Never trust a French fuel gauge / Why my GTi won't start?

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Way2go
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Way2go »

PS: On a RHD or LHD car.

If you lift the RIGHT hand front seat squab you will see and be able to read the label on the Engine ECU.

If you lift the LEFT hand front seat squab there is another ECU for the ABS.
Last edited by Way2go on Tue Mar 19, 2013 12:35 am, edited 1 time in total.
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by RobC »

(It'll be the other way round cos I assume he has a LHD car) ;)
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Way2go »

RobC wrote:(It'll be the other way round cos I assume he has a LHD car) ;)
Thank you, suitably amended for clarity of either hand. 8)
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Melchior »

Under the inlet manifold? I see nothing :( Is it part of the coil?

This is a pic of my engine bay, zoomed a bit into that area. You can see the LV wiring (coloured and a bit exposed from its plastic shield thing), the coil, then the HT from coil to distributor on the end of the camshaft.

I don't get where the ign amplifier could fit into this?

Image
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Way2go »

You have a more solid moulded inlet manifold rather than the 4 branch which is easier to see below. You need to look under between the oil filler and air inlet in the direction of the offside. It is normally mounted on a metal plate/bracket and the modulle has a flat plug connected to it if I remember right. Check it out using a torch and a mirror to see the underside of the manifold.
However, your oil filler has been relocated due to the different style of manifold so it could be the ignition amplifier has also been relocated?
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Melchior »

Thanks, I will attempt to investigate this at some point in the next days.
Despite your description of the physical location of this thing, I am still baffled as to how it is wired into the ignition system. As I said before, the low voltage wires come from the loom and into the coil. Then an HT lead from coil to distributor, then 4 HTs to each spark plug.

So where in that lot does this ign amplifier connect?!
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by mat_fenwick »

The ignition amplifier will be connected to the low voltage wires from the coil. It is this which amplifies the signal either directly from a sensor or from the ECU (depending on what system you have) to trigger the coil.
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Way2go »

As above. The fact that the wire to the coil comes out of the loom does not mean anything more than a corresponding wire enters the loom from another point - in this case a wire from the ignition amplifier or module.
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Melchior »

Had a good old gander as best I could under the inlet manifold earlier. It looks like there are extra wires I didn't see before going either into the coil or something very close to it - I can only assume this is the ign module. Considering the car's age and mileage I suspect this isn't the original coil. Do some of these coils have the ign module built into them?

My evidence gathering plot thickens today so maybe this might help diagnose where the problem is for you chaps. I started it up after resting for 4 days. She started but the K light was on and idle was mega lumpy. I was able to rev her a little but as it is very cold I didn't want to rev her hard so just held the revs up to 1500 or so to warm her up for a minute or so. By this point she was running very lumpy as soon as I pressed the throttle but with no throttle was idling nicely. Ended up with my foot on the floor, she was pulling around 2000 revs and popping and spluttering all over the place. On and off the gas a few times, suddenly she idled and revved perfectly and the K went out.

Drove to petrol station and put a reasonable amount of fancy 95 juice and a tin of Wynn's injector cleaner (€12.50 worth, can't say I ever thought it helped but I am a little dazed and confused today!) and a bit more driving and warming through.

No doubt at all this problem is getting worse. Even in neutral now she goes mental at full throttle over around 3500 revs and is very low on power in all gears above around those revs. Rarely will rev past that. Between idle speed and those revs she is pretty eager.

Knowing this, can anyone perhaps relate to the symptoms and suggest what might be causing this? I would (of course!) much rather not replace bits guesswork style.

My money is on ignition. I think if it was fuelling it would feel 'weak' and cut out or splutter around etc. But this is a little more aggressive and the popping/banging from the exhaust makes me think ignition.

IF it's ignition then it must be:
- coil
- ign module/amp
- distributor

Or a sensor somewhere? Crank/cam sensor? I would think a dicky crank sensor would mean no real action at all and I'm not sure this has cam sensor. (I used to have a Rover 420 turbo and although I never had the problem myself I know a dicky cam sensor on that engine would cause a 3500rpm misfire)

If I get some time to remove the coil and ign module, can someone give me a clue as to what kind of multimeter readings I should get from them? Hopefully this will give me an idea as to which one is up the spout, if either.

Thanks for all your advice so far :)
M
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Melchior »

Ugh, sorry for multiposting my own thread but if anyone's out there with a super nerdy service manual I'd like to know what sort of voltage/ohm values I should be expecting from the various ignition/ECU components so I can run a meter over them to see which one is failing.
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by RobC »

this link might help http://citroen.tramontana.co.hu/fuel-ex ... ion-basics" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by RobC »

and this one http://citroen.tramontana.co.hu/fuel-ex ... components" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? aka Why's my GTi dead?

Post by Melchior »

Did a bit of fault code reading just now:

31 Wrong fuel/air mixture
33 Air flow or MAP sensor / Throttle potentiometer (Mono-Jetronic)
52 Oxygen sensor system control

Then I cleared the codes and went for a drive. There is a very very slight misfire at cruise, hardly noticeable. Once she was warmed up I pushed harder and it seemed the problem was gone! But then after a little more driving, it was clear to see the problem is still there.

Then I returned home and read the ECU fault codes again. This time, no fault code was recorded (just 12, 11).

I did notice a bit of strange behaviour of the rev counter when revving it up in neutral. It only happened once and very quickly but I wonder if it is related. You can notice that at the very start of the second video:

Mostly 2nd gear and full throttle. You can see the camera shaking due to the misfire...
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Some revving in netural and then driving a bit: (notice rev counter behavior at the very start)
" onclick="window.open(this.href);return false;
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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Re: Never trust a French fuel gauge? / Why's my GTi misfirin

Post by sdelasal »

First, have you checked/replaced the basics: .... air filter, fuel filter, plugs - and perhaps inspect the plug leads and set the idle CO as to specification?
After that, i'm wondering if your have an air leak into the intake manifold - check all of the various hoses attached to the manifold. The problem might be that at light pedal, you have maximum vacuum in the intake manifold and therefore maximum potential for air leaks to do their damage - i.e. the engine will run lean because the 'air leak' is not passing thru the air meter.
At WOT, the leaks are minimal as intake manifold pressure is high. At idle, the problem can be masked, perhaps unknowingly, by fiddling with the idle air / mixture adjustment. Worth checking - perhaps spray some light oil as you move the pipes around -and see if engine rpm changes. However, because the engine management system will attempt to control engine rpm, at the idle speed, you ideally need to disable it - this usually involves connecting a couple of pins together on the diagnostic connector - check the haynes manual for info on how to do this. Steve
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Re: Never trust a French fuel gauge? / Why's my GTi misfirin

Post by Melchior »

Had a quick faff with it earlier as it couldn't make up its mind whether to behave or not. Found a screw missing from the dissy cap so I think that may well be the cause or at least part of my problem. I wouldn't say it was literally HANGING off but it wasn't far! How I didn't notice that before I am not sure.

Next step is to remove the dissy cap and check it.

Thanks @ sdelasal and it's an interesting theory and I wonder if it is contributing to the slight miss at cruise. But I can't see it would cause the major misfire at WOT and higher revs?
Dutch 1991 BX 8v GTi. 280,000km
APK (Dutch MOT) failed in May 2013, sold to a member of the Dutch Citroen forum. His thread can be found here: http://www.citroen-forum.nl/forums/viewthread/221870/" onclick="window.open(this.href);return false;
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