C30 Lazy Acceleration Topic is solved

PaulGantt · Post by **PaulGantt** » 29 May 2018, 06:21

Long time Volvo owner first time to post up. I have a 2009 C30 T5 with 139k on it. General it purrs like a kitten. Lately it has been giving me fits of lazy acceleration over 3800 rmp or so. It pulls like an ox with turbo churning up until then and then it seems as though the engine detunes right when it should be really pulling. 4000 and up are wicked slow. I run 93 octane but I am starting to think that my local gas station my be pumping bad gas. In first gear the acceleration difference is enough to produce a forward lunge when it pulls itself back. Any thoughts? Any ideas (especially cheap ones!) would be appreciated.

Thanks

Cees Klumper · Post by **Cees Klumper** » 30 May 2018, 07:37

Would be good if you can scan for codes, but my guess would be to check the turbo control valve (TCV). Just replaced the one on mine, as that had been 'McGyvered' by some previous owner/mechanic and was throwing a code, and inhibiting acceleration as you describe. They do have a tendency to fail. They are about $50 at FCP (pierburg, bit more for a genuine Volvo part) and it takes 10 minutes to fit, from underneath the car. Hope that is it as that would be a cheap and easy fix, but it can likely be all sorts of other things as well.

Post by **matthew1** » 30 May 2018, 08:56

I think Cees is on the right track. Boost related.

Look for a correlation between the cutout and boost rather than just rpm. Do you have a boost gauge? I can’t remember if your year/model has them.

PaulGantt · Post by **PaulGantt** » 30 May 2018, 09:27

I have a OBD2 reader that transmits boost I'll check it out. Today. How many PSI should I be pushing if it is fully operational?

Thanks again!

Post by **matthew1** » 30 May 2018, 09:55

Volvo high pressure turbos typically are a factory 10-12psi. Your code reader likely displays the calculated boost, not actual. I wouldn't put too much faith in that reading.

TCV, collapsing hoses... those are where I'd focus. I know you can't watch a hose collapse under boost, but if you work off that theory, you're more likely to find it if it is the cause.

PaulGantt · Post by **PaulGantt** » 06 Jun 2018, 07:37

You guys are awesome. After reading this I checked all the telemetry and boost was low and max HP was hitting 150. After reading the list of symptoms that a busted TVC has it matched perfectly. Too much boost was throwing limp mode in or I was getting too little. So a quick order of the pierburg and a (kind of) quick installation and I am back to full power. Thanks for everything, you save me a ton of troubleshooting!

Paul G

Post by **MadeInJapan** » 18 Jun 2018, 08:36

Great this was solved!! In the original post, "bad gas" was mentioned. I had an incident with one of my other Volvo's a couple of years ago with gas that had water in it sold to me and I got a check engine light and a no-start condition. After draining all my gas from the car and refilling with good gas the issues went away. The gas station denied they were the culprit and it eventually took my state's inspection people to get on the case who sent me a letter saying indeed the gas station was at fault. I also received full refund for my gas purchase. Beware of no-named cheap gas!!