iomlt Posted May 12, 2010 Share Posted May 12, 2010 I have a 14 cux 3.9 system from a rrc into a 90. all working perfectly. Then I decide to fit rubber interior and carpet to the truck and now running really poorly and the main wire (orange and something thick wire to ecu) gets hot. my question is does the ECU need a good earth as in the unit itself? all i did was lift the ecu and two relays up and fit carpet and the riveted them back on (rear bulkhead) over the carpet and then had this problem. She started and ran on say 4 cylinders and I moved her 50 feet and switch off. I noticed a slight warm plastic smell and noticed that the fuse holder was starting to melt a little (fuse is only 10amp) to the orange cable to ecu (i think its main feed to ecu) I switched off fast. Then rechecked everything i had done and still the same. So the only thing I can think of is the ecu mount itself needs a good earth. Can anyone suggest anything? Thanks Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted May 12, 2010 Share Posted May 12, 2010 No,the ECU earth is back out through the loom,you often see 14CUX ecu's hidden in plastic ice cream tubs when used for off road specials. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 12, 2010 Author Share Posted May 12, 2010 I thought along the same lines also. Just seems VERY odd that since i lifted and re-riveted the ecu back onto the bulk head i have this issue.....I have stipped the out plastic wiring casing to check for any cables that may of rubbed through etc. all in perfect condition.. Any ideas on what i could do to test whats going on? Quote Link to comment Share on other sites More sharing options...
heath robinson Posted May 12, 2010 Share Posted May 12, 2010 Does the negative wire go to the battery direct, and is it attached to the case inside the ecu? Possibly the case is earthed to the wire, and the wire isn't very well connected, or is earthed through the engine block. It's an easy one to rule out, by trying it with the earth onto the battery for a bit. hth Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 12, 2010 Author Share Posted May 12, 2010 The earths are earthed to the chassi, i see your point about the earth possible becoming lose inside ecu or pin (ecu connector) tried another ecu same fault. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 12, 2010 Author Share Posted May 12, 2010 OK had a good poke around tonight. all seems ok, wiring is as it should be. i have been meaning to put new plugs, leads rotor arm and cap on for a while (genuine stuff) that got her running again.... (so maybe when i ran her for very short journeys she got alittle flooded) i still notice the fuse getting warm.... not hot like before but warm.... but everything else is ok now.. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 12, 2010 Share Posted May 12, 2010 Have you got the right relays in the EFI setup? Some of them are not the normal type, and if you put a normal 4 or 5 pin relay in the socket, strange things can happen. I know 14CU setups had a 5-pin relay with two outputs rather than changeover, not sure what 14CUX has. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 13, 2010 Author Share Posted May 13, 2010 Good question... I pretty sure i left them as is... (metal cover type) i may of change the two over between them. It is somthing i will check thou. thank you. After the leads, plugs, rotar arm and cap its running absolutely beautiful! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 13, 2010 Share Posted May 13, 2010 Don't just swap them to see what happens there are wiring diagrams online in the tech archive etc. so you can check them without letting the smoke out. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 13, 2010 Author Share Posted May 13, 2010 Yeah i agree, but as the relays are the same (not including the fan control relay) i thought no damage would occure. I'm starting to wonder if it is a poor contact on the old type glass barrel fuse. i am thinking of changing it to flat blade type fuse to see if this cures the heat problem. In theory i could connect direct to ignition and perm live as the efi loom has its onwn fuses anyways. i just wanted to play mega safe and unterlise the two spare fuses i had in the fuse box as the efi conntection is next to the fuse box also. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 13, 2010 Share Posted May 13, 2010 Glass fuses? Yes, I'd be looking at replacing those quick sharp, VWP sell some fuse holders which pretty much bolt in place of the old ones. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 13, 2010 Author Share Posted May 13, 2010 I thought i'd keep the orignal look in the 90 fuse box. but like you say i will change! thanks Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 13, 2010 Share Posted May 13, 2010 Here's a picture of the VWP fuse boxes, they fit in place of the old ones, just swap the wires across one pair at a time. Quote Link to comment Share on other sites More sharing options...
iomlt Posted May 13, 2010 Author Share Posted May 13, 2010 missing picture Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 13, 2010 Share Posted May 13, 2010 Quote Link to comment Share on other sites More sharing options...
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