Car engine problems...
My Ford Focus (Y reg) needed the help of an AA man a couple of weeks ago after it started misfiring and then the engine management light came on. The problem was diagnosed as a faulty plug. The plugs were duly replaced and all seemed well... almost.
It seemed almost, but not quite, right and seems to be gradually be getting worse. The problem is apparent on acceleration from lower revs (under 2k) when it is misfiring again. Dropping a gear, gets me out of trouble and driving at a steady speed or decelerating is not a problem.
The car has very low mileage (33,000) and isn't used daily as I cycle to work, though I try to do at least one longer trip a week.
Any ideas please? It would be nice to have some sort of idea what the problem might be before a garage tries to rip me off as a clueless female (which I am when it comes to cars!)
Thanks for your help.
so putting your foot down at low revs gives a misfire-like lumpiness, that vanishes at higher revs?
I say...fuel injection system or throttle potentiometer. It the throttle pot is going duff, it can do similar to that..or if the Fi isn't happy, it'll do all manner of oddities.
If the management light came on, there should be a fault code stored in the engine management memory that garages can read (not just the dealer, but any garage with the kit) - that will help pinpoint the issue.
Mums fiesta used to be a total arse if it went off on one..that was Fi related as well. My Astra was like it when I got it too. I stopped it in traffic one day, did a restart and it pegged itself on the rev limiter and was revving up and down for no reason.
In the end, I unplugged every plug I could find, took the battery off to blank the stored memory on the engine and gearbox management, sprayed them all with WD-40, did the same to the throttle body and connections, blasted the intake out with carburettor cleaner, put it all together and took it for a blast down the A5 bypass.
Not had a days trouble since.
Originally Posted by Sirbendy
Yes, the AA man did that and came up with Cylinder 2 mis-fire. he tested the HT leads and the plugs. The leads were fine, but there was a very weak spark on the Cylinder 2 plug.
Originally Posted by Sirbendy
Not sure how old a Y reg or if this applies to your model of car as I have not had cause to dismantle one but I had a similar problem with my Vectra. Went through several computer diagnostic checks (and expencive replacment components) and the problem persisted. Eventually had the car electricians put it on a scope which measures the electrical output at all of the different important bits of the engine in real time.
The cause turned out to be a faulty coil pack, in the case of my Vectra and most modern cars it has a seporate inverter coil to ramp up the voltage for each spark plug. One of these coils was faulty and so was not generating enough current for the spark plug on one cylinder causing the judder at low revs under load.
A scope check will also rule out your spark plugs, plug leads and other chunks of electronics that can go wrong and should not be to expensive depending on where you go.
The car was bought new in April 2001 :)
Originally Posted by SYNACK
It sounds like I will have to take it somewhere :( Is there a chance that the new plugs are faulty too?(I hate to say weren't changed in the first place :( )
Which engine has it got? It could be a coil/coil pack like SYNACK says, but testing can be difficult at home. Sirbendy's idea of a fuel issue also holds water, when you wadge your foot down from say 1500RPM to get up to 60, your asking the engine to give you maximum power, and if the igniton or fuel systems aren't right it won't like it.
The handy thing with fords is that just about any garage you care to mention has probably worked on a hundred of them and parts are cheap. I'd head down to your friendly local garage and ask them to advise.
(and worry not about reliability, a mate of mine's focus has just reached 200,000 miles and is still going nicely...)
You can get faulty plugs but it is not common to get new plugs that are faulty. If it just gets short runs everywhere then the plugs could be dirty as the incomplete combustion lets carbon build up on the terminals. Taking them out and cleaning them or running on premium petrol (98 octane) and taking it for a good long drive at speed (100km/h) also does a good job of burning off the carbon buildup.
Originally Posted by elsiegee40
If the plugs have been in for a while the terminals do also wear down, sometimes at different rates which increases the gap between the terminals on the plug requiring much more current to build up before it will spark, that kind of thing is easy to pick up with a visual inspection by a mechanic. If they start to fail internally that is a different matter. If your car takes standard plugs and it has not had new ones in a while it may be worth simply replacing them all which depending on wear would improve performance and economy. If it takes the fancy iridium ones which are rather expensive then doing the testing (for coil issues etc) first could be more economical.
For the cost get the HT leads changed anyway.
It's a 1.6 Zetec (... that's about the limit of my understanding - You can see the word Zetec when you lift the bonnet to refill the washers!)
Originally Posted by rhyds
The plugs are only 2 weeks old (I hope) as they were changed by the garage at the time of the original fault. The AA man couldn't change them as he didn't have the right kind.
I think I'll try taking it out for a blast up the M20 this afternoon and see if that improves matters.
I'll have a look when I get home for possible causes (got a focus haynes book of lies somewhere). Another thing you could try is to whack a bottle of injector cleaner through it, i might not do owt but could be worth a try.
good point on the coilpack. Aren't they "wasted spark" units?
Weak spark on Cyl2 could indeed be coilpack related...or HT lead indeed.
Another nod to the ignition coil - I know sod all about cars but those symptoms you describe are the exact fault my Mondeo had just before the holidays. Got our bus driver to take a look and he suggested it was a clogged fuel injector, proudly announced that to the garage as if I knew what I was talking about and a bit later they rang back to let me know it was actually the coil... Soon as that was changed, normal service resumed!
Sounds like a very similar problem I had with my diesel turbo Megane.
Not sure if your car has this part.
The EGR valve (exhaust gas replacement) was blocked up and I needed new glow plugs.
Best to bite the bullit and pay Ford to do a diagnostic. Other garages (non ford) may not have the correct equipment for an in-depth test.
EGR Systems - how it works
Exhaust gas recirculation.
I don't think petrol engines have either of these parts do they?
Originally Posted by vote-for-pedro