Engine chirrup

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Wed 25 Sep 2002 06:30
Engine chirrup - dan
Hi everyone,
I have a volvo 480 turbo with the following problem:
If l accelerate hard (pedal to the metal) from a lowish speed (for example from 20mph in second). The car begins to accelerate, positive turbo pressure builds. About half a second into this process the engine gives a little stutter or momentary hesitation before carrying on as if nothing has happened.

If l turn the boost down the problem seems less prevalent. I initially thought this could be the engine ECU boost pressure limiter kicking in, but l am also wondering if the fuel pump is unable to meet a sudden increase in fuel demand. Basically l don't know.

Any info would be gratefully received.
Dan
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Wed 25 Sep 2002 23:59
Engine chirrup - dan
bump,
Oh sorry, just dropped me world atlas.
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Thu 26 Sep 2002 08:31
Engine chirrup - Dorian
Don't worry Dan, I'll pick it up...


:)


Maybe the fuel/air mix is getting really screwed up - the turbo is pumping in the air, and its doing it faster than the ECU can detect/manage so the car runs lean, causing the blip in power.

You could also try boosting the fuel pressure by fitting a different pressure regulator to the fuel rail.

Other than that, go see a Volvo specialist!

Hope you get it sorted.

Dorian.
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Thu 26 Sep 2002 20:33
Engine chirrup - dan
Cheers Dorian,
I am thinking knackered fuel pump. Running lean is not ideal, er...bang!
I have seriously considered the uprated fuel presure valve. (affectionately known as a power boost valve amongst MaxPower fraternity). It appears to be considered as a waste of time akin to the ecotek valve and that ludicrous air intake fan device that appears to be 'supercharger' with all the efficacy of a hairdryer!
Some people have reported improvements but l am more tempted to instead uprate the fuel pump itself.
Thanks,
Dan
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Fri 27 Sep 2002 08:10
Engine chirrup - Dorian
But surely if you upgrade the fuel pump to supply more pressure, then the fuel pressure valve will have to work harder to keep the pressure at its current setting.

I worked with someone who fitted a power boost valve to his old Cavvie, and he said it did improve response (but did not improve power).

Sorry I can't be much more help but I reached the end of my car knowledge :(

How about an email/letter to one of the flyboy mags (e.g. MaxPower)?

PS - I prefer SuperBike - they have some lovely centrefolds...
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