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Re: My Citroen XM 3.0 PR-Vestige

Posted: Wed Apr 11, 2018 12:08 pm
by Dieselman
Your vacuum gauge seems to be reading a bit low. It should go to absolute vacuum (30in-hg) when on the over-run. If the gauge is accurate, you have a vacuum leak.

Smoke is what you need...

I made a smoke tester the other day, which indicated a vacuum leak perfectly. Old paint tin, mini compressor, bit of rag and used engine oil. Blow smoke into the intake and watch where it puffs out.

Re: My Citroen XM 3.0 PR-Vestige

Posted: Wed Apr 11, 2018 12:31 pm
by Dean
Way ahead of you on that one but my solution was a little more Neanderthal, Vape smoke!

There was a very small leak which showed as coming from the throttle plate spindle so i am currently cleaning my spare throttle body up and making a gasket for it but it was only a very small leak, i cannot see that would drop nearly 5Hg or the degree of hesitation i have, espacially higher in the Rev range, it may affect idle............possibly.

D

Re: My Citroen XM 3.0 PR-Vestige

Posted: Wed Apr 11, 2018 6:17 pm
by Dean
Thought i had cracked something earlier when changing the throttle body, i had just swapped it (what a right barsteward of a job) out and was reaching down to connect the vac gauge to the evap fitting on the throttle body and the car cut out, started it back up and pinned it down to the plug on the ignition module, it was not plugged in fully so i pushed it on and it cut out again, tried starting it again but it was a no go, pulled the plug off and put it back on and it fired up.

Checked continuity of each pin on the plug and they were fine, plugged it back in again and it started right up. I took it for a drive and although the mis is reduced it is not gone. my new module will be here Friday so i will fit that and look carefully at the loom. Not sure if it is a coincidence or not.

New throttle body is making the same 14-15 in Hg of vac and i have no leaks anywhere now when performing a smoke test. confirmed no VAC leaks anywhere so i can move on from that idea.

D

Re: My Citroen XM 3.0 PR-Vestige

Posted: Mon Apr 16, 2018 3:06 pm
by Dean
The New ignition module arrived on Friday but i only just got a chance to fit it and start the car today, the new module is defective as she will not fire up with it so i will have to wait for a replacement to arrive.

D

Re: My Citroen XM 3.0 PR-Vestige

Posted: Fri May 18, 2018 7:21 pm
by Dean
Problem solved! i have been using her for a couple of days with a new Bosch ignition amp fitted and it is perfect, all the coughing and missing is gone. YAY!

unfortunately, i found tonight the 'New' n/s steering rack gaiter has split right the way around its circumference and the reason i was looking down there to find it is that the steering ram mounting stud has sheared out of the rack, so once again some surgery is required :roll:

Unfortunately this will require a new rack to be made up and i am not too sure how to get the rack out, certainly, without removing the exhaust i don't think it is possible...

Oh well.

D

Re: My Citroen XM 3.0 PR-Vestige

Posted: Fri May 18, 2018 7:56 pm
by MTXM
That is good news about the module and improved running Dean, although I am still a bit mystified as the one I sent worked fine on my car. I was really sorry to hear about the rack and removal is possible with the exhaust in place, although obviously easier without! Please let us know how you get on and best of luck! With regards, Matthew T.

Re: My Citroen XM 3.0 PR-Vestige

Posted: Fri May 18, 2018 9:03 pm
by White Exec
Good news, Dean, about the misfire gone. So, many dodgy units, which fail - but only partially?

Re: My Citroen XM 3.0 PR-Vestige

Posted: Fri May 18, 2018 9:54 pm
by Dean
When it was mentioned the unit controlled dwell i thought the symptoms made sense but after looking at the specs and finding it did not control dwell directly i started to doubt the module was at fault, having said that i have been using the car for 2 full days and have not had the slightest hint of a problem. To this point that would have been impossible.

I am annoyed about the rack as i fitted a low miles ram and a nos gaiter as i found the old one had split when the 2.0i engine was removed and the bushes were getting tired on the original ram.
This replacement gaiter has just snapped, the ram has sheered the stud out of the rack and the ram is leaking slightly (wet) as well.

however annoying the steering rack issue is, at least it is a straightforward job with no diagnosis required and having done the job before it should go very quickly.

D

Re: My Citroen XM 3.0 PR-Vestige

Posted: Sat May 19, 2018 5:15 am
by Dieselman
You can buy new bushes for your old ram. I suspect worn bushes is what causes the steel pipes to crack.

Good to hear the running issues are resolved.

Re: My Citroen XM 3.0 PR-Vestige

Posted: Sat May 19, 2018 9:20 pm
by misha
I'm glad that you nailed it...finally! ;)