PC Pete Posted July 6, 2019 Share Posted July 6, 2019 Ok, well, it’s been about 18 months since my 2013 R400 superlight has been on the road. It’s only done 3800 miles and tempted by the weather I thought it time to get going again. But.... on a high speed trip it felt as good as ever.... however below 2000 rpm it runs as rough as hell. Apply some throttle and you can hear a misfire. Take it on the road (ie under load) and it sounds as if it’s firing on 2! Above 2000 rpm it’s fine though.What have I done?Replaced the loom to the coil packs with Caterhams ‘’race version’Checked all of the electrical connections for breaksCycled a new coil pack through each cylinderChecked tightness of the air intake fixings.Full tank of premium fuel - it had about a third of ‘old’ fuel.Plugs look fine - original plugs- all light brown.It won’t idle before reaching temperature (nothing new here - Caterham couldn’t fix this either after it’s pbc). Even when it does idle the revs are not steady.So - anyone had this problem before? Would love to hear from you with your thoughts and ideas. The weather might change! Many thanks in anticipation Link to comment Share on other sites More sharing options...
David_Long Posted July 6, 2019 Share Posted July 6, 2019 Very difficult to diagnose this sort of thing online, but if it runs OK at high rpm, and I guess larger throttle settings too, it suggest to me it is probably a sensor issue. The Duratec (on the Caterham map) can be sensitive to faulty temperature sensor and my own experience of this is similar to your description (the one the ECU uses on the exhaust side). Also TPS is notorious for problems like this and it could be that. Either way, swapping these out, or hooking it up to Easimap may be the best way forward.Edit: Of course lambda senor may be the problem as it really only operates at low throttle settings - you could try unplugging that and see if the problem goes away (ie let the ECU use default setting). But if it is like it all the time, and from cold, then less likely. Link to comment Share on other sites More sharing options...
PC Pete Posted July 6, 2019 Author Share Posted July 6, 2019 Many thanks David. I had begun to suspect it might be a sensor. Looks like I will be visiting the Caterham parts store. That said, are they different sensors to those that Ford would have used on say an Escort or Mondeo I wonder? Link to comment Share on other sites More sharing options...
Jim 123 Posted July 6, 2019 Share Posted July 6, 2019 After an 18 month lay up have you tried cleaning the wiring connectors in the various wiring connectors and cleaning off all earth fixings. What is the state of the battery and is the electrolyte topped up. Link to comment Share on other sites More sharing options...
PC Pete Posted July 7, 2019 Author Share Posted July 7, 2019 Thanks Jimyep - just put a new battery in it. Everything else is pretty tight although maybe I should have another look re earth connections. I suspect this could be a trial and error job with various sensorsPeter Link to comment Share on other sites More sharing options...
Tazio Posted July 7, 2019 Share Posted July 7, 2019 Coil Pack, or Injector plug wiring, both known to fail.. Link to comment Share on other sites More sharing options...
PC Pete Posted July 8, 2019 Author Share Posted July 8, 2019 Thanks Tazio. Yes - the first coil pack loom failed on a track day not long after I had built it- traced to a broken wire entering one of the coil pack connectors. Managed to fix it but ordered the updated loom from Caterham. Had that further updated by an F1 team(!) using silicon seal as they do with F1 cars. Never got around to fitting it until last week when the problem occurred. Have thoroughly (visually) inspected all of the connections to coil packs and injectors but all look good. Having cycled a new coil pack through each cylinder I reckon they are also good.The hunt goes on....thanks againPetee Link to comment Share on other sites More sharing options...
PC Pete Posted July 17, 2019 Author Share Posted July 17, 2019 Well, it is fixed. I’d forgotten just how visceral that car is!Having checked sensors and wiring until there was nothing else left I tried disconnecting coil packs one by one with the engine running. It would of course struggle if the cylinder in question was firing. So when I removed the coil pack connectors on 2 and 3 and there was no difference to tick over I figured the only thing left were the spark plugs. I discounted them earlier believing that with only 3700 miles on the clock they would be fine. They weren’t. New set of NGK equivalents fitted and all is back to normal.I’ve never had a plug failure in my (long) driving career.The moral in the story is go for the cheap and easy things first! Link to comment Share on other sites More sharing options...
John Vine Posted July 18, 2019 Share Posted July 18, 2019 Please to hear it's fixed. Out of interest, what plugs were fitted originally, and which NGK ones did you go for -- and with what gaps?JV Link to comment Share on other sites More sharing options...
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