Hey guys.
A good customer of mine from the Grand Prix world bought a Saab 9-3 Aero with the 2.8 turbo Alloytec motor and I had a chance to begin tuning it on the weekend. It was cut short by spark blowout and misfires with 130,000km (80k miles) stock plugs, so his homework is to install new plugs with a tighter gap and then we'll get back to it.
I noted a few things while tuning. First of all, the commanded PE lambda of .94 in the factory tune means its aiming for 13.8 AFR at WOT and I thought no way they'll have fudged the MAF table or something but sure enough my wideband showed 14.0-14.2 out the tailpipe! How the heck do these motors not blow themselves to pieces?
I input .78 and got 11.8-12.0 at the tailpipe but even just doing that we ran into misfires . What are others running for PE settings?
The misfires did some interesting things. After a WOT run, the PCM started commanding 1.04 lambda on B1 and 1.58 lambda on B2 and the motor ran very rough. Shut the engine off, restarted, no problem. Guy had experienced this before on a warm engine startup, apparently common with US-spec Saabs, and its fine with a stop and restart. Perhaps something that's triggered by P0300 code?
I standardized the timing tables above 100% load and zeroed IAT/ECT adders but actual timing appears to come out at 5.5* below commanded at WOT. There's something else in there changing the timing advance that we can't see. I'll have to rework the timing tables over 100% load
The camshaft timing didn't seem to match what's mapped out either. The car seemed consistently in the 42-48* range with the intake cam and didn't register the exhaust cam angle at all. Has anyone had success altering the intake cam tables? I noticed the Saab Turbo X had much different settings but I'm leary to try them in fear that the mapping isn't proper.
The MAF correction table is all over the place from factory. Once I changed the table to 1 and start to correct things directly on the main MAF table the transmission started to shift firmer and quicker as the PCM saw increased airload. Might work out well with the "limited" control we have over the Aisin trans to improve the shift feel.
The max air load settings in torque management all worked well once set to 100%. I did not get into changing the desired air load (boost control) tables yet, hopefully next time around. Engine seemed to be pushing and holding 10psi.
If you have 2.8T tuning experience, post up and share your thoughts and ideas! I doubt there'll be many, would be great to converse with those that are here to hear your experiences.