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Mini Cooper AFr problems

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We are tuning a MIni cooper JCW Gp with a loba turbo. We were able to tune the boost up to 22 psi but the afr was too lean 13 AFR. Then we only change the requested lambda maps and the boost dropped 2 psi

What might be the problem?

This isn't a platform I'm familiar with but if the air fuel ratio is moving lean as you increase boost, I'd be looking at either injector duty cycle or fuel pressure as the likely culprit.

I have no explanation as to why changing the target AFR has affected your boost. Is this repeatable? If you set the AFR target back does the boost go back up 2 psi?


if you say requested lambda so i assume you are talking about the direct injection engine,in that case i would look into the the requested fuel pressure vs actual fuel pressure.


Mini's run leaner than normal cars, have you got a graph of requested AFR vs actual AFR?

I've been doing a lot of 1zz/2zz turbo'd engines lately and the AFR has a massive effect on the boost achieved, what ECU are you using?

Stock ECU, we tested the same map, lower boost good afr, i hate minis!

Sounds like your running out of fuel then, either fuel pressure, or injectors are maxed. Are you running a returnless system or have you modified it?

stock, so you think thst with higher boost we cannot achieve good afr because of injector restriction and car will lower amount of air in order to achieve desired afr?

Measure your fuel pressure and injector duty and you'll be able to work out if it's the pump thats not up to it or the injectors are maxxed

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