Focus ST170 - Misfire

[gavh]

Hello,

Got an 03 plate Focus ST170, which has developed a problem where it cuts out under hard acceleration. Its gradually getting worse and now just judders when you put the foot down. Worth mentioning that this only started happening shortly after I fitted a K & N filter but this has since been removed and still getting same problem. (also worth noting that the K&N has been installed before with no problems). When sitting in neutral, the engine revs fine - problem only seems to occur when under load.

Local garage plugged it into there computer but no DTC codes showing. Any ideas?

[ZeroSum]

Could be the coil pack?

[igiveup]

Start with HT Leads, one could be arcing, Probably worth changing spark plugs aswell, then go to the coil pack if that don't sort it.

Stick with Ford spark plugs.

[Dave_ST220]

Zetecs suffer from plug tracking,change leads AND plugs if you find evidence,dunno if ST170's suffer from it but worth a look...........

[Jon GT2]

All the above and possibly coil or fuel pump.

[igiveup]

Jon GT2 said:

All the above and possibly coil or fuel pump.

and Fuel filter

[polus]

On a side note:

You can check DTC codes by holding down the odometer buttom while turning the engine on (keep holding it down until you see the dials go into test mode and flick around to there max)...then release.

Then you can skip through all the engine parameters and DTC codes.

[gavh]

Turned out to be the fuel pump - apparently causing fuel pressure to drop from 2 bars down to only a few milli bars intermittently. Pump replaced and now working fine. Cheers for all the advice though!

[Jon GT2]

Glad your sorted matey.
Ford Main Dealer Service Manager.

Edited by Jon GT2 on Friday 8th June 17:35