Technical Multijet Max Boost Pressure - Anyone know?

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Technical Multijet Max Boost Pressure - Anyone know?

pietch

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Not quite.

1.3 75bhp- actuator controlled.
1.3 90bhp/1.9 130bhp- variable geometry turbine controlled by ECU.

Power levels differ slightly model to model, but in any case it's only the lower-spec 1.3 mjet that has an actuator (and lowest-spec 1.9 without an intercooler).

Max pressure is around 2000mbar. If the ECU sees figures consistantly above this under load it switches to 'limp-mode' and limits revs/power to prevent damage.
 
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Danny!

Thats interesting...

So on the 1.3 Multijet you could use a boost controller to up boost to 2000mbar (2bar / 29 psi) ?

Or is that the standard boost pressure?
 
Atmosheric (normal air) pressure is around 1000mbar at sea level. Therefore 2000mbar is 1 bar boost.

Thing is they all run at 2000mbar as standard. An aftermarket boost controller will have little effect.
 
Oh right... so the 1.3 multijet and 1.9 multijet both run 1 bar boost?

What is the most you can run without causing damage and getting engine light issues?

A ball and spring type valve at the same pressure may reduce turbo spool also or would a bleed type approach be better?

Thanks again!

:)
 
Erm... again-

Max pressure is around 2000mbar. If the ECU sees figures consistantly above this under load it switches to 'limp-mode' and limits revs/power to prevent damage.

You may occasionally have a spike just over this, but that's literally just for a split second. Without remapping the ECU to get over this limit, you're not going to beat it. Even so, the maximum that the standard pressure sensor can read is about 2500mbar (what we normally see when they clog/fail), but like I said, if the fuel isn't there to match the engine won't last long.

(y)
 
Danny...

Good point well made :)

Do you know anything about how reliable the fuel pumps are? I am thinking of putting on one of those digital tuning boxes to increase fuel pressure for perrformance... is this safe or is a remap better?

Thanks :)
 
Danny...

Good point well made :)

Do you know anything about how reliable the fuel pumps are? I am thinking of putting on one of those digital tuning boxes to increase fuel pressure for perrformance... is this safe or is a remap better?

Thanks :)

As no-one else has replied I will refer you to the Search function, discussions about the benefits / advantages / drawbacks to Tunit type boxes and Re-maps proliferate...
 
Danny...

Where is an easy point to take a vacume feed to check boost pressure is 100%?

I have a gauge, tee piece, hose etc.

Thanks
 
Sorry about the late reply.

From memory I can't think of any obvious vacuum take-offs, in fact all the diagnostic procedures for checking the boost pressure involve electrical checks on the sensors rather than mechanical tests.

Without using a Fiat Examiner's Recorder function it'll be tricky.
 
Thanks Danny...

I think I'll just disconnect and T-Piece something going into the intake manifold. Should give just as good results as computer results which I presume are taken from the map sensor?

My father drove a Corsa CDTi 1.3 the other day (rental) when he said is much more torquey then the 1.3 Multijet even though they are the same engine and management? Are the gearboxes different or is the ECU programme different?

Thanks again!
 
anyone reckon they can do a step by step for installing a boost gauge?

tbh if you look a a basic boost gauge installation guide the basics are the same on all cars. As long as you know which parts are which (usually easy enough to work out)

I should hopefully have a custom pod guage on the way soon so whenever I get boost guage and oil temp gauge in i'll try and get a guide up.
 
Danny...

So basically if I have increased fuel pressure (the tuning box fuel rail mod) can i take the boost to the point just before the injection light comes on which will probably be just above 1 bar on a boost gauge - right? If the light comes on I'll just windback boost a bit - right?

Thanks again :)
 
One more thing..

Danny will the 1.9 HGT Multijet Punto (2004 model) intercooler make and easy swap upgrade for a 2004 1.3 multijet Punto - are the mountings etc the same?

Thanks!
 
Danny...

So basically if I have increased fuel pressure (the tuning box fuel rail mod) can i take the boost to the point just before the injection light comes on which will probably be just above 1 bar on a boost gauge - right? If the light comes on I'll just windback boost a bit - right?

Thanks again :)

Being a Main Dealer Tech and not a Tuner, my knowledge and experience of tuning boxes is limited to what others have said, so I can't give a reliable answer. As far as I know, tuning boxes are calibrated to add 'X amount' of power to a standard engine based on it running standard boost. Forcing extra boost in (which wouldn't be a lot more than standard) may risk running lean, so without testing it on a rolling road I would be carefull.

Regarding the intercooler- I haven't looked at a 2004 1.3 or 1.9 multijet for some time and can't be certain of any differences. You'd have to find pics of both and maybe check ePer for matching part numbers, but if I know Fiat- they're probably the same intercooler.

(y)
 
Regarding running rich or lean... it seems like it does not really matter on Diesel: "Diesels are totally opposite to petrol, run it rich, and you'll burn it up. Run it lean and it has no power and runs cold,. Just don't pull the fuel back so much it starts missing, or you can damage the engine from excessive vibration, it just wears the bearings faster." So perhaps I'll just raise boost until injection light comes on and then turn back slightly?

Regarding the intercooler, I checked on a Doblo 1.3 multijet Cargo van today... the intercooler is a much better design (flow-through either end) and much bigger! Fiat claims the same hp and torque? Perhaps its bigger to allow better cooling under load as they can shift some weight?

How can I view the eper info online?

Thanks again Danny!
 
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Regarding running rich or lean... it seems like it does not really matter on Diesel: "Diesels are totally opposite to petrol, run it rich, and you'll burn it up. Run it lean and it has no power and runs cold,. Just don't pull the fuel back so much it starts missing, or you can damage the engine from excessive vibration, it just wears the bearings faster." So perhaps I'll just raise boost until injection light comes on and then turn back slightly?

Regarding the intercooler, I checked on a Doblo 1.3 multijet Cargo van today... the intercooler is a much better design (flow-through either end) and much bigger! Fiat claims the same hp and torque? Perhaps its bigger to allow better cooling under load as they can shift some weight?

How can I view the eper info online?

Thanks again Danny!

I wouldn't just turn the boost up. You won't get the power you want without changing other variables, just because diesels don't get damaged as easily running rich or lean, doesn't mean that you should.

This is what a remap is for, it changes all the variables necessary in order to maximise economy and power etc.

As far as eper goes, good luck!
 
I am only fitting a dawes device to increase spool time... I may increase boost slightly to compensate for my additional fueling - say point 1 or 2 of a bar max. A remap can not change boost on a 1.3 multijet as it is not solenoid controlled - using a boost controller is the only way.
 
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