(T) Help spluttering idle, is it me coils!?

Simple,

2 days ago engine started to make strange noises with revs jumping up and down at random intervals while idling, the frequency of this increases with the accelerator.

someone suggested coils, but i get no ignition warning light, i thought this was synonymous with coils failing?

its like it will be ticking over for 20 seconds then phut phut phut phut then back to smooth for 10 secs then phut phut phut then 15 secs then phut phut phut phut phut and the whole thing is quite annoying.

your ever present help is appreciated

What engine? Might be a coil breaking down or a plug as you have the characteristic duh duh duh. Warnings only seem to come up when it's a total failure as the occasional misfire isn't noticed

With engine at idle disconnect each coil in turn and see which one makes the least difference. Then swop two coils over, the bad one with a good one and see if the fault moves with it or not. If the fault stays at the same cylinder then it's a plug (or some other cylinder specific problem). If you're in any doubt about the plugs then renew them, they're only £3 each

decks, Is it safe to disconnect coils when car is idling to find out which one has gone???
Last time I did it I kept switching engine off then disconnecting then restarting - trouble is you have to try and remember engine note!!!

just wondered if it was safe for car and human involved?

decks, Is it safe to disconnect coils when car is idling to find out which one has gone???
Well, think about what happens when a coil dies, there's no spark and no combustion in the cylinder and no permanent damage happens as long as you're not making a career out of it. Yes there's unburnt fuel going into the cat but they're much more robust than people make out. Ask your local MOT station just how few cats they've had to fail in a year of MOTs and you get the right perspective.

Is it safe for someone to disconnect the low voltage coil connector?
Well the business end is the end of the coil on the plug, that's where the 20,000 volts is coming out so don't mess about with that end with engine running but disconnecting the coil connector, you'd have a job to feel the 12volts there.

So yes, when sorting out which is the duff coil, I find it's quicker to have the engine idling and notice the effect of disconnecting each coil connector in turn

Brought it to advance pitstop for a checkup, he had a look and listen and said it was probably the coils and set off to get some then phoned me an hour later to say he had replaced coils but problem had not abated.

another hour and still nothing was coming up on his computer to say there were any issues so he put my coils back in the engine (im not buying something i dont need) and handed me the car back with a bewildered look on his face and uttered the famous last words "Bring it to FIAT".

Anyone else got any suggestions? .... im stumped. i guess its back to fiat after xmas.

There isn't much to go on, can you describe the symptoms in more detail.
Did your mechanic check the plugs too?
Is the phut, phut sudden and does it feel like a cylinder has stopped firing?
Above idle does it rev cleanly and accelerate cleanly?
Is it only at idle that it does it?
Does it start well and fire on all cylinders at start up?
When were the plugs last changed or inspected? (A plug will give similar symptoms to a coil going)
If you listen at the rear of the car does the exhaust make the phut phut noises at idle?

The popping is coming from the exhaust too but the guy checked the exhaust system and its ok.

someone on another forum said this

This describes more or less what its like, it only is apparent when in idle or in 1st and second and moving slowly. The engine starts up fine and it usually takes about a minute before the phut phut phut starts happening at random intervals.

Popping in exhaust comfirms misfire
Might just be a bad plug with some luck
So I'd go for
Plugs
Coils (although you've been there etc)

Got any other head gasket symptoms like
losing water, temp gauge doing funny things, gurgling noises in heater circuits
To find out do a
Compression test
Head gasket leak test

Sounds to me like the engine is being starved of something. I'd have a look at the air filter if dirty... replace it... it could go back as far as a faulty waterpump or fuel pump, but im sure the latter two would be acompanied with a beep beep warning.

Other than that, replace spark plugs and possibly reset the Ecu, (there's posts on how thats done) lets the ecu re-calculate how much petrol/air to throw into the engine and can sort out some minor idle problems.

Look out for signs of mayo under the oil filler cap, would mean a new head gasket.

all i can think of at the mo

Kristian

Ok, this problem is still persisting, ive not been to fiat yet, i have noticed however that when the car first starts in the morning, the engine goes through a warmup phase and at this point the revs are around 15000 and it purrs like a kitten, however as soon as the (i asume automatic choke?) brings the revs down to around 10K it starts to feel a little lumpy and finally when the warmup phase ends and the engine starts idling, thats when the spluttering begins.

Anyone got any more ideas with this extra information?

To be honest im now looking at replacing the car and the choice is between a nissan almera (2004 1.5) and a grande punto (2006 1.2) I dont really want to leave fiat but the nissan is a nice drive plus its in my fav color red. the grande punto is there because ive heard very good reviews of it and plus i like fiat strangely enough, but im fed up with 1.2 engines yet there are very very few 1.4 versions second hand in my price range.

If you want a Grande Punto i'd go for the diesel 1.3, from the reviews i've seen of the petrol engines they lack power.

As for your problem I can only think of what has been said before. check spark plugs, air filter reset ECU and maybe giev the sensors a good clean.

How old is your battery? Can cause strange symptoms, without any computer registered warnings. Trust me... It may read 12 volts, but still be compeltely whacked.

Morten.

Don't give up on the Stilo just yet. I am having EXACTLY the same symptoms as you with my 1.6

I checked the coil packs as Decks suggested and it looks like that's the fault. I didn't have any warning light either until I started to swap and change coil packs with each other to eliminate the non-faulty ones from my enquiries.

If you haven't ested the coils yet, please do so. I'm 99% certain that is where the fault is. And it took me about 2 minutes to check them.

Let us know how you get on.

Your latest symptoms don't sound like coils
If it "purrs like a kitten" at 1500rpm but won't idle when warm then look at cleaning your inlet valve (See the Stilo guides)

Then reset your ECU by disconnecting the negative lead on the battery for an hour so it relearns the best parameters and finds out how to idle properly again

Coils are more of a "I'm working - now I can't be bothered" kind of thing and will give you a one cylinder drop out making the phut phut phut you were first describing but it's permanent with a coil and not self healing

Can you fill in the gaps with what engine? Mileage? Work done? etc

Are you losing water? Heating problems? Can you make it idle ok by adding gas?

1242cc 39000 miles manual. standard engine, nothing done to it.
just been serviced again about 12 weeks ago.

no loss of water apparent, no over heating problems, checked oil cap but no creamy residue there, no excessive moisture from exhaust, no oil leakage on the driveway from engine. even if i increase revs it still feels choppy, but yet when it first starts and does its auto warmup thingy it sounds normal for about 2 mins till the warmup finishes.

havent checked air filter yet, whats "the stilo giudes"? ill check out around the site for them.