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Aftermarket tune problem

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Hello everyone,

I've been having issues with aftermarket tune for over a year and wanted to see if anyone on this forum can help me out.

Since the new tune was installed with upgrade parts on my Lotus Exige S, car became very sluggish at high rpm range 6000~8500 rpm (where high cam kicks in) and running rich.

It's almost painful watching speedo/rpm going up on long back straight on race tracks...

Attached is data logged on last HPDE at NJMP Thunderbolt track using AIM that I also sent to the vendor tuner, who only came back with car running rich...

I'm a noob at tuning and can't tell much looking at data, so if you can find anything or direct me or need more information please let me know...

Thank you all.

Attached Files
  • 062520_Lotus-Exige-S_NJMP-Thunder_Generic-testing.xlsx
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.

What year S? 2ZZ or the Evora's V6? Unfortunately you'll need to get some more verbose logging as this isn't enough to pinpout what the culprit is. What I can say is that I've played with a couple 2ZZ engines and you're definitely whackily rich dropping into the 9's mid-high 7000 RPM and far more rich than I would think would be necessary below that. You'd need to have some reference to IAT, MAP, and your timing to really decide if/why it was intentional.

It's 2007 Exige S with 2zz engine.

Oops forgot to include IAT data when downloading...

Have no idea how to get MAP data...


It defiantly looks to be running way too rich.

Double check the hardware to rule out anything mechanical that could cause rich running, boost leak, spark plugs, slipping compressor belt etc and specifically on the 2ZZ ‘lift bolts’ for the VVTLI system which area known weak point.

Once you’ve confirmed the engine is healthy then I’d take a closer look at the map and tune the AFR to MBT, there comes a point where adding more fuel has no gains and risks the engine suffering bore wash etc.

I would say your high cam is not working, VE will be falling away which is why AFR goes rich and power fades away. When the high cam is working you will normally see a big wobble in the lambda trace when the high cam switches in which is not evident in your log.

This great video explains the VVT-LI system, it mentions the factory ECU waiting for water temp to reach 60c degrees (and 6000 RPM). Any chance you got a bad coolant temp sensor? Or a leak in the control pressure side. Or a mechanical issue with those spring-loaded rocker arms (broken springs might prevent high-lift from occuring)


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