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Join Date: Jan 2008
Location: Lexington, KY
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'85 engine cutting out

I have recently acquired an '85 Euro 930 with a K27. Has not been driven much in last 10 years. Generally the car is fine but when I really put my foot into it to get the boost, it cuts out at about 5000 in 1st, 2nd makes it to about 5000, then cuts out at 3500 in third. The cut out is immediate and shuts the thing down completely until I let off of it. It has a CD unit. If it is not pressed, it will redline. What should I look at to see what the cause of the cut out be? I know nothing about turbos, this is my first after 10 other Porsches. I will appreciate your thoughts. Rob

Old 07-27-2011, 06:11 PM
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Sounds like the overboost switch kicking in. Has the wastegate spring been changed or do you have a manual or electronic boost control? how much boost are you hitting?
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Old 07-27-2011, 06:23 PM
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Quote:
Originally Posted by IMONBOOST View Post
Sounds like the overboost switch kicking in. Has the wastegate spring been changed or do you have a manual or electronic boost control? how much boost are you hitting?
+1 Most likely. When it cuts out (and this is an important symptom of overboost cutoff) does the car buck you violently forward to where your teeth almost smash into the steering wheel....otherwise known as "face in the dash" syndrome? Or is it just going sputter-sputter-sputter loss of power? The overboost protection is really quite distinctive as it shuts off your fuel pumps immediately.
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Old 07-27-2011, 06:28 PM
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thanks. Shuts off immediately and my teeth dont quite make it to the dash, but it is dramatic. Thought I had blown the engine the first time I did it. I dont know enough about turbo charging to tell you what things it has, but lots of work done on the car, I would have to go back through the tickets to see if there are any specific things referenced. Turbo was upgraded in 87 after import
Old 07-27-2011, 06:37 PM
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Sorry, ...electornic boost control and I dont think the bar gauge is workiing
Old 07-27-2011, 06:39 PM
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OK then, either you are truely overboosting (close to 1.4 bar) and activating the overboost pressure switch, or the switch itself is defective and tripping under normal (safe) boost levels. First things first....get a working gauge, and/or disconnect the electronic boost control.
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Old 07-28-2011, 04:46 AM
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If it has not been driven in 10yrs...Things do gumm up..--FUEL HEAD-TAKE APART-

Italian tune-up--Heavy dose of MMO-Marvel Mystery Oil-Gasoline...White smoke should appear out of the exhaut...ALOT-.Don't be alarmed...If that doesn't cure it.

I would change- empty gas tank- sparkplugs-fuel fuilter-oil filter-pumps-injectors-chk fuses-etc..etc..
This is what I did for not driving mine for over 10yrs,

GL
Walt
Old 07-28-2011, 05:00 AM
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Cool

Thanks to you all. I am on my way to try to get at these things. I agree, there needs to be some additional internal tune [clean]-up. I will keep you posted.
Old 07-28-2011, 05:59 PM
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Posted about a month ago with similar condition, turned out to be tank of bad fuel.
BP had dreaded E 10 in their premium and my 84 was not happy til I ran that tank out and filled with fresh pure 92 octane. But what Mark is saying is very true, I thought my issue was
either overboost or one of the fuel pumps cutting out and starving it for fuel.
Old 07-29-2011, 03:35 AM
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not driven in 10yrs - wastegate's not opening?

OB cutoff kicks in @ 1.2bar IIRC

when I bought my car I went through exactly this, it wasn't driven often (tho not like yours in 10yrs) and the WG was frozen solid, had to put another on there

either that, or your EBC is programmed too high

it's likely overboost related, not tune up or anything else - 5k is where you'd hit OB in 1 & 2, and 3500 is where you'd hit it in 3rd so it correlates pretty tellingly IMO

good luck
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Old 07-29-2011, 04:55 AM
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Yes, I'd say that is "telling" . I am off to Parade. This will be for when I get back. Thanks for all the input! I will appreciate any other comments though while I am there.

Old 07-29-2011, 09:42 AM
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