P38 diesel fuelling issue?

[Wazzajnr]

Graphite and clay. Adjust clay proportion for hardness.

Bloody pedants!!!

 

[cpa]

Replaced glow plug timer relay, replaced engine water temp sensor, checked continuity of signal wire from sensor to ecu - and still only get 4 seconds if glow. I can only conclude ecu got a fault.

 

[wammers]

Replaced glow plug timer relay, replaced engine water temp sensor, checked continuity of signal wire from sensor to ecu - and still only get 4 seconds if glow. I can only conclude ecu got a fault.

I will repeat an earlier question. Did you reconnect the Grey/Blue tracer wire from the temp sensor to the ECU that is cut to connect the hot start. Or is that the wire you say you continuity tested? Think you need some diag on this.

 

[cpa]

Reconnected the signal wire when removed hit fix. Tested there was continuity and ok. In fact unplugged the signal wire to see if I made any difference - and it didn't. Somehow the ecu is not seeing the temp sensor.

 

[Mark Piercy]

have you looked at the plug under the reservoir tank? Is it dry or any corrosion?

 

[Mark Piercy]

what about the fuse box under the bonnet. Any signs of burnt terminals or overheated relays.
even cracked solder joints would account for voltage drops?

 

[cpa]

Thanks for suggestions. The multiplug under reservoir is dry and clean. Fuse box was new a couple of years ago - no obvious signs of burn out - none of that bakerlite smell. I think I'' gonna have to get it plugged in to a diagnostic to see what is going on in the ecu.

 

[cpa]

One other thought - I'm told there's a cold start kit which let's you manually switch on the glow plugs for as long as you hold down a button - anyone got experience of that?

 

[wammers]

One other thought - I'm told there's a cold start kit which let's you manually switch on the glow plugs for as long as you hold down a button - anyone got experience of that?

You clearly have a problem, fix it, don't mask it. Dependent on engine temp for a cold start, the ECU switches the glows on for anything from 4 or 5 seconds in summer to 9 or 10 seconds in winter. Maybe longer if it's really cold. That reading is taken from the Green two wire ECU temp sensor between cylinders 3 and 4. If it is not doing that then either the temp sensor is duff or the ECU. The timer relay is just switched by the ECU it does not control timing of glows, as long as glows actually come on it is doing it's job. The ECU temp sensor is also interlinked to the fuel temp sensor to provide fuelling info for cold starts. Get a Nanocom on it and find out what the problem is. You can guess for ever more.

 

[cpa]

Yep - sounds like the only remaining option as I've replaced and tested everything else. Ta