ZX 16v - Misfire?

gjb02 · Unread post by **gjb02** » 06 Nov 2003, 22:39

Me again, I can't think what is causing this little problem. First thing in the morning or after the car has been stood for some time..normally more than 6 Hours, the engine misfires...then it clears and runs fine, it doesn't misfire again when the engine gets hot...so it's probably not the coils (had that one last week!![:)])
It only seems to be a single cylinder misfire, and it effects all revs. The misfire lasts for about 3-4 minutes then you can feel it as it starts to fire again.
When very cold in the morning the car is a bugger to start, then misfires. It runs perfectly fine the rest of the time. No coolant loss, smoke or overheating. It's very strange...any ideas?

Diagsys · Unread post by **Diagsys** » 06 Nov 2003, 23:22

sounds like you might have an injector beginning to stick there gjb02.
If you take your car to your local citroen dealer then they can hook it up to their lexia/proxia machine and it will identify which cylinder has the misfire (saves trial and error).
Just remember that citroen number their cylinders from flywheel to crank pulley. Dumb i know but there we are!
Changing the injector is an easy quick job.

gjb02 · Unread post by **gjb02** » 06 Nov 2003, 23:57

Thanks for that, I had an idea it might be something along those lines, just one thing after another with this car!![:(] I've not even looked at the clonking from the suspension or the unmistakeable sound of a CV Joint on it's way out. Oh woe is me![:(]
I have got an engine / injection specialists round the corner from me in Norwich. I may just remove all the injectors and have them checked/cleaned. Should improve performance as well.[:D]
I noticed you replied on the speed sensor issue as well. Is there any way of checking the output with an oscilloscope or something or should I just replace it?

gjb02 · Unread post by **gjb02** » 07 Nov 2003, 02:59

Well, just did some nocturnal investigation..to see if I could see any spark tracking. No such luck, [V][:(!] pressure of coolant system a little too high too quick! An excess of steamy vapour from oil filler cap on accel, and would you like chips with your MAYO!!![:(!]
Looks like the head gasket, if the head is cracked though[xx(]!!! Is there any way of knowing without investigation? It hasn't seemed to loose any coolant, but it was a little fizzy!
It looks to be the No.2 from the flywheel end. Plenty of spark but no real fire. I really do hope it's nothing more serious than the head gasket though.
I've got a compression tester how can I disable the fuel injection for cranking only? What sort of values should I look for on a cold engine. It will have to be cold that's when it misfires.
Are there any pitfalls to look out for when changing the head gasket??

VisaGTi16v · Unread post by **VisaGTi16v** » 07 Nov 2003, 04:27

Hi,
re: mayo. Is the water temperature fine once you have been driving for 5 minutes or so? Before my thermostat was stuck open so it always ran cold and the temperature gauge reading was very low. This lead to on obscene amount of mayo, enough for 1000 McChicken Sandwiches. Once i changed the thermostat and took it on some long journies it eventually cleared.
re: suspension. Could be a number of things. Most likely is the anti roll bar drop links. Simple test for this is to remove them, only a bolt at top and bottom then drive it over some bumps and see if you still get the noise. Dont cain it around any corners with the front roll bar off though as its even more tail happy than normal! Failing that it could be the lower arm bushes which is the problem with mine at the moment. These can be bought seperatly from Citroen and dont cost too much. The drop links are about £20 each I seem to remember from when I did mine.
Cant help on the injector stuff sorry
regards
Darren

wheeler · Unread post by **wheeler** » 08 Nov 2003, 06:30

To disable the injection for cranking either trip the inertia switch (if fitted) by hitting the side of it with a screwdriver then push down afterwards to reset or unplug the double injection relay.
An ociliscope is the perfect tool for checking the sensor,if its an inductive type sensor (usually 2 wires) you should get a sine wave pattern when cranking.if its a hall effect sensor (usually 3 wires) you should get a square wave pattern.

