cx gti turbo2 runs poor

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freek
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cx gti turbo2 runs poor

Post by freek »

Hi,
My cx has the following symptoms: it starts instanty, dies after app. 10 seconds and is only kept running by moving the throttle. After a while it will keep idling but uneven.Then when driving the engine runs unevenly at constant speed and stalls the moment I have to stop. This has worsened in the last few weeks. For more than a year I was used to restarting the engine after 10 seconds, but after that it would run perfectly.
I checked the ignition (coils, sparkplug leads, sparkplugs, sparks) which seem all ok. I also changed the flywheel sensor. So I am now thinking of the fuel system. I looked for vacuum leaks but all hoses seem ok. The contacts of the thermosensors are clean. Could the fuel pressure be a problem (regulator, relais)? Has anyone had similar problems?
Regards,
Freek
andmcit
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Post by andmcit »

Generally in my experience there'll really only be two other things to
check AFTER checking the items you've already checked in your list.

I've had problems on several Cx GTi's with the fuel pump. It sits in a very
weatherbeaten position even with it's shield and it's wiring can be suspect
as well as the pump itself seizing. Is there even buzzing from under the
car below the rear right hand side seat - it will make a consistent buzzing
and these can be very noticeably loud.

The other fuel culprit may be the BIG BOSCH blue relay that lives either in
front of the car battery on a series 1 metal bumper car or ahead of the air
cleaner box on a series 2. You'll recognise it straight away as nothing else
will be the same colour, labelled BOSCH or be as large.

Other causes of erratic running?

The ECU's can cause problems with poor internal contact joints. The engine
mounts can fail allowing the engine to rock with the high torque the engine
can produce and this can cause break up of the wiring loom from the front
crossmember. In fact the wiring into the injectors can break inside the
plastic sheathing unseen by casual inspection.

Andrew
citronut
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Post by citronut »

you say you have changed the flywheel sensor,you know there are two if the car has fully electronic ignition,what model and year of CX is she
regards malcolm
handyman
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Post by handyman »

You have all the symptoms of a dodgy flywheel sensor. If you have replaced it, was it with a new one? If not put a new one in.
Something else worth checking is the cable/wiring to the fuel pump. In their wisdom, Citroen put a connector in the cabling for the pump under the footwell carpet. If you have had a damp carpet, chances are the cable is corroded. Pain in the a**e job!
Check out the connector to the BIG BLUE RELAY as well as this is probably corroded. Clean out the contacts with switch cleaner, apply a liberal dose of vaseline and tie up in a rubber glove. (Sounds like somebody having a good time!)
Citronut, early Mk2, Srs1s had two sensors, later Mk2, Srs2's had one sensor as the ECU used a clipped EPROM to allow for ignition advance.
IKBA, Handyman
handyman
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Post by handyman »

Freek, two other possible problem areas spring to mind. The air valve sensor may need cleaning as that can some times get crudded up with bypass oil. A quick spray with carb cleaner and a wipe with a cotton bud helps.
Check the throttle position sensor by lifting off the cap and looking to see if the tracks are worn, usual on very high mileage cars. If it is worn, best of luck finding a good used one!
Are your sparking plugs in good order, the right type and gapped correctly? I always found some cars preferred Champions while my currently one runs better on NGKs. I found Bosch and many other makes complete no-nos.
IKBA, Handyman
freek
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Post by freek »

Interesting suggestions! In fact the car has only one sensor. I replaced the sensor with one I once bought second hand (as a spare part in the glove box). So it could in fact be wrong as well...
The weak spot in the wiring from the fuel pump I noticed my self last year when the car suddenly could not be started at all. Has cost me a week to find it. The connector under the carpet was a bit detached probably due to a repair job of the body at that spot 4 years ago. At the same time I inspected big blue and cleaned the contacts. But I can make mistakes as well so I will inspect it once more. About the air valve sensor : where is it located? Is that in the flow meter where the throttle sensor is? Last but not least: the spark plugs. This is a bit confusing. At the moment I use NGK BP6HS; They have done 10000 km and the colour looks ok. But a crossreference from the advised Champion L82 gives B6HS.
I was beginning to suspect the fuel pressure regulator. But none of you mentions this part. So can I conclude that a faulty regulator gives other problems or is it very reliable?
Thanks! Freek
slim123
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Post by slim123 »

The very simple and common problem on these is the concertina pipe from the air filter to the throttle body housing, dont just look at it! Remove it and inspect it very carefully, check for cracks in the roots of the concertinas, any air ingress in here can cause all sorts of troubles.

