lacrits68 Posted March 6, 2013 Share Posted March 6, 2013 Hello! My disco -98my 3,9 failed MOT last week. CH were too high 250(limit 100) and CO was on the “edge” 0,5(0,5). O2 was not printer on MOT protocol. I can feel a slight “Misfire” on idle, but can’t find out why! Idle is 800+/-75rpm and I can hear some “bludring” in end of tailpipe, so some misfire is present. I have done some basic service: New parts: Pluggs champion yc11 something New pluggleads New rotor New distrb cap New coil New air and fuel filter (all ingnition parts are “lucas” branded) Stepper motor cleaned and working new vacuum hoses and vacuum cheked with startspray, no leakage. flametrap cleaned now "blowing" from heads...(flametrap or oilfiller plugg) runns very well when driven normaly! uses 12mpg average.Milage id 160tkm or 99000miles. My knowledge is now used and I could use some help from fellow V8’s gurus! please! I have an Rover Gauge loggfile if its telling something? or is rovergauge giving any additinal information that is usefull? Cheers Jan Quote Link to comment Share on other sites More sharing options...
Aragorn Posted March 6, 2013 Share Posted March 6, 2013 Looks a bit like worn out cats to me. Most lambda equipped vehicles with no cats installed will return somewhere around ~200-300HC and ~0.5-0.6 CO If the cats were working well, your CO would typically be 0, and the HC's would be in double digits. Quote Link to comment Share on other sites More sharing options...
zoltan Posted March 6, 2013 Share Posted March 6, 2013 To get low HC levels you need a very stable idle. I know it is a sneaky trick but if you add some electrical load when they make the test like rear demister screen and some lights you can often get the engine to work a bit harder in the idle range and bring the HC down a little Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 6, 2013 Author Share Posted March 6, 2013 hello! OK! any experience of E85? during MOT? //Jan Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted March 6, 2013 Share Posted March 6, 2013 I think the first thing you should do is a compression test,if you can feel and hear a slight misfire then its just that - a misfire,no matter how good the cats are the emissions will still be over.Rover V8's dont need that much help from the Cats like say a 1.8 K series does. Another useful aid is to use an infa red thermometer on the exhaust ports,any low readings compared to the rest quickly show where the misfire is. Quote Link to comment Share on other sites More sharing options...
zoltan Posted March 6, 2013 Share Posted March 6, 2013 E85 being 85% ethanol? Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 6, 2013 Author Share Posted March 6, 2013 Another useful aid is to use an infa red thermometer on the exhaust ports,any low readings compared to the rest quickly show where the misfire is. Thank you for this! Try it right away when i get home! Cheers Jan Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 6, 2013 Author Share Posted March 6, 2013 E85 being 85% ethanol? yes! "some" recomend a mix of 50% E85 and 50% normal petrol //Jan Quote Link to comment Share on other sites More sharing options...
elbekko Posted March 6, 2013 Share Posted March 6, 2013 Hmm, and here I thought E85 was 85% petrol, and the rest ethanol. I guess that explains why mine ran quite badly on it without lambda's Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 6, 2013 Author Share Posted March 6, 2013 Hmm, and here I thought E85 was 85% petrol, and the rest ethanol. I guess that explains why mine ran quite badly on it without lambda's http://en.wikipedia.org/wiki/E85 Quote Link to comment Share on other sites More sharing options...
zoltan Posted March 7, 2013 Share Posted March 7, 2013 I wonder if the management system is able to effectively adjust for the different stochiometric ratio of a fuel that is predominantly alcohol. I'd go back and get an emissions test done with a tank of ordinary unleaded Quote Link to comment Share on other sites More sharing options...
