LH 2.4.2 & DI/APC [Archive] - SaabCentral Forums

: LH 2.4.2 & DI/APC


stephen9000T
20th August 2003, 03:44 PM
:! I have heard that at WOT the LH 2.4.2 ignores the AMM and goes strictly to the LH mapping. Is this true? If this is the case that may be why my boost backs off. Not necessarily because I am getting knock per se but because my new turbo can provide more air than the mapping can provide fuel for? There literally isn't much I haven't replaced on this car so I know I do not have any leaks or other things people commonly look for. It will boost up to like 20 but as revs increase the APC backs it way down to like 12 psi, 14 or so with water injection. Can anyone confirm or deny?

Just to note I do have +40 HP LH & APC chips. So if this is true I guess I have gone as far as I can with the LH since no one is going to make custom chips for my car. I have tried fitting a piggy AMM interceptor but if the LH is going to ignore it at WOT then what's the point. Unless maybe fit larger injectors and use the interceptor to dial down the injector everywhere but WOT. Anyone?

BillJ
22nd August 2003, 03:39 AM
Which car have you got? I'm guessing a 2.3T with DI/APC?
You could fit slightly larger injectors (I don't know the injector size for the non-Trionic turbos, but the '94-on Trionic injectors are good for about 300hp at 3 bar). You could also increase fuel pressure a bit. What pressure are you running at the moment? I know Saab used different injector/pressure combinations in the US and Europe, for some models.

If the fuel system reaches its limit and the injectors are on 100% of the time, no amount of remapping or fiddling with the AMM signal will make it deliver any more fuel.

stephen9000T
22nd August 2003, 07:05 AM
Hey Bill,
I am runnig the factory 3.0 bar regulator and the factory 33.9 inejctors. It is a 92 DI/APC LH with TCS. I am not sayin the car is slow either, I just want to be able to tune it further.

BillJ
22nd August 2003, 07:37 AM
You have TCS so I'm assuming a 2.3T. I'd have thought +40hp should be well within the range of the fuel system. If you suspect it's running out of fuel, best to take it to a dyno and have them check the fuelling during a power run. However, I would expect that the boost curve programmed into the DI/APC upgrade is designed for the original T25 turbo. Even if you fit a larger turbo (which it sounds like you've done), the APC will still control boost to its programmed boost characteristic. The APC doesn't know you have a larger turbo and that it can maintain boost at a higher airflow.

stephen9000T
22nd August 2003, 09:38 AM
Hey Bill,
You are correct. I have a T-28 Super-60 and that is exactly what I think is going on. I have tried to defeat the system a number of different ways and have been unsuccessful. I mean I think the car is as fast as it was before but at just 12-15 psi. If I could bump that to 18-19 it would probably fly.