I'm assuming this is turbo related, the car will kinda "buck" or stumble when the turbo gauge is just about bottomed out, runs great other then that, I've heard it may have shaft play, I plan on looking at it tomorrow. Is there anything I should be replacing with it, can I buy just a shaft if thats the issue?

 

I think you need to describe 'bottomed out' a little better.

I am guessing that you are at wide open throttle (wot) and its bucking or stumbling. There is a boost limit set on the amount of max boost the engine management will allow. Its typically called 'fuel cut off' since that is exactly whats happening. When you hit that boost limit (about 14psi) the engine management will shut off the fuel for a sec. The car stumbles abruptly making you wonder what the heck just happened. Worry not, its protecting itself.

To get around it and go higher you can have your ECU flashed by several companies out there. This will remove that wall and let you boost higher.

In the below picture is the default boost for the common turbo. Its just under 10(9.6) and your gauge should look like the pic. If you have a 850R then your boost is about 12.

 

@ BoxPin, I'm kinda surprised that you are boosting your car with the temp below normal. Gauge looks like your temp was about 170 degrees.

@ Faster, we would consider "bottomed out" the low end and "maxed out" the top end. If the car is bucking at idle, there is likely a vacuum problem. If it's choaking at WOT, I'm with BoxPin. As for shaft play, I guess you're talking about the turbo. If that's the case and you're looking to have a performace car, you may want to look at replacing the turbo with a bigger one and having the ECU flashed.

 

@ rdpi, that boost is tame for me.

(I was expecting someone to comment on how much fuel I had, you got me )

 

I refraimed from the fuel comment due to the fact that I'm there 90% of the time. LOL

 

Less weigh = Faster car ! ! !


Shaft play = You would need to replace the "cartridge" or center section of the turbo. The other term would be rebuilding your turbo. It's not the "shaft" itself it's the bearings allowing the shaft to have "play" or to move excessively.

One of many suppliers
TD04H Turbocharger cartridge for Volvo turbocharger number 49189-01330, Colorado Turbo Rebuild LLC

Info on rebuilding, one of many articles also
https://volvoforums.com/forum/volvo-...rite-up-55357/

 

Um just a thought cause I had something similar happen to mine is it ok at 1/2-3/4 throttle but cuts only on WOT boosting?? If so check your plug gap mine was actually too big and the boost was blowing out the spark, making me think it was fuel cut! I reset the gap and it's ok now. 14psi!

 

1/2 too 3/4 its fine,It is at wot, not that I drive like that often, I just like to have the speed without the bucking when I need it. It makes sence the fuel cut off, but I will check the plug gaps today, thanks for all the info

 

Found a broken hose with yellow band on it by the turbo, fixed, runs soo much better.

 

I'm having the exact same problem on my '94 Turbo. The exact same thing. I searched high and low for answers, and stumbled across this posting. Where do I find that hose with the yellow tag on it? Thanks. I guess I should also go and buy an aftermarket boost gauge too?

 

The yellow banded hose is on the BCS to I believe the compressor housing..

Have had my bcs out for a while so im not sure exactly which one it is..

Blue I know is fresh air (intake nipple)

I think yellow is compressor housing, and red is CBV or vise versa..

Can someone confirm this?

 

Vac line routing

 

That hose is just vacuum line they sell in bulk at any auto parts store. If you want something a bit better they also sell silicone hose which is a better choice on a turbo as it will hold up to the heat better and longer. IPD and I think FCP also carry it and of course it's all over on Ebay.

They are under vacuum and pressure so make sure they are clamped on.

 

What is BCS short for? Some sort of solenoid? I printed off the diagrams you posted. Thanks for your help here btw. I really appreciate it.

 

Boost Control Solenoid .. #16 with the colored vac hoses going to it.

 

I just want to point out that you were hitting fuel cut off. That line opens your wastegate, without the wastegate opening you will build to much boost and to protect the engine your ECU has shut off your fuel.

Case closed, good work guys.

 

Ok. I finally got a chance to look at the hose with the yellow band on it. Was cracked in several places. I pulled off the air filter housing, and replaced the hose. Drove the car. It's better. From a standstill if I floor the throttle, no more bucking as it pulls good all the way up to almost redline without a hiccup. Every time! But,... from a roll on, or when on the highway when passing someone it will buck again (at about 3500rpm) once in boost. Thinking that it may still be over-boosting? I stopped by an autostore today and ordered an Autometer boost gauge & holder. Any other ideas gents? Thanks once again.

 

Get that boost gauge installed, see what is happening then we will talk.

 

Mine did the same thing ok at a standstill, some 1/2-3/4 ok but WOT from a roll would sputter, I thought fuel cut but was plug gap! 14psi stock tune!

 

Gonna do what Boxpin says and install that gauge I bought. Will also get some new plugs tonight as well. Copper plugs I'm sure are best for these cars? Will check that plug gap as you mentioned earlier. If you're getting 14psi at stock tune, then what boost level will the stock ECU cut the fuel? Thanks again.