ST170 Jerky Acceleration Between 2100rpm and 2800rpm

[Jacko9966]

My ST170 has started to do some odd things when it comes to accelerating. At roughly 2100 rpm to 2800 the acceleration is not smooth at all but below and above that it seems fine.

Also when keeping a constant throttle position in between these revs the engine hunts and feels like you are constantly dabbing the throttle.

I have recently done a full service including fuel filter.

Am personally thinking its something to do with the variable intake manifold.

Any ideas? Need to get it sorted as it annoying the hell out of me.

[Braders]

mine does exactly the same, i fort is was due to needing a service, obviously i was wrong, if anyone knows why it does this then please let me know :D

[stef123]

could it be a missfire?...

[Braders]

could it be a missfire?...

now u mention it yeahh i think it is, how do i !Removed! stop it!

[stef123]

mmm could be the pesky coil pack. this is exactly how mine started before it packed in for good.

if you are gonna change it though, i'd recommend you have a look on eBay as there are companies who sell genuine ones that have been debadged for about 30 quid delivered which compared to £101.75 from ford is pretty good. a new set of spark plugs would also be a must, genuine ones aint too bad priced at the dealers usually. mine were 14 quid but the guy gave me 6 discount.

[jasonst170]

mine did the same it's only done 26,000 new plug sorted it

[Jacko9966]

Hi Guys

Thanks for your advice, I will go and purchase a coil pack and try it later in the week. Cross fingers it works cos its starting to really annoy me.

Also going to fit some Eibach lowering springs at the weekend and look at doing the rear trailing arm bushes.

Does this coil pack look like the right one?

http://cgi.ebay.co.uk/COIL-PACK-IGNITION-F...id=p3286.c0.m14

Thanks

Paul

[Braders]

Hi Guys

Thanks for your advice, I will go and purchase a coil pack and try it later in the week. Cross fingers it works cos its starting to really annoy me.

Also going to fit some Eibach lowering springs at the weekend and look at doing the rear trailing arm bushes.

Does this coil pack look like the right one?

http://cgi.ebay.co.uk/COIL-PACK-IGNITION-F...id=p3286.c0.m14

Thanks

Paul

its doesnt say for a focus ST170, and the parts for the st170 engine half the time are totally different to that of a normal 2.0 zetec engine, for example ST170 uses different spark plugs to that of a standard 2.0...my point is i would make sure its okay first mate

[KevinKevin]

My new focus 1.8 Zetec does the same thing. Especially when you've got a cars full. Acceleration is jerky between 2000-3000. It's only 8 months old. What could be wrong with it?

[muza]

my st170 does exactly the same! more so in cold weather it seems... hence i havnt noticed it too much all summer but its bound to start again soon as it gets colder.

did you guys manage to sort it with the new coil pack/spark plugs?

[Jacko9966]

Ok bought the coild pack after confirming the part numbers are the same. Got it today and look identicle except for the missing motorcraft sticker (U can see the glue residue where it once was). Tried to fit it tonight but no luck, the torque bolts were done too tight and wrecked one of the heads and my driver.

Going to go get a new driver and tomorrow. I will have to remove the coil pack mounting plate to get more space to remove those blasted bolts (Thinking i might have to drill the wrecked one out).

[Jacko9966]

Quick Update.

Replaced the coil pack, no difference. Have also tried some fuel system cleaner after talking to some garages, this made it slightly better.

I now have no more ideas on what to do next, so any ideas are welcome.

In the mean time I have fitted some Eibach springs and bluefin onto my car, both I would highly recomend. The Eibach springs give a slightly stiffer ride but iprove the handling greatly and reduce the body roll in bends while the bluefin gives the car better throttle response and seems to be more urgent through the rev range. Definatly makes overtaking easier on the back roads where I live.

Oh and by the way I wrecked the old coil pack to get it out.

[thesilverfox]

Quick Update.

Replaced the coil pack, no difference. Have also tried some fuel system cleaner after talking to some garages, this made it slightly better.

I now have no more ideas on what to do next, so any ideas are welcome.

