Wedge engine electrics
Discussion
I have installed a Chim 400 motor with Lucas 14CUX in a 350i replacing the earlier 350 motor and its 4CU. I have used the Chim engine loom and have power to the Main and Fuel pump relays and their coils but they are not changing over when I turn on the ignition so no supply to fuel pump and probably injectors. ECU has been tested on another car and runs OK, The ECU terminal voltages I have checked appear to be correct although as the relay coils have 12V present I assume the ECU earths the other side to switch them. I suspect an earth fault but cannot find it. I had the engine running last year but it needed work so has been rebuilt but cannot get it to fire up this time, any ideas anyone.
Regards Mike
Regards Mike
Hi Ziga, there are 2 smaller fuses in the loom about 25A I think which supply the main and fuel pump relays and both of these are OK, the only 100A fuse I have is one I fitted in the main supply from the battery, this feeds the alternator and then the 2 smaller relay fuses. At the moment I still have the old engine loom attached as it is wired into 3 relays on the original relay board, and I was reluctant to start removing it until I had the engine running from the new loom, but as far as I am aware it is no longer supplying anything, the fuel pump supply having been cut and joined to the new loom..
Mike
Mike
I fitted megasquirt to my car and had similar fun. One of the significant things I discovered is that you can't trust the wiring diagrams for a wedge. You have to go back to basics and check everything. The fuse board and relay board are unlikely to be as described in the manuals.
Another common theme was wiring colours changing from one end of the loom to the other. Don't assume that one colour of wire going into the loom wrapping will emerge somewhere else as the same colour wire! There were soldered connections within the loom, plus some connectors external to the loom had one colour wire on one side and a different colour on the other side.
Alarm/immobiliser systems are another source of trouble. Take them all out and try and reconnect the wires as they would have been originally.
It's not rocket science, you just have to be methodical and don't assume anything.
Another common theme was wiring colours changing from one end of the loom to the other. Don't assume that one colour of wire going into the loom wrapping will emerge somewhere else as the same colour wire! There were soldered connections within the loom, plus some connectors external to the loom had one colour wire on one side and a different colour on the other side.
Alarm/immobiliser systems are another source of trouble. Take them all out and try and reconnect the wires as they would have been originally.
It's not rocket science, you just have to be methodical and don't assume anything.
Edited by The Hatter on Friday 21st December 09:34
Another thought... the 14CU system has an 'engine crank/running' signal going from the ignition amplifier to the ECU that tells it to start fueling (ignition is separate from the ECU on the CU, not sure what you have on the CUX). I suspect that involves the relays, so that would be worth checking out.
The steering module relay and Pektron unit are still connected, the only wire I have disturbed on the relay board is the supply to the fuel pump which I have cut from the original relay as it now gets its supply from the relay on the Chim loom, if I put 12V on this the fuel pump starts. I take your point about the wiring colours, they are not all the same as the diagram but the voltage checks I have made so far are at the ecu pins and on the relays. Thanks for the replies, all thoughts are appreciated, I will crack it eventually.
Regards Mike
Regards Mike
The Hatter said:
Another common theme was wiring colours changing from one end of the loom to the other. Don't assume that one colour of wire going into the loom wrapping will emerge somewhere else as the same colour wire! There were soldered connections within the loom, plus some connectors external to the loom had one colour wire on one side and a different colour on the other side.
Unless it's black - then it comes out as black the other end. Trouble is, all the other wires do too.Thanks Penelope, these relays are still mounted but no longer connected to anything as the air flow meter has changed from flapper to hot wire connected to the new ecu as are the new injectors, ie no power resistors, and the old ecu is disconnected, so I don't think any of this is still operational, but I may be wrong which is why I haven't removed anything until I can get the new engine to run.
This is the engine loom I have installed.
Regards Mike
This is the engine loom I have installed.
Regards Mike
mikanel said:
Thanks Penelope, these relays are still mounted but no longer connected to anything as the air flow meter has changed from flapper to hot wire connected to the new ecu as are the new injectors, ie no power resistors, and the old ecu is disconnected, so I don't think any of this is still operational, but I may be wrong which is why I haven't removed anything until I can get the new engine to run.
This is the engine loom I have installed.
