I seem to have an annoying problem, and I’m a bit lost in where to go or what to check / replace next.

When the car is sitting there on tick over fully warm, if you apply the throttle to rev it up to say 2000-3000 rpm, it seems to skip a beat before it will pick/up (rev up) ! You also notice it whilst driving, when pulling away from traffic lights, it will want to semi stall before it pulls away. One test I have done, but I believe it don’t really prove anything conclusive, when I un-plug the O2 sensor, it does not do it at all ! It picks up and revs smoothly as it should do, But I’m guessing it’s just the ECU switching maps or closed/open loop to compensate for the O2 sensor not being plugged in.

Just to add, the main problem I recently had. The car was hesitating / stuttering on boost from 3k onwards, reading many post I changed the ECU from a AE802 to a AE801, Bought new plugs, leads, Air filter, MAF + O2 sensor, Replacing all of these has cured the stuttering on boost problem, but the engine skipping a beat on initial acceleration still remains, Hence why I suggested that un-plugging the O2 sensor was not really a viable test, as I have a brand new O2 sensor in and it does the same.

Has anyone else suffered this problem or cured it ? I have searched on here for many hours but can’t seem to find anyone else that has had a similar problem.

Just for info,

Car is a UK2000 MY00
Runs on V-power
Completely standard apart from a PPP back box and samco Y pipe

Thanks in advance

 

Had the same thing with an na Forester a few years ago, new coil pack cured it.

 

Thanks for the suggestion :-) was there any other issue with your failed coil pack, did it just skip a beat when applying the throttle or was there a misfire thru the rev range?

 

No misfire as such, just a stumble on initial throttle, mainly when pulling away. Irritating. I changed the coil pack after new plugs and leads didn't fix it. Best try and substitute a known good one first, a new NGK one isn't cheap. Maybe you could see if there are any codes. Mind you, at this age, your coil pack is probably at the end of it's service life anyway.

 

Thanks for confirming the symptoms Yep will definatley borrow one to test out before i go and buy a brand new one @£149

Cheers bud for your help

 

Another suggestion might be to convert to Newage individual coil packs? They can be bought used for much less than a new single pack and there's also a plug and play loom available for the conversion.