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Okay, the joke may be on me.
Saturday I modified a spare APC per the instructions on the saabworks.com "straights" page. Fairly painless process, although a very anxious time. I posted intital results a few days ago.
After a few days drivign, I am now puzzled. Instead of achieving stable higher boost at higher revs, I have an unpredictable result. I suspect the additional boost is maxing something out, probably in fuel delivery. I wonder if some of you might have suggestions (no warranties expected).
1. Boost seems intermittent: sometimes it's wild (peaking at 3/4 to 7/8 redzone, and sometimes it doesn't even reach the red zone. There may be some trick to be sure it'll kick in, but at present, test runs on the same road on consequetive days have yielded varying results. I suppose I can take it out and wiggle the connections to see if any are loose, but other than that, any suggestions?
2. Knock detection: when boost does climb above 60% red zone, it usually cuts back pretty quickly into early red, then builds again. I assume this is knock detection. Yes/no? If knock detection, what are choices: back off on "P" setting? enrich fuel with bigger injectors? other?
Car: 87 SPG, Saabworks-recipe APC with F and P fully cranked in, 3.0 bar FPR, K&N open filter, Saab sport exhaust, SPG9 AID, timing set at 20 btdc.
Note: prior to the Saabworks APC mod, car had same setup with Redbox APC aggressively "tweaked" per Kevin K's recommendations. Would pull 40 - 50% red on good day, and back off only as revs climbed.
Any suggestions greatly appreciated. Thanks.
Jim Watts
87 SPG: The Stealthbomber
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