99 Volvo S-80 T6 Turbo overboost

SimLyons · Post by **SimLyons** » 21 Jan 2014, 19:48

I purchased this car in September and had it shipped to me, arriving October 1st. It's been a pretty constant challenge since then. The interior and body are perfect. Extremely well cared for.

The engine and trans have been something else. The traansmission was replaced 60K miles ago. The engine gave the previous owners no real issues an it was serviced per Volvo's recomended schedule with Mobil One, synthetic.

I had the change the alternator right away and then a whole chain of work/maintenance needs (105K miles is major for this car).

Now, months later, it is running just OK. I had a coil failure this weekend so I replaced 2 of the last night (IPD's brand). I already had 2 in there from October. I'll add the final 2 next month (tight budget).

This Code came up with "Turbo Overboost". And it really did! I felt it from my toes to my head. But part of that also resulted in majo cut-backs, not to idle but to the feel of no boost. I let off and then it was just ok. I put my foot in it again and it would go like a mad rabbit for a few seconds and then back off again, After 3 mikes the Check Engine light was on. During this run/test I also got a coule of "backfire" noises, maybe in the intake.

I was in 2nd and 3rd gears when this all came up. I'm going to erase the code and go out again to see if it's still there. Anyone experience this? I've never seen overoost like this.

SimLyons · Post by **SimLyons** » 21 Jan 2014, 21:01

After reading many similar posts here, I went out and took another look under the hood. Sure enough, I found a cracked vacuum hose going to the TCV! Replaced the hose and it runs like that proverbial sewing machine!!

Lucky me! And thanks to you guys who have posted your experiences.

matt5112 · Post by **matt5112** » 21 Jan 2014, 21:22

Glad to hear it was a simple fix.

If the transmission is still shifting well, it might be worthwhile to install the TransGo shift kit to help slow down wear on the clutches.

SimLyons · Post by **SimLyons** » 04 Feb 2014, 22:47

The transmission is really my only concern at this point. It has 60K on it, after replacing the original. It seems there are no issues...yet I "think" I feel a 'rough' shift from 3 to 4. Not harsh, but more of a quick chatter. When I drive it moderately I don't notice it.

I am not aware of the Transgo shift kit. If you can give me more info I'd like to follow up.

Thanks! Sim