chris956 Posted July 8, 2014 Share Posted July 8, 2014 Hi Guys , my car has suddenly developed a curious misfire. It happened in the very hot weather. So much so that it was idling on 3 cylinders. Despite this , when on full throttle it would clear its throat and be fine. I cant replicate the misfire and a low speed start in 6th gear going to full throttle does not necessarily cause the misfire when car under max load So far I have new plugs , new petrol , cleaned air filter, balanced the Throttle Bodies and checked the lamda sensor wiring so no avail. Next step is to borrow a set of coil packs to swap over and see if it rectifies the problem instantly in which case I`ll invest in a new set of those too. So , if there is any kind soul out there near Kent , SE London or surrounds would kindly lend me some to test for 30 minutes Car is a R400 Duratec superlight with Throttle bodies Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 8, 2014 Share Posted July 8, 2014 You say you have checked the lambda sensor wiring. Have you disconnected (unplugged) the sensor at the joint part way along the cable ? If it runs fine with it unplugged ... the lambda sensor is at fault. Link to comment Share on other sites More sharing options...
chris956 Posted July 8, 2014 Author Share Posted July 8, 2014 Thanks , I`ll give that a go. I read somewhere on here whilst researching the problem that the Lambda only works below 3k revs for emission control ??? If that is the case and I`m more than happy to be told otherwise it shouldnt make any difference higher up the rev range should it ? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 8, 2014 Share Posted July 8, 2014 Mine (k-series) developed a horrible mis-fire. I was about to start swapping coil packs, etc, when BlatChat suggested unplugging Lambda. Magic cure 😶🌫️ If this proves to be the case ... remove the sensor and search on eBay for the part number etched on it. Link to comment Share on other sites More sharing options...
chris956 Posted July 8, 2014 Author Share Posted July 8, 2014 Just back from test drive - Could not get it to mis behave at all. Re connected the Lambda and went round again with the same result - good as gold One thing I did do before leaving was on close inspection of the connections on the COP I noticed that the engine cover that goes over the top of them was rubbing on the corner of one of the connections. It had left a small tell tale sign of dust on the connection and a rub mark on the underside of the cover. This would have been pushing down on the end of the connector on the COP on the far end. Maybe just maybe, this rubbing caused some sort of oscillation or vibration that effected the connector and hence the circuit. To be on the safe side I added spacers to the cover to lift it off a couple of mm. So its fixed for now. I need to get back on track which will be the acid test and will try the lambda connector should I need too. Thanks for your help Link to comment Share on other sites More sharing options...
mic Posted July 8, 2014 Share Posted July 8, 2014 Check the coil loom, common cause of misfires. Injector plugs and TPS also known to cause problems. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 8, 2014 Share Posted July 8, 2014 The Duratec master has spoken It may be you cleaned up an electrical connector by disconnecting and reconnecting. I worked through my engine bay and put a couple of drops of anti-corrosion liquid in each connector. Link to comment Share on other sites More sharing options...
John Vine Posted July 8, 2014 Share Posted July 8, 2014 As mic says, Duratecs can suffer from a number of misfiring problems. IME (and I've encountered all these!), they can be caused by: Fractures where the wires enter the TPS Fractures where the wires enter the COPs Dirty COP connectors (especially #1) Faulty COP(s) Often, a good clean of the COP connectors is sufficient. Do you have the flexi-coil loom fitted? (Info here and here.) This has silicone-sheated wiring and is much more resistant to high-frequency vibration (which causes the fractures). IIRC, the Ford COPs are about £30-£35 each, but you can get the equivalent thing cheaper here. JV Edited by - John Vine on 8 Jul 2014 20:44:14 Link to comment Share on other sites More sharing options...
chris956 Posted July 8, 2014 Author Share Posted July 8, 2014 Quoting John Vine: As mic says, Duratecs can suffer from a number of misfiring problems. IME (and I've encountered all these!), they can be caused by: Fractures where the wires enter the TPS Fractures where the wires enter the COPs Dirty COP connectors (especially #1) Faulty COP(s) Often, a good clean of the COP connectors is sufficient. Do you have the flexi-coil loom fitted? (Info here and here.) This has silicone-sheated wiring and is much more resistant to high-frequency vibration (which causes the fractures). IIRC, the Ford COPs are about £30-£35 each, but you can get the equivalent thing cheaper here. JV Edited by - John Vine on 8 Jul 2014 20:44:14 Cheers for all the suggestions and links - yes mine is a 2012 car and has the flexi coil fitted and looks identical to your photos. No evidence of split wires but I did as posted above find a COP rubbing on the engine cover. So far the misbehaving has gone but I need to give it a proper drive to make sure. Link to comment Share on other sites More sharing options...