benj · Unread post by **benj** » 08 Nov 2003, 11:41

Are there any pitfalls to look out for when changing the head gasket??
wouldnt say pitfalls just a right pain in the arse
youl have to take the complete inlet manifold system off and out of the car, then either disconnect the downpipe or the manifold from the head - both equally fun. you may as well recon the head while your at it, i paid a 100£ for a stripdown, decocke, skimmed head and reseated valves, i supplied all the seals etc. it would be silly not to.
ive just down mine so if you decide to do it yourself you can ask me whenever you get stuck!
darren! have you cancelled that cheque? the units are still in the back of my metro, ive been working nites and lost touch with reality, il send um ya dont worry!

gjb02 · Unread post by **gjb02** » 08 Nov 2003, 13:37

Could it be any worse than the head change on a ZX TD?? I spookily had to change the cylinder head on my ZX TD almost a year ago, I think I'm jinxed!![V] The TD was a nightmare, done in situ, those bolts on the back of the block for the intake/exhaust manifolds!!!
I'm going to do some more investigation before I start ripping stuff apart. Compression, coolant levels/pressure. How much tissue I've got to stem the blood when I inevitably cut my hand.[:D] Best make sure my tetanus jab is up to date as well. Oily hands and open wounds, ohh.
What about all this, taking the cams out to take off the head? Madness!![:o)]
Any ideas how long it should take, all in?

benj · Unread post by **benj** » 08 Nov 2003, 13:57

nah thats a load of rubbish mate dunno why they say take the cams out, theres no need, i had no problems anyway
i reckon two full weekends of work, less if you have everything ready

gjb02 · Unread post by **gjb02** » 08 Nov 2003, 14:04

Haynes book o lies, is going to get a battering soon. I'm off out to work on it now, after a cup of tea, maybe a bit of a wander around town, couple of hours on the computer...it'll be dark by then. Ah well not today then.[:p]
I can't bring myself to start it. I had a back operation last year, and standing over an engine does me in for days after!![:(] I'm only 32 years old for christs' sake!![:D] Why me???????????? LOL
Have to go and source a Headset and bolts as well. GSF don't stock them[:0]

benj · Unread post by **benj** » 08 Nov 2003, 14:22

yea, i got a head set from my local motorists shop, its quite good quality but you dont get the little oilway filter thats in the head , u must chage this!
how about getting a new cam belt as well hey! adds up dun it!

gjb02 · Unread post by **gjb02** » 08 Nov 2003, 17:13

Well, strange to say the least!! Just started up the car ( the best start it's had all week.), no misfire. Only ran for 30 seconds, then stopped the engine. Removed all the spark plugs, and did a compression test, they all read 150psi / 10bar or there abouts (stone cold engine). Yet the coolant still bubbles and pressurises quickly, there is a distinct smell of exhaust in the expansion tank and there is mayo in the oil filler.
Has the head gasket gone or what?? If I strip it all down for nothing I'll be gutted, the cheapest I've found a Head Set is £70 delivered. Then head bolts, timing belt , filters oil ...etc , and then there's my precious weekends.
What else would froth up the coolant like that, and cause those sort of bubbles? And where did the misfire go??
Why are the compression readings so even? Heads tend to seal more when they're hot, not cold, don't they.

VisaGTi16v · Unread post by **VisaGTi16v** » 09 Nov 2003, 01:17

Gareth: does it get up to temperature? Could be a blockage in the cooling system or thermostat gone leading to bubbling and mayo
Ben: nah not cancelled it, no worries, they probably would have got lost if you sent them last week anyway due to the postal service strikes

gjb02 · Unread post by **gjb02** » 09 Nov 2003, 15:12

Could you explain why a blockage would cause bubbling and foam in the expansion tank. I've not heard of that one before.
The mayo side of things I can just about handle, I'll remove all the breathers give them a damn good clean and put them back on. The engine did seem to warm up ok, when it was running fine. It always came up to temp quite quickly, within 5 minutes or so. It did go a little high one day in traffic, nearly 100 deg c but no warning light! Never went high after that.
I would love if it were just the thermostat and/or a blockage, could save a whole lot of time and money.[:D]

EDD · Unread post by **EDD** » 09 Nov 2003, 16:52

Try checking the ceramic part of your plugs, look for small black spots or lines if there is any it will be an indication of tracking between plug and suppressor cap.And would be hard to spot in the dark. I had a similar problem on a Primera.