No4 injector (relay)

any 1 got any idea's why the garage I bought my p38 off has wired a relay up to the no4 injector??? with a power supply off the starter??:doh: I have removed it now and just wired the hot start fix as written about on here start fine every time aslong has you wait for the heater plug symbol go out either way it was wired up !! great site thanks all
Griffo

No 4 injector is the needle lift sensor, no idea why someone would put a relay on it, but it might just cause a rich mixture to help starting.

The needle sensor measures the start of injection as a reference point for ECU. Why anyone would put a relay on it defeats me.

wammers said:

The needle sensor measures the start of injection as a reference point for ECU. Why anyone would put a relay on it defeats me.

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I agree, but it might just confuse the ECU into pumping more fuel Not a good idea though.

Datatek said:

I agree, but it might just confuse the ECU into pumping more fuel Not a good idea though.

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Yeah he said there was a feed from starter must have been from selonoid switching feed. So whilst cranking it would put full potential through needle circuit telling ECU to advance and increase injection for starting. Maybe because the ECU coolant temp sensor was knackered. Sort of a long winded way of going about it.

ok guys thanks I will have to ask him.. would this do the same as the cold start relay ??? would it be worth changing the temp sensor?

griffo said:

ok guys thanks I will have to ask him.. would this do the same as the cold start relay ??? would it be worth changing the temp sensor?

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A few issues here. Starting problems cold and hot can be caused by ECU coolant temp sensor not working. The hot start is what it says, to assist hot start, it tricks the ECU into thinking the motor is cold, this causes ECU to activate heater plugs when engine is hot, and change injection parameters, but it also works when starting from cold. So If your ECU coolant sensor is duff. That could be your problem and you may not need the hot start kit on the vehicle if you change it. I would think the relay was a very roundabout method of doing it, changing the ECU temp sensor would have been easier i would think. Try a new one and disconnect the hot start then see what happens. If vehicle starts ok hot and cold it is sorted.

just had a good look thro the service history and since xmas it's had two Diagnostic test's where its then had new glow plugs new sender unit new compresser assy new rear springs with a bill for £1100.. will try temp sensor asap the guy must have been having starting problems with it, I have noticed it's a bit smokey when you boot it