1998 S70 T5 Rough Idle, Crap Boost,

[donnyglaze]

Symptoms and background on issues. I don't know if they're related or not.

1. Rough Idle. Installed ARD Green Tune, car ran great for a year. A few weeks ago, on morning start ups, RPM goes to 1500, then drops to 500ish, sounds like its going to stall, but pulls it out to 800. Saw a corresponding dimming in the dash lights with the rev drop today. It has started to do this at redlights now too.

2. Engine Coolent temp isn't parked at the 3 oclock position all the time. For the most part, it hangs out 2 lines just below the 3 oclock position. First noticed 2 weeks ago.

3. Boost no longer feels like the ARD tune, it feels stock. First happened a week ago. I stepped on the gas a few times, and the boost finally came back. Now, I cannot get it to hold boost beyond what feels like stock, maybe below that. Turbo is still spinning, I can hear the 'woosh' when I let off the gas.

4. Codes pulled: P0455 (normal), P0442, P0108, P0171.

5. Corrective action done: I cleaned the MAF and Idle Control Valve and cleared the codes. We will see how that works tomorrow.

Anyone have any ideas or tips on getting this under control?

[kahl]

I would check for a vacuum leak first. The hose on the intake manifold on passenger side and the hose going from the oil trap to the intake pipe. When I had that P0108 it was the barometric sensor by the passenger headlight. I would also change the thermostat. I would also inspect the TCV hoses for chaff, especially the one that is on the underside of the turbo.