Just scoping for ideas here really.
I've got a track car (road course, not drag), which is an S4 shell, with a 1.8T AJL (Same as AEB) and a 5speed 01A installed in it. Stripped out, running a stock engine, stock tune (180hp AJL tune), stock harness, stock airbox etc. Exhaust is stock bar a decat pipe.
I broke the first engine (a 180k sludged up junker that came out a scrap car) due to oil pressure issues, and fitted the engine out of my own 1.8T Quattro which i parted out last year. That engine was rebuilt about 35k ago with rods, rings, bearings etc and ran fine in my old car. On taking it out on track with the new engine, there was an awful missfire at high revs, which was improved by unplugging the N75. I regapped the plugs at the track and that improved things, but a strange hesitiation became evident around 5000rpm. I assumed it was a coil/plug issue, so did a TFSI coil conversion and a new set of BKR6E's along with a new MAF as i had it laying around, again from the car i parted out.
Took it out again, and this time the missfires were all gone even back on normal boost (circa 10-11psi), but the hesitation remained. It feels like the engine just doesnt want to rev any more, power goes away and it just goes flat. If you keep the foot in, it WILL rev higher, but it just doesnt feel nice. Shift gear and boom, power returns and it start accellerating properly again.
I was worried that the high mileage fuel pump was struggling, so installed an AFR meter. AFR's look spot on, mid 12's at full throttle, tapering down towards 12.2ish after a long pull thru 4th down the straights. However if you rev the engine past 5k in 3rd, the AFR drops into the 11's and starts jumping up and down a lot, IE the meter will start displaying say 12.2 11.4 11.7 12.4 11.7 11.5 etc. Further down the revs its much smoother.
I dont recall any of this happening on the old engine, but it had plenty issues of its own so maybe i just never noticed. it also never happened on the old car from what i remember, so its something particular to this installation.
I wondered if the IATs were getting a bit high, its on a stock intercooler, but that doesnt really explain why the power comes back as soon as you shift. If it was IAT's i'd expect the power loss to be across the board in every gear.
Unfortunately the cars not Insured or Taxed for the road, so taking it out locally for testing isnt really possible, i've also not managed to get any VCDS logs or similar, because i'm usually on my own and trying to drive on track and piss around with a laptop simply isnt possible.
Any ideas?
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