Whilst the pipe is off, give the trottle body insides a good cleaning using lots of carb cleaner and a tooth brush, also give the air flow meter in the air filter top a good clean with the carb cleaner.

Also it is allways helpfull to squirt through all the vacume pipes with carb cleaner.

In my humble experience the pressure regulator dont give much trouble, but dont forget, these cars are now getting well past the design life and all sorts of new troubles will surface.

It is worth pointing out that after spraying all the carb cleaner around, the car will be difficult to start, but it will go when the carb cleaner has gone through.

Regards
Slim
citronut
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Post by citronut »

handyman wrote:Freek, two other possible problem areas spring to mind. The air valve sensor may need cleaning as that can some times get crudded up with bypass oil. A quick spray with carb cleaner and a wipe with a cotton bud helps.
Check the throttle position sensor by lifting off the cap and looking to see if the tracks are worn, usual on very high mileage cars. If it is worn, best of luck finding a good used one!
Are your sparking plugs in good order, the right type and gapped correctly? I always found some cars preferred Champions while my currently one runs better on NGKs. I found Bosch and many other makes complete no-nos.
IKBA, Handyman
well my H reg (1990) 2.5TRI AUTO saffari has got two flywheel sensors,i allways thought it was all CXs with no dizzy had the two
regards malcolm
DoubleChevron
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Post by DoubleChevron »

Hmm,

this screams vacuum and wiring problems to me. I reckon you'll have a few completely seperate problems. The low speed cutting out will be a vacuum leak, off idle it's reasonable as the turbo's blowing and the amount of airflow is disguising any small leak, at idle the turbo's not blowing and any minor leaks will show up as an unsteady idle, and the car will die as there is air being sucked in downstream of the Air Flow Meter.

My suggestion would be to bypass the intercooler (that takes a leaky cooler out of the equation, so ruling it out), and the *all* the hoses between the AFM and inlet manifold.

Then (on the Turbo I at least with injection & ignition computers) there is a LOT of places the wiring will need to be fixed up. The connectors above the battery near the air-horns were dodgy on my car, if you remove the spare wheel and remove the shrowd under it you will find another 4 big multi-block connectors. The only way to get these reliable is to buy a bag of new press in terminals and replace the connectors.

good luck
Shane L.
'96 Big BX 2.1TD exclusive slugomatic (aka XM)
'85 CX2500 GTi Turbo Series II (whoo hooo)
'96 Xantia VSX slugomatic (sold !!)
and of course, lots of old Citroens, slowly rusting away in pieces ;)
citronut
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Post by citronut »

i agree with an air leak in the induction somewhere,but colin says he has checked all of the vaccum pipes,the easyest way to find a leak in the inductionis with a can of carb cleaner,with the engine running spray the carb cleaner around all of the vaccum pipes and inlet manifold joints,
regards malcolm
andmcit
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Post by andmcit »

Past hassles with Cx's listed here with other replies have triggered
some further recollections which I've done my best to forget!! :wink:

Thing is, most of the problems I've encountered myself or heard of with
other people's Cx experiences are an all or nothing dead or alive problem.
Whilst air leaks can be right sod to trace and sort the engine will usually
still run. Loose pipework off the intercooler or turbo WOULD allow the
engine to run, hot or cold, without there being ANY power to accelerate
from stationary; I've experienced this with a Turbo2 which would scream
past everything on the road effortlessly and cut out embarrassingly on a
bend where the engine would rock a duff lower engine mount and pop the
main intercooler pipe off!!

