Tim V-W Posted June 6, 2009 Share Posted June 6, 2009 this bl**dy misfire that is. It has been around since I fitted the new 1800 engine in winter 2007/8 but as I hadn't done any long trips when it was a 1400 it may have been around before. Initially, on our way down to the IoW it started as an intermittent missing under part throttle load but was not apparent at tickover or under hard acceleration. It got worse and once on the return trip the engine 'fluffed' and died. It poured with rain that trip and I suspected water in the electrics. I have gone through a process of changing stuff Leads Plugs fuel filter coil I have checked the resistance of the TPS and removed the fuel gauge sender and the tank looks clean. Following these changes things seem to improve and I had many short-ish trips over summer 2008 free from misfire. Then on this years IoW trip it returned with a vengeance and on the way home it was as bad as it had ever been and after a bit of a heart stopping moment overtaking on the M3 the car finally stopped as I turned hard left into a service station. It restarted immediately and we were able to get back to Rugby but once again just about home hard left turn and the car stopped. This time restarting was really difficult and I made the last mile with loads of revs and freewheeling with no real power available. This time I removed and refitted the inlet manifold and throttle body ensuring no air leaks. Again the car starts and runs fine with no sign of the misfire on a 10 mile-ish run. Then on Wednesday on the way to the area meet the misfire returned within a few miles (as soon as the engine was hot?), but once again was not apparent at tick-over or at full chat. On the way home, it got worse and once gain the car stopped when I threw it hard into a roundabout. I just do not know where to go with this next so I would be grateful for any suggestions. I don't care how trivial or radical, just throw them in and I will give them a go. Thanks Tim N432FLR with new wheels :) here Link to comment Share on other sites More sharing options...
davidvoas73 Posted June 6, 2009 Share Posted June 6, 2009 When you went from 1400 to 1800, did you change anything on the electrical side? Are all connections clean and sound? Is the ECU for a 1400 the same for an 1800, I have a spare ECU from an 1800 K series having gone to Emerald if you want to try a swap? Other than what you have already listed, have you checked the following: Earth(s) to starter motor, engine to chassis rail, sometimes there is a low voltage one near the ecu. Crank Sensor, and wiring If EU2 engine, check the distributor cap/rotor arm You have changed the plugs, are they all nipped up correctly? Other reports on BC of them occasionally come loose which results in misfire Pay attention to how close the high tension lead from the coil to the distributor is in relation to the tps and/or crank sensor wiring, this can cause intermittment misfires, especially if the cables are moving about. airborne tweaked supersport Link to comment Share on other sites More sharing options...
shn7 Posted June 6, 2009 Share Posted June 6, 2009 Tim, I think I've finaly got the solution for a long standing mis-fire/tickover problem I've had for the last two years. Fit a shorter alternaotr belt was the solution. The problem seems to have been the alternator casing touching the chassis rail. There was less than a business card thickness gap. I'd changed all sorts of things over 2 years and this latest change seems to have hit the spot. Can't see the logic to it but who cares if the problem has gone. Steve. Sussex (West) AR Not forgetting Percy the Polar Bear who recommends Puddle Pet Care Link to comment Share on other sites More sharing options...
pascoe Posted June 6, 2009 Share Posted June 6, 2009 I had the same problem,it turned out to be the roter arm earthing thro the centre. Fitted new not missed a beat since Regards Willie Pascoe Link to comment Share on other sites More sharing options...
Mavic82 Posted June 6, 2009 Share Posted June 6, 2009 Tim, I reckon a brainstorm on all the possibles and not so possibles and a tick sheet. Starting working through them methodically one at a time. Happy to come and help if you want. The trouble with left handers seems to bring in mind fuel or electrical problems. Particularly the later after the rain of the IoW. And make sure you have changed the king lead. Cheers Guy Link to comment Share on other sites More sharing options...
