3.2 Missing Badly

[APKhaos]

My virgin 85 engine has me worried. Towards the end of a 4 hour run yesterday,
it showed its first sign of trouble.....
Cruising between 3000 and 4000RPM in 5th, any slight increase in accelerator
pressure produced a really nasty miss. The car would shake, buck, and
generally act like the engine was converting itself into a core in quick
time. Pressures and temps were fine. Same thing happened in 4th gear. After
a few minutes of sweating bullets, I found that going hard on the gas
produced normal acelleration - although a slight increase in gas pedal still
produced a violent miss.
The whole episode lated around 10 minutes, then the symptoms vanished -
everything normal again. Exept for my sphincter, which remained three knots
tighter the rest of the way home.

It had been raining all day. New plug wires, rotor & cap, and great leakdown
results just a few months ago. Ran it again late last night, and the problem is now hard on - missing and bucking at anything less than full gas pedal - not drivable!!
Anyone with a 3.2 seen this or similar
behaviour??

[dtw]

I had the opposite problem- everything BUT full throttle worked. At FT, it sounded like yours.

Thinking I had a moisture problem, I cleaned all the items you checked. Nothing. Finally took it to the wrench who replaced the mass air flow box.

Turns out there is a rheostat inside there that has about four positions that correspond more or less to idle, 1/3, 2/3, and full throttle. The fourth position on the rheostat (FT) was baked. So at that position the motronic didn't know what to do and the whole system choked.

Sounds like this could be the same in your case. The part was $300, minimal labor.

Heheh. My neighbors appreciated me trying to diagnose that one at 8am Sunday morning. With a test pipe and 4" outlet too.

------------------
Dave
1972 911T (E motor) RSR replica project
http://members.nbci.com/dtwinters/garage/

[This message has been edited by dtw (edited 07-30-2001).]

[twin plugged targa]

You can check the air flow sensor easily.
Disconnect harness, looking at terminals number them 1, 2, 3, 4, starting from the left (the last one is a blank).
Now turn off ignition and with air intake boot off, connect digital ohm meter across # 2 and 3 of socket!.
Then move vane inside air flow meter through it's range of travel- resistance should change without interruption!.
Now test the plug with ignition on and corresponding pin # 3 and ground should give approx. 5 volts
I tested mine when I had ign. problems.
Be careful!
Do not assume that because it was raining that it MUST be the cause!.
I made this assumption which lead me down the completely wrong track!.
Do you have a Bentleys?
If not then it is a 100% value for money for this and other easy checks!.
Also once you have done the other diagnostic checks, do not ignore the fact that you may have a problem with your distributor 'end float' (ask me how I know ).
If your dist. cap and/or rotor are damaged then look in this area!!!!.
Again if you do not have a Bentleys order one now (and no I am not on commission)
It has already saved me $$$$$$$$'s
hope this helps - good luck
rgds Ben

[This message has been edited by 86ragtop (edited 07-30-2001).]

[poorsche]

I had the exact same problem your describing. Between anywhere from 2800rpm to 3700rpm slight gas peddle pressure would make car miss violently. But more than slight pressure would be no problem. Very hard to keep constant road speed.

My problem disappeared after much cleaning and checking. Don't know what did it. Took air meter off and cleaned inside with spray. Lots of black soot came out. Replaced O2 sensor, head temp sensor, distributor cap, regapped plugs and cleaned all electrical connections. Also cleaned and lubricated distributor's internal weight things(not sure what they're called or do but mine were seized).Did it all at same time.

I'm interested to know what it was if you can isolate it.

------------------
Joseph
'86 T-look

[APKhaos]

Thanks Guys!
Hit the garage with serious intent to track this down, only to find that the symptoms have completely vanished!! Have driven the car several times with no problem. I'm starting to think that water ingress was the culprit - it was raining heavily for most of the four hour run, and the problem showed up right at the end of the run.
Maybe we've dodged another bullet??
Tony K
85 Carrera