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Re: Inconsistant boost.... could DI pack be at Fault? Posted by Ari [Email] ![]() ![]() In Reply to: Inconsistant boost.... could DI pack be at Fault?, Nick ![]() |
Boost gauges were marked differently in different years - some had lines on the yellow, some didn't, so without seeing the gauges for every year, it's tough to know exactly where your car is (or isn't) boosting to.
A stock car in good condition with good gas should boost to the top of the yellow, just touching the red. But boost gauges are not precision instruments, so each car is different. But just hitting the red is OK. Going into the red is not OK, not unless you've modified the APC.
Mutungee's point is well made - the proper spark plugs gapped to the right setting is critical in the turbo.
DI pack problems show up as misfiring - you wouldn't see boost issues, you'd feel the engine miss or stumble under boost. You haven't been describing that. Once the plugs are ruled out, I would look at a few other places.
If the engine starts to knock, the Trionic/APC will dial back boost slightly. Your engine may be on the hairy edge of knock, and on some days it wants to knock (warmer, dryer) and not on others (cooler or wetter). Also, you will get more boost on a cooler day - the air is denser, and the intercooler works better. There is a small but perceptible difference in performance between 32 degrees and 60.
The other possiblity is that the linkage on the wastegate actuator is sticky. The wastegate controls the boost level, and if it hangs up occasionally, you could actually be overboosting. Make sure the linkage is moving well.
Good luck!
posted by 140.157....
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