Tim V-W Posted June 6, 2009 Author Share Posted June 6, 2009 Thanks all so far, keep them coming. Should have said I also replaced the rotor arm and Dizzy cap. Steve, what was happening when the alternator touched the chassis as someone (Guy?) mentioned that my alternator seemed very close to the chassis rail? Guy, I have been erring towards fuel just because the way the car feels when it loses power is like fuel starvation, i.e. the throttle and engine reaction seem disconnected and there is no power unless you rev it like mad. Would an electrical fault give the same symptoms? Cheers Tim Link to comment Share on other sites More sharing options...
Mavic82 Posted June 6, 2009 Share Posted June 6, 2009 Tim, It was indeed I that observed the proximity of the alternator to the chassis. Not sure what the issue may be other than vibration though. Can't imagine that was the issue on the M3 though 😳 Electrical issues could form a similar feel to the failure. Think of the soft cut rev counters or in my case the king lead that failed on the pickup. I spent ages cchasing a fuel issue that was not there. It would be helpful to identify a condition that always highlights the issue, that way you can more readily test things when you try them out. Guy Link to comment Share on other sites More sharing options...
davidvoas73 Posted June 6, 2009 Share Posted June 6, 2009 Are any wires to items like the tps, crank sensor ... under any tension or likely to be whilst cornering? Those wires are quite fragile, to solve similar issues I have repaired/replaced the connectors. Probably not 100% accurate but on a K series fuel delivery will be governed by fuel pump, fuel pressure regulator, injectors, butterfly valve in throttle body, ecu. Fuel pumps tend to work pretty reliably, intermitment electical faults being possible? FPR - not a lot to go wrong there. Injectors - unlikely to fail - I have some original 1800 ones if you want to eliminate them Butterfly valve - again unlikely, unless its sticking? Have you checked the throttle cable & return spring? ECU - try a spare? Another possible? Lambda sensor going lean/rich? After a decent run, whip the spark plugs out - what colour are the electrodes - light grey/brown indicates mixture is about right, Black = rich, white = lean. airborne tweaked supersport Link to comment Share on other sites More sharing options...
Irrelevant Posted June 6, 2009 Share Posted June 6, 2009 Reckon fuel too . .. the baffles in the tank OK? No crushed pipes? Does a 1400 fuel pump pump the same as an 1800? (think they do but not sure). Link to comment Share on other sites More sharing options...
shn7 Posted June 6, 2009 Share Posted June 6, 2009 Tim, Can't be 100% sure ot was alternator chassis shorting but the effect I had was an intermittent mis-fire below about 4k rpm and it would tickover erratically going between 500 and 2k rpm and sometime dying completely when dipping the clutch with throttle closed. It would always re-start straight away. I'd been wishing it to die and not re-start so a hard fault could be traced but this never happened. I had a Gates alt belt fitted which was 738mm long. Just replaced with a CC supplied 735mm one which now gives about 4mm clearance to the chassis. Steve. Sussex (West) AR Not forgetting Percy the Polar Bear who recommends Puddle Pet Care Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 6, 2009 Share Posted June 6, 2009 Noooooooooooooooooooooooo - not again 😳 Link to comment Share on other sites More sharing options...
tbird Posted June 6, 2009 Share Posted June 6, 2009 Bit off the wall but I had a similar problem years ago, not on a 7, but it finaly traced to flakes of paint coming loose in fuel tank and blocking outlet , as soon as I stopped the suction stopped and the flake of paint dropped away, would be ok until another one got disturbed, maybe on a bend, bloody 🙆🏻 to find tho, had to remove tank and get it steam cleaned in the end good luck Link to comment Share on other sites More sharing options...
Johnty Lyons Posted June 6, 2009 Share Posted June 6, 2009 Crank sensor wire touching a HT lead jj N.I. L7C AR 🙆🏻 Membership No.3927. 240BHP 1900cc K Series 40th Anniversary Link to comment Share on other sites More sharing options...
