focus stumble/flat spots -any ideas

[steveo3002]

2004 petty 1600 focus , its all serviced up to date and no fault code lights or codes

 

when accelerating from low revs its got a stumble /lumpy flat spots , does it regardless of foot flat to floor or progressive pedalage

 

any ideas ?  feels like in the old days when a good thrash would clear it but not on this one  

[oldcars]

Airflow meter? Kia was like this, but it did throw the check light up and give a fault code, not a MAF code but a code.

[Stanky]

+1 on the MAF - if you have a code reader check it for fault codes and potentially disconnect the MAF - resetting it to the 'default' map, though this will put the EML on I suspect. See if it still bogs down with the stock map.

 

if you can get to the MAF easily give it a blast with contact cleaner or carb cleaner (I think this is probably a bit harsh, but worked on the Kia we used to have) and see if that perks it up at all.

 

I suspect a secondhand MAF for a 1600cc Focus won't cost very much, a new one for a 2004 Kia Rio was £400 from ECP so we kept it going with regular doses of carb cleaner and then sold it and made it someone else's problem.

[sierraman]

Possibly the ISCV, but just as likely candidate is a vacuum leak from one of the hoses. Check for perishing.

[steveo3002]

its had isv and hoses chasing another problem

 

pretty sure this one doesnt have a maf 

[The Moog]

Have you got Aircon? Try turning it off

 

The puma pulses when Aircon is switched on. Dunno why

[steveo3002]

does have a/c ...might be slightly worse with it on but does the same on or off

 

would a throttle pos sender be likley?   move pedal and engine takes a while to catch on whats happening?

[twosmoke300]

How many miles - oxygen sensors on these for really lazy but don't show a fault code . Ideally you need to monitor the voltage on live data with a scan tool or even better a scope . It should go from .9v ish down to .1v and back about once a second . If it's taking two or three seconds then the sensor is toast . This assumes it's all up to working temp btw

[twosmoke300]

Oh and some have a pipe with a t piece under the manifold that splits . It comes from Ford complete with pcv valve ( which fail sometimes) for about 25 quid iirc

[steveo3002]

its had the pipe and valve already

 

will look at the o2 readings , its done around 150k ish

[steveo3002]

o2 readings seem to check out...cycling  up and down every second

 

any ideas folks?  

[cpjitservices]

Has it got an EGR Valve ?

[steveo3002]

Has it got an EGR Valve ?

honestly ..i dunno lol

 

any ideas folks 

[egg]

New spark plugs solved this issue on my Fusion.

[egg]

Have you got Aircon? Try turning it off

The puma pulses when Aircon is switched on. Dunno why

I think the engine revs are increased slightly with Aircon on?

[steveo3002]

New spark plugs solved this issue on my Fusion.

what brand did you get

[egg]

Just fairly cheap DENSO.

[egg]

How many miles - oxygen sensors on these for really lazy but don't show a fault code . Ideally you need to monitor the voltage on live data with a scan tool or even better a scope . It should go from .9v ish down to .1v and back about once a second . If it's taking two or three seconds then the sensor is toast . This assumes it's all up to working temp btw

 

I just tried this test on my 1.6 2002 Fusion for my own interest and to hopefully help the OP. This is what my oscilloscope looks like (up to temp).

 

[steveo3002]

thanks for that

[egg]

thanks for that

 

No problem, I'm not sure if I know if that means it has had it or not! As a comparison mine has done 110,500 miles

[steveo3002]

any ideas how you check the tps ?   

[egg]

any ideas how you check the tps ?   

 

I think it will come up as a fault code if there is a problem? There are probably some parameters to check, but again I'm not sure how to interpret!

[steveo3002]

yeah youd think if some fault there would be a code come up , really doesnt drive very well at all but relucatant to start throwing random parts at it 

[mrbenn]

I'd be putting genuine Ford plugs/leads/coil on it with these symptoms and no fault code.

[steveo3002]

yeah coil and leads did pass my mind as internet says they fail often , but wouldnt it register a misfire on the log?

[SiC]

No, not always. Some have to be misfiring on a cylinder almost constantly for it to trigger.

[Guest Hooli]

I think the engine revs are increased slightly with Aircon on?

 

You can feel the drag of the aircon clutch kicking in & out on some engines if it's a bit slow to react & correct it's revs.

[The Moog]

Puma feels like someone is pulling on the handbrake as you drive.

 

Missus Moogs focus you can definitely feel it kick in and out.

[Guest Hooli]

Partly seized compressor? that'd add a lot of drag as it kicks in.

[Twiggy]

I had exactly the same problem with mine, a Focus C-max  1.6 Zetec, same engine I think.  replaced the coil pack, no change, the plugs, no change, injector cleaner and Cataclean, no change. Then the plug leads - problem solved.  Once off I checked the leads with a multi meter and found one totally dead, the other three giving readings on 20k ohms from around 4 to around 17 depending on the length. I got them through my local garage who warned me that the were extortionately expensive, but said OEM from Ford was the only way to go. I suppose it would have made more sense to have checked them with a multi before buying a new set. So, take them all off and check them first........... hope it works.