F355GTS Posted May 5, 2017 Share Posted May 5, 2017 I had my Duratec 2.0 checked over and some adjustments made to cam timing etc to smooth out the power delivery, a rather scruffy head porting was cleaned up. New head gasket, plugs etcOn the rolling road yesterday under load it started developing a bad misfire when the engine reached around 85 degrees and progressively got worse. Inspection of plugs confirmed 2 and 3 were fouling badly. If it was left to cool to around 75 degrees it ran fine then the problem repeated at 85 degreesMoving the plugs around didn't change anything nor did moving the injectors, we fitted a brand new coil again no changethe 2 Steve's suspect injector control or coil driver in the MBE 967 but I'm struggling to understand - the ECU is under the dash away from any heat source. Need to try and get it fixed pronto or will scupper attendance at DHD next weekend :( All and any help/ advice appreciated Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 5, 2017 Member Share Posted May 5, 2017 How does the HT side work on your engine... one coil and traditional HT leads to each plug?What plugs did you fit?Jonathan Link to comment Share on other sites More sharing options...
F355GTS Posted May 5, 2017 Author Share Posted May 5, 2017 Single coil, Wasted SparkPlugs are BR7EFS gapped to 37 thou which are the recognised plug/ settings for the engine Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 5, 2017 Member Share Posted May 5, 2017 How about finding an HT tester and seeing what's happening in the plug leads as it gets hot?Or trying different plug leads if that isn't possible?Jonathan Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted May 5, 2017 Support Team Share Posted May 5, 2017 Hi Mark, Although I don't have an MBE I have heard of the coil drivers failing on ECUs - I vaguely remember having a similar issue with an Emerald. I guess the easiest test is to borrow a known good ECU, load your map onto it and test. The fact that it's a pair of cylinders with the problem certainly points at coil driver. Looking at the pinout, cylinders 2 and 3 are off pin 18 so that would certainly make sense with your symptoms.Shaun Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 5, 2017 Member Share Posted May 5, 2017 That's clever. Connection to getting hot... bad connection to that pin? And was the ECU disconnected during the work?Disconnect and have a look at the pins?Jonathan Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted May 5, 2017 Support Team Share Posted May 5, 2017 Just thought - why not use a spark tester. you can get those in-line ones but I just found this on MachineMart website: https://www.machinemart.co.uk/p/gunson-spark-indicator/ Link to comment Share on other sites More sharing options...
Mark Durrant Posted May 5, 2017 Share Posted May 5, 2017 IIRC SBD can test the ECU Link to comment Share on other sites More sharing options...
revilla Posted May 5, 2017 Share Posted May 5, 2017 Ignition breakdown voltage generally reduces with increasing temperature. However the temperature of the intake gases probably doesn't rise too much with increasing engine temperature (I'm gueasing the air doesn't hang around long enough to take in much heat) so the breakdown voltage across the spark gap won't change much - but coil packs / insulators / plug lead insulation will get hot so you could reach a point where they start to break down before the air gap at the plug. I would be looking at the wasted spark coil pack for those two cylinders and associated HT wiring. Not sure how the Duratec is laid out ... are the coil packs and leads identical pairs like on a K Series? If so could you swap them round and see if the missfire moves with them? Link to comment Share on other sites More sharing options...
F355GTS Posted May 5, 2017 Author Share Posted May 5, 2017 Thanks so far guys, We've swapped the coil pack for a brand new one with no change, today I swapped the pins (18 and 36) on the ECU to effectively test the coil lead, it seems to be running fine but I'm concerned I can't really create the load as on the RR, if I run it on the road (currently sorned and need to check MOT) I may be able to but reality is it won't get to 85 degrees in those conditionsI've been looking for a spare ECU but they're few and far between it's a 967EG with ford coolant sensor input, I'm not sure what is different wit the Ford sensor input Casting my mind back I did have a similar problem with my VX once where the crank sensor was failing when hot and losing count of the teeth......hmm Link to comment Share on other sites More sharing options...
Molecular--Bob Posted May 5, 2017 Share Posted May 5, 2017 Hi MarkWould the crank sensor cause only a single ignition channel to fail? Not unknown for ignition drivers to fail, but cheap to fixAnd the scuttle is on its way to you, had to do family stuff at short notice so been away.Ian Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted May 5, 2017 Share Posted May 5, 2017 Hi MarkI had the same coil set up on my Duratec...Cylinders 2 and 3 do seam to corespondent with the ignition coil management given the testing done. The supply is +12V is common to both coils so that must be OK, the ECU switches to earth, not knowing the ECU wiring, I'm assuming that pins 18 and 16 control the two coils switching to earth. If this is the case then I'd expect the miss fire to move to cylinders 1 and 4 if it was a coil driver fault.... though I appreciate that this can't be replicated without another session on the rolling road....If I take the engineering point of view that there are no coincidences, i.e. the probability of a coils driver fault appearing at exactly the same time as some engine work being low (but not improbable and it could still be a freak coincidence), then the fault would be as a result of some work that has been done as part of the engine change....i.e. what wiring was disturbed?As mentioned above a weak spark may become more apparent under higher load or temperatures.....Were any other setting changed on the rolling road session such as the coil dwell (from memory this is around 3ms but I'd need to check, longer periods can overheat the coil and lead to breakdown) or any temperature corrections? The ECU may also run voltage corrections as well for both injector times and dwell this is may be another factor to consider....but I'd expect this to be across all cylinders....Sorry nothing definitive here are there are many variations that could cause this...but I'd stay with the basics and what has been changed...It could have been as simple as a bad connection at the ECU if the wiring has been disturbed.....fingers crossed...CheersIan Link to comment Share on other sites More sharing options...
