how to ' chip' the ecu
how to ' chip' the ecu
#3
03-12-2014, 02:26 PM
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#4
03-12-2014, 02:58 PM
afaik, rev limit is RPM based. exceed the RPM limit, and injectors are shut off (or throttled way back, not sure which... I know some cars I've had, the injection is cut back to 50% if you hit the rev limit, and only shut off completely if you manage somehow to go much beyond the rev limit)
I would *think* that for a different sized engine, you'd need a different air/fuel map... are you using the volvo injectors and fuel pressure regulator, or the ones that were originally on the Alfa ? btw, the LH2.2 volvos were all 2.3L. my 1992 LH2.4 turbo has the redline at 6000rpm.
the processor in that LH 2.2 ECU is a Intel 8048 (LH2.4 uses the somewhat faster i8051). very simple/primitive 8 bit industrial control processor, architecture dates back to the 1970s. The original 8048 had 1K byte of ROM, the 8049 had 2K. there are developer versions 8748, and 8749, these have ultra-violet eraseable, programmable ROM, so they can be experimented with. you need a 'PROM programmer' compatible with these processors to program them. They run typically at about a million instruction cycles/second (really really really slow by modern standards)
my guess is, the software has a main loop that goes around once per injection cycle (half turn of the crank, or quarter turn of the distributor). this loop reads the MAF value, reads the O2 sensor, reads the coolant temp sensor, and calculates the fuel injector duty cycle based on those plus RPM, probably using a table in the ROM, and fires the injectors. this main loop also times how long before the next hall pulse, to keep track of the RPMs. to raise the rev limit might require extending that table map, which could potentially be difficult if there is insufficient ROM memory for it.
are you using the volvo ignition too, or sticking with whatever came on that alfa ?
I would *think* that for a different sized engine, you'd need a different air/fuel map... are you using the volvo injectors and fuel pressure regulator, or the ones that were originally on the Alfa ? btw, the LH2.2 volvos were all 2.3L. my 1992 LH2.4 turbo has the redline at 6000rpm.
the processor in that LH 2.2 ECU is a Intel 8048 (LH2.4 uses the somewhat faster i8051). very simple/primitive 8 bit industrial control processor, architecture dates back to the 1970s. The original 8048 had 1K byte of ROM, the 8049 had 2K. there are developer versions 8748, and 8749, these have ultra-violet eraseable, programmable ROM, so they can be experimented with. you need a 'PROM programmer' compatible with these processors to program them. They run typically at about a million instruction cycles/second (really really really slow by modern standards)
my guess is, the software has a main loop that goes around once per injection cycle (half turn of the crank, or quarter turn of the distributor). this loop reads the MAF value, reads the O2 sensor, reads the coolant temp sensor, and calculates the fuel injector duty cycle based on those plus RPM, probably using a table in the ROM, and fires the injectors. this main loop also times how long before the next hall pulse, to keep track of the RPMs. to raise the rev limit might require extending that table map, which could potentially be difficult if there is insufficient ROM memory for it.
are you using the volvo ignition too, or sticking with whatever came on that alfa ?
Last edited by pierce; 03-12-2014 at 03:19 PM.
#5
03-15-2014, 06:51 PM
Turbobricks Forums
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You will need to create an account over at turbobricks to take with him.
I believe his name is mike (thelostartof)
Done
You will need to create an account over at turbobricks to take with him.
I believe his name is mike (thelostartof)
converting the alfa to LH 2.4 would require a crank position sensor, and a whole lot of notches machined into the flywheel at precise angles.
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