new guy posting, volvo 850 turbo wagon boost problem

cookiemonster131 · Post by **cookiemonster131** » 11 Jun 2013, 09:24

okay so here is my story. 170,000 miles on a 95 Volvo turbo wagon automatic.

timing belt done at 140k

new parts in past 5k

snabb downpipe, all silicone intercooler hoses, new vacuum lines, new pcv system, new ipd heavy duty compressor bypass spring (blue spring), ipd stage 1 computer tune, new plugs wires cap and rotor, and an open air filter.

it had a stutter in the boost build up but always made strong boost according to the factory gauge. after installing the bypass compressor spring it was building less boost and still had the stutter. So I ordered the IPD HD TCV and replaced it today. I went per the programming instructions from IPD. I am building a little more boost than I was but not as much as before the mods. also it is still stuttering...

anyone got any ideas? I am a mechanic by trade so I am not stupid but I do not want to keep throwing parts at this car. I was thinking maybe the wastegate diaphragm is bad but it doesn't seem like it would stutter seems to me it would just not hold any boost...

any help is much appreciated!

Thanks ahead of time

Cookie

Marcobrick · Post by **Marcobrick** » 11 Jun 2013, 11:30

I think a bad wastegate diaphragm is more likely to lead to boost spikes and/or overboost? Double check ALL turbo hoses, vac lines etc and their routing. When you say "stutter" do you mean the boost is fluctuating, or is the engine actually stuttering like a misfire or bad surge?

cookiemonster131 · Post by **cookiemonster131** » 11 Jun 2013, 12:04

also i forgot it also got 2 new VOLVO o2 sensors.

stutter as in it is pulling and looses power and picks back up. plus the boost is not building up in the gauge like it was before all of this started. i realize the stock gauge is not great but it is still a good baseline.

Post by **matthew1** » 11 Jun 2013, 12:15

Check TCV vac lines are correct.

cookiemonster131 · Post by **cookiemonster131** » 11 Jun 2013, 12:25

just checked the tcv lines again and they are correct per IPD instructions

Post by **matthew1** » 11 Jun 2013, 13:30

Ensure that the underside of this large intake hose is not slipping off.

cookiemonster131 · Post by **cookiemonster131** » 11 Jun 2013, 13:33

just checked all around the intake hose and it is securely on correctly on both ends...

Post by **matthew1** » 11 Jun 2013, 13:39

Wastegate diaphragm/spring then. I'm with Marco. It's a '95, all OE is nearly 20 years old.

cookiemonster131 · Post by **cookiemonster131** » 11 Jun 2013, 13:48

thanks for the answer everyone. So matthew you are in agreement with me that the wastegate is bad most likely correct?

Post by **matthew1** » 11 Jun 2013, 14:03

To me, it's just the most likely thing after the next.

Given the symptoms: bad gasoline (maybe) -> vac lines -> big hose -> TCV -> new TCV -> new CBV