GulfSeven Posted July 27, 2021 Share Posted July 27, 2021 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. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted July 27, 2021 Share Posted July 27, 2021 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: Link to comment Share on other sites More sharing options...
timb2117 Posted July 27, 2021 Share Posted July 27, 2021 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) Link to comment Share on other sites More sharing options...
GulfSeven Posted July 28, 2021 Author Share Posted July 28, 2021 This is the 310 Sigma engine with the standard factory ECU. Link to comment Share on other sites More sharing options...
GulfSeven Posted July 30, 2021 Author Share Posted July 30, 2021 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. Link to comment Share on other sites More sharing options...
Dixa1225 Posted July 30, 2021 Share Posted July 30, 2021 Nothing to lose by putting a set of plugs in. That's what I would do to eliminate the possible cause. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted July 30, 2021 Share Posted July 30, 2021 Check the plug gaps are correct...not as bought...should be about 1mm - 0.9mm Link to comment Share on other sites More sharing options...
GulfSeven Posted July 31, 2021 Author Share Posted July 31, 2021 I took the plugs out to have a look. They seemed a bit black, but all had 1mm gaps. Link to comment Share on other sites More sharing options...
Keeny Posted August 28, 2021 Share Posted August 28, 2021 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 Link to comment Share on other sites More sharing options...
GulfSeven Posted August 28, 2021 Author Share Posted August 28, 2021 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. Link to comment Share on other sites More sharing options...
Benton Posted August 28, 2021 Share Posted August 28, 2021 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 Link to comment Share on other sites More sharing options...
GulfSeven Posted August 28, 2021 Author Share Posted August 28, 2021 Yes they said it is quite common, although I didn't find anything searching Blatchat. Link to comment Share on other sites More sharing options...
ScottR400D Posted August 28, 2021 Share Posted August 28, 2021 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. Link to comment Share on other sites More sharing options...
ScottR400D Posted August 28, 2021 Share Posted August 28, 2021 There is a thread - IMMOBILISERS AND MISFIRES - CONNECTED ? from 2003! Turned out to be a broken PCB. Link to comment Share on other sites More sharing options...
Benton Posted August 28, 2021 Share Posted August 28, 2021 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 Link to comment Share on other sites More sharing options...
AG2728 Posted August 28, 2021 Share Posted August 28, 2021 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 Link to comment Share on other sites More sharing options...
GulfSeven Posted August 28, 2021 Author Share Posted August 28, 2021 TPS could have been an issue too - see below. Link to comment Share on other sites More sharing options...
GulfSeven Posted September 13, 2021 Author Share Posted September 13, 2021 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 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. Link to comment Share on other sites More sharing options...
Benton Posted September 13, 2021 Share Posted September 13, 2021 #18That's good news! I'd love to know how much time/money Caterham spend having to fix stuff "under warranty" judging by what I read on BC and my own experience. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted September 13, 2021 Share Posted September 13, 2021 That`s probably why they cost so much in the first place! Link to comment Share on other sites More sharing options...
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