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Re: Well some final thoughts Posted by Justin VanAbrahams [Email]  (#32) [Profile/Gallery]
(more from Justin VanAbrahams) on Fri, 28 Dec 2001 11:57:46
In Reply to: Re: Well some final thoughts, Johann F, Fri, 28 Dec 2001 08:27:46 Members do not see ads below this line. - Help Keep This Site Online - Signup |
From what I have read online, the general consensus is "Why bother?" The LH system *is* damned primative. It only knows two things, and that's how much and how dense the air coming into the cylinders is. Until 2.4.2 it couldn't even account for load or throttle position. It has no control over ignition, and it's batch-fired. It only uses the O2 sensor to tailor the mixture for the benefit of the catalytic converter - for maximum performance you're better off simulating 0.5v and dumping that into the ECU and letting all the work be done by the AMM. It is not adaptive, and works strictly off of preset fuel maps - some of which are variable (looks at rpm by airflow) and some of which are fixed (looks only at rpm).
I think the cat vs. no-cat discussion here is *slightly* moot, since no matter what you do you are still dealing with very limited fuel variation. Removing the cat serves one purpose - and that's releiving backpressure. My own, lame, seat-of-the-pants estimation is that there is no benefit in doing so at the power levels "we're" running... at ~1bar of boost I couldn't tell a spit of difference in *anything* on my 9kt with a working 3" cat and a hollowed one - maybe at more boost or something, but certainly not at that point. Moreover, removing the cat won't net you any *real* performance since the O2 system is still assuming you've got one - you need to lose that in order to "wake up" LH, and even then I'm not sure what you'd end up with since LH loves so dearly to lean out my mixture at higher RPM.
Someone on Turbo! posted the link below which maybe someone here wishes to invest in. Click on 16bit EPROM emulator and read away...! Depending on how much it costs, perhaps we could organize a contigent to group-buy it, then appoint someone to actually get some maps from various LH boxes and see where that gets us. The EPROMs themselves are cheap, so making a batch of them in various configurations would be easy. Or, once the maps are made anyone with an EPROM burner could actually produce them.
My only closing thoughts is that I think - *think* - there is a specific reason why LH did not last very long. Every major manufacturer developed their own EFI system coming out of the '80s, and all of the smaller ones moved to Motronic as quickly as possible. Volvo is a great, relevant example of this - they used LH for *four* years only. BMW and VW never used it, going from L-Jetronic and CIS, respectively, to Motronic. It's crap I tell you, and I'm not gonna take it anymore!
Er... wrong movie.
FWIW, my 5-door spent many minutes last night idling with a Volvo LH 2.2 ECU, green-top injectors, and Volvo AMM. Seemed alright, but it's too wet and too cold outside to take a 20-year-old-Saab out for a joyride... hopefully things will clear up this weekend.
-Justin
posted by 66.123.95.1...
, Fri, 28 Dec 2001 11:57:46 <-- Viewing This Message, Fri, 28 Dec 2001 11:35:45
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