I just had a very worrysome thing happen while driving my '87 911.
I adjusted the valves and changed the oil last week. I noticed the car smoking "more" than usual on the 80 mile drive home. The idle was also a bit stumbly. It would drop to 600rpm, stumble around and then hike back to about 850rpm (my idle has been a bit rough for the past 6 months... this was just more rough than normal).
I figured that my first attempt at valve adjustment was not up to par and I'd have to recheck everything ASAP.
The next day, while driving in traffic, the car seemed to lose power (under mild acceleration). It lasted about 1 second and then returned to normal. Sort of a hiccup. The car didn't die, it just wouldn't respond to more gas... like it was bogged down.
Today I decided to recheck the valves on the passenger side (and the headstuds). A couple valves appeared loose, so I tightened them up. Then I went for a quick drive to see if I noticed any change in valve noise.
About 10 minutes into the drive (oil temp at 160+-... not totally warmed up), I pulled out onto a 55mph road and gave it a quick 5-60mph burst (switched gears before 5k rpm). It felt smooth and fast. I was just congratulating myself when the motor bogged down. I gave it some gas, then some more gas... nothing. It would not respond to throttle input.
Fortunately I was heading downhill, so I pushed in the clutch and started to coast. I noticed the RPMs would oscilate from 200-2000rpm, as though the computer was feeding fuel to the motor to keep it from dying. Up, down, up , down. I blipped the throttle but nothing happened.
I released the clutch and tried to give it a little gas, but it just bogged again. The motor would not respond to throttle input.
With the clutch in I coasted down the hill. Watching the tach bob up and down like someone else were tapping my throttle. I pulled into a parking lot ((high "G" right hander), and coasted to a stop with the clutch in.
I sat there shaking for a minute... then noticed the idle had retuned to normal. I gave the throttle a blip, and the motor responded. I pulled out of the lot, and headed home. The "hiccup" did not return on the 2 mile drive home.
Does this sound familiar to anyone? What could cause this.. DME relay, Head Temp sensor (I have the original 1 wire), TPS??? The car runs very well, except for this.
Please help me sort this out before Winter sets in. I'd like to drive a bit more before the long, cold, sleep.
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Dan Tolley
1987 911 Coupe
http://www.cheaterswayside.com/911/gallery.asp?sort=0&userid=294