part throttle hesitation on 2.5T engine

[NDT]

All,
I'd be grateful for any help.
Our S-Max 2.5T (which develops a new fault every month or two) is now hesitating at light throttle.
Idles ok, pulls like a train at mid/full throttle.
No fault codes showing up.

Independent garage says it doesn't feel like a coil pack going.
Waiting for a dioagnostic check at the Ford dealer.

Any thoughts?

[LuS1fer]

Plugs?

[NDT]

New plugs a month ago.

[NDT]

New plugs a month ago.

[NDT]

Ford can't find anything wrong with the car.
The only stored code is PO61A - PCM Torque Performance.

[LuS1fer]

I'd check gaps as forced induction can blow them out but otherwise check vacuum pipes etc.

[NDT]

Thanks - assume you mean a small air leak is throwing mixture off at part throttle?

[LuS1fer]

Yes or any gunk in pipes that can block them. Check the breather too as that is essentially a "leak" of sorts too.

[Justin S]

Could be mucky Air flow meter. That wont show up a fault code.

[JPearson]

Thottle body needing a clean?

[NDT]

Thanks guys.
Might be a job for the weekend to check those out.

N

[Justin S]

Very easy to remove the airflow meter. 2 torque screws and a hose clip and a wire clip

[ST GOZ]

Sounds like your boost solenoid is sticking, very common on the Focus ST, if it was plugs the hesitation would be under load when the plugs are being stressed.

[NDT]

ST GOZ said:

Sounds like your boost solenoid is sticking, very common on the Focus ST, if it was plugs the hesitation would be under load when the plugs are being stressed.

The problem is off-boost.
We had the boost solenoid replaced a few months ago - it was sticking open and causing overboost.

[NDT]

Cleaned MAF sensor - made no difference.
CO is spot on at idle so assume it's not the lambda sensor.

Any other thoughts?

[edition]

Did you manage to sort this issue?

[Terry steward]

I've been having a very similar problem,Hesitation at 1500,1950,2050 and 2700 Revs,and surging in between,,originally Diagnosed by garage (that I HAD to use,as Warranty company wanted vat registered repairer),as Inlet manifold solenoid,,replaced,but made no difference,took it back,they put back on laptop Diagnostic,,,different faults turned up,that PCM low torque one came up,I searched and found either Map sensor or Boost solenoid,,so Have Had Map sensor put on,,again,no difference,my own mechanic,then used A Solaris Edge Diagnostic machine,,which has come up with Boost Solenoid,we ran out of light on sat,so he is coming back to do it,,the problem is far worse,when car. First started and cold,,I have Just got a spare Coil pack to try in case the BCS doesn't work.

[liquidfox]

Just a tip for those replacing sensors on these engines, Mister Auto usually do the exact same OEM parts but at a fraction of the cost Ford charge. Ford charge £65ish for the Boost Solenoid for example, MA charges £21 for the exact same part!

[farmeryellow]

I had this issue with my s max last summer.
Engine cutting out (still running on idle). This issue did not always flag up a fault code and never a check engine light.

After lots of online looking found nothing,.......funny enough the symptoms were the same as i had with my old TVR griff the cure was to change the fuel relay.
the s-max has no fuel relay the modern day version is the fuel pressure sensor
The part is about £40 and easy to change
I changed it and it sorted the issue.

[Terry steward]

Thanks Guys,I have had Intake and Exhaust solenoid changed,as that is how the Garage interpreted the Fault codes !!! £554 later,,,Wrong !!! So,although it's at My own expense as I didn't want to deal with them any longer and my pal isn't vat registered,so the Warranty company won't deal with him,,,I had him change The Map Sensor and the Boost solenoid,,although it gradually improved with each replacement,it still didn't sort,,,I had a S/H but tested to be fine AFM,I fitted myself,,,hallelujah that dramatically improved the running,,,but it is still hesitant when cold on first morning start up,,,new Plugs and I have had a couple of tanks of Shell Optimax gone through now,,That really livened up the car and all but got rid of the sluggishness,BUT there is STILL the first AM start up Slight hesitation and Surge,,,and even as it warms,low down Revs have a Hestitancy,,So I will try the Fuel Pressure Sensor,,I believe it is the same part as the Map sensor ?? As it looks the same,and has the same Part code on the Euro car parts website,,only each has its description difference in its Department.

http://www.eurocarparts.com/ecp/c/Ford_S-Max_2.5_2...

http://www.eurocarparts.com/ecp/c/Ford_S-Max_2.5_2...

As you can see,one has "Map sensor" in the description part no the same !!!