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940 Low boost issue '93 940 w/garrett turbo

B

brf0007

New member
Joined
Jul 9, 2009
Location
Dallas Texas
1993 940 Turbo sedan with a Garrett turbo, and 230,000 miles.

Here are the things that have been checked/replaced in the last month, its a long list:
*removed, inspected re gaped spark plugs to 7mm.
*Cleaned all ground points and used a conductive grease on them after cleaning
*cleaned and deoxidized the battery terminals and cables
*replaced the coil
*replaced the cap and rotor
*replaced the plug wires
*replaced knock sensor
*replaced fuel pressure regulator
*Cleaned oil/vapor trap (that was nasty)
*cleaned "flame trap" PVC elbow where the vac line goes into the intake manifold
*replaced all rubber fuel lines
*replaced fuel pump and fuel filter
*cleaned the throttle body
*cleaned the intake manifold, and replaced with new gasket
*replaced ALL intake hoses
*replaced ALL vacuum lines
*Replaced ALL coolant hoses
*cleaned MAF
*removed and cleaned injectors
*new injector seals
*cleaned, deoxidized all engine compartment harness connections
*replaced idle air control valve
*replaced auxiliary suppression relay
*replaced coolant temp sensor (the one under the air intake for cylinder 4)
*replaced heater control valve
*replaced thermostat and thermostat housing
*replaced oil filler cap o-ring

ok thats the list of things replaced in the last month. The problem is, that no matter what I do, I cannot get more than 5psi boost. I borrowed a manual boost controller, and attached it in the vac line from manifold to the turbo, and no matter how i dialed it in, i still only got 5psi. The turbo spools slower than molasses, and when taking off from a dead start, I get no boost for a long time, and she falls flat on her face.

When I replaced the intercooler hoses, I noticed a fair amount of oil on the outlet side of the intercooler, and more on the intake side. so I then decided to check the shaft play in the turbo, and I believe that there is too much, because I can see it and feel it moving. I also think I noticed some points on the blades where they contacted the housing... so I am thinking I need a new turbo. I dont want to pay for a brand new one, rebuilding is a viable option, but cheapest in the area is $320, not including if I need new blades. so more than that. I am trying to find a used/salvage turbo, but I can only seem to find the mitsubishi turbos.

If anyone has any thoughts on anything I may have overlooked, or has any ideas on salvage yards that might have the turbo I need or anywhere I might be able to find one at all, I don't care where, please, please, please let me know!
 
brf0007 said:
1993 940 Turbo sedan with a Garrett turbo, and 230,000 miles.



ok thats the list of things replaced in the last month. The problem is, that no matter what I do, I cannot get more than 5psi boost. I borrowed a manual boost controller, and attached it in the vac line from manifold to the turbo,
Click to expand...


 It does not go here I belongs in the return line from the waste gate to the turbo. i.e.. (Tfest picture jack!!)
P1000994.jpg


brf0007 said:
When I replaced the intercooler hoses, I noticed a fair amount of oil on the outlet side of the intercooler, and more on the intake side. so I then decided to check the shaft play in the turbo, and I believe that there is too much, because I can see it and feel it moving. I also think I noticed some points on the blades where they contacted the housing.
Click to expand...

Are you sure you have a Garret turbo? By 93 I believe all of the 940s had Mitsus in them. You can score a 15g for cheap,i.e...http://forums.turbobricks.com/showthread.php?t=175371 and a rebuild kit for about $100, i.e...http://www.gpopshop.com/mitsubishikits.html
 
as far as i can see you hooked up that boostcontroller the wrong way, should be between compressor side and wastegate as seen in the picture. the connection you used (if you have the same turbo as in the picture) is for the compressor bypass valve.

first thing to do if you got that same turbo: remove that compressor bypass valve and block off the hole in the turbo with a metal plate. big chance your compressor bypass valve is leaking boost like those things always do.

use an old style plastic bosch cbv and your problems will most certainly be solved
 
kelley_aj said:
[/COLOR] It does not go here I belongs in the return line from the waste gate to the turbo. i.e.. (Tfest picture jack!!)
P1000994.jpg




Are you sure you have a Garret turbo? By 93 I believe all of the 940s had Mitsus in them. You can score a 15g for cheap,i.e...http://forums.turbobricks.com/showthread.php?t=175371 and a rebuild kit for about $100, i.e...http://www.gpopshop.com/mitsubishikits.html
Click to expand...