The plugs, HT leads, flywheel sensors or coils would probably break up
under load and heat and whilst being the favorite key suspect and the
'villain of the piece' these seem unlikely here. Cutting out intermittently
leading to massive backfiring with dramatic pops and bangs on trying to
restart on a 2.5 TRi was a duff coil - this wasn't easy to swap over with
another set as the wiring had been rewired to specifically suit the
connections on the apparent Citroen supplied update repair kit. This
doesn't actually sound the likely cause in the problem being discussed
here but would help eliminate the coils. The Cx's aren't renowned for
great wiring and I'd still suspect poor wiring to the injectors or the main
loom to the engine.

On a reread, for the engine to initially run and then stop I believe the fact
the engine warming up and continuing to run, albeit roughly, is significant
and for me still points to the fuel system. My 2.4 Prestige would only run
for a few seconds and then die, and whilst I systematically swapped
everything with second hand items, it turned out to a a duff air flow meter.
I was never able to see the spares donor working so was going on bluffs
and promises from the scrapyard owner about everything being in full
working order... :x

Are known good and working 100% parts being substituted in the process
of elimination...?

Andrew
freek
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problems solved at last!

Post by freek »

Hi,
I finally succeeded in solving the problems. In the last few months I did not have much time to look at it, and regarding it as a hobby I could wait. In the mean time I searched the internet looking for clues as well. I was determined to find the solution myself and not bring the car to a repair shop and having a big chance to loose a lot of money. Real CX experts are scarce unfortunately...
I found out that there were no vacuum leaks in the inlet manifold (I pressurized it by using a bicycle pump after closing it with all kinds of materials: cups, tape, etc), that the resistance of the temp sensor was right at low and high temperatures, the fuel pressure regulator was not leaking, and the auxilary air valve was ok as well. What was left to check was the wiring. So I decided to clean all the connectors (and there are many!) under the bonnet: under the spare wheel, above the left wing, etc. Until yesterday I was not completely athough the behaviour of the engine had improved. I finally found the clue on http://web.telia.com/, a swedish site. There is a grounding point located above the battery, below the black box on the L/H front of the wheel arch. I cleaned the contact thoroughly and today the car runs perfect again. At expense of spare time but without replacing expensive parts. Nice hobby!
Freek
ps according to the repair manual of the gti turbo there is a 'injector relay' (nr 734) near the blue fuel injection relay (731) at the front right side. However my gti turbo2 only has the blue relay at this spot. Where is the other one located?
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AndersDK
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Re: problems solved at last!

Post by AndersDK »

freek wrote:ps according to the repair manual of the gti turbo there is a 'injector relay' (nr 734) near the blue fuel injection relay (731) at the front right side. However my gti turbo2 only has the blue relay at this spot. Where is the other one located?
The one located under the RHS headlamp ? This is the special relay placed here to act as an impact sensitive fuse, to disrupt the fuel pump supply on accidents.
Donno if this was replaced by other safety means on the last versions.
Anders (DK) - '90 BX16Image
DoubleChevron
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Post by DoubleChevron »

OMG .... Gee's sorry none of us thought of suggesting the earth point. That's the first thing that always should be cleaned :( I guess we all just assumed it was checked by default.

There should be an injection relay next to big blue (there is on my GTi Turbo), this powers the injectors themselves.

seeya,
Shane L.
'96 Big BX 2.1TD exclusive slugomatic (aka XM)
'85 CX2500 GTi Turbo Series II (whoo hooo)
'96 Xantia VSX slugomatic (sold !!)
and of course, lots of old Citroens, slowly rusting away in pieces ;)
freek
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Post by freek »

I did not notice the earth point earlier because it is hidden behind two airco hoses. Advantage of my search is that I know now the location and state of many critical points under the bonnet (but surely not all :( ) So no problem Shane!
About the injector relay: this must have another location in the t2. All information I found until now however is about the t1.
Freek
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