Some kind of cutting issue , aud s2 avant aby,,maxxecu

[S2_avant 19930325]

Hi guys ,, when i get on the gas ,and about at 5000 rpm it start to like fuel cut or something ,but still not like fuel cut , it fuel cuts unevenly , car is still pulling but not good , it like sputters , i took a maxxecu log,, here is the link ,, active for 7 days ,,,, https://we.tl/t-pSFcFzWf9msprwFV
i do not get something wrong in th log ,, like a code,, nothing there ,,, i should be something mechanical correct ,, it happends under boost only ,,, if there is some issue with the catch tank for vetilation i have , can that make these kind of issues ??

[RedV6]

Fuel filter? When was it last changed?

[S2_avant 19930325]

But that should show on the fuel preesure in the log .. the filter is pretty new

[Beppo]

Maybe you have a set boostcut and the boost overrides the limit?

[hashluck]

Assuming no boost leaks I would be looking at coil packs (or plugs or POS). This is a useful resounce https://forums.quattroworld.com/s4s6/msgs/22611.phtml

[K Simmonds]

I don't know much about the Maxxecu but assuming you've adequate fuel delivery and the car hasn't got any boost leaks I'd start looking at the ignition system as mentioned above.

Does Maxxecu retain the same ability as Motronic for pulling fault codes?

[S2_avant 19930325]

Maybe you have a set boostcut and the boost overrides the limit?

No boostcut

[S2_avant 19930325]

Assuming no boost leaks I would be looking at coil packs (or plugs or POS). This is a useful resounce https://forums.quattroworld.com/s4s6/msgs/22611.phtml

Coil packs as i understand .. if one is bad its bad.. it does not start to go bad on a certain rpm.... plugs worth checking for sure ...

[S2_avant 19930325]

I don't know much about the Maxxecu but assuming you've adequate fuel delivery and the car hasn't got any boost leaks I'd start looking at the ignition system as mentioned above.

Does Maxxecu retain the same ability as Motronic for pulling fault codes?

Maxxecu is a pretty good standalone.. can connect my mobile to it and read fault codes and what i want .. no fault codes

[hashluck]

Coil packs as i understand .. if one is bad its bad.. it does not start to go bad on a certain rpm.... plugs worth checking for sure ...

Not so for coil packs, if one is breaking down or tracking through wiring or boot, it could quite easily only become apparent under load at wide open throttle. For sure when it breaks completely you would have a misfire at idle but usually a hard fail is not how they (begin to) fail. I am betting (from my own prior experience) that this is one of more coils packs (and if changing one change them all anyway). Also change spark plugs, check gapping and tightness, beware NGK fake plugs, buy only from a reputable source. Also check for oil in spark plug well and change rocker cover gasket if there is any there.

[S2_avant 19930325]

Not so for coil packs, if one is breaking down or tracking through wiring or boot, it could quite easily only become apparent under load at wide open throttle. For sure when it breaks completely you would have a misfire at idle but usually a hard fail is not how they (begin to) fail. I am betting (from my own prior experience) that this is one of more coils packs (and if changing one change them all anyway). Also change spark plugs, check gapping and tightness, beware NGK fake plugs, buy only from a reputable source. Also check for oil in spark plug well and change rocker cover gasket if there is any there.

So how do i measure the coils with a multimeter to see wich one is bad ? The spark plugs i can check ... I really want to find out what the problem is and not just change the coila and plugs without nowing what the issue is ... is there a recommende coil that is better then original if tuning has been made to the car ?

[K Simmonds]

It's certainly worth trying another set of plugs but if everything else checks out I'm fairly certain the problem will be one or more of the coils, I've experienced the same issue you describe when a friend had his car on the dyno at VRS. That was a high mileage LHD RS2 which pulled fine to 5K RPM then ran like crap on what looked like the original coil packs, as Will had just rebuilt the engine and checked everything else was in order we agreed that it was probably the old coils causing the issue. Will fitted a spare know good set which sorted it, that was ten years ago, do you know how old your current coils are?

I don't know of reliable way of checking the coils other that to try them on another engine, as they get very hot any electronic values you can check when cold will probably change when they're on a running engine. The best bet if replacing them is to upgrade to modern coils using a harness from Alex.

[hashluck]

I had exactly the same experience as described above. Unfortunately VCDS does not help with misfires and certainly not to a particular cylinder level. That said, if 1 coil pack fails (a when not if scenario) then they will all begin to fail so just change them all. The original coils (Beru ZS043) are available or there is a 'smart coil' upgrade option which should be easy to search on-line. All of my comments relate to ABY S2.

[Beppo]

What about dwell time for the coils? I hade an issue with stutter when we put boost up and hade to increase dwell time for the spark to be powerfull enought.

[K Simmonds]

What about dwell time for the coils? I hade an issue with stutter when we put boost up and hade to increase dwell time for the spark to be powerfull enought.

Yes, by rights if you upgrade to modern coils the dwell time does need to be altered but that should be straight forward enough with Maxxecu, not so easy with Motronic.