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DeFreest DeFreest is offline
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Join Date: Apr 2012
Location: NH
Posts: 256
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Strange running 930 after engine rebuild. Thoughts?

I would like to ask the 930 turbo experts for help in diagnosing my poorly running engine issues.
It is a 1987 930 turbo all stock except for a 1 bar boost spring and an adjustable BL-WUR.
This past winter I had a local wrench rebuild the top end of the engine as I had a broken head stud. The car ran surprisingly well even with the broken stud. I installed an Innovate wide band A/F gauge about a year ago and before the rebuild the engine would idle at 13.8, cruise at 14.0 and while under boost run 12.3 plus or minus .2 so it never ran what I would consider lean. I had the A/F gauge on there for a while before rebuild so I know how it ran before all this.
Now after the rebuild it runs lean. I have the idle set to 13.8 and it idles at 950 steady as a rock. When I press on the throttle jus a little bit it immediately goes lean to 16.5 Ė 17.0 and wonít have good throttle response at all. Not drivable at all. All this is taking place while parked and is no different while driving. I donít run it as its way to lean for a turbo. It also will pop when you try to give it more gas pedal.
I checked the WUR and itís right on spec. I even removed the adjustable BL-WUR and installed my stock non adjustable one and it ran the same. So itís not the WUR
Fuel specs are 6.75 bar system pressure.
Non adjustable WUR:
2 bar at 50 deg F cold pressure
3.9 bar warm up pressure
2.9 bar @.5 bar pressure on the boost port.
These specs are the same before rebuild and it ran great.
Timing is set to 2 deg BTDC vacuumed hose installed.

So my question is what would make it go lean just off of idle and stay lean through out to WOT?
Keep in mind this engine has maybe 2 hours on it.
One thing I noticed is there was no vacuum on the hose that hooks to the outside of the pot on the dist. shouldnít there be some vacuum at idle on this hose?

Iím wondering if there is a vacuum leak somewhere.

OK fellow Pelicans what do you think it is?
Old 04-05-2013, 06:34 PM
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