'99 S70 T5 Many codes P0445 P0136 P0245 P0448 P0136 P1332 etc.

[bmdubya1198]

My cousin's S70 has been acting up again, and I need some help here.
I've found several threads about a similar set of codes (give or take a few), but I don't think there was every a solution posted to any of them. Here goes the list of codes...
P0031
P0037
P0136
P0245
P0445
P0448
P1332
P1655

So far, we've replaced the pre-cat O2 sensor (with the correct Bosch part, NOT the universal one). I tested the VVT solenoid for proper resistance and it's within spec. We recently replaced almost all of the vacuum hoses, and they are all attached properly and not damaged. I swapped the TCV from my car, and that made no difference. Swapped the purge valve from my car, also made no difference. I also read one of these threads on Volvo Forums and someone suggested an issue with the positive battery cable to the main fuse box, but that is in good shape. I looked at the main ECU relay as well per a thread over there, and one terminal looks a little black at the base of it on the relay, so that's a little suspect.
There is no obvious damage to any wiring, and the two main ground straps on the cam cover look to be in good shape and are screwed down properly.
Does anyone have any idea what could be wrong here? I am at a total loss.

[abscate]

You need to wipe off all those codes and monitor them for a week to see what comes back first. That will give you some guidance

You can't really test those solenoids in DC - they have to work in at a few 100s Hz I believe.

[erikv11]

Doesn't really help but hmmmmm ... viewtopic.php?t=43634

[bmdubya1198]

Doesn't really help but hmmmmm ... viewtopic.php?t=43634

Yeah, I saw that thread, but as you also see, there was never a clear solution. Oddly enough, the codes are almost exactly the same.

You need to wipe off all those codes and monitor them for a week to see what comes back first. That will give you some guidance

You can't really test those solenoids in DC - they have to work in at a few 100s Hz I believe.

I've already cleared the codes several times, all the codes come back immediately upon clearing. I have had the battery disconnected for 20 minutes or so as well, and that also did nothing.
I tested the VVT solenoid on ohms, and it was within the specs posted on here Ozark Lee, I believe.

[bmdubya1198]

So, after replacing that main ECU relay that looked burnt, nothing changed. However, I noticed that the Emissions Systems fuse (20A) was blown. Replaced the fuse, and instantly the car was running MUCH better (it was stumbling a bit, noticeable breakup in the exhaust). Within minutes, the CEL turned itself off.
After checking, there are no codes present. Short term fuel trim is jumping around a little more than I like, but it's within +/- 20%. Before, it was at 0 because I couldn't get a reading from the upstream O2 sensor. For some reason, the bank 1 sensor 1 O2 sensor (upstream) is giving me no signal on the O2 sensor test still on Torque. Like I said, no codes, but it's not showing any readings.
Since the car has been running a manual boost controller to keep boost up with the assumed boost cut the ECU was implementing, we switched it back to the TCV, and it's only boosting around 5 psi. The car should be running around 12ish, so something is still wrong.

[erikv11]

... the Emissions Systems fuse (20A) was blown. Replaced the fuse, and instantly the car was running MUCH better (it was stumbling a bit, noticeable breakup in the exhaust). Within minutes, the CEL turned itself off.
After checking, there are no codes present. ...

Eureka! I understand there may still be some issues with the car but almost certainly you have solved this odd and lengthy collection of codes. Hopefully the fuse was random, but at least you know to look there

[bmdubya1198]

... the Emissions Systems fuse (20A) was blown. Replaced the fuse, and instantly the car was running MUCH better (it was stumbling a bit, noticeable breakup in the exhaust). Within minutes, the CEL turned itself off.
After checking, there are no codes present. ...

Eureka! I understand there may still be some issues with the car but almost certainly you have solved this odd and lengthy collection of codes. Hopefully the fuse was random, but at least you know to look there

Hopefully. It's always the simple things that take the longest to track down. I just have that mentality where I assume the absolute worst any time anything comes up, like some kind of wiring damage somewhere. Maybe I'm just crazy and enjoy tearing apart engines too much...

[bmdubya1198]

I've been told the car is running great and at stock boost with an ECU hard reset!