Martin7H Posted July 7, 2022 Share Posted July 7, 2022 Hi My 7 has developed a misfire (webers), it happened a couple of weeks ago when the engine warmed up, but then cleared. Today I've taken it out; it started alright then after about 4 miles it happened again, I managed to limp home. After a few checks it was confirmed no spark on cylinders 2 and 3. Plugs were found to be ok. The ECU is the MBE 912 ver 3. Should I suspect the coil pack and change it?Any advice would be greatly appreciated. Thanks in advance.Martin Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted July 7, 2022 Area Representative Share Posted July 7, 2022 I'd replace it. Is it a wasted spark system?For some reason the coil pack on my VHPD (in the 21) is a Vauxhall item. Sadly when it failed there was noting available off the shelf. Link to comment Share on other sites More sharing options...
Martin7H Posted August 1, 2022 Author Share Posted August 1, 2022 Latest updateI have replaced the coil pack, but the symptoms returned. I have just changed the spark plugs; it started instantly and sounded ok. I took it for a drive; it all performed well, then after about 4 miles and with the temperature reading normal, it misfired and lost power. I managed to get back. I let it cool down for a short while. It then started ok, all cylinders firing as shown with a strobe. After about 5 minutes there was no spark on bank 2 and 3. As it's a waisted spark if one lead fails I assume it will bring its pair down? I going to change the leads. What is the part number for HT leads? If that doesn't work it's the ecu? Dose anyone have any thoughts on this? Thanks Link to comment Share on other sites More sharing options...
SM25T Posted August 1, 2022 Share Posted August 1, 2022 How about the temperature sensor that provides info to the ECU ... not the one for the gauge. Link to comment Share on other sites More sharing options...
Area Representative Andrew Gilbert Posted August 1, 2022 Area Representative Share Posted August 1, 2022 Is that MBE the original? I have read that these are showing their age, unfortunately replacements of those are just not readily available it seems. Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted August 1, 2022 Area Representative Share Posted August 1, 2022 "I have replaced the coil pack, but the symptoms returned. I have just changed the spark plugs; it started instantly and sounded ok. I took it for a drive; it all performed well, then after about 4 miles and with the temperature reading normal, it misfired and lost power. I managed to get back. I let it cool down for a short while. It then started ok, all cylinders firing as shown with a strobe. After about 5 minutes there was no spark on bank 2 and 3. As it's a waisted spark if one lead fails I assume it will bring its pair down?"Hi Martin, I had exactly the same problem with my VX car many years ago (maybe 2003-04). Very occasional stutter that got worst until it would only run on 2 cylinder and limp badly along. Left to cool down, the car would run fine again sometimes for a good run but more likely for 5-10 miles and then back to 2 cylinders and enforced cool down. The final time though I limped it home and even when fully cold, it wouldn't start on 4.One of the lads was an electronics wizz and checked the ignition system and determined that there is a pair of transistors (I think he said) in the ECU and one was breaking down with age when it got hot which sounded very logical. These 50p items were obsolete even then and whilst they could be replaced, it just wasn't cost effective as they were in such short supply as to be not worth trying to locate them.I ended up buying a new MBE ECU with loom costing around £550. Loaded with a base map for my carburettor car and it was plug and play. The car ran perfectly after that and as a bonus, the fuel range went up from 150 to 180 miles/tankful which helped spending the money! As a further comment, I happened to price a similar ECU from MBE last year for a friend having issues with his VX car, and was surprised the price hadn't gone up very much over the last 20-odd years so could be an option for you?Nick Link to comment Share on other sites More sharing options...
Area Representative Andrew Gilbert Posted August 2, 2022 Area Representative Share Posted August 2, 2022 buying a new MBE ECU with loom costing around £550. Loaded with a base map for my carburetor car and it was plug and playSounds the way I'm looking to go, mine is OK but its the original ECU. Link to comment Share on other sites More sharing options...
Martin7H Posted August 13, 2022 Author Share Posted August 13, 2022 Final diagnosis with a Fluke Scopemeter. Started the car on the drive with two pick ups attached to input of the coil pack; two healthy traces displayed. After about 10 mins engine tone changed as associated with firing on two cylinders, and trace for bank 2 and 3 fell to almost zero. MBE ecu now dispatched to Oddified. Hopefully this will sort the problem. Link to comment Share on other sites More sharing options...
Martin7H Posted September 7, 2022 Author Share Posted September 7, 2022 Update.The ecu is now refitted and all is well. Both output drivers were replaced, as a precaution; but only one was found to be the route cause of the problem. The unit was bench tested pre and post component change. Ian at Oddified Racing was really helpful and the service was first class; so worth mentioning here for anyone else who may experience problems with the older MBE units.Martin Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 7, 2022 Member Share Posted September 7, 2022 Thanks for adding the answer.Jonathan Link to comment Share on other sites More sharing options...
Area Representative Andrew Gilbert Posted September 7, 2022 Area Representative Share Posted September 7, 2022 yes thank you Martin, one to be aware of for those of us with original equiped cars. Link to comment Share on other sites More sharing options...
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