Looking at the wiring it goes from the rail sensor to a MAF sensor and tees off to the tuning box, I will try unplugging it and see what happens.
If the car doesn't start, its probably because its got no feed from the fuel pressure sensor.

The car will run with no MAF connected, but I don't think it will without the fuel pressure sensor connected.
 
Hi got home and started car which I had running yesterday. Today hard to start lumpy and loads of black smoke followed by white smoke. It then died and would not start when it did it was only for seconds. Unplugged grey box. Car started straght away but engine management light stayed on and revs seemed to stay in a safe mode low revving. Seemed to run ok apart from safe mode. Whilst runni plugged in grey box and it cut out immediately. Grey box rattles like mad. I now need to work out how to get the wiring back to standard. Any help advice very very welcome. If anyone breaking td4 I will buy wiring loom
 
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How does this crap tuning box join to the cars wiring? Normally they just contact between the factory plugs and the sensor they modify the signal of.
 
Hi thanks for the reply this is the exact unit and harness I have fitted on mine https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/202099697435
It is plugged into the fuel rail sensor and I believe the MAF sensor. The harnes on the link is exact to mine.
I may be being a bit thick here - but that eBay link is a box with a wire coming out that only has 2 connectors. Assuming 1 is output, that means it can only have 1 input. I would presume 1 of the connectors fits the fuel pressure sensor and the other connector is where the original loom connector plugs to - so it basically fits between the sensor and original loom altering the fuel pressure signal only.

From my links earlier, if you undo the 2 screws holding the box's cover on, the gubbins slides out and there are 2 rotating switches which presumably can be used to set modes.

Edit : the links I found earlier were all in furrin languages so couldn't understand any of them.
 
I can't believe that rusted connector (looks like something you'd have indoors on your computer!) is original.
It is a serial data D connector of the type used to connect printers and other peripherals to a PC, before the USB became standard. There's nothing actually wrong with them, providing they are used in the correct place. I've used them for projects in the past. They're offer a good, screened electrical connection for low current applications at a low cost. There not weather proof however, hence the rusting on this example.
 
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I may be being a bit thick here - but that eBay link is a box with a wire coming out that only has 2 connectors. Assuming 1 is output, that means it can only have 1 input. I would presume 1 of the connectors fits the fuel pressure sensor and the other connector is where the original loom connector plugs to - so it basically fits between the sensor and original loom altering the fuel pressure signal only.

From my links earlier, if you undo the 2 screws holding the box's cover on, the gubbins slides out and there are 2 rotating switches which presumably can be used to set modes.

Edit : the links I found earlier were all in furrin languages so couldn't understand any of them.
Hi I have opened the grey box
I may be being a bit thick here - but that eBay link is a box with a wire coming out that only has 2 connectors. Assuming 1 is output, that means it can only have 1 input. I would presume 1 of the connectors fits the fuel pressure sensor and the other connector is where the original loom connector plugs to - so it basically fits between the sensor and original loom altering the fuel pressure signal only.

From my links earlier, if you undo the 2 screws holding the box's cover on, the gubbins slides out and there are 2 rotating switches which presumably can be used to set modes.

Edit : the links I found earlier were all in furrin languages so couldn't understand any of them.
I opened the grey tuning box up this morning inside is a very wet circuit board, it is covered in protective wax but I suspect water is the devil. Photos of inside gubbins attached. I'm very nervous about playing about with the settings, as i know little about tuning chips, I don't want to blow the ECU.
received_1853001691377131.jpeg received_1853001764710457.jpeg received_1853002028043764.jpeg received_1853002231377077.jpeg
 
These tuning boxes can only trick the ECU into thinking it needs more fuel, it is always best to have a remap in my opinion, have you managed to find out what this box was attached to fuel sensor or MAF sensor and reinstate the original plug ?
 
These tuning boxes can only trick the ECU into thinking it needs more fuel, it is always best to have a remap in my opinion, have you managed to find out what this box was attached to fuel sensor or MAF sensor and reinstate the original plug ?
Hi going to strip it down tomorrow, so will report back and put full details on.
 
At last, what a struggle this has been but finally with the help of this site I have removed the tuning chip box and wiring loom. The chip was wired into the rail pressure sensor fortunatey the original plug was still on so it was an easy removal. Refitted boost sensor which has always been unplugged may be something to do with the tuning box. It' running sweet as a hippo. A massive thanks to all that gave very knowledgeable advice.
 

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