RangeyRover Posted October 22, 2012 Share Posted October 22, 2012 Ok From the top, Bought a 148K Km 1999 Disco 2 V8. Running fine when I got it, but was given a "spare" MAF with the car. The car has been bought as a Stop Gap for a few months whilst we get established down under. Started running rough, with misfires when cruising at 80 - 100km. This got progressively worse. So... Spent a couple of hours changing leads. Jesus H! What a place to put the coils! The wires fell apart in a couple of cases so i thought I was onto something. Still ran rough. Started it this morning, ran rough as hell and when revved up coated the floor in black soot. Changed the plugs to Bosch, not the forum recommended NGK BPR6ES fired up and ran sweetly, but an extended run saw the misfire still there, but the engine now runs sweetly if you hold the revs high, but misfires still at lower revs 1200-2000. roughish idle still. The black smoke wont have helped the O2 Sensors i'm sure. Not sure which way to jump. I may buy some NGK plugs as reading around everyone swears by them but NGK recommend the PFR5G? I have a Nanocom on order. Is there any way to test the O2 Sensors or the MAF with multimeter or scope, both of which I have access to. I'm aware the when the nanocom comes it will be a good idea to reset the adaptive learning for the fuelling as well as check the fault codes. Ideas all welcome guys as this is frustrating. I bought the rover for fun and reliable transport for a few months.?! Yeah I know Land rover and reliable.... Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted October 22, 2012 Share Posted October 22, 2012 Well done on the move down under! Megasquirt it... i know you've got the parts Quote Link to comment Share on other sites More sharing options...
mickeyw Posted October 22, 2012 Share Posted October 22, 2012 So it runs OK ish with clean plugs, not really the plugs that are the problem then. If you can keep the plugs clean (by sorting out the mixture) it will no doubt run OK. O2 sensors may or may not have been fooked before, but I bet they are now with that much much sent their way. I guess it's a game of check every engine sensor and its connector is sound. Is there an EFI troubleshooting guide same as the one for hotwire systems? I suppose maybe not, as that is what the testbook connection is meant for. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 22, 2012 Share Posted October 22, 2012 You should be able to watch O2 sensors with meter or scope, suspect they're Titania type so guess you'll see a fluctuating 0-5v on them (with ECU connected) but the RAVE manual should tell you more. Not sure about MAF but RAVE should know voltages if anything does. Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted October 22, 2012 Share Posted October 22, 2012 The Bosch Motronic on DII's uses a pair of 0-1v Zirconia oxygen sensors.(For the upstream ones,not sure what Aus spec had - upstream only or downstream aswell)You can monitor their activity via the black wire from the sensor and a good earth.They should switch from 0v to around .8v once a second when at cruise conditions if all is well.Its unlikely that the maf is at fault as they always seem to read low,this makes the engine run lean as the fuel map isnt wide enough to make the oxy sensors see a rich mixture.Live data should show 22-25 Kg/Hr at idle and 90+ Kg at 3000rpm engine hot all loads off. You might find that all that is needed is an adptive reset now you have changed plugs/leads - if the sensors are working. If its done lots of miles on duff leads with constant misfires the long term trims will be very rich and the ecu will be struggling to narrow them down.Much kinder to do a reset than use loads of fuel hoping the trims will right themselves. NGK may recommend a platinum plug,but the smaller gap of the BPR6ES plug needs less voltage to fire,giving the coils and leads a much easier time.Forget Megasquirt and all the mods - its a good system as was the Lucas Sagem "Gems" system before it.Most problems with them come back to plugs and leads - which will cause problems however the engine is fed.Better to use ordinary plugs and change them more often - it also lessens the chance of the plugs seizing into the head. A nice road trip down to Albany when its fixed will be a good test - shout when you go,I'll come with you,drop me off at the Nullaki Peninsula. Quote Link to comment Share on other sites More sharing options...
