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turbo diagnosis - help from the group


Anthony

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Hi group. I have been helping a friend get his turbo sorted after many unsuccessful trips to a local BMW specialist. The car has had so many things done to it, it feels a bit like a big nest of cabling that we are slowly un tangling. 

Background: 

The car is part of a collection of that has a few turbos so I have the luxury of being able to drive cars back to back to compare. This particular car didn't seem to be making boost despite having a new Kuglefischer (rebuilt) and Turbo installed (nos). The car runs like a NA car at then at 5500 it sort of hits a wall and slowly climbs through. Because of the "new" turbo we decided to go through a number of key settings and make sure to reset / baseline before going forward. 

Compression:
140, 140, 142, 140 (4-1)

 

Timing:
25 degrees max

Pertronix in distributor and Pertronix Coil

 

Swapped with a known good unit timed the same  (no change)

 

Fuel curve: 

The rebuilt pump was installed and because they didn't know how to setup the pump correctly, they used the verbotten screw to richen the pump up to attain a stable idle (no threads showing). Linkage rods, throttle cam and pump we all set incorrectly and as a result the car was running very rich. AFR was low 8's and high 7's at WOT. 

289mm rod was measured at 276 - throttle butterfly was not opening correctly. This has been corrected. 

Reset this all and now the WOT setting (logged) maxes out at 11.6 and stays in the 11.8-12.5 range. I can share the log. Curiously at the 5500rpm wall there is a pronounced leaning step on the log of about 0.5 AFR. 

Checked fuel pump pressure with a proper gauge, very stable at 28 psi at WOT as measured at the cold start injector. 

 

Boost limiting valve: 

Thought I found my issue, boost limiting valve on charge pipe was not opening and has a pronounced rattle (not a little rattle but a big rattle). Swapped with a known good unit that I could actuate with my hand and medium pressure. NO CHANGE......hmmmm. This is where I started to really start to think we have a legit boost issue. Maybe I took for granted that this car has a new turbo, I started to look at the manifold for cracks, gaskets etc. Notice that the #1 gasket  (head / manifold) is flipped (who does that?). 

nothing visibly damaged, all clamps in place and tight. 

So that is where I am at. I am prepping to pull the turbo manifold to correct the gasket and inspect the turbo, housing, manifold etc. Prior to that I was thinking of rigging a way to pressurize the cold side of the turbo to see if there are any major leaks. 

 

Thoughts? 


Anthony

 



 

 

Edited by Anthony
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What does the boost gauge say from 3k revs onward? 

10 hours ago, Anthony said:

didn't seem to be making boost

 

'59 Morris Minor, '67 Triumph TR4A, '68 Silver Shadow, '72 2002tii, '73 Jaguar E-Type,

'73 2002tii w/Alpina mods , '74 2002turbo, '85 Alfa Spider, '03 Lotus Elise

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