Regards Mike
Ok, As you can see I've deleted all those diagrams that you don't need...."I wasn't even close with that lot was I"This is the engine loom I have installed.
Regards Mike
ECU Negatives
ECU Pin 4
ECU Pin 14
ECU Pin 40
ECU Pin 27
ECU Battery Positive
ECU Pin 15
ECU Ignition Positive
ECU Pin 19
@ Main Relay Terminal 85 Blue/Red Switched Negative From ECU Pin 12
Switches Positive To ECU Pin 2
Switches Positive To Injectors
Switches Positive To Air Flow Meter
If the above aren't all ok I doubt ECU Pin 16 Blue/Purple will switch negative to Fuel Pump Relay Terminal 85
Is the above connector ok?
Have you wired in the ignition switch or are you using a jump cable?
What about the inertia switch once you've sorted the problem?
Hi Penelope, I have been picking up the Wedge wiring again but so far without success. As your checklist all ECU negatives pins 4, 14, 40 and 27 show no resistance to battery negative, pin 15 has battery 12v and pin 19 is +12v when the ignition is on but ecu pin 2 is not switching to +12v. All main and fuel pump relay wiring checks out ok for continuity and the ecu runs ok on another car. At a loss now so any ideas welcome please.
Mike
Mike
Hi,
Some years ago I swapped my flapper setup to hotwire after buying this from ebay:
Complete working Rover V8 3.9 EFi hot wire injection system off 1991 Discovery. Includes plenum chamber and inlet manifold assembly with injectors and fuel rail, 14CUX ECU, Lucas airflow meter and undamaged EFi loom.
I found this on youtube: https://www.youtube.com/watch?v=NkH5lvJaISw
I followed his instructions and found it relatively easy to set up.
I found some notes on the wiring changes:
Connect permanent 12V to thick brown wire on main connector battery supply via fuse
Fuel pump power supply to white/purple from main connector
Earth wires to motor frame
Single wire with spade connector to -V on coil
Ignition supply white/grey from main connector to +12V op coil
Hope this helps.
Erik
Some years ago I swapped my flapper setup to hotwire after buying this from ebay:
Complete working Rover V8 3.9 EFi hot wire injection system off 1991 Discovery. Includes plenum chamber and inlet manifold assembly with injectors and fuel rail, 14CUX ECU, Lucas airflow meter and undamaged EFi loom.
I found this on youtube: https://www.youtube.com/watch?v=NkH5lvJaISw
I followed his instructions and found it relatively easy to set up.
I found some notes on the wiring changes:
Connect permanent 12V to thick brown wire on main connector battery supply via fuse
Fuel pump power supply to white/purple from main connector
Earth wires to motor frame
Single wire with spade connector to -V on coil
Ignition supply white/grey from main connector to +12V op coil
Hope this helps.
Erik
Thanks Erik, this was the same video I followed. It looks straight forward enough but I've missed something somewhere. I assume as you connected the fuel pump supply that you used the main and fuel relays on the new loom, have you removed the originals on the relay board?
Regards Mike
Regards Mike
Edit....Having re-read your opening post, I think I've got the below a touch wrong, you very likely have relays inside the vehicle and not under-bonnet. This doesn't alter any of the testing methods
Hello mikanel
In your opening post you mention you had the engine running last year. What's changed since last year?
I don't use a meter on its own to check for main earths and supplies at an ECU, a meter will show voltages through poor connections
To test wiring to ECU------------------------------DISCONNECT ECU-----------------------------------------------
Now use a 21 Watt bulb to check the earths and supplies at the ECU plug but take care not to prod into the terminals and open them up, you can earth one side of the 21 Watt bulb to the car battery and connect its other side in turn to the positives at the ECU plug
now connect one side of the 21 Watt bulb to the battery positive and connect its other side in turn to the earths (negatives) at the ECU plug...........You should see a fully illuminated 21 Watt bulb and will be able to then measure the voltages at those earths and supplies while the bulb is connected to them...........the 21 watt bulb puts close to a 2 Amp load on the cables and connections which makes the test a close to perfect one
Once you are satisfied that all is good with the +s & -s at the ECU you can then move on.....
