850 Manual Turbo 1995 Getting Only 0.5 BAR

gizmaster_1 · Post by **gizmaster_1** » 29 May 2021, 20:19

Hi All.
I'm at my wits end...I bought the car used here in Canada a few years ago, it's a four door 5-speed Manual Turbo, woodgrain interior with sunroof. I found out only a handful came into Canada. Someone installed a greedy kit and must have upgraded the turbo as it has a T16 Turbo in it. The car was running really great for about a year, boost was sitting at around 1.2 to 1.3 BAR at WOT. Then one day the boost wouldn't go over 0.4 to 0.5 BAR. I replaced spark plugs, installed new wires, performed a stage Zero, replaced vacuum lines, installed an IDP Boost Valve, Rebuilt the turbo and upgraded the Blow-Off Valve spring and diaphragm, installed a new fuel pump and replaced all Turbo air pipes and hoses with a silicone set. I've done almost everything and can't seem to get my boost back. Please Help!!!

Post by **jreed** » 30 May 2021, 06:35

It sounds like you went thru and checked or replaced parts in many of the typical trouble spots already. I've never worked on a high pressure turbo car like yours, so my ideas may not be of much use to you... but three things I can think of to check: 1) is the boost gauge accurate? 2) is the fuel high enough octane? 3) is the knock gauge working OK?

Post by **matthew1** » 30 May 2021, 11:40

I'm not saying it's vac lines, but it's vac lines.

Ok, that's a bit of hyperbole, but these can not be checked enough.

What about intercooler? I blew my intercooler on my 850T and boost was very low until I replaced it. It suffered a fine-ish crack visible from underneath.

Post by **Sveedy** » 30 May 2021, 11:57

^ Exactly what mine did a few months back. I got on it a bit hard on day, and the next day it was like I had flipped a switch.
Shop found the leak with a smoke test, after I spent way too much time chasing other ideas. 8" long crack in the plastic bottom of the intercooler. Installed a do88 with no plastic.

Post by **matthew1** » 30 May 2021, 13:21

Symptoms of an IC leak is terrible bogging at anything more than 1/3 throttle, awful MPG.

gizmaster_1 · Post by **gizmaster_1** » 20 Aug 2022, 11:42

I have double checked all vac lines and all are good. I found another issue though...after idling or driving for about 39 to 35 min the engine starts to slowly die out, eventually stalling. After it finally stalls out, it will not start no matter how much I crank it. I have to wait about 30 min to an hour before it will start up again.

gizmaster_1 · Post by **gizmaster_1** » 20 Aug 2022, 11:44

P.S. any ideas if the stalling issue could also be the cause of loe boost? Also if I try to hammer the throttle it will bog out.

Post by **BlackBart** » 20 Aug 2022, 12:35

These guys are smart ^^^

Sounds like a pressure-side leak in the IC or connections to me, or vacuum control lines.

Also - is the IDP Boost Valve replacing a stock turbo control valve? I think I’ve read some complaints about the reliability of this ipd part.

Post by **scot850** » 20 Aug 2022, 16:12

When you fitted the IPD boost valve (TCV) do you mean this thing?

https://www.ipdusa.com/products/8901/IP ... lvo-120152

If so, how hard did you turn the middle 'leg' in as seen in the picture? If you did it more than 3-4 turns your TCV is junk. I have asked IPD multiple times to add a note to their instructions to make that crystal clear to installers. The 2 side ones are ok, as they bottom against a flange. The middle one has a small filter gauze behind it. If you crank the middle leg all the way in it crushes this against the valve jamming it.

If you did not do this, I would do as suggested and have it smoke tested for leaks/cracks in the induction system.

Neil.

Post by **Sveedy** » 20 Aug 2022, 16:23

The two might be different problems. The not starting etc kind of sounds like a fuel delivery problem. The next time it doesn't start, check your schradar valve on the fuel rail and see if you have fuel pressure.