Just about the cheapest mod you`ll see... *Update - Now with added boost*

I can't find a switched pot less than 1K either.

As you were.

 

So on the loop wire, which goes from the switch back to the switch:



... I solder a resistor. The spec of this resistor appears to be 400~500ohm. Is there any risk of heat build up or is this manageable? Which way should the resistor be soldered in? Or not direction sensitive?

 

Yep, resistor will replace that looped wire, or part of, if the resistor doesn't reach.

No polarity issues with resistors.

Heat from soldering shouldn't melt anything unless you're using a huge iron and/or you're clumsy with it.

 

Great, thanks.

It was heat from the resistor in use I was thinking of.

 

Personally I`m dealing with a 300 car here, (and I`d have to pretty cack-handed to wind it too far anyway), so no great loss if it blows up!

All opinions and ideas are, of course, welcome however, so I appreciate what you are saying.

Yep.

My setup, and the alternative;



The total resistance of the circuit is the sum of any resistors in series. In my case, I only have the one (variable) resistor rated at 0-1000 Ohms.

Wired the way it is, it actually runs 1000-0 Ohms, with the `danger` being that if it were to be wound too low it could cause ECU issues. Going to zero wouldn`t be an issue, since that would be the same as switching it off, but the `danger zone` would be in the low-hundreds Ohms range.

Accidently setting it this zone would be unlikely to happen (IMO) since you would have determined the `sweet spot` during testing and would know where the knob would have to sit accordingly (and could fit a physical `stop` if required)

For avoidance of any doubt/worry though, and as suggested previously, the alternative would be to add a fixed resistor of around 500 Ohms in series. That would give you a range of 1500-500 Ohms. So if you were to accidently wind the pot to it`s lowest point you`d always have a 500 Ohm `buffer` provided by the fixed resistor.

Fixed resistors aren`t directional, so can be wired either way round, and since we are dealing with no appreciable voltage here (probably around 5v) then heat build up shouldn`t be an issue either.

 

i think the comment amout the moble phoes is to do with EMC... this can be a big problem and before a car or any electrcial item is type approved to be fitted to a car it has to be EMC checked.. ie the ecu is bombared with electro magnetic radiatio to make sure its not going to whap out and give you full beans when you dont want it, but like wise other electrical items fitted to the car should also be checked to make sure they dont give off the radiation, or do anything mental when its applied to them.

 

True of course, but doesn`t really apply to simple potentiometer...

 

...except that simple potentiometer is on the end of some longish wires which may act as an aerial for what comes to/from your phone (and other devices), possibly inducing unwanted currents in the original wiring.

On the other hand...judging by the ease with which you could access/splice into the original wiring at the pump, it isn't a shielded cable there. So I wouldn't worry at all, as the devices at either end of this original wiring must be resilient to a bit of rubbish induced in the wiring, or it wouldn't work as installed.

 

Exactly...

At one `end` is the ECU, at the other the pulse generator (IIRC) that measures the pump plunger position (it`s this signal that`s being altered to trick the ECU into thinking the plunger needs moving further, thus suppyling more fuel, BTW).

It`s housed within the fuel pump...with a 120amp alternator whizzing away right beside it...

I think it works on a current loop (probably around 20mA), so the `correct` way to do it would be to determine the current draw at open circuit, and again when the circuit is operating at it`s max values.

You could then work out the `safe` resistance that could be applied, and install the requisite resistor. That`s too much fannying around for my liking, and finding the `sweet spot` with a pot does exactly that, albeit `blindly`.

 

Parts in stock now, thanks to a marathon session earlier in Maplin

Totally useless customer service tbh, in 2 separate shops. It took probably 30 minutes to get the resistor sorted and I had to go through the catalogue and came out of it knowing more about resistors than they did :

• 1k switched potentiometer part number is KU91Y
• Resistor I think is 510 ohms, part no M510R. I hope it's right: the colours are green/brown/black/black. If I'm out, it's a ten-fold error.

 

Eyre Electronics

This is going to help global warming no end!

 

And, if it works, 8-valve tuning

Stay tuned, but stay indoors!

 

I live in Scotland, the chances of me being outside for the next 6 months are slim to none.
I think your 8v diesel has more torques than your 16v as it is. Even before tuning.

Top tip for you, do not let the smoke out of the stripy tic tacs.

 

Time was components like these were on the shelf, so you could just walk in, pick up, pay and go, but now they only seem to keep them under the counter or in the stock room. I spent a good 20 minutes hunting round, before resorting to asking, and the sales bloke just pulled it out of a box, under the desk...

That resistor is indeed 510ohm (+/- 20%)


I have recently been forced (by MOT rules) to fit a `proper` exhaust. Side-exit would have done, but it was easier to just fit a full system a mate had going spare.

DTM from a VR!



Needed a section of the old one cut off to extend it slightly, and while it`s the same bore, it was only after I chopped a piece to length I realised the stainless section has a flared end, so required some bodgery to get the consequently larger sleeve to tighten up. All sealed nicely though, and MOT friendly.







Never noticed how much smoke this mod can put out on full chat, before, but now with upswept tail-pipes I can see it can be quite significant!

Turned down a little there`s virtually none however.

Hopefully tomorrow will see some bigger injectors in my possession (cheers Ade. Missed the Postie today, so they should come in the morning.)

Weather permitting I`ll be fitting those in the afternoon. Confident it`ll be running about 120bhp+ this time tomorrow.

 

So your adding injectors (which I believe were mine originally BTW!) to the 'evry' mod? Too much fuel! Needs more boost!

 

I was intending on using the mod with injectors.

Talk to me about wastegate adjustment for more boost...

 

Anyone wanting any resistors let me know, I have about a billion. They can be hard got sometimes, and at the same time not worth paying for just one.



Great work Stu, love these sort of posts!

Do you intend removing the pot once you hit a value/setting your happy with?

BG

 

Ta!

I like the fact it`s switchable, so I can just potter around as normal with normal consumption, then switch it on when needs must, since in full bore mode it drinks the fuel like it`s a petrol!

 

for those thinking about adding injectors to this mod:



that was a perfectly good 1z piston fried till the first ring showed up, 0.216 injectors and one of these while using the stock turbo

please use with caution and if you want to develop a good engine, forget this mod exists and get a good ECU tuner

BTW here is what happens when you give them way too much boost and timing advance at the same time:

 

Thanks for your input, but please don`t `scaremonger` without substantiation, as you tried early in this thread.

Is this your own engine/experience?

Was the first one running increased boost levels too?

With the second one, how much was `way too much` boost?


The injectors I`ll be using have .205 nozzles, and I`ll be increasing boost to no more than 18psi (which research shows is the best safe level).

All modifications from manufacturers specifications hold risks, of course, so some modicum of thought, and responsibility of use will be what prevents damage/failure.

What I suspect is the likely case in your examples is an irresponsile pursuit of power gains;

In the first instance a fixed resistor of too low resistance was used or the potentiometer was set too low, and left on constantly, resulting in combustion temperatures in excess of safe levels leading to the piston melting.

In the second case the boost had been wound up as far as the used method would allow, and timing advanced too far, again far in excess of safe levels.