Turbo Blahs

[WWDTM]

I am having problems with my 1986 930 ( 911 turbo). With the accelerator fully depressed and the rpms climbing to 3200 RPM,when the turbo is to kick in the engine bogs down until the accelerator is released slightly. The turbo will generate 0.6 bar as indicsted on the dash gage but not if the pedal is fully depressed. If the accelerator is not fully depressed then I can generate about 0.4 to 0.6 bar with out too much issue. I also notice that the fuel consumption seem high at 20-21 litres per 100 KM or 11.5 to 12.5 miles per USgal. I have changed the fuel filter,the air filter and the ignition coil. Any ideas on where is should be looking to solve the turbo bog.

[9dreizig]

Look at a couple of the threads going on here, there are a few things you need to check..
How does it start/ idle?? Can you get full boost ?

[WWDTM]

The Cars starts easily and idles fine. I do not get full boost because as soon as I depress the accelerator too much it bogs down. I get about 0.6 bar at the dash gauge. It seems to get more boost before it bogs down when the outside air is colder i.e. in the morning or late evenings. I drive the car at approximately 4000' elevation.

[RarlyL8]

Could be that your WUR is dumping too much fuel on boost. Do you have a way to check the AFRs with an air pump or on the fly?

[AFM744]

Also, are you getting brown/black smoke when it bogs? Does it bog if you floor it in neutral for a sec, or just under load?

If it shuts off abruptly I'd say your wastegate isn't working and you're getting fuel cut-off. If it bogs under load I'd be looking for ultra-rich exhaust smoke to support that theory.

[WERK I]

So many questions to ask regarding this problem....

1.) Is the engine stock?
2.) I noticed you are new to Pelican. Is this a recently purchased car? (This may have been going on for a while prior to you acquiring the car) or....
3.) ......Is this a new development?

That aside, I would check everything on the pressure side of the intake. In other words, from the outlet of the turbocharger to the intake ports of the engine. This would seals, IC, Blow-off valve or recirculating valve, throttle body, manifold.

Check to see if the distributor is advancing/retarding correctly. Check for binding in the advance mechanism in distrib. Check vacuum lines to distrib.

[beepbeep]

As other people mentioned, check for obvious air leaks (intercooler O-rings to begin with).

I believe it bogs beacuse of over-rich condition. You either have control pressure too low or there is lot's of metered air leaking out.

Pressurize inlet (check Alan L,s posts on this) and find leaks. When that's done, check your CIS control pressure.

[WWDTM]

Thanks for the suggestions. The engine does not bog down in neutral only under load. I have no way at this time to verify the AFRs. when in bogs down the smoke is definitely black suggesting rich mixture. The engine is all stock. I have had a suggestion that it might be the O2 sensor because when the engine is cold it doesn't seem to bog down (as much) I will check for leaks on the pressure side.

[mark houghton]

Nope, it aint the 02 sensor. That little jewel really only affects mixture at low rpms. You're definitely rich as a pig. It's probalby - IMHO - the WUR not controlling fuel pressure correctly when under boost. One way to find out would be to disconnect (and plug) the boost pressure hose that goes to the WUR. If it doesn't bog, then that may be an indication of a problem with the boost circuit in the WUR. But I wouldn't recommend running on boost without the hose connected, 'cause then you run the risk of running too damn lean and melting down. If you try this test (and I never have) then only for a very short period.

That's the worse case scenario. Check the obvious stuff first, like o'rings/hoses/pipes to/from the turbo and intercooler. Usually, though, leaks in those areas also can cause rough idle symptoms...which you don't seem to have.

Have faith, you'll find the cause. Keep us posted!!!