Check for vacuum leaks. Spray some starting fluid around the intake manifold, throttle body, etc…while the car is running at idle. If the rpm’s rise, you’ve found your problem. Be careful with the starting fluid! Post back what you find.

 

Would a vacuum leak be causing me to run that lean and the pitting? A friend of mine said he’s worried it’s detonation in the combustion chamber. I’ll definitely try the starting fluid

 

+1 on the vacuum leaks. Do you access to a smoke machine? It could also be your throttle body too.

 

I recommend you move this post (create a new post), or have an admin move this post to the S40/V50 forum. You’re probably going to get more model-specific advice there. That said, a few things to consider regardless:

• I can’t imagine simply a cat back would cause that much trouble. However, if the car was in “off” condition beforehand, doing upgrades certainly wouldn’t help, always go for Stage 0 before anything else.
• The PCV is a well known failure point, which can cause all sorts of issues on P1s, not sure if it could cause the issue with the plugs, but your car can definitely run “off” if it’s not addressed.
• Was/is there a CEL before/after the exhaust /CAI install?
• What does the maintenance history look like? How many miles, how long have you owned it? Is it burning or leaking oil, if so, how much and from where? How many miles on the old plugs?
• Might seem silly but what gas grade are you using? While 87 AKI is required, these cars run noticeably better on 91 (what is recommended). Even my NA 2.4i runs better on 91 and on a turbo engine, I’d say it’s not even a question.
• How’s the car driven/in what scenarios? Driven hard occasionally, daily, 6th gear WOT pulls, etc.? Further, especially with the T5 P1s (and this is likely not tied to your problem, but it’s something to consider) you should let the car “cool down” (idle) after hard driving to ensure the turbo cools down and is oiled properly before turning off.

 

Stage zero has been done, 162,000 miles. There is a cel code since I took the cat out. No burning oil or leaking, only run 87 really and I’m pretty hard on the car for sure

 

I did not realize you took out the cat, I see it in your first post now. Replace the plugs (if you haven’t yet), get it tuned, and run 91+ for a while. Your car is probably dumping a sh*t load of fuel (or very little) into the engine because O2 sensor readings (if still present) are all off (still expecting a cat); your friend’s concerns about knock are likely not far off, it’s probably not knocking thanks to a knock sensor but pulled timing and wonky AFRs? For sure.

Disclaimer: I am not a tuned car expert or person in any way, hopefully someone with the tuned P1 T5 crowd can chime in on my assumptions.

 

Working towards tuning it very soon, do you think it would be a good idea to replace my downstream o2 in case in fouled out?how would I move this discussion to s40 thread

 

If you’re continuing to drive your car before it’s tuned, I’d wait until just before. That said, I’m unsure if it’s necessary, maybe just visually inspect it. As for moving, I believe @Admin might be able to help (not sure if mods can do it as well). Worst case, a new thread might be necessary.

 

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Don't recall if we looked at the ETM of our 08 C30 T5 but recently cleaned the 00 S70 SE Base and the car ran much smoother. It was not super dirty but I believe there was enough gunk to make the butter fly sticky. Could be partially open so too much air.

Not for your car or the 00 S70 but they all are about the same. When cleaning do not leave any lint / fiber from whatever you'll use to wipe, especially around the butterfly pivot areas. The goal is to clean the throttle body walls and the butterfly edge where it seats so it doesn't stick. Should also push open the butterfly to clean the back. Being the 00 S70 SE is an NA I didn't have to remove the ETM so (CIP) Cleaned In Place. Careful not to bend anything or spray too much into the pivot area. Just mist and clean or spray on whatever you will use for wiping.

(EDIT: Found that picture on eBay to help someone else with cleaning. I just noticed the tape on the bottom right corner of the ETM and it says 2000 S70 Turbo. Not sure if the NA and Turbo uses the same ETM so could be the one on my car?)
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Don't recall if we looked at the ETM of our 08 C30 T5 but recently cleaned the 00 S70 SE Base and the car ran much smoother. It was not super dirty but I believe there was enough gunk to make the butter fly sticky. Could be partially open so too much air.

Not for your car or the 00 S70 but they all are about the same. When cleaning do not leave any lint / fiber from whatever you'll use to wipe, especially around the butterfly pivot areas. The goal is to clean the throttle body walls and the butterfly edge where it seats so it doesn't stick. Should also push open the butterfly to clean the back. Being the 00 S70 SE is an NA I didn't have to remove the ETM so (CIP) Cleaned In Place. Careful not to bend anything or spray too much into the pivot area. Just mist and clean or spray on whatever you will use for wiping.

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View attachment 237040

That is great you were able to get that to work without changing it. That's awesome haha 🤙

 

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BTW my plugs looked like that also!
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Those don’t look bad, just old…..
Just replace them. What have you done to it over the last six months? (Performance mods?)

 

Catless 3 inch cat back, cold air intake and elevates turbo intake pipe replaced the plugs still not running well I’m going to test for a vacuum leak this weekend

 

How many miles on that plug?

 

I don’t have a clue one of the previous owners did them

 

UPDATE: cleaned the throttle body and the maf sensor. Still has the surging rough idle definitely think it might be a vacuum leak

 

Smoke test it. If there's no leaks, it's likely your tb if I had a guess. Sometimes they just fail and you can't save them unfortunately. It could also be both a vacuum leak and a tb though too.

 

While you still should check for vacuum leaks obviously, I’m still fairly certain it’s the lack of tune. TBs, while they can get mucked up, very rarely go bad on a P1 to my knowledge. IIRC there’s a way in VIDA (if you have it) to test the TB but I’m unsure if I’m remembering correctly.

If my assumption is correct (that it’s pulling fuel due to wonky AFR from the O2s on grounds of no cat, and that it’s pulling timing to prevent knock), you might be able to make things slightly better by running 91 through for a while, that is if it’s bumping right up against that knock sensor reading. Since these cars “adapt” to their conditions it may take a bit for things to improve (much like it took a bit for things to get worse). There’s a way to “reset” the engine adaption in VIDA, if you have it, as well; I did it after some fairly major work done on the emissions system and it helped with MPGs (though not performance/smoothness) a ton once it adjusted.

 

Setting things up for a tune this weekend unfortunately no one even close to me dyno tunes Volvos so Hilton is my best option, I’ve reached out to him by email and messenger but haven’t heard back in multiple days any other way to get a hold of him?