S W Autos & The Mouthy Blonde

[Al115]

I thought the T4s had a MAP sensor on the intercooler outlet pipe?

[pyaap]

Originally Posted by Al115

I thought the T4s had a MAP sensor on the intercooler outlet pipe?

Yep, Phase 2s have an additional one on the inlet manifold too.

[Al115]

So in that case, how does the ECU not measure the boost?

I'm well confused!!!

[Dan F]

I was also told by a Volvo dealer that the EMS2000 ECU in T4s do not measure boost directly they calculate it from various sensors.

[Ross9]

Incidently, although the discussion points at not measuring boost directly and thus allowing cars to keep on boosting as long as there is no detonation, it is perfectly possible to bypass a fuel cut very cheaply and not blow an engine up, as long as the internals can take it, again it's done by fooling sensors.

MAP sensor, or AFM, they provide a voltage signal to the ECU that at a certain level cuts the fuel to protect the engine. You simply cap the voltage signal by intercepting it with a simple electronic signal to prevent it reaching the level that cuts the power.

This obviously means if the cut is at 15psi, and you cap it at 14.8psi, then run 18psi, the ECU adds the same fuel for the 18psi as it does for 14.8psi, so you need to check it;s not leanign out and if it is, adjust the fuel rail pressure to compensate, which will however skew the fulling at lower rpm, but it's inavoidable.

is this a bodge, yes, totally, and your better to remap the car, but it's cheaper and can be made to work effectivly, I held the scottish fwd record up until the last 1/4 day of 2005 usign the same fuelling set up as I detailed above, so it can be done.

If an ECU doesnt directly measure boost pressure etc as was mentioned, it musy have some sensors that allow it to determine boost levels etc, so I imagine you just trick these as well in a similar fashion.

Ross

[foggyjames]

Apologies for bumping a controvertial thread. Just a quick point re: the software vs hardware debate. I hope the trouble doesn't kick off again...

The advantage of "the Julie route" over chipping (ie: boosting, and fuelling/sparking to match) is that with her larger turbo she will have to run less boost to make the same power, since the turbo is pumping a larger volume of air. Charge air temps will be lower, combustion chamber pressures will be lower, and turbo lifespan will be longer. Will these things have a significant effect on a well maintained chip-only car? Probably not, in the scheme of how long most people keep their cars. If you still want to be driving your T5 in 15 years time, you might want to choose carefully.

This all assumes that the new parameters are within the 'headroom' of the stock ECU. For example you can put a 15G from an original T5 on a 940 turbo and it'll run slightly more than stock boost on 95 octane without pinging. Clearly Julie can do something similar with her car.

Of course the best situation is to make hardware modifications, then tailor the software to make full use of the hardware, as no amount of 'self learning' can ever be as efficient as tailored maps, especially with regard to ignition advance. This shouldn't really be a debate of hardware vs software - you wanna do both!

I think "exhaust / IC / larger turbo / remap" running limited boost (circa 1 Bar / 15 psi) is a proven route for gaining upwards of 300bhp (crank) on a real-world car (talking about a T5 here, of course), measurable on a dyno of your choice, whilst retaining the original characteristics of the engine...ie: decent spool-time, reasonable MPG, etc, etc. Naturally some cars will do better, some will do worse. I don't we can say much fairer than that, can we?

cheers

James