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Location:
Madrid - Spain
Registered:
August 2002
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Boost limits
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Mon, 24 January 2005 20:24
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How do the toyota factory computers know to cut ignition/fuel when boost pressure gets too high. It is obviously not measuring pressure cos my 1G cut varies depending on the weather. Normally it will cut at about 16psi, but this morning I fiddled with the bleed and it was hitting 19psi no problems. Shame the roads were a little wet and 3rd gear was spinning the tyres. 
Anyhow back to the question. What is telling the ecu that something is wrong. Is the AFM reaching the end of it's travel? or is it something more fickle than that?
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Boost limits
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Mon, 24 January 2005 23:30
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AFAIK with the 1G-GTEs the ECU only cuts igntion when the AFM maxes out.
This morning being wet, damp and cold the air would have been much more dense and of course greater boost levels reached without the AFM flap maxing out.
On more advanced AFM ECUs such as the gen2 3S-GTE from ST185grpA, there is a secondary MAP sensor which the ECU monitors and then cuts the ignition when a max boost level is reached (these usually also drive the boost guage on the instrument cluser).
Similar happens with MAP sensor ECUs of course - the limit of the MAP sensor is reached (~5.0V) and the ECU cuts ignition. This is a real problem on 1JZ-GTEs cos they only use a pissy little 2.0bar absolute sensor, versus say a gen3 3S-GTE which uses something MUCH bigger (~2.5-3.0bar)
Sorry for the long winded reply, im bored.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Boost limits
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Mon, 24 January 2005 23:41
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Thats pretty much what I expected.
I think it is a little cruel though. That means the less grip I have, the more power it makes.  ........hmmmm water injection..........
Anyone had any success with water injection????
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Location:
adelaide
Registered:
May 2002
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Re: Boost limits
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Tue, 25 January 2005 00:43
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my older bro had a VN v6 commowhore for a while with a supercharger bolted on and rebuilt/balanced internals... it was good for a fair bit of power with the ecu tweaked and the blower hooked up..
to cut a long story short, he hooked up a bit of water-injection into the inlet somewhere, with household items, and he said it helped keep intake temps down and stop detonation...???
anyway thats the only time ive seen it in operation in someones engine bay..
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Location:
Wollongong
Registered:
November 2004
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Re: Boost limits
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Tue, 25 January 2005 01:07
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| blackRA28 wrote on Tue, 25 January 2005 11:43 |
my older bro had a VN v6 commowhore for a while with a supercharger bolted on and rebuilt/balanced internals... it was good for a fair bit of power with the ecu tweaked and the blower hooked up..
to cut a long story short, he hooked up a bit of water-injection into the inlet somewhere, with household items, and he said it helped keep intake temps down and stop detonation...???
anyway thats the only time ive seen it in operation in someones engine bay..
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There are quite a few commodores running around with turbos and aftermarket superchargers that have done the water and methanol injection, it is there to cool intake temps to avoid detonation, the AFM will still reach the top of it's threshold as the water is injected basically side by side with the fuel, no where near the AFM, quite a long way after, so water injection is a bit useless in this case...
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