Hi Lads,
Rex Has his KingPinny 'budget hack' on the Dyno the other day for its post-build, pre-thrash checkup. It makes respectable grunt with AFR's sticking nicely between 12.3 and 11:1 for the whole run.
However at the top of the run just prior to limiter (perhaps 500rpm) the AFR suddenly makes a dead vertical up past 14:1 which is where the operator jumps off the acceleratix. We repeated the run three times, peak power was within 2-3rwkw and the same massive sudden vertical leanout condition.
The dyno was done as a favour so no fault finding was performed, Rex was thinking that perhaps the AFM may be faulty (NIssan's are renowned for them) causing the ECU to basically drop the injector duty cycle right off.
The engine R32 RB20DET and is stock, along with the ECU and turbo etc. Only modifications are filter, exhaust and intercooler setup. Boost is un-modified but up to 11psi due to removal of restrictions in pipework etc.
Rex has considered AFM maxing however it seems more likely that Mr ECU would just go massively rich safety-like instead of lean.
Anyone seen/heard similar problems? He has seen a couple of other graphs with the same problem, but not an explanation.
Rex has some diagnosis to do on Mondey such as AFM peak voltage etc, but would be good to have some things to check if He runs dry ideas wise. It also seems very unlikey to be a fuelling issue because of the shape of the graph.
Have included printout below if it helps...
Thanks Lads
Rex