310R hesitation between 5,000 rpm and 6,000 rpm

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GulfSeven
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310R hesitation between 5,000 rpm and 6,000 rpm

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.

aerobod
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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:

James

timb2117
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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)

GulfSeven
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This is the 310 Sigma engine with the standard factory ECU.

Tim.

Gulf Racing 310R

GulfSeven
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I've booked it in for the 27th of next month so hopefully it'll be resolved one way or another.

If anyone has experienced anything similar on a Sigma I'd still be interested.

Tim.

Gulf Racing 310R

Dixa1225
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Nothing to lose by putting a set of plugs in. That's what I would do to eliminate the possible cause.    

Tom_Arundel
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Check the plug gaps are correct...not as bought...should be about 1mm - 0.9mm

GulfSeven
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I took the plugs out to have a look. They seemed a bit black, but all had 1mm gaps.

Tim.

Gulf Racing 310R

Keeny
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How old and how many miles have the plugs done?, think I I read on this site about failing cat lamba sencors causing running rich problems 

please update when you get to the bottom of the problem 

GulfSeven
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The car is at Williams at the moment, and apparently the issue is caused by the immobiliser relays vibrating. I believe they've fixed the issue by adding more vibration damping, but I won't have the car back for a few days to confirm.

Tim.

Gulf Racing 310R

Benton
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Well that's certainly different!  
Presumably there's a "history" of this happening before, that Williams knew about, otherwise I would have thought you be very lucky to identify that as the cause of the problem