98 C70 seems like no boost

Post by **phils94850** » 13 Nov 2014, 16:32

I purchased this yesterday.. its a 98 saffron 5 speed with 204k miles. The main thing ive noticed, it feels like there is no boost. I removed the turbo heat shield and checked the wastegate and it wasn't stuck or anything. The previous owner said he did the PCV on it awhile back so I don't know if there is a vac hose connected wrong or what. Any ideas where to start ?

Post by **northernlights** » 13 Nov 2014, 16:42

Wow....nice ride!

The Compressor Bypass Valve likes to get leaky with age, and the boost slowly goes away. If you check it with a vacuum pump at the fitting it should hold vacuum. If it doesn't, then Kinugawa sells an inexpensive repair kit with real Mitsubishi parts. It's a very annoying job to do with the turbo on the car, but it can be done.

Here's some info.

https://www.matthewsvolvosite.com/forums ... 66#p319366

Post by **phils94850** » 13 Nov 2014, 16:44

Ok.. I'll check it. Thank you northern

Post by **scot850** » 13 Nov 2014, 23:26

Also check the TCV (turbo control valve) and it's associated tubing that tends to crack and split with age. The TCV slowly looses it ability to allow boost with age also.

Neil.

Post by **Atis** » 14 Nov 2014, 01:54

How does that no boost feels like?
Is there any rpm range where it is a bit a more powerful?
My diagnostic list:
1.)vacuum hose check for right connections (check the check valves as well)
2.)boost leak find
3.)TCV check (get a 9V-12V battery and 2 pieces of wire), it should click and open/close the vacuum connections; if it is not working, swap polarities
4.)check WG actuator setting

(The usual no boost root cause is TCV or major boost leak)

Post by **phils94850** » 14 Nov 2014, 06:08

Usually around 2500 rpm you should feel the boost coming on and as you go up in RPM's.

Post by **phils94850** » 14 Nov 2014, 09:57

hooked up my boost gauge and it shows the car is boosting like it should

. Did find my rear cam seals are leaking so that's next on the list..

Post by **FLXC90** » 15 Nov 2014, 09:22

Does it feel like its not boosting in upper ranges where your R does, like a LPT that behaves differently than your HPT 850, and you just need to get used to the boost coming in earlier, and peaking out lower?

Beautiful car!

Post by **phils94850** » 15 Nov 2014, 14:27

Actually it feels like it doesn't boost as good in the lower RPM, my R has a chipped ecu and boosts 15lbs. so im probably just use to that.
The C70 is a HPT car

. Thanks for the compliment

Post by **FLXC90** » 15 Nov 2014, 15:06

Now I'm twice as jealous!