F355GTS Posted May 6, 2017 Author Share Posted May 6, 2017 Many thanks all for suggestions, I'm away for the weekend in sunny Wales so will pick up on this in Sunday evening Link to comment Share on other sites More sharing options...
F355GTS Posted May 11, 2017 Author Share Posted May 11, 2017 An updateI've swapped the coil driver wires to prove the loom, checked as far as I can all the ECU connectors and replaced the crank sensor, plugs and HT leads.Back on the rollers and it was all going well for about 20 mins then when put under heavy load (load site 7, 1700 rpm, 6th gear and the rollers very tight) and it started misisng again with cylinders 2 and 3 fouling badly.We swapped the ECU for another - no change, swapped injector connections (2+3 to 1+4 etc) again no changeSo it seems it's not the ECU, loom (as far as I can check), coil, leads, plugs, injectors or crank sensor and I'm pretty sure the 2 Steve's are mapping it right It drives fine under normal loads and tbh we're all a bit lost where the problem is that's causing the middle two to foul under heavy load Link to comment Share on other sites More sharing options...
Pendennis Posted May 12, 2017 Share Posted May 12, 2017 Have you done a compression and leak down test Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 12, 2017 Member Share Posted May 12, 2017 Back on the rollers and it was all going well for about 20 mins then when put under heavy load (load site 7, 1700 rpm, 6th gear and the rollers very tight) and it started misisng again with cylinders 2 and 3 fouling badly.How quickly and consistently does it recover after that?Jonathan Link to comment Share on other sites More sharing options...
F355GTS Posted May 12, 2017 Author Share Posted May 12, 2017 Hi Ian i haven't but the engine was inspected and given a clean bill of health, what were your thoughts? Link to comment Share on other sites More sharing options...
F355GTS Posted May 12, 2017 Author Share Posted May 12, 2017 Hi Jonathan, if you restart immediately afterwards it will fail straight away, left to cool to 70 or so degrees it will be OK for a while but perhaps 5 minutes later will fail Heat is the obvious thing and failure always seems to be around 80-85 degrees (on the dash) which is why I thought crank sensor as have seen those break down at high temps Link to comment Share on other sites More sharing options...
Pendennis Posted May 12, 2017 Share Posted May 12, 2017 Hi Mark, is strange isn't it. Did you say you've changed the coil pack?I was thinking of a bad earth on the crank sensor, but suppose any sensor breaking down would affect all for pots not just 2 & 3, so if injectors and loom on 2 & 3 are not the cause could only be coil pack, ecu. If 2 & 3 are leaking i'd guess it be worse under load, does it smoke? Might be worth checking fuel pressure at load see if the regulator misbehaves but surely that would affect all four pots Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 12, 2017 Member Share Posted May 12, 2017 A lot of this is out of my league and it's repeating my post #6 and Ian's (and William of Occam's) logic in post #8 but having swapped all of those bits what's left includes the connections. And I imagine that many of the connectors were separated and reconnected in the work before the problem occurred. I'd go over all of those with wiggling and a good look at the pins. And then I'd wiggle them again when the problem recurs. Jonathan Link to comment Share on other sites More sharing options...
F355GTS Posted May 12, 2017 Author Share Posted May 12, 2017 Thanks Ian, yes coil pack replaced and sides swapped and the problem remains with 2&3. I did have to repair the crank sensor wiring last Spring but it ran fine since then, I've ordered some proper shielded cable and new connectors again, also I'll buy another new sensor just to be sure.Having said all that I'd never drive it in the way it was on the RR ie up a steep hill in 6th and 1700rpm so maybe the problem has been there longerI'll check the fuel pressure too Does anybody know the recommended or max gap for the Crank position sensor to trigger wheel? mine is something like 52 thou which seems high but there's no in and out adjustment Link to comment Share on other sites More sharing options...
Pendennis Posted May 12, 2017 Share Posted May 12, 2017 Presuming you are using standard crank wheel and sensor? But you are correct there is no adjustment although it should be pointing at tooth 9 @ TDC. However, I cannot see how just pots 2 & 3 would be affected, same if fuel pressure is too high although we do not know fuel rail construction and the branch take off's may allow more flow but then the injectors must be faulty and you've already swapped them.Are you using cam timing sensor?Strange this, I think compression and leak down test is worthwhile as well check fuel pressure does not rise for some reason, fascinated to know what the cause is though Link to comment Share on other sites More sharing options...
F355GTS Posted May 12, 2017 Author Share Posted May 12, 2017 Hi Ian No not using the cam sensor, thought on the crank sensor is that it may be losing count, have had it before on a VX when it was hot although that wouldn't start but fired on one or two cylinders Link to comment Share on other sites More sharing options...
Pendennis Posted May 13, 2017 Share Posted May 13, 2017 Yes I agree, recently on my Duratec I had similar but not identical problem and it turned out to be damage earth sheathing on the sensor wire Link to comment Share on other sites More sharing options...
Area Representative Piers300 Posted May 13, 2017 Area Representative Share Posted May 13, 2017 A missing flywheel tooth can cause weird things to happen. Not sure about your ECU, but if it has say 90 teeth entered and there are only 89, then strange things happen. Piers Link to comment Share on other sites More sharing options...
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