2005 WRX hesitation/flat spot

[dolomite16v555]

Hi all,

My 2005 WRX has an intermittent spot of hesitation when accelerating in 4th & 5th gear whether on part or full throttle, it boosts very well in 1st, 2nd & 3rd. The car has a stage 1 remap done by Andy Forrest (by a previous owner) and associated intake and exhaust mods to suit the map. I fitted an up-rated Walbro fuel pump thinking that would cure the issue but it hasn't.

Any advice appreciated.

[ScoobieWRX]

Could be overboosting, then running a bit too lean and sensing some Knock/DET. As a result it will pull some timing hence the hesitation. Could be fuelling going too rich even. Might just be your MAF sensor playing up. Really need to pug in and take it for a drive to see what's going on.

[dolomite16v555]

Thanks for the info, think I need to rule out the MAF first and take it from there.

[Vixpy1]

MAF very unusual on that year of car, reset the ecu first then get the plugs changed

[dolomite16v555]

Cheers - will give that a go, would the ecu reset upset the remap? Would you go for standard replacement plugs or something like NGK Iridium in a cooler heat range?

[Vixpy1]

It won't affect the map and pfr7b is the plug , gapped to .65

[dolomite16v555]

Cheers, got the plugs so will fit them this weekend and see if the problem goes away.