In the mean time I have fitted some Eibach springs and bluefin onto my car, both I would highly recomend. The Eibach springs give a slightly stiffer ride but iprove the handling greatly and reduce the body roll in bends while the bluefin gives the car better throttle response and seems to be more urgent through the rev range. Definatly makes overtaking easier on the back roads where I live.

Oh and by the way I wrecked the old coil pack to get it out.

Hi there,

I can see you're not having much luck, but I have one suggestion that has not been touched as yet.

When I had an ST170, I experienced some dreadful jerking/'loss of power' characteristics not too dissimilar to what you've described.

Firstly, I thought it was the inlet manifold runner controller (IMRC), as the solenoid is apparently known to disintegrate, being mostly plastic and whatnot. Then I thought coil pack. Then I wondered if the spark plugs were dodgy.

However, Ford had a good look and found out it was the fuel pump that was faulty - basically, I realised then that I only noticed the sluggish performance when the fuel was less than 1/3 of a tank - the pressure in the tank was obviously low and the engine was requesting the fuel and the pump couldn't keep up, resulting in embarrassing jerking when putting my foot down too hard (and often softly too).

Got it done under extended warranty, but Ford said it was around £200 plus labour normally - I'm sure it can be done cheaper though.

It might not be the cause, but it's certainly worth bearing in mind.

tsf.

[Jamo_SportsTech]

have you looked at the spark plugs? mine was missing badly.. like a tractor through all rev ranges.. some muppet pressure washed the plugs before i bought it and they were having a 1" deep bath lol! tested the HT leads?

[Jacko9966]

Hi there,

I can see you're not having much luck, but I have one suggestion that has not been touched as yet.

When I had an ST170, I experienced some dreadful jerking/'loss of power' characteristics not too dissimilar to what you've described.

Firstly, I thought it was the inlet manifold runner controller (IMRC), as the solenoid is apparently known to disintegrate, being mostly plastic and whatnot. Then I thought coil pack. Then I wondered if the spark plugs were dodgy.

However, Ford had a good look and found out it was the fuel pump that was faulty - basically, I realised then that I only noticed the sluggish performance when the fuel was less than 1/3 of a tank - the pressure in the tank was obviously low and the engine was requesting the fuel and the pump couldn't keep up, resulting in embarrassing jerking when putting my foot down too hard (and often softly too).

Got it done under extended warranty, but Ford said it was around £200 plus labour normally - I'm sure it can be done cheaper though.

It might not be the cause, but it's certainly worth bearing in mind.

tsf.

I have noticed it is doing it with a full tank as well and like the other person commented it does it worse in the cold.

It also does it now when you keep a constant throttle position between 2000 and 3000 with it being worse at around 2100.

Could it be the duel mass flywheel as my clutch's biting point is really high?

I think I have no choice but to take it to a ford dealer sometime and will let you know the outcome.

[Jacko9966]

have you looked at the spark plugs? mine was missing badly.. like a tractor through all rev ranges.. some muppet pressure washed the plugs before i bought it and they were having a 1" deep bath lol! tested the HT leads?

Thanks for the advice but I have replaced both the spark plugs and HT leads with no improvement. The car does not seem to miss fire when it becomes jerky, you do not even notice the gaugues move at all but you just feel it, no odd sounds either.

[HarryST170]

I have noticed it is doing it with a full tank as well and like the other person commented it does it worse in the cold.

It also does it now when you keep a constant throttle position between 2000 and 3000 with it being worse at around 2100.

Could it be the duel mass flywheel as my clutch's biting point is really high?

I think I have no choice but to take it to a ford dealer sometime and will let you know the outcome.

Hi, I have a focus st170 and have the same problem but it's higher up the revs, anything above 4500rpm and the jerking stars.

This problem started about 2 weeks ago and at the start of this week it got much worse. No power coming from anywhere and it was a pain to drive, jerking started at about 3000rpm this time.

I changed the spark plugs but nothing changed so booked it in and the garage said it was the coil pack. Got it back Friday apparently it was 'running like a dream' at least by that statement i know nobody had been out taking it for a drive.

