Hi all, I’ve just bought myself a 2009 Focus ST3 with 64500 miles.
its the first one I have had and only driven one in the past so have nothing to compare this one with.
When driving around town with normal acceleration it tends to hold off a bit then kick in, I’m aware there is such things as a turbo lag but not sure this is what it is or if it is normal.
also on an open road when giving it a bit it does the same thing when on full boost it seems to back off then pick up again. The acceleration doesn’t seem smooth and almost like it comes and goes in stages.
hard to explain
again is this normal?

 

I’ve the same car mine had a boost flutter. It would almost feel like a miss fire at low throttle position but driven hard it would feel fine. I fitted new plugs and a boost solenoid

 

Does new boost solenoid etc cost a bit?

 

Not saying it will fix yours maybe get someone to look at it first. It was about 70 quid I think Volvo fit them as a service item at a certain mileage.

 

I get that, just wondering a rough cost as if it is the cause I know what I’m working with. I’ve got a warranty with the car that’s still in play so I’m going to speak with the dealer I brought it from and see what they will do first.
it does feel like a boost issue or maybe even a fuelling problem. Had an st170 that had a similar problem that turned out to be a fuel pump

 

Mine had no warning lights no stored errors it just didn’t feel right at low boost. I had people telling my that’s how they are re-mapped but I wasn’t happy. I did the plugs at the same time so could have been over that fixed mine.

 

Yeah Same with mine, no lights etc. Doesn’t feel right but as I say I’ve nothing to compare it with as I can’t remember what the last one I drove was like. Wasn’t sure if it was ‘normal’ or not. Guessing not.

 

Mine never did that, always pulled nice and clean through the rev range.

Boost solenoids are a common failure on them and generally dont give any fault codes so I would consider changing it just to rule it out.

 

https://www.mister-auto.co.uk/boost-.../7-28197-16-0/

 

One thing I have been told about these cars is buy proper sensors and plugs not cheep ones

 

Pierberg make the standard sensor for Ford. This is the one I removed from ours.

 

Fit RS spark plugs as they are better than the ST ones, so im told.

 

sound advice above rs plugs and boost solonoid is a good place to start and have seen the pierburg ones for around Ł40 if you shop about and as mentioned they are genuine too, if it has the symposer still fitted bin that and blank that sod off, im breaking a 2010 st3 at moment https://passionford.com/forum/ford-f...ml#post6793498

 

out of interest what’s the benefit of the symposer delete

 

apart from the pathetic false noise either blanking it of fitting a non symp hose has got to help with airflow and is also a common source for air leaks etc, so getting rid of it is good thing

 

Looks a quick easy job I’ve just ordered a bung off eBay from pumaspeed lol.

 

So, it’s been into a local reputable garage, they’ve had the car for a couple of days, ran a smoke test and found a boost leak from two pipes around the intercooler. Replaced the pipes thinking that was solved but still doing the same. Either runs at half boost or runs full boost then drops off intermittently. They want to charge me a small fortune to replace the boost solenoid when they’re only Ł20-40 to buy.
How difficult are they to replace on the driveway?

 

I did mine from under it on the 2 poster at work. It’s 2 pipes and an electrical plug. It’s on the chassis rail near the turbo. From under it may be an arse if you can’t jack it up enough and support it to properly get under it. The hose clips are a sort of arms length fiddle lol

 

I’ve got a decent set of ramps to get the front end up far enough so might tackle it myself.
the garage were on about replacing the solenoid and a “diaphragm” as clearly the original parts they changed hasn’t completely eradicated the problem. They needed doing either way as they were knackered.

would a bad map be a possible cause? They have said it’s mapped but can’t tell what it has in it so I’m slightly concerned it could be a “back street garage map” and not one that’s good for the car.
I was hoping I’d got a standard car, turns out it’s got a mountune intercooler and a remap lol

 

Ford charge Ł90-Ł100 for a boost solenoid, I got a new one off Matt Lewis Motorsport on eBay Ł45 iirc, I had a couple of minor issues with my focus rs, replaced the coils and the boost solenoid and all seems good now

 

I’ve got a solenoid coming tomorrow, hopefully I manage to fit it ok and it solves the problem.

 

Keep us updated, I know the map sensors can play up on them too , but they give a fault code IIRC

 

So, put the new part on, the old one didn’t look that old to be fair. Took it out for a drive still feels the same.
Am I just being picky and finding a problem that’s not actually a problem?
i just don’t think it’s right that when my foots right down it doesn’t always run full boost.
under normal acceleration I can feel like it’s hitting flat spots then going again.
this can’t be normal right? Is it turbo lag?

 

Mine boosts off the scale and holds it. Pulls really well but I don’t think mines standard

 

Mine does most of the time just occasionally hesitates under throttle. Mines not standard as it turns out, mountune intercooler and a remap. No idea what map is on it though. I’m wondering if it’s a bad map. I’m looking to have it re done soon so I know what’s on it.

when you are driving yours around town with say half throttle does yours hit flat spots where it holds off then comes back to life again? Hard to explain what I mean when I say flat spots but that’s all I can think of calling it..

 

It did yes I got mine cheap as a bit of a fixer upper lol. 2500 it had a miss fire a sort of hesitation as you say above. I fitted new plugs and the boost solenoid and mines fine now. Also only use optimax in it. I really like the car now

 

Did you put standard or rs plug in it? I might try that next, I’d rather do that then spend Ł90 an hour labour at the garage.
I can’t fault the car other than that, it flies and sounds really nice as the last owner took out the standard exhaust resonator. Bodged it though so it’s leaking on a weld so that’s something else to sort..

 

Standard ones but I’ll probably fit RS next time I service it

 

I think I’ll go rs, heard they’re better so might aswell if they’re being swapped

 

If someone can access Ford ETIS you can see if t's had the Ford approved Mountune remap, I'm not able to at the moment as off work but anyone who can have a look will be able to tell. They used to have a link to the Mountune software for if it needed to be re-loaded for any reason.

 

If somebody can have a look into this for me that would be great 👍