No, I'm not 100% sure. I am going to take the turbo and waste gate off this weekend to check the waste gate operation, so I will have a 100% answer this weekend. But the guy at IPD said that if its a straight waste gate actuator rod, its probably a Garrett.
 
Nils said:
as far as i can see you hooked up that boostcontroller the wrong way, should be between compressor side and wastegate as seen in the picture. the connection you used (if you have the same turbo as in the picture) is for the compressor bypass valve.

first thing to do if you got that same turbo: remove that compressor bypass valve and block off the hole in the turbo with a metal plate. big chance your compressor bypass valve is leaking boost like those things always do.

use an old style plastic bosch cbv and your problems will most certainly be solved
Click to expand...

im not understanding how to hook up the BMC then. Can someone take that picture and put some arrows in it to show me what is going on?

so, what you are saying is, remove the current waste gate, block the hole for the current waste gate, and install a blow off valve like on most aftermarket turbo installations?
 
Nils said:
its not really "old"...what i mean is this thing http://www.rsphysse.anu.edu.au/~amh110/blow_off_valve.htm

the vacuum hose from the manifold goes to this cbv. there?s a vacuum hose from the turbo inlet side going to the wastegate (the round black "box" under the turbo as seen in the picture....in that hose you connect the MBC)
Click to expand...

OOOOHHH, ok, thank you. Very much appreciated. I found said CBV online for $25, so I think I will just replace it, because with 225,000 miles, it probably should be replaced anyway. I plan on rebuilding the turbo, but if I run into bent or pitted shafts, or damaged blades, what do I do then? is it possible to purchase "upgraded" blades? something that spools faster, but fits in the same housing so I dont have to go cutting flanges and/or changing exhaust manifolds?
 
my old '93 was only running 5psi of boost. I didn't mess with the wastegate. I just replaced the crushbent 2" exhaust the PO had put on with the IPD system. 7psi with no other changes.

Make sure you don't have an exhaust restriction.
 
OK, I realized our issue here, the car is a 1993 model, made in September of 92. Perhaps this is why it might have a Garrett? Anyway, lets pretend its the TD04, and lets pretend that my CHRA is all FUBAR. Are all TD04 housings the same? do they all have the same exhaust inlet flange regardless of application? and if not, can I get a TD04 from another application, and use my turbine housing on the "new" turbo? or...basically, is the profile of the turbine the same on all TD04 turbos?
 
Just post a "Want To Buy" and get a volvo 13C for you car. You can usually find a good one for under $100.

No, not all TD04 are the same.
 
tryingbe said:
Just post a "Want To Buy" and get a volvo 13C for you car. You can usually find a good one for under $100.

No, not all TD04 are the same.
Click to expand...

does the 13C bolt up directly to my exhaust manifold? or will it require modification? I dont really want to go messing with what those Swedish engineers determined was the appropriate size compressor and turbine for that engine.
 
brf0007 said:
does the 13C bolt up directly to my exhaust manifold? or will it require modification? I dont really want to go messing with what those Swedish engineers determined was the appropriate size compressor and turbine for that engine.
Click to expand...

i'd say find the boost problem first before doing any unnecesairy turbo swap/upgrades.
99% chance you spend money and time and in the end still got that boost problem...with a useless 13c.

simply said: if you got a hole in your fueltank switching from 95 octane to 100 octane wont fix the hole in your tank.
 
I appreciate the concern, and you are right, its best to start with the smaller, less expensive things first. Which I have. The problem appears to be that there is an oil delivery issue with the oil getting to the bearings which caused the shaft to have too much free play, and the veins of the compressor have contacted the compressor housing. That's basically why its not making the right amount of boost. As for why its not getting oil, that's a different matter which will be solved at the time of turbo replacement. And since i already have to spend money on the turbo anyway, I might as well upgrade the turbo.

Nils said:
i'd say find the boost problem first before doing any unnecesairy turbo swap/upgrades.
99% chance you spend money and time and in the end still got that boost problem...with a useless 13c.

simply said: if you got a hole in your fueltank switching from 95 octane to 100 octane wont fix the hole in your tank.
Click to expand...
 
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