Bas_zelf Posted January 24, 2009 Share Posted January 24, 2009 Hi every one, My name is Bas, i am from the Netherlands and i am new to this forum. I was reading through this forum becouse my Disco 1 V8 3,9 EFI wont start. It was always idling a bit difficult, especialy when hot. Over the last few months it begun to get more and more difficult to get it started untul it wont start at all anymore. I think the ignition is ok as there is a nice bright spark, but the spark plugs are wet. So there is a spark and petrol, but no bang! I guess the mixture is all wrong. Another thing that may give a clue is the fact that when i push the accellerator, i had to to it gradually untill the engine reaches about 2000 rpm otherwise it would stall. Another pointer to a rich mixture? Has anyone got any pointers for me? Thanks in advance Bas. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 24, 2009 Share Posted January 24, 2009 Welcome I understand (from reading rather than experience) that rich mixture is often due to the temperature sensor telling the ECU the engine is cold - i.e. "running on choke". There are quite a few knowledgeable V8 types on here who will know more about it than me Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 24, 2009 Share Posted January 24, 2009 Mods, can we make it sticky that for V8 EFI problems the first answer is ALWAYS: Technical Archive -> V8 EFI Flapper / Hotwire (as appropriate) fault finding guide, work through it methodically and post up any unexpected findings. The other default answer for V8 problems is: Replace all ignition components with GENUINE PARTS and report back if it's still dodgy. (although I don't think that's the case in this instance) Quote Link to comment Share on other sites More sharing options...
teabag Posted January 24, 2009 Share Posted January 24, 2009 What ever it runs like, It will not start with wet plugs clean & gap them first. Then if you have problems but only when the engine is hot, replace the ECU coolent temp sensor it's the one just to the rear of the thermostat housing. A faulty sensor will tell the ECU to allow the injectors to stay open longer so giving a rich mixture which is only ok for a cold start. Quote Link to comment Share on other sites More sharing options...
Bas_zelf Posted January 24, 2009 Author Share Posted January 24, 2009 What ever it runs like, It will not start with wet plugs clean & gap them first. Then if you have problems but only when the engine is hot, replace the ECU coolent temp sensor it's the one just to the rear of the thermostat housing. A faulty sensor will tell the ECU to allow the injectors to stay open longer so giving a rich mixture which is only ok for a cold start. Thanks guys, for your answers. I already had been looking on the tech archive and have been seaching this forum for quite a few hours using the words Petrol and Starting as key words, but it didnt bring the solution. Althoug i learned a lot while reading.. I have replaced a few items (coil, dizzy cap, plugs, battery), disconnected the Lambda sensors and replaced the resistor near the ECU for a 470 Ohm one, but nothing helped.' I tested the coolant temp sensor and the fallue read a little over 3K Ohm, wich should be ok with ambient temperature just above freezing, so no problem there i thought.... Until i started to test other things this afternoon... all readings were the same. It appeared my multi meter is fooling me, so i went to the local hardware store and bought a new one. The coolant sensor has a resistance of just 0,148 mOhm... Unfortunately there is no way of getting a new one on saturday so i will have to wait until monday to get a new one. Or is there perhaps a limp-home value so i can put a resistor in the connector to try it? And is it correct to gap the (NGK BPR6ES)plugs at 0.6 mm? i didn't look at that when i replaced them... Ok, thanks for thinking with me and sorry for the probably sometimes incorrect spelling Cheers, Bas. Quote Link to comment Share on other sites More sharing options...
teabag Posted January 24, 2009 Share Posted January 24, 2009 I dont have a workshop manual so I can't confirm your restance values. Plug gap should be 0.9 http://www.ferodo-brakes.co.uk/pages/prici...ns/NGK-cars.asp And this may also help http://www.carelect.demon.co.uk/rrind.html And welcolme to the Forum Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 25, 2009 Share Posted January 25, 2009 I'd change the scale on your multimeter, you should ideally be reading in K-Ohms (0.148M = 148K) which puts your sensor somewhere near -70 DegC so I'd say that's faulty. You can affect a temporary fix by sticking a resistor in place of the sensor, anything from 3K to 300 Ohms would get you going and put the mixture somewhere closer to correct. At -70 it will be chucking in massive amounts of fuel. Quote Link to comment Share on other sites More sharing options...
Bas_zelf Posted January 26, 2009 Author Share Posted January 26, 2009 Here's a little update: Today i was at the local stealer to get the temp sensor, they didn't have it on the shelf so i have to go back at wednesday. I wrote down the partnumber (PRC3505) to check it at home and i noticed they made a mistake.. The same i made, becouse it is the wrong part, wrong sensor. I looked the part up in my workshop manual and the picture shows the one on the thermostat housing and de descibes it as temp sensor for ECU. But that is wrong, its a switch for the cooling fan! That also explanes the very low reading when i measured the resistance. 0.148 mOhm is next to nothing, wich i thought didn't make sense. If that would have been the value the ECU was calculating with, it would have thought the engine was melting... Probably no fuel then.. So no soaked sparkplugs becouse of that.. When i was looking on the sites of several parts dealers, i came up with two possibilities; partnumber PRC8783 or partnumber ETC8496. Anyone who knows the difference between them? Its for a 1996 hotwire 3.9 EFI auto. I dont think the local LR dealer can tell me. When they come up with a switch when i specificaly ask for the ECU coolant sensor. And besides that, they ask about 30 Pounds fo a 8 Pound part... The resistance i measured over the the right sensor was a little over 4 K-ohm so that is about right with these temperatures, but i'll replace it anyway just to be sure... Lets hope it'll cure my car! I'll keep you informed. Bas. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 26, 2009 Share Posted January 26, 2009 ETC8496 is the flapper coolant sensor (from engine no 25D16061B), before that it was EAC3927L. PRC8783 seems to be the Hotwire sensor. Any should work. Quote Link to comment Share on other sites More sharing options...
Bas_zelf Posted January 26, 2009 Author Share Posted January 26, 2009 Thanks FridgeFreezer! Thats a to-the-point answer to a long story! I'll order one first thing in the morning Quote Link to comment Share on other sites More sharing options...
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