J888PRB Posted October 2, 2022 Share Posted October 2, 2022 Hi AllMy 420r picked up a misfire this week. On inspection it is cylinder 1 (front).I've popped in new plugs - no changepopped on new coils - no changenow left scratching my head. Has anyone any experience of similar. Any advice welcomed.Car is a 2016 420r - 13000 miles.Thanks Link to comment Share on other sites More sharing options...
R400svn Posted October 2, 2022 Share Posted October 2, 2022 Id go for the wiring loom to the coils. Link to comment Share on other sites More sharing options...
ChrisC Posted October 3, 2022 Share Posted October 3, 2022 Yes, Friends 420R stopped firing one cylinder at a Trackday at the beginning of the year. Swapped coil packs and plugs with no change in symptoms. Loom connections all checked out ok. Eventually diagnosed as the ECU coil pack driver. MBE provided first class support, replaced the coil pack driver for a very reasonable charge. Link to comment Share on other sites More sharing options...
J888PRB Posted October 3, 2022 Author Share Posted October 3, 2022 Thanks everyone Running diagnostics check on it tonight.I see Caterham sell the wiring looms direct so me point shopping around. Hopefully easy install? Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted October 3, 2022 Area Representative Share Posted October 3, 2022 Local Duratec owner had exactly the same problem - No 1 cylinder. After substituting the obvious it was the ECU at fault. Link to comment Share on other sites More sharing options...
John Vine Posted October 3, 2022 Share Posted October 3, 2022 I had exactly your problem on my 2008 R400D. The cause was a fractured (brown) wire in the #1 COP connector. It was difficult to spot at first as the fracture was partly obscured by the connector itself. The cure was to fit the sub-loom (3AL080A). I had to splice this into my main loom, but your 2016 loom may already come with a plug 'n' play Econoseal.ETA: Some pics here. And a bit of history here.JV Link to comment Share on other sites More sharing options...
J888PRB Posted October 3, 2022 Author Share Posted October 3, 2022 Spot on JVthe wire had sheared off in the connector. Bit of faff to isolate but great result that it was only this.ordered the new loom (£44) and will fix the old one as a spareas clearly yet another week link im new to C7 ownership and can see already it will be a love-hate relationship. Link to comment Share on other sites More sharing options...
John Vine Posted October 3, 2022 Share Posted October 3, 2022 Pleased to hear you've confirmed the problem! Do you already have the Econoseal connector in your main loom?The upgraded coil loom has fatter, silicone-sheathed wires, and is much more resistant to engine vibration. Re your old loom, I'd suggest that the best place for it is the bin.While on the subject of Duratec engine vibration, another weak point is the TPS (Throttle Position Sensor) loom. CC supply a "race" version, also fitted with silicone-sheathed wires. You may already have this, of course. If not (and if CC are out of stock), it's not difficult to make up your own.JV Link to comment Share on other sites More sharing options...
J888PRB Posted October 4, 2022 Author Share Posted October 4, 2022 Hi JohnOld coil loom repaired - still misfires but all 4 cylinders are working so all a bit odd., no longer isolated to cylinder 1.Rather frustrating.will try new loom when it arrives Thursday before freaking out. will look at tps next but none in stock as you say and beyond me to make one.....supposed to be driving to Spa in 6 daysBetter warm up the M3 Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted October 5, 2022 Area Representative Share Posted October 5, 2022 And the Elephant in the room is....the ECU ! Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted October 5, 2022 Area Representative Share Posted October 5, 2022 And the Elephant in the engine bay.........the ECU ! Link to comment Share on other sites More sharing options...
John Vine Posted October 5, 2022 Share Posted October 5, 2022 Yes indeed, it could well be the ECU. Worth checking that the earth is sound.As for the TPS race loom, making your own is straightforward. This is the one I made up some years ago while waiting for CC stock to arrive: The wiring is from domestic mains cable. The LH connector (to the TPS) is the 3-way from the existing loom, and the RH one is a new Econoseal 3-way male (ESC3M). I replaced the original 3-way connector with an Econoseal 3-way female (ESC3F).If you do find that your TPS wiring is faulty and CC don't have the race sub-loom in stock, you're very welcome to borrow my homemade one in the interim.JV Link to comment Share on other sites More sharing options...