elbekko Posted March 7, 2013 Share Posted March 7, 2013 It should be, lambda's don't see a stochiometric ratio, they just see a combustion result and if it's close to stoich. It's the same situation for LPG, and they can tune rich/lean fine too. Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted March 7, 2013 Share Posted March 7, 2013 A misfire is a misfire - until its burning on all 8 forget whats coming out the back,the missfire will weaken that bank as the oxygen sensor will see an excess of oxygen from the partially or unburnt charge from the misfiring cylinder.This then drives the fuel trims rich - outcome,higher Co and higher HC's from the unburnt fuel.... Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 7, 2013 Author Share Posted March 7, 2013 Hello! Did measure temperature on manifolds....one side is 230-250c and other 190-200c ! Is there any tricks to locate where misfire is? Computer give no "misfire" codes on either "banks". cheers Jan Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted March 7, 2013 Share Posted March 7, 2013 You need to look at the individual ports and check their temp in exactly the same place,perhaps the top bolt on each port or say 1/2" out form the edge of the head on the manifold.190c is alot less than 250c,so I would expect the problem to be on 190c bank.Have you been able to do a compression test yet ? Checking the HT waveforms with an oscilliscope is the nice way to check the ignition system,but thats a stage further on. Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 8, 2013 Author Share Posted March 8, 2013 Good morning! Is anyone familiar how to "read" rover gauge results? Played aroun with it an measured "longterm lambda" fuel trim settings...! Left siden one that is aprox 250C in temperature is spot on "0" on scale BUT left one with temperature is 190c says "increasing" 2-3 "staples" 16% off "0" point! Same in "short term" only worse the its off 46%. Can anyone help me wthat this means? //Jan Quote Link to comment Share on other sites More sharing options...
Tanuki Posted March 8, 2013 Share Posted March 8, 2013 Has it been serviced regularly? (Oil-changes in particular). I'm thinking that at that sort of mileage you could be suffering from the beginning of camshaft-lobe-wear issues. Do a compression-test too - you could have a burned exhaust valve. Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted March 8, 2013 Share Posted March 8, 2013 Good morning!Is anyone familiar how to "read" rover gauge results? Played aroun with it an measured "longterm lambda" fuel trim settings...! Left siden one that is aprox 250C in temperature is spot on "0" on scale BUT left one with temperature is 190c says "increasing" 2-3 "staples" 16% off "0" point! Same in "short term" only worse the its off 46%. Can anyone help me wthat this means? //Jan Your Avatar does not say where in the world you are,but for a 1998 Discovery with a distributor I'm guessing its EFI system is a Lucas 14CUX. I think this is where part of your problem is,in that your code reader is looking at long term trim values.Your ECU is not adaptive and only runs immediate short term trims,when read with Testbook they show a value of + or - 25%.In reality they shouldnt go more than 10% if all is well..What diagnostic system are you using ? At 99k miles it is more than likely the cam is well worn,even with good oil and proper service intervals.As Tanuki says a compression test is vitally import,if its down on only one cylinder it will never run properly. Quote Link to comment Share on other sites More sharing options...
lacrits68 Posted March 8, 2013 Author Share Posted March 8, 2013 hello! I guess I have to gop and buy an compression tester then! Is it difficult to do thet test? What is thread of rover pluggs? To choose is M10 x 1,0, M12 x 1,25, M14 x 1,25, M16 x 1,5 och M18 x 1,5 threads! Yes it's an 14cux EFI machine! And its have got propiate servicing (dokumented by dealer) so it should be in good nick! It runs and starts very well and do not consume any oil between oil changes! Ill get back with com test results! //Jan Quote Link to comment Share on other sites More sharing options...
duncmc Posted March 10, 2013 Share Posted March 10, 2013 A compression test is easy to do. I use an old Gunson's compression tester that was my Dad's. It has an M14 thread. Take out all the spark plugs. Then with a fully charged battery crank over the engine for about 10 secs and note the reading down. Do this with the throttle wide open, and I do it with a warm engine. Then post the results up here. Results will be different depending upon whether you have a low compression or high compression engine. Quote Link to comment Share on other sites More sharing options...
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