wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

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wurlycorner
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wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

First proper appearance on here of this particular CX of mine.
I've owned it for something like 20 years. It's been off the road for about 12 of them. Can't remember what caused me to buy this one (I already had inherited another previous to it :lol:
Short summary of the 'entertainment' that this particular one has given me over the years...
Clutch release bearing siezed on me, changed the clutch in the road outside my mums house over the course of a few weeks when I was in college (it's a 2 flywheel sensor car and the driven plates that actually fit it are quite rare - though I didn't know that until after having bought one, only to find it didn't fit...)
Had it collapse onto the ground off axle stands in the front garden while I was in the middle of replacing some rear hydraulic pipes (not while I was under it - I just heard the horrible crunch/crash while I was walking to the shed to collect some tools). Damaged a sill cover, dented the floor on one side and pierced a rear door ( all replaced/repaired)
Changed the rear arm bearings in the road while I was living in Soton
Gave me my first welding job replacing part of the inner arch below the battery tray (I did a crap job, mainly because I used the wrong gauge steel)
Transit van drove then drove into the passenger side of it while I was living in Soton (still wearing the battle scar :cry: )
Main loom caught fire causing the car to suddenly shut down in smoke in the middle of crossing a junction in the one-way system in the centre of Oxford (due to a previous numpties use of uninsultated spade terminals to replace the fittings on the ABS relays under the spare wheel). Caused damage to the loom all the way from the rear of the car (ABS computer under the rear seat) through to the engine bay :evil:
Developed an annoying intermittent starting fault that, together with completely rotten battery tray eventually caused me to take it off the road (and replace it with another, of course ;) )
Then most recently while towing it on a trailer from a garage to the barn, caught me out by jack-knifing itself and the (borrowed) Disco tow-car on a dual carriageway, ending up in a crash barrier. Disco smacked the arse end of the CX, Disco was written off, trailer had minor damage, credit card duly seriously hammered... CX has no noticeable damage :lol:

Anyway... Since being in the barn and moving it round a couple of times, the flexi front brake lines have burst.

Two Sunday's back, I went over to the barn for first time (proper) in ages, fixed my compressor and then moved on to planned job no.2 - swapping the brake flexi's:
Image
So that I could get back to moving it without the issues associated with having holes in your jugular :D
Unfortunately though, it wasn't playing. Wouldn't start (meaning couldn't get it off the deck to even get at the hoses :evil: ) so spent the next few hours trying to suss out what was wrong (without any of the service manuals to hand, so working just off grey cells last called into use about a decade ago and without the help of a multimeter :roll: ).
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It's the problem it's had intermittently for ages and I never got to the bottom of, normally because it cleared within a few minutes of randomly fiddling with stuff (probably completely unconnected to the actual cause). That day, it was in hard fault mode, so at least I stood a chance...
I've always thought it was an ignition fault (having previously sorted what I found to be a fault on the wiring loom between the battery and 'Big Blue') but... Nope. Spark fine, fuel pressure fine, so... That means it's the injectors not firing for some reason.
Memory told me the injectors should had a common live feed all the time and the ecu puts them to ground individually, whenever they need to fire. Without the wiring diagram though, there wasn't much I could do.
The injection loom has never been in great shape generally (rotted loom wrap and cracked connectors) so I had re-wired one end years ago, but not got round to the other end, so I pulled that out to take it home and test/rebuild if needed.
Image
Image
Swapping the loom with the blue cx behind in the pics behind wasn't an option unfortunately btw - later car (single sensor, no cold start injector) so not compatible.

Also thought that maybe in the course of all this, I'll finally get to the bottom of what the loose wire lurking in this area is :lol: (when I renewed the multi-connector in that area, I was never able to work it out)
Image

wurlycorner
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

Sunday just gone, I spent some more time on it - this time armed with multimeter and service manual 8-)

About 4 hours spent and of course... Still haven't got to the bottom of the non starting :evil: injection loom all bells out ok, have live feed to one side of the injector plugs as I should when the ignition is on, checked out loads of the rest of the kit all ok to spec... Yadda Yadda...