So spark plugs and coil pack haven't worked for me!

[wrc62]

Hello everyone! I'm French, excuse me in advance for any spelling mistakes!

I have a problem on my car which is very similar to yours

I mounted a rally in Focus ST170, my engine is original, it has 95 000km is therefore Duractec 173cv. In the first race with the car, early concerns have started ...

The car has no power, she refuses to climb into the towers and when I push my accelerator pedal a little too strong, self grazing, as if she "choked". The problem has worsened over the miles.

Car stalled, I accelerate, the car turns up in nickel, the problem is not obvious that stock with a gear engaged and the slowing is perfect.

Final service last night, candles are taken apart, nickel electrode by cons Thread full of oil, it cleans, it starts, and the problem is still there we decided to give up for fear of damaging the engine.

The car does not heat, my water temperature and oil are good, there is no smoke in the exhaust and no consumption of water and oil!

I thought that the concern could come from the fuel filter, so I changed it was very dirty but not stuffy.

I expect to receive new spark plugs and new ignition wires before retrying the car, as you can imagine, it is not always easy to try a racing car with the neighborhood!

Some of you have ever had He commend this trouble? Have an idea of where you can go wrong?

Admission is entirely original, the exhaust is "home", I kept the rear silencer and catalyst is poured between the two is a pipe-line.

Before mounting competition vehicle, the car had already emptied the catalyst, and I've never had any worries

In late April I attended my second rally, following the concerns of the first race so I changed the spark plugs, ignition cables and fuel filter. Practice session one week before the race, SAR self works perfectly.

Then comes the day of the rally car at the screwed up early at the outset of the first special I saw that I had no power for miles and then over the cuts have emerged and become worse, operation until losing a cylinder at the beginning of some special. We dropped out of the fourth special after a change of spark plugs assistance that has not changed the problem.

After the race the car was taken at Ford HS coil verdict ... It thus goes a new coil.

Practice session yesterday, the car runs properly for about twenty miles, but I still feel what was not all his horses, I was able to make good suspension settings, but a sudden bang, back cuts .....

You open the hood, the coil is boiling, let cool, it starts and remain committed, it was therefore said that I burnt the coil again.

On the way home I plug in the diagnostic software on the car, no error code at the coil, for the cons I have the following error code: P0141 Oxygen sensor (H02S) 2, Line 1 heater control, circuit malfunction. Probable cause: wiring, H02S, ECM

In your worries in a lambda probes could cause these symptoms or is this actually the new coil has blown again?

I do not know how to solve this problem, could you help me? Thank you very much in advance!

[wrc62]

To get a clearer picture of the problem, here is a video of the first rally of the year, listen to the output pin until the end of the video you can hear the cuts, and as you can imagine, j 'was at the bottom ... but the car is not moving!

[Michael 20]

My Focus has had the leads, spark plugs and timming belt chaged and still the car jerks, splutters and backfires. I'm wondering if the spark plug leads are in the wrong order. Next i'm replacing the solinoid etc, or it could be the fuel pumb. Eiter way, it's giving me the !Removed!.

[dan_st170]

Hi there, im new to the forum and seem to find the same with my st170. I have a mate how only buys fords and knows them inside, he had a press realese st170 and that done the same for his 5 years of ownership. To be honest all we seem to find is its to do with the vvt setup and changing all the parts possible never cure it or if it seems to it will be for a short time.

If thats any help theres my 2pence on your situation.......But i will admit its !Removed! annoying!

[FOCA]

My Focus has had the leads, spark plugs and timming belt chaged and still the car jerks, splutters and backfires. I'm wondering if the spark plug leads are in the wrong order. Next i'm replacing the solinoid etc, or it could be the fuel pumb. Eiter way, it's giving me the !Removed!.

It is unlikely that the plug leads are in the wrong order, unless it is only firing on 2 cylinders

Its sensible to replace the plugs 1st, as they are relatively inexpensive items and are a "service" item amyway