jeffbebe 1560 Report post Posted July 18, 2014 PO had fitted one of the MAFs backwards and I was running on 98. Have switched to 95 (the M70 is pretty low compression so should run fine on 91 too) and correctly installed the MAF and it's running better already! Fuel consumption from city to BM Workshop Botany 11.9L/100 in free flowing highway traffic. Much better but still running on 8-10 cylinders, I reckon. Quote Share this post Link to post Share on other sites
kiwi535 538 Report post Posted July 18, 2014 (edited) The 535 had a sticker in the fuel flap saying 91 ron.i only used. Higher for the occasional trip or for ghymkhana etc It did feel nicer with 95 and got slightly better economy,prolly same $ per km Edited July 18, 2014 by kiwi535 Quote Share this post Link to post Share on other sites
will 169 Report post Posted July 19, 2014 What colours are the wires in the plug? My auto Disco used to do 25-30l/100, used to struggle to get 400kms on 100l tank! At least yours can do 250kmh... Have you had a gas analyser on it? Would be a good start to figure if the mixture was rich. Check what fuel pressure it has in the rails and make sure it holds the pressure overnight. Would also pay to pull a few injectors and check the spray pattern, if any show poor pattern, get the whole lot serviced. you need to put a stick shift in.. 1 Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted July 19, 2014 Yes M70 run fine on 91 It makes no difference if you put 91 or 95 in it Reference: have tried on runs to AKL and back on several ocassions on both Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 20, 2014 What colours are the wires in the plug? My auto Disco used to do 25-30l/100, used to struggle to get 400kms on 100l tank! At least yours can do 250kmh... Have you had a gas analyser on it? Would be a good start to figure if the mixture was rich. Check what fuel pressure it has in the rails and make sure it holds the pressure overnight. Would also pay to pull a few injectors and check the spray pattern, if any show poor pattern, get the whole lot serviced. you need to put a stick shift in.. 1) Will check 2) haha! 3) No... Good idea! 4) Yes please Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 21, 2014 Reference: have tried on runs to AKL and back on several ocassions on both This is the DIY I found - http://twrite.org/shogunnew/files/fontes/DK_Motor_Refurbish.pdf - looks pretty comprehensive but you reckon it's not worth it, right? Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted July 22, 2014 This is the DIY I found - http://twrite.org/shogunnew/files/fontes/DK_Motor_Refurbish.pdf - looks pretty comprehensive but you reckon it's not worth it, right? That is much more comprehensive than the one I used, and looks really good. However, the last one i used was also by Shogun, so i suspect this link is a revision. The brushes were my biggest trip up point, though the one i used also said nothing about syncronisation either, though thats built into the EML unit anyways, and constantly adjusting When you are searching on the M70 V12 engine, you will see the name Shogun pop up a lot, he is the go to guy for not only the M70 engine, but E32 750iL, and can tell you anything you want to know of the top of his head, seemingly down to particular wire colours to particular places etc. I dont know if he knows the E31 850Ci to the same level of detail, but the M70 engine is the same between the 850i/Ci and 750i/iL. When typing stuff into google, i tend to include his name as a keyword. Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 22, 2014 Good to know, thanks Andy. Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted July 22, 2014 i dont have much planned for this weekend, so ill give it a crack on some that i have here, and follow that manual, and let you know how i get on. they are very fiddly and delicate, no wonder they are common failure point on an otherwise reasonably bullet proof engine. Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 22, 2014 I found some cheap professionally recon'd one ex-USA ($350 inc shipping for both), so I'm going to wait til they arrive then attempt to recon mine as backups (or for sale). Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 23, 2014 What colours are the wires in the plug?One is red/black with yellow dashes the other is white/yellow also with yellow dashes. Any ideas? Quote Share this post Link to post Share on other sites
will 169 Report post Posted July 23, 2014 Red/black/yellow should come from fuse #6. It powers the hazard flasher relay and crash control module. Will be easy to check if it is by connecting a multimeter to it, checking if it has +12v, then remove fuse #6. White/yellow is normally the RXD to the diagnostic plug (in most BMW's), cant find any trace of a white/yellow/yellow in any of the e31 models. As the engine is essentially two 6cyl motors, most sensors would be duplicated. So, if there is not a duplicate plug on the other side, I can only assume it is for something unrelated to the engine controls, possibly a sensor for the crash control which never made it into the car?? You could check the plug on the crash control module for this wire, seems the most likely place to find it if the red/black yellow wire is connected to fuse #6. Easiest would be to remove the module and check for continuity between the white/yellow/yellow wire in the mystery plug and any of the pins in the crash control module. Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 23, 2014 Thanks Will... How do you find this stuff out?! That could be potentially a massive finding. Currently the car's diagnostics are not working. BM Workshop said they'd need to pull modules until they found a faulty one that's interrupting comms. If it's simply that it isn't plugged in, it could save a huge amount of time (Josh and I were going to spend a day pulling modules!!) Quote Share this post Link to post Share on other sites