RangeyRover Posted October 23, 2012 Author Share Posted October 23, 2012 New bpr5es fitted. Softer misfires and feels better massively overfuelling though. just noticed leak from heater dropping onto th o2 bank sensor connector. Next check there. What will the system do if I disconnect both? Thanks for all replies on phone s o answers short. More detail later. RR Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 23, 2012 Share Posted October 23, 2012 Basics that cause overfuelling - coolant temp sensor, air temp sensor (probably inside the MAF but you should be able to measure it). Both will have the effect of running with the choke on. Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 23, 2012 Share Posted October 23, 2012 Its unlikely that the maf is at fault as they always seem to read low,this makes the engine run lean as the fuel map isnt wide enough to make the oxy sensors see a rich mixture.Live data should show 22-25 Kg/Hr at idle and 90+ Kg at 3000rpm engine hot all loads off. Tell that to mine that was reading about 4x too much! This is also how I've learned that, contrary to the RAVE, a Bosch will run quite well without a MAF (although I'm still puzzled how, perhaps someone on here can explain, the only answer I get on RR.net is "various sensors", which is absolute c**p). So definitely give that a go. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 23, 2012 Share Posted October 23, 2012 will run quite well without a MAF (although I'm still puzzled how, perhaps someone on here can explain, the only answer I get on RR.net is "various sensors", which is absolute c**p) Something along these lines I suspect: http://www.megamanual.com/v22manual/mtune.htm#alphan With maths you can infer/guess a lot of stuff from very little info, although it's less accurate it's suprising what you can get away with. Quote Link to comment Share on other sites More sharing options...
RangeyRover Posted October 23, 2012 Author Share Posted October 23, 2012 Got some good information from this document. http://www.google.com.au/url?sa=t&source=web&cd=2&ved=0CDUQFjAB&url=http%3A%2F%2Fp38arover.com%2Frover%2Fp38a%2FEngine_Management%2FBOSCH_521_Systems.pdf&ei=qY6GUOyPF8-5iAeluoDwCQ&usg=AFQjCNHPmqfSShI1F-610XJnSL4ScD-oXA Sorry for the long url, phones don't like PDF weblinks. The doc says that through software witchcraft the maf will be ignored if faulty. I am now driving better, thanks john for the coolant temp sensor. Forgot about that will Check tomorrow. Anyone got pin outs for the maf and IAT? Above 3000 or so it pulls like a train. Below that it splitters and pops occasionally. My guess is that it goes open loop at that point and ignores the o2 sensors. It is a guess tho. Off to pull the lead off the MAF... Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 23, 2012 Share Posted October 23, 2012 Something along these lines I suspect: http://www.megamanua...tune.htm#alphan With maths you can infer/guess a lot of stuff from very little info, although it's less accurate it's suprising what you can get away with. Interesting! Thanks for link, I've been searching for an explanation like that. Quote Link to comment Share on other sites More sharing options...
RangeyRover Posted October 23, 2012 Author Share Posted October 23, 2012 Forgot to say thanks to everyone for the help and advice. keep it coming, nanocom on way via dhl in morning i will get to the bottom of this! Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted October 23, 2012 Share Posted October 23, 2012 One thing to add,Motronic will very quickly defer to open loop if it cant trim - within a few seconds.I cant remember what rpm/throttle opening the ecu would normally go open loop during normal driving but its quite high - more so than the Gems or 14Cux before.If it goes open loop due to implausible sensor inputs,It then uses backup values to keep the engine running,the only one that has no backup is the crank sensor. Any of the sensors failing on your car should not be too expensive,esp if you can find an alternative to Mr Barbagello's dealerships. Are West Coast Rovers still going ? They were breaking a crashed DII v8 last time I was there.(Long time ago) Quote Link to comment Share on other sites More sharing options...
RangeyRover Posted October 29, 2012 Author Share Posted October 29, 2012 To finish this tale. I bit the bullet and bought a nanocom evolution. Prompt delivery, via DHL to Perth WA I am very impressed with this little piece of kit. Bit of a pain to unlock the features you bought, but once done, a standalone unit. talks nicely to the Motronic system, haven't used any other features. User friendly, intuitive interface, with real world info about the faults stored. Read the faults, WOW, there were plenty. Misfires, on many cylinders, MAF faults, which I think are a hangover from the previous owner, Lambda sensor faults Reset adaptive values and cleared all faults as there were too many. From previous experience with BITE (Built in Test Equipment) from the Navy, I reset the faults to see which ones were persistent. So with the ECU reset, I started the car which ran smoother but still coughed burped and farted round corner, But.... then the Plugs cleared themselves, different car! Smooth as silk. There is a failed O2 sensor on the right hand bank, but it seems happy to ignore that now. Well happy. Thanks everyone for the help, advice and patience, There are other issues to address with regards to the leak from the top inlet for the heater matrix, but the vehicle is now giving me the confidence to say it will be worth it. Thanks all RR Quote Link to comment Share on other sites More sharing options...
mickeyw Posted October 29, 2012 Share Posted October 29, 2012 Glad to hear of your success RangeyRover. It certainly inspires me that there are benefits to OBD systems, and aftermarket devices such as Nanocom. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.