'Chipping' a Xantia Hdi90

rmunns · Post by **rmunns** » 12 Sep 2009, 22:51

Does anyone have any experience of doing this, please?
Recommendations? Results? Problems?
Performance differences, fuel consumption improved?

citroenxm · Post by **citroenxm** » 13 Sep 2009, 21:10

You might want to ask the question on the Peugeot 306 Fourm,

the 306 only ever got the 90 bhp unit from factory, and the 306 boys are always putting the BHP up, with a Simple re-map...

A friend of mine has just chipped - well, re mapped his 306 from 90bhp to 125bhp...

Performance stunning, fuel economy no change, if not slightly better... no mods needed to the Fuel System.

Its almost like the difference between the HDi 90 and 110bhp units fitted to the Xantias, the 110bhp is more eficient, and better on fuel then the 90bhp..

Paul

citroenxm · Post by **citroenxm** » 15 Sep 2009, 15:16

A chipped Xantia

Theres your answers to your question

Paul

PS: oo, a day later, my "Neat Link" title worked!

rmunns · Post by **rmunns** » 16 Sep 2009, 22:03

There seems to be two ways of doing this - please can anyone explain the pros and cons of each;

(a) remapping in the car (a specialist would take an hour or so to do this)

(b) fitting an in-line gizmo that could be done myself

The first looks like about £350, the second about £130. And of course second could be done at leisure at own home.

I'm obviously inclined to (b) but am wary.

citroenxm · Post by **citroenxm** » 16 Sep 2009, 22:11

Were did you get that price from???

A remap should cost no more then about £150 quid from someone who knows, possibly an indy...

Fitting just an intercooler wont make a difference, as you need a bigger turbo, and an ECU which a different program in it, IE: A remap, so that puts you back at the start...

Unfortunally, due to the HDi being "electronically" controlled, putting on an intercooler wont make much difference, this is due to the fact that the power increase is down to how the ECU handles the Injection Time of each injector, PLUS the inter cooler, HDi 90 and 110's have different turbos fitted..

Paul

KevMayer · Post by **KevMayer** » 16 Sep 2009, 22:49

The inline gizmo will be an electronic circuit which you fit inline with the fuel rail pressure transducer signal to the ECU.

The gizmo tells the ECU that the fuel pressure is lower than it really is. The ECU then controls the pressure regulator on the pump to give you higher fuel pressure and, hence, increased performance.

The fuel pressure will range from say 200 bar at tickover to around 1300 bar at full throttle. So the gizmo will give you say 220 bar at tickover and 1350 bar at full throttle.

The fuel rail has an overpressure relief valve so you probably can't overpressurize anything.

citroenxm · Post by **citroenxm** » 17 Sep 2009, 10:07

Hasn't the ECU got set Paramiters though, and if anything goes outside the settings it will flag the ECU light??

I had this with the Boost Electronic valve, it was not working and the turbo was going over pressure and limping the car...

Or does the Gizmo also over come the fuel pressure settings in the ECU?

paul

KevMayer · Post by **KevMayer** » 17 Sep 2009, 16:46

On the fuel rail there's a pressure transducer which I believe is fed with 5 volts DC. The transducer sends a voltage from 1V to 4.5V (say) which represent tickover up to full throttle, to the ECU where the volts sent depends on the pressure measured. These figures used are just to demonstrate the principle. They're not accurate. You can find the actual voltages on the net.

So, the ECU will expect to see something like 1 volt coming back at tickover. The ECU then knows 1 volt = 200bar (say).

On the pump there is a pressure regulator on the output. The ECU map determines what the pressure should be regulated to depending on engine speed and load etc.. So, when the map sees the engine on tickover it will expect to see 1v which it believes is 200bar (say).

The gizmo is an op amp circuit which intercepts the voltage from the pressure transducer to the ECU and reduces it slightly. The ECU sees this low voltage as a low pressure and tweaks the regulator to increase the pressure until the ECU sees the correct voltage returned for the pressure it expects to see according to the map.

This way, the ECU doesn't know that anything is wrong and no settings are changed. The gizmo just fools the ECU into giving you more pressure while the ECU thinks it's giving the correct pressure.

I've got one on my C5. It cost £85 from Ebay.

rmunns · Post by **rmunns** » 17 Sep 2009, 17:52

Just a m.o.f.;

Hdi90 engines are not turbocharged. And hence there is no intercooler.
Hdi110's have intercooled turbochargers.

JohnD · Post by **JohnD** » 17 Sep 2009, 18:11

rmunns wrote:Just a m.o.f.;

Hdi90 engines are not turbocharged. And hence there is no intercooler.
Hdi110's have intercooled turbochargers.

Not so! HDI 90s do have a turbo but don't have an intercooler.

citroenxm · Post by **citroenxm** » 17 Sep 2009, 20:46

Thanks JohnD you beat me to it!!

YES the 90 DOES have a turbo! but NO intercooler! Its only the DW8 in the 306's that DO NOT have a Turbo - ALL DW10 and DW12 engines have a turbo, I know Ive just changed a HDi 90 Xsara engine into a HDi 110 engine with absolutly no problems what so ever, even after 1000 miles, so beleve me I know the 90 has a turbo....

And KevMayer, Thanks for the brilliant explanation! I like it.. I did wonder about those Gizmo's but wondered exactly how good... Better then a remap I guess, and you can go back to standard setting when selling comes along...

Paul

KevMayer · Post by **KevMayer** » 17 Sep 2009, 21:15

The gizmo on my C5 is a 'TDI Tuning' box.

It's got an adjustment screw so that you can vary the amount of gain (or voltage reduction in this case). I've tried turning the screw to increase the pressure gain and you can feel an increase in performance but it doesn't do much for the economy.

At the standard (out of the box) setting I can feel an increase in power/torque and get about 2 mpg more on economy.

miked · Post by **miked** » 17 Sep 2009, 21:43

The proper tuning boxes break into the wiring loom between the ECU and the injectors. They sample the injector firing pulses from the ECU and send out a modified (re-mapped) set of pulses instead. I would guess KevMayer yours works on this principle.

Beware of the too cheap to believe plug in modules which just trick the ECU by modifying a sensor reading. I have heard that some are nothing more than a couple of resistors in a box.

KevMayer · Post by **KevMayer** » 17 Sep 2009, 22:14

My box is just a simple op amp arrangement.

The plug onto the pressure transducer has 3 wires. Red, Black and blue from memory (but don't rely too much on my memory !).

It gives you Red= +5 V, Black= ground (or possibly -5 V), blue= regulated output.

My box has a lead with 2 plugs. One plug fits into the pressure transducer, the other plug fits into the original lead.

The box is supplied by the poz and neg wires and the blue wire is split. It goes in blue and comes out yellow. All the bits in the box are a simple voltage reduction op amp arrangement. It's probably a couple of 741 op amps and some resistors. I know it could be assembled for a fiver, but I only realised what was in it after I bought it.

Having said all this, It does appear to work.

rmunns · Post by **rmunns** » 18 Sep 2009, 06:59

Sorry about the mistake I made regarding the 90Hdi engine being turbocharged.