John Vine Posted October 5, 2022 Share Posted October 5, 2022 Just been looking at my notes....Back in May 2013, I was discussing TPS wiring problems with Tony in Parts, and he mentioned that "current" cars no longer used the race loom as the standard loom had been changed. So maybe your wiring will prove to be ok!JV Link to comment Share on other sites More sharing options...
ScottR400D Posted October 5, 2022 Share Posted October 5, 2022 As the loom did appear to have a broken wire and now that it's been off and 'repaired' the nature of the issue has changed I would have thought the fault still lies with the loom. Proof of the pudding should be fitting the new loom arriving tomorrow. Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted October 5, 2022 Area Representative Share Posted October 5, 2022 Scott & JV - As mentioned a few threads ago a member in my area with a recently home built Duratec car had exactly the same snag, miss fire on number 1 cylinder. Three of us went around in circles swapping plugs, coil overs & finally replacing the sub loom to the coil over. This moved the miss fire around a few times but always came back to number 1 cylinder.Due to the symptoms we suspected the ECU which was sent of to MBE via CC. The circuit(s) controlling number 1 ignition were faulty as was something else which is why the snag sort of moved a few times. We put this down to the 'corrective tap' the ECU was given a few times.Can't beat percussive action on electronics to realign the internals !!Also believe it or not another snag was the rev counter refusing to budge off 1000 rpm. Replaced it.There is a theme here once again - defective brand new components. Link to comment Share on other sites More sharing options...
John Vine Posted October 5, 2022 Share Posted October 5, 2022 Thanks for that, Geoff....rev counter refusing to budge off 1000 rpmVery topical. (But the problem there appeared to be the dipswitch setting.)JV Link to comment Share on other sites More sharing options...
ScottR400D Posted October 5, 2022 Share Posted October 5, 2022 Geoff, your final statement turning out to be true would certainly be no surprise but we seem to be talking about a 6 year old car here! Link to comment Share on other sites More sharing options...
J888PRB Posted October 5, 2022 Author Share Posted October 5, 2022 Hi everyone - update - thanks for all your thoughts and I am adding detail to help with all your thoughtful suggestions. new TPS fitted with no change. symptoms originally were cylinder 1 not firing at all - the fixed wiring loom sorted that out - all 4 cylinders now running the new symptoms are rough idle (not much worse than standard)when gradually accelerating under load the car is cutting in and out hence thinking TPSDoing a night drive tonight I also note that the gear shift light is dimly glowing and not going off after the stuttering which is odd so wondering it could be related to the rev limiter?? Presume all of this is pointing back to the ECU as you all hinted at needing some work, I was hoping not as supposed to be driving to Spa on Tuesday and can't get that done in time I don't imagine.With the ecu - can that just be flashed and reinstalled or is it more involved than that? the new coil loom arrives tomorrow I hope so i will update if that changes or improves the symptoms.. my next thought was a full wiring loom, but I'm clutching at straws. Would prefer to look at the ecu first. JV - your notes are correct - mine doesn't have a connector for adding that loom you made - the wires track back into the main loom.GB - I will look up MBE tonight and call them tomorrow thanks again for reading/advising chaps Link to comment Share on other sites More sharing options...
J888PRB Posted October 5, 2022 Author Share Posted October 5, 2022 Thanks Chrislooking more like this could be the issue. Will speak to MBE on a separate note - great build blog. Quick question though - I followed your blog for checking the diff torque. My resistance was circa 45 lb ft - newly serviced Titan diff - but I was rotating clockwise on the passenger side not counter clockwise as per your write up. little to no resistance in the counter clockwise direction. Any thoughts? Link to comment Share on other sites More sharing options...
J888PRB Posted October 5, 2022 Author Share Posted October 5, 2022 Have anyone got a contact at MBE - thanks Link to comment Share on other sites More sharing options...
John Vine Posted October 6, 2022 Share Posted October 6, 2022 Re #18:...mine doesn't have a connector for adding that loom you made - the wires track back into the main loom.AFAIK, CC didn't fit that Econoseal 3-way connector as standard, but it's required for the race sub-loom. Does your TPS wiring look like this thin, spindly stuff or is it more meaty?The photo shows the fracture in my original 2008 TPS wiring.JV Link to comment Share on other sites More sharing options...
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