Beelzebub Posted June 6, 2009 Share Posted June 6, 2009 ISTR Angus had a problem with "something" in too close a proximity to the crank trigger wire. I can'r remeber exactly what it was. Caused a misfire similar to yours & took a lot of tracking down. A search of the archives may reveal the details. D. Link to comment Share on other sites More sharing options...
FlymoFraser Posted June 7, 2009 Share Posted June 7, 2009 Tim linky to the Angus site which may help here Good luck with it, unfortunately it's the bit I understand least about on cars (or houses) R287 Mobile Jaffa Cake- It's black at both ends with a smashing orangey bit in the middle here Link to comment Share on other sites More sharing options...
Tim V-W Posted June 7, 2009 Author Share Posted June 7, 2009 All good stuff, thanks Ian - No not again, same one as before getting worse I think ☹️ tbird - I have looked in the tank via the sender hole and the tank looks clean. However, I intend to remove and check the pump, partly because the other day the pump was 'whirring' rather than clicking when I turned the ignition on and seemed to take longer to pressurise and switch off than it usually does. My engine is EU2 so the coil is the old cylindrical type and is mounted on the front of the offside footwell with the HT lead well above the sensor wire and so far much wiggling of both has not produced any issues. Keep them coming. Cheers Tim Link to comment Share on other sites More sharing options...
ECR Posted June 7, 2009 Share Posted June 7, 2009 When you get the missfire watch the rev counter. If that flicks in sympathy it would tend to indicate a fault in the ignition circuit rather than fuel. This will at least narrow things down a little I have had a problem with injectors which gave me a misfire at higher revs/throttle openings. I (Alex Wong actually) traced it to dirty filter buckets in the top of my injectors. The filters are so small (and never mentioned usually) that I didn't know they were there (I assume your injectors will be the same). Pull the fuel rail off and check for debris as rubbish there acts as a flap valve and restricts fuel flow. The only other long term misfire I had was traced to loose/dried out connectors to the alternator (crossflow). You'll crack it in the end. Don't give up .... Ex Chairman Roger Link to comment Share on other sites More sharing options...
jingars Posted June 7, 2009 Share Posted June 7, 2009 Tim, I have a similar engine with a similar issue; see here. I don't have easy access to the car at present (building work on the house) so I have only had one run with Pat The Plumber since the above, and the car didn't miss a beat. I have yet to check out Johnty's suggestion, but I would add it to your list of suspects. Please post how you get on - and good luck. Link to comment Share on other sites More sharing options...
davidvoas73 Posted June 7, 2009 Share Posted June 7, 2009 Tim, I am just south of Solihull, if you want a second pair of eyes .... blat mail me. David airborne tweaked supersport Link to comment Share on other sites More sharing options...
Tim V-W Posted June 7, 2009 Author Share Posted June 7, 2009 OK, I have done a couple of things and for now it seems to have gone away! It has rained here most of the weekend so I have - replaced the fpr with the one that came with the 1800 - removed and cleaned the contacts on the MFU - removed the boot honeycomb floor and disconnected the fuel tank breather at the one way valve. i.e. removed it from the pipe that used to connect it to the carbon depth charge thingy. This afternoon it dried up and I went out for a blat. I drove for the approx miles that it usually takes before the mis fire appears and then drove some more. I threw the car around trying to provoke the problem and then I cam back and let the engine cycle through the radiator fan on / off a few times. Still no sign of the mis fire. It ticked over really rough when hot and nearly stopped a few times. Not convinced, but here's hoping. Does this give any one any further ideas? Cheers Tim Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 7, 2009 Share Posted June 7, 2009 Here's hoping !!!!! Link to comment Share on other sites More sharing options...
tbird Posted June 7, 2009 Share Posted June 7, 2009 Vacuum building in fuel tank? seems pretty unlikely, but when scraping the barrel and all that Tim Edited by - tbird on 7 Jun 2009 23:37:36 Link to comment Share on other sites More sharing options...
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