Fiesta Strange Behavior With Knocking/Pinging Noise

[Jaro1]

Hi All, I have recently bought a Fiesta Zetec 2004 1.4 petrol.

When I got it, the engine was misfiring going up any hill in higher gears(gear 3,4)or when changing gears a little sooner. What the car was doing, was a pinging/knocking noise occupied with juddering and no acceleration at all. I am not too sure where the pinging is coming from, sometimes it sounds like left side of the front of the car, sometimes it sounds like the exhaust.

I thought it would be the spark plugs, so went to local garage and had them replace the spark plugs. The old spark plugs were black and dry. They have changed it and the car was running fine with occasional pinging.

However after few weeks it started doing it more and more. Now, when idle the engine will shake a little sometimes, and does the same juddering and pinging noise with no acceleration when i am in low rpm and change to higher gear, or going up a hill.

Also, the fuel consumption doesn't seem right, as it has done around 140 miles on 3/4 of a tank.

[speedhunter1992]

Failing coil pack?

[Olas]

you can buy fault code readers off ebay for 12-15 quid.

most likely ignition fault but it can get expensive if you just guess at which parts to change. service it amd check for spark.

[speedhunter1992]

You could look for evidence of arcing - if any of the rubber insulation on the HT leads or coil pack has white burn marks. If so, the insulation may be failing. That or the HT is taking an easier path to ground because something further down the line is not carrying it.

[Olas]

speedhunter1992 said:

You could look for evidence of arcing - if any of the rubber insulation on the HT leads or coil pack has white burn marks. If so, the insulation may be failing. That or the HT is taking an easier path to ground because something further down the line is not carrying it.

In this case a miss will be logged on a certain pot - the code reader tells you which pot.

[speedhunter1992]

Olas said:

In this case a miss will be logged on a certain pot - the code reader tells you which pot.

This ^

I might be wrong, but if a fault is logged for a misfire on cylinder-'x', the check engine light will be on (a mate of mine also has an 04-plate 1.4 Zetec and had a check engine light for a misfire). Is it?

[Jaro1]

Thanks guys, just bought obd2 reader from eBay. So far, engine light is not on so not sure! Will give the cables a check when I finish work

[Jaro1]

Checked the car today with the reader - Cylinder 3 misfire. I have replaced, plugs, coil pack and ht leads - it still misfires under 2k rpm, then its fine? The car does feel a bit swifter though

[speedhunter1992]

Now that you've changed the ignition components, is it still just cylinder 3 which is misfiring?

If it is, I guess you can rule out any fuel system components other than cylinder 3's injector.

[Jaro1]

Yes, still just cylinder 3 that misfires

[speedhunter1992]

Was there any noticeable difference between the condition of the old spark plugs from cylinders 1, 2 and 4 and that from cylinder 3?

[Jaro1]

speedhunter1992 said:

Was there any noticeable difference between the condition of the old spark plugs from cylinders 1, 2 and 4 and that from cylinder 3?

Yes, the spark plug was more black not oily black but dry black kinda thing

[frank drebin]

Could you swap pot 3's components {plug , coil etc} with another and reset the on board computer. See if the problem moves with the components?

[speedhunter1992]

Jaro1 said:

Yes, the spark plug was more black not oily black but dry black kinda thing

Hmm...I suppose if the misfire was present when you bought the car, you have no idea how long the engine has been run with the misfire. The carbon deposits on that plug could just be a result of the misfire over a period of time - that cylinder running rich because the fuel is not always being burned completely. On the other hand, if the misfire has only just started to occur, it may be that cylinder had been running rich already, due to a fuel system issue, and fouled the plug, causing the misfire.

What, if any, service history do you have for the car? And how many miles are on the odometer?

[Jaro1]

Wish i didnt buy this pile of crap! Bought it as a learner not having a clue about cars with 1min test drive.It has a lot of history I think upto 2018, with 95k on it

[speedhunter1992]

Jaro1 said:

Wish i didnt buy this pile of crap! Bought it as a learner not having a clue about cars with 1min test drive.It has a lot of history I think upto 2018, with 95k on it

That sucks My mate has had an 04-plate Zetec for a couple of years now and it's not done him too bad - the misfire he had was down to a severely corroded plug - are you aware of windscreen washer jets not being sealed on the earlier cars, letting rain track through the hole in the bonnet and, ultimately, onto one of the spark plugs? - but it doesn't sound like yours has that problem. And I've had a P-reg Fiesta with the 1.25 Zetec for 9 years now and the engine in that one has been bulletproof from 81k miles up to the 133k it's on now.

If I were you, I'd be tempted to start by servicing it with new air and fuel filters if they haven't been changed for a few years, and maybe run Shell V-Power or similar for a few tanks to see if that clears things up. They're at least easy and inexpensive things to try and rule out before delving deeper.