Area Representative Nick Chan Posted April 28, 2005 Area Representative Share Posted April 28, 2005 Just finishing off my re-furb of my 1997 HPC and come to start the engine and its definitely running on the middle two cylinders only ☹️ No's 1 and 4 are stone cold. We have checked the spark at the plugs and think we have eliminated the coil pack by connecting the signal for cylinders 2&3 into 1 to get a strong spark so it seems to indicate a problem with a capacitor in the system. The question is though is there anything between the MEMS unit (MBE 906VVV) and the coil pack or is it built into the coil pack? The fault is intermittent and had happened to me last year when I used the car. Typically it would run fine and then occasionally the car would miss dreadfully for a short while and then run fine. It happened so infrequently though it was more a nuisance than a problem and I thought it was fuel related as it managed to clear itself - it didn't matter whether the car was hot or cold and could happen after a good run. Is the MBE system a black box that is thrown away if faulty? Do they breakdown at all though or is there a more likely culprit as mentioned above? Any ideas? Thanks Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
Don Cook Posted April 28, 2005 Share Posted April 28, 2005 My car did the same thing. It turned out to be a faulty connection in the immobiliser. Link to comment Share on other sites More sharing options...
EFA Posted April 28, 2005 Share Posted April 28, 2005 Nick, Confirm you have reversed the connections on the low tension side of the coil, and the fault moves from 1&4 to 2&3? Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted April 28, 2005 Author Area Representative Share Posted April 28, 2005 Don, the car hasn't got an immobiliser. Arnie, we took the LT lead off the coil pack and made up some temporary connections to reverse the connections i.e. No.1 plug was running off the feed for No.2 and 3 and then No.1 was sparking fine, so the problem tends to point towards something before the coil pack. Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
I reply to every thread Posted April 29, 2005 Share Posted April 29, 2005 Do a search on the WSCC site - I have a recollection that someone there had the same problem with a VX that was eventually traced to the MBE. Go over there & flail about a bit & Blatman will come to your assistance Link to comment Share on other sites More sharing options...
Chelspeed Posted April 29, 2005 Share Posted April 29, 2005 There are usually ignition amplifiers within the MBE box, two off, ie one for each coil, for a 4 cylinder wasted spark application. Sounds to me like one of these has gone tits up. I say they're usually within the box as I only have experience of 912, 941, 967 and 970 MBE boxes. If they're not part of the ECU then they'll be external within the loom, usually small flat black plastic boxes about 2 inch square on a metal heatsink. If they are external then still likely to be one of these and much easier to change. If they are internal then when you take the lid off there are a number of large power transistors on a heat sink, I presume these are they. I'd give MBE a ring and see if they can repair it. Link to comment Share on other sites More sharing options...
EFA Posted April 29, 2005 Share Posted April 29, 2005 Nick, I had an HPC a year or so ago, also with a 906. It sufferred an intermittant missfire due to a duff HT lead, which eventually caused the coil driver triac in the ECU to fail. The part is obsolete so you cannot get the ECU fixed. If its still intermit. get some new HT leads. If its dead on 1 & 4 you'll need an ECU and a map. If you can get an MBE 956E, they are pretty easy to wire in and I have a suitable ignition map. You'll find these for sale from time to time on ebay or racecar forums. You can also then uograde to include a throttle pot so you will get mapping. = better fuel economy and response. It'll also support injection should you catch upgraditus. Emial me if you need the map. Its on a chips BTW. Link to comment Share on other sites More sharing options...
EFA Posted April 29, 2005 Share Posted April 29, 2005 Graham - triacs are in pairs in these ECUs - only 2 ign circuits. 970 has 4! Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted April 29, 2005 Author Area Representative Share Posted April 29, 2005 Thanks for the replies. I'll try and borrow some leads of another VX (and I know where there is one that hasn't run for quite a while ) and also have another look at the kit I have got for the offending items. Doesn't look like the car will be going out this weekend though ☹️ Cheers Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted May 9, 2005 Author Area Representative Share Posted May 9, 2005 Well. Still got the problem and I am sure its the MBE system. I have spoken to them and they have confirmed that its an obsolete unit and will cost £300 plus £150 for a new loom to have another one made suitable ☹️. Caterham spares have also confirmed this information and quoted £450 for a unit that will be easy to replace (presumably with the loom connections to fix in per MBE themselves). I don't suppose anyone has got a spare unit that is suitable for sale? Or should I be considering a much better unit as Arnie suggests (am I restricted to MBE or should I consider the cut down Emerald that was at the motorshow or any others?) with a view to using only the ignition part now and possibly upgrading the rest of the fuel system in the future. What do you reckon? Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
Paul McKenzie Posted May 9, 2005 Share Posted May 9, 2005 Nick, YHM - I have one for sale if you want it. Paul Link to comment Share on other sites More sharing options...
Mark Piper Posted May 9, 2005 Share Posted May 9, 2005 Nick, I guess a 967 is no good then? Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted May 10, 2005 Author Area Representative Share Posted May 10, 2005 Thanks Paul for the offer. I'll speak to MBE and see if the module is the same for wasted spark and a dizzy set up. Mark - not sure, I'll ask MBE when I speak to them about Paul's unit. Anyone else got one spare? Cheers Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
BarryT Posted May 10, 2005 Share Posted May 10, 2005 Hi Nick, I've got a spare one. I repalced it with a 967 so I could have a throttle pot, and play with the timing. Mine is off a 91 Vx race car with dizzy. Barry Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted May 10, 2005 Author Area Representative Share Posted May 10, 2005 Hi Barry, Sorry, yours is the same as Paul M's and I will need to replace my wasted spark system for a dizzy. I have got some info from DTA this morning so I might going the whole hog and buying a 3D setup new if I can't get a direct replacement for my 906VVV Thanks anyway Nick Now the Orange HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
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