TheRecklessEngineer Posted June 19, 2009 Share Posted June 19, 2009 Hi guys, My project vehicle has an MOT booked in 2 weekends time - however, I have an issue with MS and I'm after some suggestions. It's an MS 2.2 running 029v and EDIS, on a 3.5V8 using a flapper loom mostly, with some extra bits for EDIS. I've had a quick look at some brief logs I took last weekend and I have a lot of voltage spikes. This has the effect of making the engine run quite unevenly. It occurs using the dizzy and EDIS. The attached image shows the worst of the lot. The first thing I am going to do it run extra grounds from the sensors back to the battery - but apart from this, has anyone got any suggestions on what might cause this noise and how I can eliminate it? I need to get this sorted quick as there is still quite a lot to do on the truck! Quote Link to comment Share on other sites More sharing options...
Dave W Posted June 19, 2009 Share Posted June 19, 2009 I suspect you are correct to ensure good earths from the block to the battery. It's worth remembering that a very common problem with the original flapper installation was failure of the earth connection on the rear of the LHS cylinder head which is where the original loom was earthed. You could well be seeing the same problem if you have used the existing earth connections in the loom. If you have the MS earthed using the original loom you might want to provide a more reliable earth direct to the battery, this was one of the changes LR made when they moved to the hotwire system. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 19, 2009 Share Posted June 19, 2009 When Mr Fridge helped me wire mine (although I made my harness) I remember him saying how many efi system have issues that are often hard to fix - but are often poor 'Earth(s)' related. As such I took note and : Remade with welding cable 50mm2 a new lead from "Battery Neg / Earth to Chassis" Cleaned the mounting on the Chassis to bare metal and bolted Earth lead on F T Ran a seperate 50mm2 welding cable Earth from "Gearbox / Engine to chassis" Earth - and to a 2nd point (not same one) The ECU had grounds back into it, all made common by the internal earth block and .... Then all the ECU earths ran these to the battery Negative terminal HTH Nige Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 19, 2009 Author Share Posted June 19, 2009 Thanks guys - much as I was first thinking. I'll move the engine/battery ground from the bell housing to the LH cylinder bank with the flapper grounds, and add additional grounds to CTS,MAT,TPS sensors and EDIS running back to the battery. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted June 19, 2009 Share Posted June 19, 2009 Personally i wouldnt ground sensors directly to the battery. I'd ground all the sensors to a grounding block on or near the ECU, the connect the ECU to this block and then the block back to the battery. That way you ensure everythings on a reasonably consistent ground plane. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 19, 2009 Share Posted June 19, 2009 What Aaragon said - ground sensors back to the ground on the ECU connector if at all possible and then ensure a good ground from ECU to battery. If you ground the sensors back to the battery you can have differences in voltage over the cable & connectors between the sensor, battery, and ECU which will cause that sort of problem. The whole top row of the connector (barring pins 3-6 from memory which are SPR1-4 on V3) is ground, so I suggest running each sensor back to it as you have plenty of pins to solder to, and then 2-4 good wires from the connector back to ground. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 19, 2009 Author Share Posted June 19, 2009 Did what I said above and bingo - no more spikes. 'spose I'd better make up the rest of the loom now...and bolt the doors on, and bonnet, sort the suspension, sort the inner wings, fit all electrics, bleed brakes, refit front propshaft etc etc.... 2 weekends? Easy Quote Link to comment Share on other sites More sharing options...
steve_d Posted June 19, 2009 Share Posted June 19, 2009 Rather than just moving the engine earth I would add more. I think the RRC had about 5 earths as standard. Steve Quote Link to comment Share on other sites More sharing options...
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