Technical HELP: Engine Man Light / Missfire / Loss of power

[IanCC]

Hi

I've got a problem with my 55 plate 1.2 petrol Punto. It's only done 18k miles

Until a few weeks ago the car ran perfectly and the engine was very quiet and smooth.

Then one day when I started the car the engine was rough and missfiring - the engine management light came on and the car had very little power. After leaving for a while and restarting the car ran fine - however the engine management light stayed on for a few days before clearing.

A couple of weeks ago the problem came back - engine management light on - really rough / juddery engine / low power. I replaced the HT leads however the problem remained. On starting the car, the revs would drop right down to 900 then jump back up a little before going back down to around 750 where it sat in idle.

I put the car in the garage I use - the lad said that the coil pack was faulty - he replaced both coil packs using spares from the local breakers - at the same time he also replaced the plugs.

When I got the car back I noticed that the engine didn't sound as smooth as it had done before, however the problem seemed to have gone.

After a couple of days, the same problem occured. Engine management light back on - heavy judder from the engine and loss of power. The car went back into the same garage - he said that it must have been a faulty coil pack that he got from the breakers - so he got another and replaced it.

Again - when I got the car back it was fine - a lot smoother and fairly quiet engine. However I noticed that when I started the car it did make a bit of a rough noise as it fired. Also when idling and driving every now and then I could feel a slight blip from the engine like the power dropping for a split second. When accelerating I'd sometimes get a little hesitation but then it would run fine.

That was a week ago - today the car has got the same problem - engine management light on - low power and judder when idle. Increasing the revs increases the intensity of the judder. I'm going to have to take it back to the garage again - but can't believe it's the coil pack again.

Lost for ideas - had a quick browse on the web and I'm wondering whether it could be the ECU or something with the air mass flow sensor.

Any ideas?

 

[adricho]

Hi

I've got a problem with my 55 plate 1.2 petrol Punto. It's only done 18k miles

Until a few weeks ago the car ran perfectly and the engine was very quiet and smooth.

Then one day when I started the car the engine was rough and missfiring - the engine management light came on and the car had very little power. After leaving for a while and restarting the car ran fine - however the engine management light stayed on for a few days before clearing.

A couple of weeks ago the problem came back - engine management light on - really rough / juddery engine / low power. I replaced the HT leads however the problem remained. On starting the car, the revs would drop right down to 900 then jump back up a little before going back down to around 750 where it sat in idle.

I put the car in the garage I use - the lad said that the coil pack was faulty - he replaced both coil packs using spares from the local breakers - at the same time he also replaced the plugs.

When I got the car back I noticed that the engine didn't sound as smooth as it had done before, however the problem seemed to have gone.

After a couple of days, the same problem occured. Engine management light back on - heavy judder from the engine and loss of power. The car went back into the same garage - he said that it must have been a faulty coil pack that he got from the breakers - so he got another and replaced it.

Again - when I got the car back it was fine - a lot smoother and fairly quiet engine. However I noticed that when I started the car it did make a bit of a rough noise as it fired. Also when idling and driving every now and then I could feel a slight blip from the engine like the power dropping for a split second. When accelerating I'd sometimes get a little hesitation but then it would run fine.

That was a week ago - today the car has got the same problem - engine management light on - low power and judder when idle. Increasing the revs increases the intensity of the judder. I'm going to have to take it back to the garage again - but can't believe it's the coil pack again.

Lost for ideas - had a quick browse on the web and I'm wondering whether it could be the ECU or something with the air mass flow sensor.

Any ideas?

oright mate, i have a 2002 punto sporting and i had the same problem until a week ago.. the engine management light came on, judderingg.. sounded rough etc.. i bought a brand new coil pack and that sorted it for a week. then a similar sound came... but not as bad.. so i changed the spark plugs and now it seems to have gone.
the only thing now when i start it is a squeek noise not coming from the fan belt though? i wonder if you have had a similar noise?
but the engine managment light is still on and i have been told sometimes they need resetting after they have came on.
thanks

 

[sixpotman]

What make and type of plugs did he use?

John

 

[mahol]

New HT Leads thats what mine was i had misfiring, no power, really rough sounding engine. but i noticed you've already done this??? i know this sounds stupid but im guessing they they fitted right? have you tried getting a brand new coil pack instead of one from a breaker if you look around i don't think they are that expensive. Do the spark plugs have the correct gap? are the HT Leads connected properly. Just a few ideas for you i really can't think of anything else, got a stumper there lol

i remember being told (although it was for my steering wheel fault) that sometimes the fault codes that are held in the ecu need to be removed or it can come back because the error is still there in the ECU which could cause this 'limp home' mode effect which could be whats happening?

 

[IanCC]

Thanks for the replies

adricho - I haven't had the squeak you mention. However to clear the warning light you need to rev the engine to about 5k let it drop back to idle and repeat 2 times. This clears the engine management light.

Bit of an update - In the stick at the top of the forum I found a post about coil/emu. I did the test where you disconnect one coil at a time and try and start the engine to identify the faulty one. Sure enough - one of the coils was shot. Bought a new coil this morning from europarts for 20 quid. Fitted it in 2 mins and started fine without misfiring.

However tonight I've noticed the hesitation back again in idle - feels sometimes like it's about to stall but doesn't (not quite that bad but best way I can explain). Also the rev counter was sitting at 1100 on idle but after a couple of mins in idle starts to drop down to 900/800 and there's a little judder. I popped the hood and I can hear a little click coming from one of the coils when the car hesitates in idle.

The spark plugs have been replaced by the garage - I'm wondering whether he's got the gap right - could this cause the hesitation and drop in revs?

HT leads have been replaced with BOSCH ones - I'll check em to see they're fitted right.

 

[rallycinq]

The click is a spark going the wrong way.

Try checking in the dark and identify where the spark is jumping from.

The engine management light comes on because unburnt fuel is passing down the exhaust past the O2 sensor(s). It takes a bit of running to get rid of that fuel.

Don't rev the nads of the car when cold.

Cheers

SPD

 

[jayjenks1992]

Sounds to me like the ecu mate. You car will probley running on two cylinders. The ECU for punto's are IAW 59F.M2 you can them from ebay for about £150 or you can get it done at a garage for about £250. If you did want to do it you self you will find the ecu at the back (not bottom) of the engine . You will have to take your air box off. When you have changed it your engine management light with be flashing so you will have to start your car and let it warm up yill at standered tempreture and then rev it to 5000 rpm 3 times and it should disapper if done correctly.Hope this helps.