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Title: P0351 Post by Dave2302 on Mar 20th, 2014, 8:19pm Hi Guys, It's not too often I get stumped, but this problem is giving me a real headache !! 24V Cosworth BOB Engine. Car stood a while (6 months with little use It has developed an intermittent misfire / jerking at 2/3 - WOT around 4000 rpm upwards. Also intermittant rough missy idle, sometimes stalls, will start straight up again. Fuel pump is almost new Walbro, filter and lines all new. Compressions all even at 180 psi. I have swapped leads, coil pack, edis module, new plugs, Air Flow Meter (MAF), IACV there is no EGR, and VIS etc is all working correctly. No air leaks on intake. I have W/B Innovate AFR meter fitted, and fuel pressure gauge, all showing normal readings, AFR's bounce around a bit when idling rough, I think this is unburnt fuel going down exhaust due to misfire and Lambdas are therefore struggling to correct fuelling. TPS ECT and IAT battery voltage etc all correct, on live data. The only fault code showing which comes and goes is P0351 "Ignition Coil Primary A / Secondary Circuit Malfunction" Does this indicate a possible bad wiring between EDIS Module and Coil Pack, that's about the only bit of wiring I've not checked. Thinking of running 3 new wires to eliminate that possibility. Anyone had this, or know exactly what this code is telling me ??????????????? Cheers Dave |
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Title: Re: P0351 Post by Snoopy on Mar 21st, 2014, 7:53am With your expertise and knowledge I think you have answered your own question. It seems the logical thing to do in the light of what you have already done. replace those three wires and see what happens. |
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Title: Re: P0351 Post by Andycan on Mar 21st, 2014, 8:23am I have a similar problem and have started to check everything Dave has but don't have a reader so sort of doing it in the dark lol. As it could be these wires are they on the plug that fits from underneath the coilpack on the n/s? also where is the edis? Do we have a wiring diagram for these? I was considering rewiring the whole of the engine bay loom this summer if we get good weather and I can find out where everything is lol. |
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Title: Re: P0351 Post by Dave2302 on Mar 21st, 2014, 9:12am Should have googled that code first LOL............ The fact it says "Coil A" is telling me that it is Cylinder 1 (&5) coil, circuit or misfire. This could be Plugs, Leads, Air Leak, Wiring or Ignition Coil, but as Snoopy wisely said, in light of everything I've done the wiring should be the next thing to eliminate !! Andycan.............. Get a proper scan done at least, it will point you in the right direction. When diagnosing a problem like this the first thing I do is a scan, then a look at live data, usually that points me to the problem. This problem I've finally had to get round to installing the Innovate W/B Lambda kit and also hooked up a fuel pressure gauge in the cabin. Very useful bit of kit that W/B AFR meter, and knowing what the fuel pressure is doing also helps but even with all this info it still doesn't tell me exactly where the problem lies. All the parts I have swapped are known good spares I have, imagine what the cost would be if I'd had to buy all these !! What I realised late last night is that this Puma 24V has been built over 3 years now, and was built from parts off my 24V Ultima Estate. The Engine (Fuel Cut Off) loom was a new one 3 years ago, but the rest of the wiring from EECV ECU plug to big square engine multiplug was made by myself from a (now) 19 year old Scorpio main loom................. It seems logical that although the wires I used checked out ok 3 years ago, it is highly likely that I could have a duff one now ;) I think I'm going to (hopefully) get it running right for my event next weekend then over the winter rip the main loom apart and build a modular loom inside a trunking, so it is easier to get at and replace wires in the future............. After all this is a rally car, and as such gets leapt 6 ft in the air, and driven over some very harsh gravel tracks ;D Will let you know what happens when I replace the 3 LT wires ;) Cheers Dave |
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Title: Re: P0351 Post by amigafan2003 on Mar 21st, 2014, 10:37am Check earth wire (i.e the one back to the EDIS unit) for that coil. Measure its resistance compared to the other two. |