But, with the help of some hieroglyphics...
Image
Image
I tracked down exactly what the spare/stray unconnected wire was in the area around the injector loom connectors and... It's not meant to be connected to anything 8-)
Nb: the wiring looms info looks an awful mess, but is actually really really good.

So, I'm back to thinking the fault can only be either ignition related (of sorts - I know the ignition system itself is working, but might not be sending the firing pulse to the injection ecu) or a fault with the injectors themselves (unlikely that all 4 would intermittently dir together?)

Next job is to bell out the wires between the injection and aei ecu's (easier said than done, given one is in the engine bay and the other is in the pax footwell somewhere). I'm assuming that link is what provides the pulse to fire the injectors (since it's the AEI unit that picks up engine rotation sensors, not the injection ecu).

According to the oem service manual, this is the wiring schematic for the 2 sensor series 2 CX Gti Turbo;
Image
This doesn't show any bloody link between the AEI and the Jetronic ECU.

However, the series 1 CX Gti Turbo schematic shows the following;
Image
(clear link from B3 on the AEI to 21 on the Jetronic ECU)
That link is also shown in the main wiring schematic for 2 sensor M22/669 GTi Turbo's in the ignition section of the manual, so I think that's right.
The wiring diagram shows this;
Image
I want the connector ("3B") that sits between loom Z2 and IC so that I can bell out to/from it. I can't find the damn thing anywhere and it's not shown in the main wiring loom layout drawing or the conenctor pin out table (annoyingly - otherwise that would give me the grid reference on the layout drawing)
Can any other CX owners help tell me where this connector is please?

In the mean time I thought it might be worth checking the aei ecu itself for any damage, so hoiked it out:
Image
Top looks a lot worse than it is really. It's aly, just causing the thin paint to flake off.
Underside however looked awful :roll:
Image
Quick brush over of the top
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(that will clean up and paint ok)
A bit of wire brushing down and scraping with a screwdriver and the bottom actually isn't that bad:
Image
Rest should clean off nicely with deox gel and re-paint fine.

After I'd got it out, I thought I might have found the cause - Image
One of the pins in the black connector is slightly pushed in, but... alas that's not one of the pins involved in sending the pulse signal to the Injection ECU.

Now... :-k do I have the guts to bend the tabs, open it up and probably destroy the seal between the 2 halves of the case in the process..? 8-[

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CitroJim
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by CitroJim »

This is a great blog Iain and I'm enjoying it immensely :D

I've seen Xantia V6 gearbox ECUs looking like your AEI ECU as they live under the battery tray - a stupid place if ever there was one - I've cracked them open only to find them perfect inside...

Reseal with good electronics-grade silicone sealant and all will be good...

Hope the starting issue is soon found and looking forward to the next instalment ;)

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demag
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by demag »

Err I know this might sound a bit heathen, but have you tried a bit of Easy Start just to see if it fires?

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Peter.N.
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by Peter.N. »

My word what devotion :wink: The last CX I had was a CX25 DTR Turbo Safari which had no engine electronics whatsoever, what it did have though was a porous block which resulted in the head gasket failing about every 15,000 miles, bearing in mind the fact that I covered something in the region of 160k while I had it, that equates to about 10 head gaskets, such was my love for the car I willingly endured this.

Not that it was a difficult job as the head is facing you when you lifted the bonnet and after I had done a few modifications I could have the head off in about 20 minutes, the most fiddly and time consuming part of the job was re adjusting the tappets every time, it wasn't OHC of course.

I had that particular car for 7 years and it was the best car I had ever driven, the handling was second to none and comfort - well I don't need to say more. I was very sorry to see it go and although the replacement XM's, 15 years worth, were good they didn't measure up to the CX and I found the C5 disappointing.

I wish you every success with yours and hope you get it sorted soon. Mine gave very little trouble except for the once or twice a year head gasket change.

