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[SOLVED] 310R hesitation between 5,000 rpm and 6,000 rpm


GulfSeven

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I've noticed this on the road a few times, but it was very repeatable on track today. It's mostly noticeable in 3rd gear, but I have noticed it in 2nd gear too. Between 5,000 rpm and 6,000 rpm the car hesitates when on full throttle. It's almost like the rev limiter is kicking in, before the rpm then continues to climb. Has anyone else experienced this or got any ideas what it could be? The car is a 2020 310R.

I'm going to let Williams take a look at it, but it would be good to get an idea of what the issue might be before hand.

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It may be the engine mapping, I'm not sure about the Sigma engines, but if the Caterham default map is fundamentally the same as used in the Duratecs, the default Caterham map is a bit lean in that range, so can hiccup a bit, especially when transitioning from part to full throttle. Fiddling with the TPS to move it in it's holes a little to change the throttle site may make it a bit more smooth in that range, as long as it still stays at throttle site 0.0 to 0.4 when at idle.

The Duratec with plenum seems to have two "waves" at full throttle that transition between rich and lean fuel needs on an injection time per revolution basis. You can see the fuel demands at 5000RPM are near a low, then rise quite a bit at 6000RPM before leveling off again. This map is for my re-mapped R400, the Caterham map certainly had hiccups in a few places compared with what mine does now. I've tweaked it over the years to be a perfect match of lambda values to my engine's needs.

Each engine is going to be different depending on tolerances, cam, intake, operating environment, etc., but the Duratec does seem to have the two climbing extra fuel needs in the 2000-3000 and 5000-6000RPM ranges:

Fuel.thumb.png.d32cc9fe220b528d61b89836b0f0b251.png

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Different car (K series) but identical issue absolutely identical, only fixed after many many dead ends, with new ECU essentially a one remapped by kmaps, instant fix. (Obviously if your ecu is unlocked you dont need new just a remap)

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  • 4 weeks later...

I've not heard of that before. 

Presumably they're talking about engine vibration, if it was vibration from the chassis or road it wouldn't be at the same revs all the time, and it's hard to be see where enough vibration could come from the engine to do that. 

If that's what they say, they should know, but I'd want a full explanation of that, which might be of interest to Sigma owners on here. 

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Since I'm currently having issues with my immobiliser (though it's a bit late now, since I've handed the problem off to Caterham), but just for better knowledge going forwards, does anyone know where roughly this relay hides under the scuttle?.
Update - it seems apparently the relay(s) are contained within the immobiliser unit as a whole

 

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Mine is a Duratec but I had exactly the same symptoms you describe - a misfire high up the rev range.

I changed all the usual suspects, plugs, coil packs etc but still the same.

My dealer couldn't diagnose it and said it was likely to be the imobiliser which they then modified.

Still no joy. Took it to Northampton Motorsport who put tested it on the dyno and it proved to be a failing throttle position sensor.

Andy

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  • 3 weeks later...

I finally picked up the car from Williams today - I had to wait for a new windscreen and roll bar to be fitted (also under warranty) at the same time...

I gave it a good few tests on the way home, and I can confirm that the hesitation isn't there anymore - it accelerates smoothly all the way to the shift light now *thumbup*

Apparently the TPS settings were all out too, so they've been reset to the factory settings. That's made a big improvement to driveability, so I can only assume the TPS settings were wrong when the car left the factory.

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