Shanrad Posted October 1, 2016 Share Posted October 1, 2016 I have a 1994 3.9 discovery and for 2 months have had a lot of issues with poor running and black smoke so i got a rovergauge to see if i can find the issue but iam not clear on how to use it.the readings iam getting are: MAF READING: 99% THROTTLE READING: 100% IDLE BYPASS: 99% It says i have fault codes but how do i find them. Cheers Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 1, 2016 Author Share Posted October 1, 2016 ive now found out how to check fault codes. Iam currently getting codes 14 and 15 which are coolant and fuel temp sensors. Ive replaced the coolant sensor already so is there any there reason these codes would be coming up? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 1, 2016 Share Posted October 1, 2016 Yes, if they fail -very common, and makes the ecu think it is -40C, so makes it very rich. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 1, 2016 Author Share Posted October 1, 2016 Okay so in your opinion it seems like they have just failed and will need replacing? Cheers for the fast reply mate ? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 1, 2016 Share Posted October 1, 2016 Yup 1 Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 1, 2016 Author Share Posted October 1, 2016 Awesome. Thank you for the help. Iam hoping this has been the issue the whole time, it has taken such a long time to figure out whats going on. the rover guage and you guys have been such a massive help, so thanks again. Is there a reason the throtle sensor would be sitting at 99%? Quote Link to comment Share on other sites More sharing options...
sierrafery Posted October 1, 2016 Share Posted October 1, 2016 The only problem is that if the coolant temp sensor fails for good as to send the ECU to default this should be visible on the coolant gauge too so that fault code could have been hystorical... though the fuel temp sensor has no visible feedback so replace that ASAP 1 Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 1, 2016 Author Share Posted October 1, 2016 Would it still have that fault code if ive reset the ecu? Ive ordered new coolant temp and fuel sensor either way just to be sure. Unsure why the throttle position sensor is always reading 99% though Quote Link to comment Share on other sites More sharing options...
Ex Member Posted October 1, 2016 Share Posted October 1, 2016 Most likely wiring problems if you get faults after new sensors. Always manual check each sensor at the ECU connector and the by itself. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 24, 2016 Author Share Posted October 24, 2016 New sensors have finally arrived today and installed. I still have the same fault codes and its still running like carp. Can anybody tell me how to check them correctly in a step by step? Thanks to all that have been helping me out. I really appreciate it Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 24, 2016 Share Posted October 24, 2016 Have you cleared the codes? Normally need to do this as they are permanently stored. If they return, them it must be wiring issues, most likely along the injector loom, due to the heat and vibration. Hotwire efi diagnostics are in the tech archive which does a pin by pin test of all the ecu inputs/outputs, comes in very handy. Quote Link to comment Share on other sites More sharing options...
sierrafery Posted October 24, 2016 Share Posted October 24, 2016 I have a diagram only for the 95 modell so confirm if the sensors have both a red/black wire one side of the plug , the ECT a grey/white and the FT a green/blue on the other side?... if it's so i can help you. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 24, 2016 Author Share Posted October 24, 2016 Ive cleared the codes and still the same. I also tested the resistance step by step from the hotwire efi and it seems there is no resistance or iam doing it wrong. I don't think thats my wire codes sierrafery but ill have a look tomorrow as its dark now Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 24, 2016 Share Posted October 24, 2016 No resistance or no connection? (sorry, just trying to clarify) If no connection, there is a break in the wire. If there is no resistance (0 Ohms) then you have a short in the loom. Again, I would suggest examining the injector and temp sender harness along the inlet manifold. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 25, 2016 Author Share Posted October 25, 2016 Yeah no resistance mate. Ive now tested to see if there is any voltage at the coolant and fuel temp sensor. Checking each wire on both plugs has told me there is 9.10v on one wire and 5.05v on the other...same reading on both plugs. Does this mean there is no break in the wire if its getting voltage? Quote Link to comment Share on other sites More sharing options...
sierrafery Posted October 25, 2016 Share Posted October 25, 2016 in both the unplugged plugs you have to get solid earth one side if not that's the problem Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 25, 2016 Share Posted October 25, 2016 Yup ^^ Sounds like it is shorted to the throttle position sensor VCC wire, this is run at 5V, whereas almost, if not all, the rest of the system is at 12V. I forget which colour it is, but a glance at the wiring diagram will tell you - it is in the same loom as the injectors and temp sensors.... Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 25, 2016 Author Share Posted October 25, 2016 Little update. Had an auto electrician friend come up tonight and that there was a track burnt out in the ecu. After fixing it up the rovergauge say it has no fault codes and everything seems to be okay but iam no professional at reading the rovergauge. I have a picture of it but i cant upload to show you because apparently the file size is too large. After all this the bus wont start. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted October 27, 2016 Author Share Posted October 27, 2016 If the rovergauge is saying these while trying to start does it mean its fine or? obviously something isn't right ? Throttle position sensor :6% Stepper: 100% Maf: 1% Injector duty 3% Pulse width: 16.64ms Any help would be great..cheers Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 27, 2016 Share Posted October 27, 2016 Doesn't seem to far off to me. Quote Link to comment Share on other sites More sharing options...
Shanrad Posted November 8, 2016 Author Share Posted November 8, 2016 Okay cheers. still no luck with getting it running. could the ecu be buggered possibly? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 8, 2016 Share Posted November 8, 2016 So what's it doing now? Quote Link to comment Share on other sites More sharing options...
Shanrad Posted November 8, 2016 Author Share Posted November 8, 2016 Same as it always has done since doing the head gasket and removing the gas.Smells fuelly when i try start it and sometimes starts and sometimes doesn't. has no fault codes anymore though which is good Quote Link to comment Share on other sites More sharing options...
Shanrad Posted November 8, 2016 Author Share Posted November 8, 2016 One thing i haven't checked is the regulator . could this make this kind of issue? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 8, 2016 Share Posted November 8, 2016 If you've knocked the vacuum pipe off the regulator that wouldn't help. As you've got the rovergauge I'd be checking everything is basically looking OK and in-spec before fiddling with more bits. Also, RV8's can get really fussy about fouled plugs, as yours was running rich due to faulty sensors it might've fouled the plugs up which wouldn't help starting. Quote Link to comment Share on other sites More sharing options...
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