John Vine Posted July 8, 2014 Share Posted July 8, 2014 Good news about the flexi-coil loom. Did you manage to detect which cylinder was misfiring? (For example, was one primary cooler than the others?) COPs can certainly fail, as I discovered on a recent tour through France. My R400 began to suffer an intermittent misfire, ofter clearable by a couple of stabs on the loud pedal with the clutch disengaged. After a while, the misfire became permanent. I stopped and found primary #1 practically cold. Happily, I had a spare COP with me (bought after a day of misfires at a Llandow trackday several years ago), and that fixed the problem entirely. In fact, the engine is now running sweeter than ever. JV Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 9, 2014 Share Posted July 9, 2014 If you want to save your fingertips ..... I have a non-contact laser thermometer you are welcome to use. Link to comment Share on other sites More sharing options...
chris956 Posted July 9, 2014 Author Share Posted July 9, 2014 JV - it wasn't that severe so nothing that obvious I'm afraid. SM - cheers for the offer , already have one. Link to comment Share on other sites More sharing options...
chris956 Posted July 13, 2014 Author Share Posted July 13, 2014 UPDATE UPDATE Took the car out for a drive and this misfire has returned. Firstly on partial throttle and then it dropped to 3 cylinders for ages despite trying to coax it back onto 4 with full throttle. This was the perfect opportunity to see what cylinder was not firing. Slung it over in a parking space and whipped the top off held by my glamorous assistant ( who thought we were out for a pleasant drive not a testing session 😳 ) The old spit on the finger and touch the headers revealed number 1 was way colder than the others.. maybe the suspect has been found. Whilst I was at it I disconnected the Lambda sensor and set off home. That made not difference to start with and then about a miles from home it started to run spot on Back in the garage and checked that voltage being delivered to number 1 coil and it was 12.5v and consistent with the others. This further leads me to suspect dodgy coil pack. Hopefully I`ll be getting a loaner to swap it out to see if makes the difference ..... Link to comment Share on other sites More sharing options...
chris956 Posted July 15, 2014 Author Share Posted July 15, 2014 New coil pack from Euro car parts (£22) installed and all is well with the world again. At that price I`ll probably replace the other 3 for the hell of it. Amazon that was linked too above ( thankyou) only had 1 in stock and ECP were the next best on price Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 15, 2014 Member Share Posted July 15, 2014 Well done. Was that the one that was squeezed by the cover? Jonathan Link to comment Share on other sites More sharing options...
chris956 Posted July 15, 2014 Author Share Posted July 15, 2014 Quoting Jonathan Kay: Well done. Was that the one that was squeezed by the cover? Jonathan No it wasn't but it can't have helped. Number 1 coil was the culprit. The intermittent problem finally became a permenant problem which made it far easier to diagnose .... Thankfully Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 15, 2014 Member Share Posted July 15, 2014 Thanks Jonathan Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 15, 2014 Share Posted July 15, 2014 Good news Link to comment Share on other sites More sharing options...
John Vine Posted July 22, 2014 Share Posted July 22, 2014 Quoting chris956: Number 1 coil was the culprit.How interesting/odd that #1 also failed in my case. Is there something special about that position, I wonder? Anyway, very pleased to hear all is now well. JV Link to comment Share on other sites More sharing options...
chris956 Posted July 22, 2014 Author Share Posted July 22, 2014 Quoting John Vine: Quoting chris956: Number 1 coil was the culprit.How interesting/odd that #1 also failed in my case. Is there something special about that position, I wonder? Anyway, very pleased to hear all is now well. JV Hmmm , very suspicious 😔 The coil pack which was in #1 position clearly on inspection had not been there all its short life as it had 3 dots on it indicating it came from #3 ...... I guess I`ll never know for sure. Link to comment Share on other sites More sharing options...
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