Poor idle MK1.5

[James3891]

Hi,

Got an 03 1.6 Zetec that's had a bone shaking intermittent idle since January.It's done 130k.The car starts perfectly each time and often quiet first 10 seconds then strongly vibrates, revs flutter a little between 1.5-2k but doesn't majorly idle hunt.

Once driving it's smooth although feels under powered at times, pulling off at lights, needing to drop a gear on slight inclines that i'm told it should handle fine.I've had the engine looked at a few times for any leaks and there's nothing, all hoses and valves fine.

No fault codes and had service about 5 months ago, doesn't burn much oil.Put redex in and given it a good run.There is a popping/knocking noise that comes from the head and the exhaust put put's slightly.It can go from a slightly rough idle to shaking the mirrors like a tractor and the engine seems to rock back and forth slightly.

Out of interest just pulled the spark plugs , 1 and 2 from the drivers end look nearly new still and came out fine, number 3 was really tight and had a lot of oil on the barrel but not in the gap.The 4th looks to have been really over tightened and at an angle to the point i think it would cross thread so left it alone.

Been mentioned to me the oil on the plug could mean it has a leak and might cause low compression thus making the noise piston slap.Does that sound feasible?.

Going to have a word with my mechanic of many years who did the service as he's the one i bought the car off , hoping not but could the 2 plugs have been jammed in (one at a severe angle) on purpose to hide something and intefere with the running?Keen to see how the thing actually drives when it's 100%.

[Tdci-Peter]

1 hour ago, James3891 said:

The 4th looks to have been really over tightened and at an angle to the point i think it would cross thread so left it alone.

Can you hear gas leakage (chuffing) around that 4th plug?

It sounds like that plug is damaged and may not be sealing. An air leak around a plug could cause bad idle, it will upset the mixture (weaken it) in that cylinder.

If it is leaking, then it really should come out, but I think that is a job for a very experienced mechanic, it may well damage the head. Even if it is not leaking, it may be oiled up or clapped out. No knowing how long it has been like that.

[James3891]

I'll have a listen for leakage around it.

The knocking noisedoes seem to only come from deep down the half of the head with plugs 3 and 4 in it, with a hand on it the left (drivers side)feels calm and the right can feel the vibration and rocking movement through the cover.

The 3 plugs i got out are new NGK's but wonder if the 4th was already like that pre-service and my mechanic has left it alone.If not he's put them in like that, i am going to mention it to him.There is an oil leak under the rocker cover i've found so could be the gasket has gone and oil got in that way so new gasket going on next week.

If there was a piston/head issue and low compression from a leak could the spark plugs have been really tightened to purposely try and trap as much pressure as possible?.Another random thing is if the car drops just below quarter of a tank of fuel it turns over a lot before starting and drops to 500 revs, nearly stalling.

[Tdci-Peter]

20 minutes ago, James3891 said:

Could the spark plugs have been really tightened to purposely try and trap as much pressure as possible?

No, it would make no difference at all to low compression problems. Curing leaks from a spark plug will just be a matter of cleaning the sealing area & fitting a plug with a new seal washer.

I suspect someone changed the plugs some time ago, banged in the new plugs with a powerful impact driver, and got one cross threaded.

"Men" with their high power tools and pressure washer toys cause many, many problems!

Re Low fuel problems: I can't see a link at the moment.  As far as I know, the pump is submerged in the tank, and generates quite a high pressure, to feed the injectors. Sensitivity to low fuel level can only happen on the inlet side of the pump, inside the tank. Some sort of split or leak in the pump assembly, perhaps. The fuel filter is usually on the outlet, high pressure, side of the pump.

I think the one plug that may be leaking, and may be very old, should be dealt with first. It may cause or complicate other problems.

[James3891]

Ok thanks , i will get the plug issue dealt with soon and let you know what was found.

[James3891]

Just to update this , all spark plugs had been changed on the service but from what i could find out a different mechanic to my usual one had probably used an impact driver.

The 4th one isn't crooked thankfully but really tight so still a risk of cross threading so not removed it yet.One of the 3 i got out did have a different gap so wonder if it had been dropped, going to get them all evenly gapped in the week.They are 1mm pre-gap at least.

There is a definite misfire still that was there before the plug change but don't suppose it's helping.Probably doing the Cat no good.Definitely no leaks on hoses or anything so looking at a few other easy options to try.

Been told a possible misfire could be a sticky injector , its had a couple of Redex treatments initially but been told to get some Forte trade only stuff as it's quite potent.

The only other thing i can think of that have been constant are the leads which i've read a few times should ideally be Ford genuine leads.Mine aren't but look fairly new, very clean connectors.I've put dielectric grease on the boots now but no real improvement.Looked at them on a cold damp night and no sign of them tracking/arcing.Are genuine leads really a big deal on the Focus and non genuine ones possible misfirers? Will get there eventually.

[Tdci-Peter]

On 15/09/2016 at 10:44 PM, James3891 said:

needing to drop a gear on slight inclines

The Ford 1.6 engine has been said to feel a bit feeble in the low to mid rev range. Max torque is not until 4000 rpm, and max power at 6000 rpm, so it will need downshifts to get it to really go. So that may not be a malfunction.

3 hours ago, James3891 said:

Are genuine leads really a big deal on the Focus

I very much doubt it. Good quality non-Ford leads will be just as good. The trouble is, finding good quality ones. Price is not a reliable guide. Reputation is better.

You can check the lead resistance with a multimeter, from end to end. It should be a few kohm (as I recall), but more important, should be consistent from lead to lead (longer ones will be a bit higher), and not rise when bent or stretched. You have already checked the insulation by the dark, arcing, test.

Bad idle and rough running is still most likely to be plugs / leads / coil pack related. But bad idle can also be throttle body problems, if ignition causes have been eliminated.

I would have thought injector problems would have effects going right up the rev range. But I am no expert on that!

 

[James3891]

Yes i think it's doubtful to be an injector but a cheap fix attempt that will probably do it some good anyway.I think the 1.6 is a little bit underpowered in places, i've been in the 1.8 petrol and although not such a revvy drive (i had a 95 Civic previously for 7 years so used to even more revs) it would keep pulling whilst i'm downshifting.It's hard to make out but does sound like it's misfiring under acceleration still when i listened under the bonnet.I'll check the throttle body.I saw some leads that fit that weren't expensive (£20 odd) but seemingly fit , Brexi or Bremi i think they were called, oem bmw make from what i could find out .I couldn't see why they'd be any less decent than the £60-90 Ford leads.

[James3891]

Quick update , decided to get the 4th plug out and it came out easily, difference was this time i tried to take it out of a warm engine rather than a cold one previously.Simple lesson learned.All plugs fine but gapped a fair bit under 1mm, so put them back to 1mm.The engine itself now runs fairly quietly and calmly and for first 5 minutes after start up and doesn't seem to genuinely misfire.The noise now comes from the air box/filter, a bubbling,gurgling , lumpy almost misfiring noise comes through it.Seen a few reports of that noise but no real solution.After about 5 minutes at idle it gets really unhappy and produces a proper misfire out through the exhaust.A touch of the throttle eliminates it instantly and it corrects itself til the next time a few minutes later.Going to try the Forte stuff, then maybe look at a coilpack if that fails.