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Title: Re: P0351 Post by Dave2302 on Mar 21st, 2014, 10:44am Thanks, yes that's one of the 3 (trigger) wires I'm going to bypass, will run a 3 core from EDIS module direct to coil pack then try it :) Cheers Dave |
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Title: Re: P0351 Post by amigafan2003 on Mar 21st, 2014, 8:33pm I had a similar issue on my Westfield with a Pinto running TB's and Megasquirt. The ecu controls the coils directly by grounding the trigger wire (in the same way that the EDIS does) - the wiring to the coil was ok but the VB921 coil driver had a poor earth path leading to misfires at high revs just on that coil. I understand the EDIS has a common earth path rather than one for each driver, so it's likely to be a fault between the EDIS and the coil. |
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Title: Re: P0351 Post by Dave2302 on Mar 27th, 2014, 5:48pm I think I may know what my problem is ;) I have changed just about everything and re wired EDIS completely, all to no avail, misfire still there, tacho also twitches erratically when engine is missing. This all started when I put the car back on the 24V Scorpio ECU, as previously I have had it running on a V6 Mondeo manual ECU, which does not have EDIS Module, the coil drivers are built in to the ECU, same on the original Puma 4 cylinder engine.............. The Rev counter on V6 Mondeo and Puma is fed from pin 48 on ECU. The Scorpio Rev Counter is also fed from Pin 48 ECU, but that also goes to Pin 2 EDIS Module, and is the IDM line, a very important signal for the EDIS. I stuck the Mondeo ECU back on and the Misfire is gone. Put the Scorpio ECU back on again with EDIS Module, misfire is back !! I'm betting the electronics in the Puma rev counter are different to Scorpio and interfering with the IDM Signal to EDIS, causing the misfire. Unable to test this today, as rally was cancelled so I've got the front exhaust off the car doing some upgrades but once some new downpipe gaskets arrive, I'm going to disconnect the rev counter feed and see if the misfire goes away !! As usual, comments welcome ;) Does this sound feasible ? Or is my brain now misfiring ;D Cheers Dave PS All that P0351 fault code is really telling me is that there is a misfire on cylinders 1 & or 5..............It is triggered by a spike when coil "A" sparks, so could be a duff injector, air leak, HT lead, plug, etc etc, and I have ruled most everything like that out ;) Dave |
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Title: Re: P0351 Post by Dave2302 on Mar 28th, 2014, 3:58pm Well, that was a complete load of cobblers.................. Disconnected Rev counter, still the same Tried a 3rd EDIS Module, still the same............. Fooked if I know, very disillusioned, don't think I've ever come across a problem like this that seems un solveable :'( Cheers Dave |
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Title: Re: P0351 Post by Matt on Mar 28th, 2014, 4:56pm have you tried it on a standard BOB ecu? |
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Title: Re: P0351 Post by Dave2302 on Mar 28th, 2014, 8:46pm Hi Matt, Yes 2 of them LOL, still the same but with all the gearbox codes ;) Cheers Dave |
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Title: Re: P0351 Post by Dave2302 on Mar 31st, 2014, 1:21pm Cured ;D Matt was on the right lines ;) It turns out it wasn't the same on a standard ECU that was not reflashed !! What happens if you use a standard ECU with a Manual box is firstly you get a load of fault codes for all the Auto Box related bits that aren't there, and second you feel a dip in power as the Auto trans that isn't there tries to shift........ This is the stock ECU retarding the timing at the shift points, and is not the same as the misfire under load that I was getting when it was reflashed with Manual Gearbox settings ;) I had wrongly assumed that it was the same fault, road test was too short !! Assumption is the mother of all fcuk ups, and boy was this one a mother ;) It turned out to be a wrong selection in the Auto Gearbox delete !! I have rectified the problem in the Binary file, and now it pulls cleanly up to the rev limiter in all gears......... No Gearbox Fault Codes, No Torque Dips and No Misfire Under Load............. So the Auto Gearbox Delete has now been tried tested and fixed, and is working fine :D Happy Bunny, Time for Coffee and Hamlet and take the rest of the day off ;D Thanks for listening, and thanks to Gozz and Matt for posting me parts on the hurry up, to try to cure the problem / eliminate things. Cheers Dave |
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