Intermittent GTi running issue + clutch query

[maxgreenwood]

I plan to get to the bottom of my GTi engine's little foibles when time and money allows to get it running as smoothly as I can.

On a light throttle typically at a steady speed it's as if there is a fueling / vacuum / ignition problem which makes it miss slightly or unsmooth at any rate. Sometimes it seems to run smoothly for a time, so it seems intermittent.

The garage have repaired the MAP sensor in the ECU, found 1 leaky vacuum pipe, tested the compression, new plugs, I fitted Magnecore HT leads, fuel pressure ok, they went through it. Anyway I was going to start with investigating the air-flow meter, maybe replacing. Might have access to a Pug 1.6GTi one, not sure if will be correct type though.

The ignition distribution is apparently the 'leak-off' spark type, no distributor rotor. The ZX engine apparently. No CAT.

I would welcome any other suggestions as to what to look at.

And why does my clutch pedal feel heavy? New clutch 10k ago. Are they heavier than, say the 16, which is the only other petrol I have experience of?
If the cable is cutting into its surround does that make a significant difference?
It is a bit high, which I plan to adjust slightly , it seems there is room for it.

Any advice welcome.
Thanks
Max

[mat_fenwick]

I knew there was something I was supposed to be doing!

[Way2go]

Anyway I was going to start with investigating the air-flow meter, maybe replacing.
Max

I don't think you have one of those as your ECU is Bosch 3.1.

Open the air box and find it empty!

[bx petrol auto saloon]

Dear Max.
Sorry to hear of the problems Max
Have you checked the tappets Max I know mine has shims, but
even still they should have a clearance that can be checked with feeler
gauges
As for the clutch problems Max, the best place to start with that, is
at the clutch pedal first. Disconnect the clutch cable from the top of the
pedal and ensure the pedal is free.
You can,t tell by just looking at the clutch cable, to see if it is tight
and running smoothly through itself, so I would at this point put a new
cable on to try it ( if it is no better then, you haven,t lost any-
thing )
After those items mentioned above, then the problem lies with the
clutch itself a tight pedal in the clutch can be a few things, one
an ungreased first motion shaft, where the release bearing sits. two
and most probable, is a tight/old clutch pressure plate.
What NEW parts did you have fitted to the clutch then Max and
where from. I do that new clutches from G.S.F are rubbish. The driven
plates can be quite soft and wear quickly, resulting in a high pedal bite.
leading to premature renewal of the clutches. for your information a
new clutch should give a low bite on the clutch pedal
I hope this helps Max
All The Best.
Vince.

[maxgreenwood]

Hi Vince,
Thanks for the tips,
The garage said the clutch was fine, but the bite point is high but then so is the whole pedal so I thought adjustment might cure that. New clutch was 2 owners ago at 55k in March 2010, now has 65k on it.
On the invoice it says 'clutch unit' £68.12 ex vat , so that might be an indication of what type. My 16 was fitted with the proper sort and that certainly has a nice light low bite point and loads of progressive control. The Gti has a high bite point and comes on much more suddenly, I have to be careful at lights.

I'm not sure about tappets, I don't know loads about cars and that sounds a bit too deep for me, unless it's easy to check clearances.

[MULLEY]

Might either be a non LUK or Valeo clutch fitted which might explain why its a bit stiffer (if the cable is ok), or you might be unlucky & its a duff clutch As long as its not slipping, i'd just adapt your driving style, far cheaper than replacing it, just because you prefer the feel of a lighter clutch pedal. Hopefully its the cable or pedal box instead.

[maxgreenwood]

Yeah it's ok I don't mind too much, it would make a massive difference if it was like the 16's though.
I'd rather get smooth engine running first.

[bx petrol auto saloon]

Dear Max.
You have to remove the rocker cover Max, mind the rubber gasket
as it should be gasket sealered to the alloy head at the four points
where the rubber gasket curves over the rocker-shaft caps This
needs to be sealered the same way, when you put it back together.
otherwise may leak oil when you start the engine up again. Remove the
spark plugs and cover holes with large cloth, to elimate the chance of
dropping a nut or something down the plug holes. With the plugs out
you are now able to turn the engine by hand easier using the crankshaft
bolt. You need to find out which valves are inlets and which are exhausts
by looking at the respective manifold. You should then turn the engine
over until you the find the valve clearance gaps on the back of the
camshaft lobes. I should expect to be able to get an 8 thou gap on the
inlets and a 10 thou gap on the exhausts
This is not an easy job at all Max you really need to know
exactly what you are doing
To adjust them if they are tight, is even worse, as you need to
have a collection of thinner shims to fit, and to increase the gap. And
this requires a micrometer to do this. and you need to remove the
camshaft to do this.
I have got to check mine though, so I will let you know how I get
on first.
My 8 valve SAAB has the same set up and they only need to be
checked every 60,000 miles
I hope this helps Max.
Vince.

[MULLEY]

Vince, i've been informed that the gasket doesn't need to be glued, not sure if this is correct or not though??

[maxgreenwood]

id probably get the garage to make those adjustments.

so tappet/valve clearances being out could cause a occasional misfire?

we had a misfire with the saab cured by them adjusting something similar i think on the cam followers - the exhaust gases were not escaping properly, but that was misfiring on one cylinder every revolution at idle, disappeared when revved.

This one comes and goes every 2 -3 seconds.

.............I just spoke to the garage and they said anything being out there would have shown up on the compression test.

[bx petrol auto saloon]

Dear Matthew.
Sorry for my late reply Matthew Thank you for your kind
advice. I understand that the rocker cover, shouldn,t be glued on, with
mine just the four very very small points, at which the rubber gasket
turns through 90 degrees, was sealed. and so it should be I use the
same dark green sealer that they use on Rolls Royces, it is very very
good stuff Not cheap at £ 20 for a small bottle though
All The Best Matthew.
Vince.

[maxgreenwood]

Turns out my car doesn't have an air flow meter!
Just a pipe from the manifold direct to the ecu. I am going to have to learn more about this engine.

i have found loads of useful info on the BX DIY site, including where everything is in my engine, which i was scratching my head about.

http://citroen.tramontana.co.hu/fuel-ex ... components

[Way2go]

Turns out my car doesn't have an air flow meter!
Just a pipe from the manifold direct to the ecu. I am going to have to learn more about this engine.

i have found loads of useful info on the BX DIY site, including where everything is in my engine, which i was scratching my head about.

http://Citroën.tramontana.co.hu/fuel-ex ... components

Did you not notice my reply at the top of the thread?

Anyway I was going to start with investigating the air-flow meter, maybe replacing.
Max

I don't think you have one of those as your ECU is Bosch 3.1.

Open the air box and find it empty!

[Oilyspanner]

The valve clearances are pretty reasonable to check, but a totally different ballgame to adjust, thankfully they rarely need adjustment (at least on the diesels) and the petrol engines use pretty much the same parts. my record for having the camshaft in and out of the head is sixteen times (Xantia with snapped cambelt and six new valves)

[maxgreenwood]

Did you not notice my reply at the top of the thread?

sorry Way2Go, i missed that, been a bit flat out. Looks like there are plenty of things i can check though.
thanks
Max