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Registered
Join Date: May 2007
Location: Granbury, Tx
Posts: 202
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Slow boost rise
I recently bought an 86 turbo and though I have experience with other models, I don't know to expect on this car. The car originally would not build sufficient boost (.5 bar max) so I removed the exhaust to check the turbo. The turbo seemed to spin freely, but the cat was about 50% clogged. I replaced the cat with a straight pipe and now it will build to .8 bar but sometimes seems to build boost slowly. Sometimes I will drive it in the morning and at about 2800 RPM there will be good boost, then I park it for an hour and at full throttle it doesn't hit .8 until 4500 RPM. I have replaced all the o-rings, the pop-off valve gaskets, the vacuum hoses to the distributer and can't find any other leaks. I am about to conclude that the turbo may have issues but I would be surprised that it could behave intermittently, and it doesn't smoke.
Does anyone have any suggestions?.....Thanks for any advice. |
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07-19-2007, 04:03 PM
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,249
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did you do anything with the wastegate?
they don't last forever... might be worn out. |
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07-20-2007, 09:40 AM
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A fellow Pelacanite
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What are the pop off gaskets you changed ?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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07-20-2007, 09:49 AM
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Registered
Join Date: May 2007
Location: Granbury, Tx
Posts: 202
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The nylon (looking) flat ring gaskets at each end of the pop-off valve were completely deteriated. They may also provide a cushoning effect to reduce noise when the pop-off valve slams open or shut. I forgot to mention that I also removed and disassembled the waist gate and it seems to be working and sealing fine and I installed a new waste gate gasket.
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07-20-2007, 03:05 PM
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Join Date: Aug 2005
Location: Michigan
Posts: 3,381
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If it's pretty much stock. You could have a faulty boost gauge sending unit. Mine was all over the place then I changed the sending unit out and not it's consistent. It's wrong, but it's consistent. I've heard that they are notorious for being inaccurate.
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Bill 997.2 |
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07-20-2007, 05:23 PM
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A fellow Pelacanite
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OK. that part is known as the recirculation assembly to me.
Did you change the seals on the pistons inside there too ?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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07-20-2007, 11:25 PM
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Registered
Join Date: May 2007
Location: Granbury, Tx
Posts: 202
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If we are talking about the same thing (a spring loaded piston that is sucked open with vacuum when you let off the throttle to reduce back pressure on the turbo) then mine does not have seals on the piston. The piston just slides on in the bore in the housing. Perhaps there should be seals.
Also today I went ahead and removed the exhaust to take a good look at the turbo. There is definately too much radial slop so I guess it is time for a turbo. I am surprised it wasn't smoking. Now for a new question...I have an old worn out turbo that on the tag says 3LDZ with no yrailing numbers. It came off an 87 car that had some mods and may not have been the original turbo. The one off my car (86) has 3LDZ followed by a series of numbers. Mine has a smaller inside diameter on the intake throat than the other and the other also has more blades on the compressor. So the question is if I buy a new 3LDZ which version works best on the 930s? |
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07-21-2007, 11:32 AM
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A fellow Pelacanite
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I looked on PET, there is only the gaskets you changed, no seals.
A K27 turbo will be better than a K26.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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07-21-2007, 02:23 PM
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