ehall

I have an 86' 951 that has recently begun to suffer from a periodic shutdown under heavy accelleration. It also occurs under passing situations in 4th gearat around 80 to 90 mph.
When it occurs, I lose complete electric and engine. This happens just long enough to provoke heart failure or involuntary bowel movement, depending on the traffic condition involved, and resolves itself just as instantly. I have noticed a voltage gage fluctuation when tis happens that resembles a politicians polygraph lines. Where should I start? Fuel filter? DME relay? Coil? Dist? HElp please!

Rich Sandor

check all your grounds and electrical connections first..

fast951

When you say "Complete Electric" do you see the "warning" lights on the dash, or literally nothing?

ehall

Would a lose ground cause a total failure including engine shutdown? If so it makes sense because of the dureation of the event. Thanks

ehall

By complete electric, I mean a total system failure, including engine. It lasts less time than I feel I could count zero-onethousand, I'm going to start checking for ground probs, but this only occurs under hard acceleration. I was thinking that this should happen much more often if it were simply a loose ground. Reelly baffled. Thanks

James Herne

Something similar śtarted to happen to my car after rising the boost pressure.
It was like this - when driving 4th or 5th gear with low rpm (approx 2000), and then hardly stepping on the pedal, car started to accelerate and suddenly motor lost all power. I think there was some misunderstood about the pressure in the DME/KLR. Then when driving mildly for about a minute, everything was OK again. But this might not be the problem with your car.

alpenweissisnice

I understand the whole "involuntary bowel movement" comment related to experiencing a cut-out of any kind...My car (I discovered) will suddenly cut out under full boost when the gas tank is damn near empty...It is a scary moment. As for the eletrical failure, I honestly didn't notice, as I was under full boost and running at about 90...I haven't experienced the problem since. I thought perhaps it was overboost protection, (and maybe it was, in the end) but the only variable was the gas tank being almost on "E"...Filled the car, no problems since. Let us know what you find...

Danno

"By complete electric, I mean a total system failure, including engine."

Do all your gauges die? Like the tach and speedo?

ehall

Yep. All gauges die too.

schless

I HAD THIS EXACT PROBLEM
It turned out that the vacuum line to waste gate from the 'cycling valve'. Tit that comes off cycling valve broke and WASTE GATE GOT NO VACUUM TO OPEN UP!. Boost goes to HIGH and the DME shuts off the injectors.
FIX-GOT A PIECE OF BRASS TUBE FROM HOBBY SHOP, CUT TO 2" LONG AND JAMED INTO CYCLING VAVLE then hooked vacuum line from wastegate back on.

ehall

Thanks for the idea. Any thing else I should know when I look into this? Is there a test I can do to see about vacuum valve? Sorry for the delay reply. Long month.

kevin Dubois

right now i have a problem just like yours. under very hard acceleration my battery slides back and the positive terminal touches a small piece of metal thus shorting out the entire battery. it will cut all the electrical on the entire car for a second, not jus the DME cutting fuel (all your electrical will still work when that happens, jus the engine stopps running). the short term fix i did was put a rubber gasket over the metal, the long term fix i do tonight, and that is srapping the battery down, so that way i can autocross this weekend for the first time!

Peckster

Your car should have a clamp to hold the battery down. Is your's missing?

User 41221

Another thing to check it your reference sensors. The insulation on one of them in my '84 had fallen off allowing it to short against the engine under hard acceleration (um, okay, its a relative term, and yes, I know I am talking about an NA), causing the same symptoms that you describe. Black tape "fixed" the problem for about a year, until I was doing some other maintenance on the car and got around to replacing it.

Regards,

ehall

Thanks to all who have given me ideas. I will definitely look into the vacuum boost issue, as I know that my battery is well secured. I replaced about 3000 miles ago after the old battery failed. I replaced the right rear hatch struts, that include the defrost connection, and created a short after replacing the broken electric fitting. Shortly after, I began having the problem in this thread. Now I have this problem without heavy rpm load, and I now have a problem at start up withno power and difficulty idling until I rev the engine hard. I am now thinking my original thoughts, that The fuel filter and DME relay need to be replaced, as well as taking a look at the vacuum issue. Let me know if any of you have any furhter thoughts. Thanks again.