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Strange idle issues/oil pressure/code 83

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Old May 14, 2008 | 08:20 PM
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Default Strange idle issues/oil pressure/code 83

First of all, it's a 94 Z28 A4 with roughly 136k on the clock. Not the healthiest motor, wasn't babied before I owned it.

While idling (in any gear.. park or not) I generally idle right around 1k on the tach, which is a bit high I think for an A4. Anyway, every now and then the idle surges up to 1200, down to as low as 400...almost stalling out, then suddenly jumps back up to anywhere between 600-1000 (on the tach). All the while, my oil pressure drops accordingly... as idle drops, so does oil pressure... below 20 (probably 16-20 psi) all the way down to maybe 8-10 PSI.

I should mention there are quite a few issues that could cause this. There's a small vacuum line below the TB that runs to the EGR solenoid, and it's broken. There's also a vacuum line coming out of the fuel line wire loom that's broken. The elbow doesn't seal well around the TB, and when I push the diaphragm on the EGR valve (when the car is off) I can hear air escaping (probably from the gasket of the EGR). Early next week i'll be installing longtubes and getting rid of all EGR components. Soon eough, I'll have a CAI that will take care of the leak around the TB.

What I don't understand, however, is the oil pressure and how it directly relates to my idle speed, what effect would a vacuum leak have on oil pressure?

There's a code 83 that is stored (SES isn't on) that says TCC circuit or something similar. All of my research shows reverse lockout, but that's for m6, not A4s. I notice a hard 1-2 shift ever now and then, could that be related to the TCC solenoid/code 83?
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