I'm assuming that you are using under-bonnet main and fuel relays that are attached to the replacement loom
Noted that you have disconnected the fuel pump cable from the interior fusebox and extended it through to the under-bonnet fuel pump relay of the replacement loom.....Should be good to go
xxxxxNOTExxxxx
I appreciate that correctly wiring the fuel pump isn't going to give you that missing switched positive from the main relay to the ECU pin 2........checking for good pos and negs at the ECU might
xxxxxECU Pin 12xxxxx
xxxxxMain Relay Terminal 85 Blue/Red Switched Negative From ECU Pin 12xxxxx
"""""""WITH ECU DISCONNECTED"""""""
Applying a momentary (quick on/off negative to ECU Pin 12 Blue/Red Cable should switch the Main Relay On and ECU Pin 2 should have now gone live (Positive) quick on/off (you can use a 21 watt bulb to see it switch in and out)
xxxxxIf there is something wrong with the loom (incorrectly wired or internal short circuit) a problem could occur when applying a direct quick on/off negative to ECU Pin 12xxxxx......Use a cable with a 5 Watt bulb in series with it to apply that momentary negative, a 5 Watt bulb draws less than 0.5 of an Amp and will prevent any incorrect wiring from burning out if there is something incorrectly wired or an internal short circuit
If this above test doesn't work.......I suspect an incorrect type relay is fitted to the replacement loom or the wiring between ECU and main relay is faulty
Sometimes a relay with built in diode causes a problem if the diode is in the wrong direction
Hello mikanel
In your opening post you mention you had the engine running last year. What's changed since last year?
I don't use a meter on its own to check for main earths and supplies at an ECU, a meter will show voltages through poor connections
To test wiring to ECU------------------------------DISCONNECT ECU-----------------------------------------------
Now use a 21 Watt bulb to check the earths and supplies at the ECU plug but take care not to prod into the terminals and open them up, you can earth one side of the 21 Watt bulb to the car battery and connect its other side in turn to the positives at the ECU plug
now connect one side of the 21 Watt bulb to the battery positive and connect its other side in turn to the earths (negatives) at the ECU plug...........You should see a fully illuminated 21 Watt bulb and will be able to then measure the voltages at those earths and supplies while the bulb is connected to them...........the 21 watt bulb puts close to a 2 Amp load on the cables and connections which makes the test a close to perfect one
Once you are satisfied that all is good with the +s & -s at the ECU you can then move on.....
I'm assuming that you are using under-bonnet main and fuel relays that are attached to the replacement loom
Noted that you have disconnected the fuel pump cable from the interior fusebox and extended it through to the under-bonnet fuel pump relay of the replacement loom.....Should be good to go
xxxxxNOTExxxxx
I appreciate that correctly wiring the fuel pump isn't going to give you that missing switched positive from the main relay to the ECU pin 2........checking for good pos and negs at the ECU might
xxxxxECU Pin 12xxxxx
xxxxxMain Relay Terminal 85 Blue/Red Switched Negative From ECU Pin 12xxxxx
"""""""WITH ECU DISCONNECTED"""""""
Applying a momentary (quick on/off negative to ECU Pin 12 Blue/Red Cable should switch the Main Relay On and ECU Pin 2 should have now gone live (Positive) quick on/off (you can use a 21 watt bulb to see it switch in and out)
xxxxxIf there is something wrong with the loom (incorrectly wired or internal short circuit) a problem could occur when applying a direct quick on/off negative to ECU Pin 12xxxxx......Use a cable with a 5 Watt bulb in series with it to apply that momentary negative, a 5 Watt bulb draws less than 0.5 of an Amp and will prevent any incorrect wiring from burning out if there is something incorrectly wired or an internal short circuit
If this above test doesn't work.......I suspect an incorrect type relay is fitted to the replacement loom or the wiring between ECU and main relay is faulty
Sometimes a relay with built in diode causes a problem if the diode is in the wrong direction
Edited by Penelope Stopit on Wednesday 12th June 12:32
mikanel said:
Thanks Penelope I will try the load test on the loom.
Regards Mike
Once you're sure all is well with the positive and negatives, follow the above test procedure (earthing Pin 12 to check main relay switching)Regards Mike
Nothing will work until the main relay is actuating and supplying ECU Pin 2
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