2 replies to this topic

[norwegianminiman]

Hi everyone.

My SPi is playing up again, and wont start

Here is what happens:

Upon turning on the ignition, the red warning light ignites, but the fuel pump doesn't run. A distinct chattering sound if heard from the relay pack. When I then try cranking, the relay in the pack closes, but nothing further happens.

I have tested all the other functions (lights, indicators, horn, radio, heater etc.) and they all work.

We (me and my dad) have removed the relay pack, as we had some problems with moisture in it last winter. That didn't help. We have opened the pack, to see if there was any oxidation causing a problem. The inside was clean as a whistle, and it occurred to me to plug it back in with the cover off to watch the relays. Main relay works fine, starter relay works as far as I can tell, but the fuel pump relay chatters. I tried holding the fuel pump relay shut to see if the pump would then go, and was greeted by the smell of hot wires (so... a short somewhere... great... ) but no fuel pump. The fuse did not blow however, indicating the short is before the fuse.

I have measured the continuity of the wire between the relays and the starter solenoid.

I am not sure where the wire between the relay pack and inertia switch go, so finding out where the short is has been difficult.

After going through the wiring diagram for the umteenth time, I am starting to suspect the earth for the ECU could be a major part of the problem, but trying to follow the wiring loom to find the earthing point is a lost cause, as I am sure many of you know.

This all came on over the period of a weekend, but we have been having a LOT of salt on the roads, and I have had trouble with salt causing corrosion in the wiring before. I have investigated, and as far as I can tell the repairs are still whole.

So...

Any suggestions?

[Sprocket]

The engine loom ground point is on the triangular brace on the bulkhead cross member behind the ECU itself, and is well discussed in various topics

Chattering relays are a good sign of a grounding problem, since the power source tends to find a ground through other components with all sorts of wierd and wonderful things happening that cannot be easily explained.

shorted and or melted wires need to be investigated imediately as this could cause more severe damage to both the car and its wiring.

Edited by Sprocket, 21 March 2011 - 10:25 PM.

[norwegianminiman]

Right, time for an update I think.

After rooting around the wiring for a while, found a 7-11 volt drop in both the feed wires to the relay pack. After replacing them, most things work.

The engine now cranks, fuel pump both primes and works properly with no nasty smells (my guess there would be a bad connection in the feed wire getting hot)

ECU starts up and regulated most things. while cranking, it controls the stepper motor and injects, but seems unable to earth the coil.

I have tried seeing if it provides a spark, which it doesn't when controlled by the ECU (jumped it to earth with some spare wire and got a spark). I have measured a steady 13+ volts feeding to the coil, the resistance on both sides seem good, no shortage. I have tried measuring continuity of the earth wire (coil to ECU) and it seems to be whole. ECU has no bent pins (checked just to be on the safe side)

I have measured a signal from the crank sensor (well... It injects as well, so would indicate that works)

At this stage I'm getting rather stumped :/

Any suggestions?