hi all - just bought a 94 850 turbo the other day and when driving it home on the highway i noticed that there is an ever so slight hesitation at speed that cycles at around every 4-5 seconds - it feels as if the engine is losing a slight amount of power but no drop in revs or decrease in turbo volume is noticed on dash instruments (hard to detect small changes though) - i know that it likely needs to have the lower ball joint replaced on the passenger side (or some other components once i get a good look at it), could this have anything to do with the situation or should i start troubleshooting the vacuum lines and turbo housing? thanks for reading and for any insight you might have
steve

I think When you buy one if you dont have records its better to do a master R&R.
When I bought mine (which is stick- not turbo with a blown engine) I put in an engine with 60k I changed clutch, water and fuel pumps and relay and filter and injectors9(vac-air hoses, full tune up,FPR too). Later the rack and both a-arms . Its been running trouble free non stop for six years 80k. Your hesitation could if not turbo related could be simple maintenance like clogged fuel filter which no one ever replaces, or worn cap points and/or rotor, old ignition cables. checking codes will not detect all these problems. Plus codes pile up if they are not deleted or caught on time because one problem triggers another code later one. Before I changed the injectors I had severe missing on a trip: it was a seal in the injector dried up . The mechanics were puzzled because there was no check engine light or codes present.For $125 I had rebuilt all five injectors and put them in myself. Problem solved plus better mileage and power. good luck.

Sound like the AC compressor kicking in, then releasing faster than the idle air controller can respond. It is not suspension related.

Correct, read the codes in both of the A & B boxes, writing them down, then erase them all. B-2 (cruise control) should have a 1-2-2 which cannot be erased if everything is working. Any codes remaining will need attention.

You have some fun work ahead, vacuum lines, fuel filter, all fluids, etc.

Klaus
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Two great Volvos, a 1967 220 and a 1998 V70R

ac low on gas will constantly kick in affecting idle and performance.

I doubt the ball joint would be related to what you describe. I would start by pulling diagnostic codes.
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Optimist - half full, Pessimist - half empty, Engineer - The capacity is twice what it needs to be.