Peter

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CitroJim
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by CitroJim »

Peter.N. wrote:Not that it was a difficult job as the head is facing you when you lifted the bonnet and after I had done a few modifications I could have the head off in about 20 minutes, the most fiddly and time consuming part of the job was re adjusting the tappets every time, it wasn't OHC of course.
Ahh, the joys of an OHV engine :D Reminds me of many head gaskets I've done on A series BMC engines... Definitely the worst part was the tappets...

I still remember the rule of 9s :)

wurlycorner
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

demag wrote:Err I know this might sound a bit heathen, but have you tried a bit of Easy Start just to see if it fires?

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This isn't just a 'starting' problem - the engine either runs, or it doesn't. When it doesn't run, it's because it's not firing at all (spark is there but fuel not being injected) so yes - while squirting, easy start would cause it to fire, but it wouldn't keep running, unless I kept my finger on the easy start trigger.
It's just the same intermittent fault that it's had for about a decade, currently manfiested as a 'hard' fault - which is actually a bonus tbh, because it means I might have a chance of actually finding it at last :-D

When I get the engine running again, the only progress to expect on this car, is front brake flexi's changed and it will then go on the back-burner again (behind the 3rd gen prelude I need to put back together after having been resprayed, the Activa that I need to sort various niggly problems on and the 4th gen prelude that needs cambelt, power steering lines and general tarting up in the engine bay). Then I will reassess which one is next :-D

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demag
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by demag »

Ah, got it now. I thought it was getting fuel but not starting sorry.

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wurlycorner
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

:shock:
Some progress today!!!
1. Found a wiring diagram that my car actually matches
2. Found the connector in question
3. Found that someone has previously come to the same conclusion as me as to what the cause is (they have run a slave wire in to replace the original)
4. Confirmed the original wire is indeed dead
5. Found intermittent poor connection in the 15mm length between solder joint of new/old and the AEI plug, because... It looks like the wire got too hot during soldering and has gone hard/brittle (it snapped while I was pulling it :roll: )

More detective work to go, but... Nice to have found something where I had suspected the fault might be...

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CitroJim
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by CitroJim »

Excellent :D Citroen wiring strikes again! You were jolly lucky to actually find a diagram that matches your car... That's so rare I expect to hear about it on the 5 o'clock news :lol:

Seriously, good work Iain!

ekjdm14
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by ekjdm14 »

More on this one please!!! :D

wurlycorner
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

Not much progress to report unfortunately.
To complete the rewiring, I need to replace the pins on that wire, either side of a 3 pin connector. I have completely failed to find a matching female and male replacement pin in the right size (after weeks of seraching, it's evident that only males are sold ANYWHERE in that size :roll: ) so I have resorted to buying some new 3 pin connectors to chose between (I hate using non oem look parts).
I've also spent weeks de-rusting the back of the AEI ECU in readiness. Aside from that, work, work, work has got in the way.
As coincidence would have it though, I'm intending to get over to the barn tomorrow to have another go...

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Sloppysod
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by Sloppysod »

Interesting Blog, but just one thing, you do know Petrol goes off!! If petrol has been lying around for a while it losses its' 'bang'. I rebuilt an Fuel injected motorcycle, it was off he road for just over a year, and had trouble starting it, what had happened was the fuel in the injectors had waxed over, I had the injectors ultrasonically cleaned, then it started first time every time.

http://www.bp.com/content/dam/bp-countr ... ndling.pdf

THe CX GTI is a lovely car, when they are going, I had one only for about 2-3 months, occasionally when I booted it the front would lift so quick the front wheels would almost break traction!! I was too young an inexperienced to realise at the time it was probably a dodgy height corrector.

wurlycorner
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by wurlycorner »

Yep, I know that's a problem with unleaded these days.
This one has been fairly frequently run over the years though with not much in the tank, so needing frequent top ups from a can.

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CitroJim
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Re: wurlycorner's silver s2 CX Gti Turbo - troublesome sod...

Post by CitroJim »

I can attest to the fact that petrol will live unharmed for at least six months - It did in my Pug of Love as it stood abandoned for that length of time before I revived it...

Started first time and instantly!

Then passed an MOT with almost zero emissions recorded on that old petrol...