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Technical Running on 3 Cylinders?

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Technical Running on 3 Cylinders?

G

goneleft

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Hi All,
Over the weekend I clocked up some big miles in my 1997 899cc Cinq. Nearly 700 over 3 days.
Its been running fine with a bit of squeaking formt he alternator belt.....Until this morning. It just managed to limp the 12 or so miles to work.

It was very under powered and had a really rough idle.
It only seems to be intermittent and gets less frequent when its running at temperature. No warning lights that I noticed.

I'm thinking thats it's possibly only running on 3 out of four cylinders and because its intermittent I was going along the line of no spark.

I was going to run it and remove each HT lead one by one to find the responsible cylinder. Is this a good idea/ safe to do?

If it is the case and it isn't running on all cylinders, am I OK to drive it home without doing any damage or would it just be wiser to get it towed.

Any help would be much appreciated.
Cheers.
 
My first guess is that one of the coils is giving up.
 
I'll had similar problem, but never got round to fix it.

I'll found that cylinder 2 wasn't running, i have tried replace the coil, ecu but wirh no luck, last thing to try as to take the head off and see if there is anything wong.

Anyway, i have remove each ht lead when the car was running and shocked myself :p.

You can start the car, let it run for like a min, then remove each spark plug and see if they are wet or dry.

IF it is wet, then that cylinder is not running.

Also at night time, get someone to start the car and look and see if u see any blue spark, if there is then it could of one of the ht leads giving up.

Hope it works and that's the advice i got, when mine was fooked!!

Good luck
Ming
 
right done all that. seems to have cured most of the problem. it still seems down on power though.
theres no oil in the water or gunk in the oil.
the water level had gone down, by about half a pint though the bottom hose conection to the radiator was abit wet so it could just be a slow leak.
If the head gasket has gone could it be blowing from one cylinder to another?
The exhuast note seems to be abit deeper and more "rumbley" than it normally is.
Any ideas?
 
Last edited:
yeah they do smell abit fuel-ish. It does get slightly better when its warm. got some new plugs coming and i think im going to order a head gasket and one for the rocker cover too.
 
First thing is to find out if it is running on 3 cylinders or just misfiring.

You can do this by touching, or spitting on the exhaust branches. The one it's misfiring on will be much, much, cooler. The plug of the offending cylinder will be wet with petrol. If not, then suspect misfire.

If yes, it can only be plug, lead or poor compression: likeliest cause of the latter is one of the valves not closing. Often, if you start the car at night with the bonnet open, blue flashes will reveal a duff lead or HT connection.
 
I've just taken another look. Had the breather hose off the rocker cover and it really semlt liek exhuast fumes and i thought I could see some too.

New HG time?
 
If the HG has gone between two cylinders then you get an uneven idle, but at higher revs where the gas speeds are higher its much less noticeable.

This can be checked by pulling the plug leads off one by one and seeing which plug has no effect on the running. Make sure you complete the test not just stop at the first one that doesn't kill the engine.

If the HG goes between a cylinder and a water way, then you have a right gusher of water system and weeping half a pint ain't it.

If the HG goes between a wtaer way and an oil way, you loose water, but gain oil quantity and mayo.

If you have two plugs not killing the engine, and they happen to be 2 and 3. Swap the coils as a starting point. If the failure is still on 2 and 3, then its possibly the HG, if the failure moves to 1 and 4, its the coil.

Cheers

D
 
I've jsut done waht rallycinq suggested and removed the plugs one by one but none of them killed the engine.
all made it idle roughly but not of them actually stopped it dead?
ideas anybody?
cheers
 
OK, so that should mean that you have all four firing, beacuse if one isn't, and then you take another one away, it will usually stop.

Are there any more 'tappety' noises than before. Regular tapping sound from under the top of the engine?

Cheers

D
 
A little but the tappets were always noisy and the injector makes a right racket.
When the HT leads are off the tapping noise gets a lot worse.
 
Lumpy running and a petrolly smell turned out to be a dicky CTS on my '96 cinq. It cost about twelve quid from a local motor factor, and went in in about ten mins. I went through all the other stuff that's been suggested, and this was the only thing that made a difference.
 
One thing i found with mine the other day when it began firing on 3, was that the metal cone filter was brushing up against the HT leads at the coil end, i opened the bonnet and the spark was occasionally jumping towards the filter as opposed to the plug!

Made a rubbed barrier to go between the two, and the problem disappeared :)

I don't know if this will apply to you, as i don't know what induction set up you run, etc, but i thought i'd offer my tupence worth :)
 
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