2.5 DSE Plug in Chip tuning D.I.Y !

Hi this is my first post so go easy on me

I've had a P38 DSE for about 4 years now.

Everyone knows that the standard P38 diesel without a some sort of tuning, wether its a plug in chip or a trip to your local superchips is a bit slow at least on pull away. (to be honest it should come with a calender not a speedo )

There seems to be loads of different plug in chip options from £100-350....

....but

I'm a bit of a tight arse and wanted to make my own :doh:

Now before you all go Nnnnooooooooo in a long movie type way, hear me out.

After checking a couple of different plug in boxes it seemed they all did one thing in common.... increase the fuel injected from the high pressure fuel pump.

After checking the RAVE circuit diagram, it seems the logical way to increase the fuel injected without ballsing everything up is to alter the signal between the Fuel Quantity Feedback Sensor in the pump and the ECM.

(By the way its probably everywhere on here but if anyone wants the rave manual you can download it free here) \/

The Green Oval - Downloads | Land Rover Data

Anyway thats pretty much as far as I've got now.

I just have to figure out what the current signal being sent is and the work out the two most extremes then tweak the signal a bit.

Now I'll unleash my idea to your comments.

Cheers guys,
Nik

Personally if it were that important to me id get it remapped

yeah but I want to learn how it all works and do it myself.

Giving it to someone else isn't the answer for me.

I've always done my own repairs on my cars including endless ones on my Rangie.
I enjoy it even though I do swear a fair bit at the time.

Good luck

cheers

I'm surprised no one has attempted this before.

usually with anything like this, trial and error is gonna be the key, but the error could be costly.

the only true way to sort this is to find out what signal difference is. it seems the boxes, or at least the good ones alter the mapping depending on requirements.

opening the injectors for longer won't achieve this.

i dont think its as simple as modifying the signal to allow more or less fuel by a set percentage.

the chip boxes and the whole chipping re mapping basically says that the oem got it all wrong and heres how to do it!!

if you need more power, buy a petrol!!!

you could try building a device to increase the voltages from the accl pedal to the ecu. dunno how successful it would be, also if you can modify the fuel pressure sensor by way of a resistor to increase rail pressure thus lobbing more fuel in!!

Thanks for the reply gavbriggs.

Just so were clear, I don't want to open the injectors for longer periods. Just hold more pressure in the fuel pump. (this is what two of the boxes I have checked do)

As far as increasing the voltage to the ecu from the pedal.. I don't think this will make any difference, maybe just pull away when it should be at tickover.

The fuel rail pressure sensor you mentioned is exactly what i'm talking about apart from the p38 diesel doesn't have a fuel rail. It does however have the fuel quantity feedback sensor in the pump.
And yes some sort of resistor in the way may alter the signal if I get it right.

Does anyone have a plug in tuning box on their diesel that you can see what wires are being used from the pump to the box?

ie so that I can check a few more boxes to determine the best sensor to tamper with.

Nik2009 said:

I'm surprised no one has attempted this before.

Click to expand...

Im not

Tamper? now theres a good word

Omega 2.5 td (BMW Engine) Spec, and opinions? - MIG Performance Vauxhalls post 4 seems to confirm your theory!!

is it injector 4 that carries the fuel pressure sensor?

nathan5346 said:

Tamper? now theres a good word

Click to expand...

dont go tampering with yourself!!!:doh::doh:

Why are you not surprised nathan?

There are tons of people with diesel range rovers that there must be some that are curious about the performance side of things.

I do admit that there probably isn't many that also know electronics, and maybe not many that would risk playing around with that sort of thing but still.. there's gotta be a few. All it takes is for someone to open up one of those boxes and take a look at the goods inside.

I can't be the only one that wants to know what you get for your £100+

Nik2009 said:

Why are you not surprised nathan?

There are tons of people with diesel range rovers that there must be some that are curious about the performance side of things.

I do admit that there probably isn't many that also know electronics, and maybe not many that would risk playing around with that sort of thing but still.. there's gotta be a few. All it takes is for someone to open up one of those boxes and take a look at the goods inside.

I can't be the only one that wants to know what you get for your £100+

Click to expand...

Youve answered your own question

if all else fails just get the butler to push harder, that should be good for 10 bhp!!!

Cheers gavbriggs, yeah the omega has the same setup and the 3 a 5 series bmw from what I read.

The middle injector you mentioned houses the needle lift sensor (X318) and its only uses are to tell the ECM exactly when to start injection sequence for timing and also to back up the engine speed signal.

Unfortunately this sensor wouldn't do much in the way of performance increase if TAMPERED with from what I can see. Just maybe change the timing a little.

Its definitely the signals from the sensors within the pump.

Never though of manual labour

I've got a book on the Bosch diesel pump and can look it up for you. PM me.

As regards why no-one has asked before, you've answered your own question: for £100 you can get a plug-in chip that's proven safe, works, improves driveability and economy and takes 5 minutes to fit. Why would anyone in their right mind think that that is more expensive than anything you can DIY

I can totally understand your quest for knowledge and I've no doubt you will eventually succeed to get some small improvements but do it at theoretical level where there is no risk to your motor.

And I can tell you already that its not as simple as adjusting a single sensor. The Bosch EDC works on a 3D fuel map. The chips work best by removing the dips in the fuel map surface which correspond to the revs and loadings the emmision tests are done at. By changing one sensor statically you will only change one facet of the fuel map. If you're lucky you might lift the full surface a few percent but it will still have the same dips.
I have the analogue powerbox plug-in which physically uses the MAP sensor so that tells you one input the box uses. It gives a big burst at 2000rpm when the turbo comes up to full boost. The digital models don't use the map sensor using an adjusting 3D fuel map instead and give a much smoother improvement.