will 169 Report post Posted July 23, 2014 (edited) If your diagnostic is not working, I would start by checking continuity in the RXD (white/yellow) and TXD (white/violet) wires from the diagnostic socket pins #15 and #20 respectively to the 2 ECU's and the EML unit in the engine bay. (pins #87 in the 2 ECU's and pin #13 in the EML for RXD and pins #88 in the 2 ECU's and pin#55 in the EML for TXD). The 850 is renowned for bad electrical connections in the splices etc. The first (and main) splice for TXD and RXD from the diagnostic socket lies between it and the ECU's/EML units. I would be inclined to find these 2 splices and then disconnect the other inputs from them (which come from various units inside the car), leaving just the 2 ECU's and the EML units connected. I would then check if I was getting some sort of diagnostic information. If this were the case, I would then connect the interior wires one by one to see when TXD/RXD stopped. This would then tell you which cluster of modules was shutting the system down. This diagnostic system is pretty basic, disconnecting modules will not disable the diagnostics, the reporting system will simply report the particular module is not responding. As the various modules are scattered through the interior of the car, you would be pretty much be stripping the car apart to get to them. Be nice to be able to target the problem to save all that stripping..!!! If you get stuck, feel free to bring it down to my place and I will have a looksee.. Edited July 23, 2014 by will Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 23, 2014 Thanks Will... If I get stuck (which is a distinct possibility), where is your place? Quote Share this post Link to post Share on other sites
will 169 Report post Posted July 23, 2014 Near te Uku on the way to Raglan off SH23. Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 23, 2014 Sweet... Might be the perfect excuse for a wee drive to one of my favourite parts of New Zealand!! Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted July 24, 2014 what diagnostic system are you using? I/We have been unable to read both banks on both my M70 cars using any scanner from $25 unit to one the same as Jeff Gray BMW. I suspect that's a red herring for you and prehaps no M70 can???? but im not saying im right, just sharing my experience. http://wedophones.com/Manuals/BMW/ leads to....: http://wedophones.com/Manuals/BMW/1991%20BMW%20850i%20Electrical%20Troubleshooting%20Manual.pdf This link^^ may also help you, reasonably simple to follow once you get the hang of it, and details every single plug on your car Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 24, 2014 Interesting. Guido at BM Workshop Grey Lynn has been working on these cars since they are new and said they're diagnostic equipment would ordinarily work on the M70. Plenty of info at there on the web about connecting with the older systems. Will keep reading and keep trying. Seems an absolute waste of money trying to fix faults without the direction of diagnostics. Quote Share this post Link to post Share on other sites
will 169 Report post Posted July 24, 2014 Just remember that the diagnostic capability of a '91 e31 is likely to be the same as an e30, or, at best, marginally better. The quickest way will be to go back to the basics of gas analysers, timing lights/meters, compression gauges, leak testers and so on. When I was back home, I had an Allen tester in my workshop (1998 era). Was pretty good at working on BMW's/Mercs which I specialised in. It would read timing, do gas analysis, provide an electronic compression/balance test etc. When I still had a problem it could not pinpoint, I would go to my mate down the road and put it on his rolling road which was a dynamic one, could load the car up as if it was actually driving under various loads. The main components in your car are the 2 ECU's for the motor and the gearbox ECU, they control 95% of the car's running. Things like the traction control only have an input when required. You should be able to unplug just about all of the other controllers and still drive the car as there is no CAN BUS to worry about, there is minimal interface between the various units. The e31 is basically a simple car ruined by over complicted wiring and add-ons which are badly installed. I have not worked on one before, but, looking through the various wiring and workshop information I have, it is like working on 2 6cyl Motronic BMW's siamezed into 1.. Quote Share this post Link to post Share on other sites
jeffbebe 1560 Report post Posted July 24, 2014 Yep, you're bang on as far as I can tell, Will. Two engines stuck together. Twice the problems but neither particularly complicated. I was going on the advice of BM Workshop who said they didn't think it was worth doing anything else (even compression and smoke tests) until the diagnostics were functioning properly. Josh and I will have a crack at it this weekend... If we can get it down his drive. Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted July 24, 2014 yep not much info you can suck from them, more or less didnt start till the Siemens DMEs replaced Bosch Quote Share this post Link to post Share on other sites
