a second)

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Re: C5 X7 no start (or only runs for fraction of a second)

Re: C5 X7 no start (or only runs for fraction of a second)