94 LHS Intermittent Engine Cut-out

I have a very odd problem with my 94 LHS, 3.5L (as they all are). It runs
fine below 1500 rpm, but above that, it cuts out erratically. It is not
setting any codes. The dealer connected it to the diagnostic computer and
they say the crank and cam sensors are getting un-synchronized and that is
what it shutting it down. It shuts down for a a half a second, and then runs
for maybe 2 seconds. It has never quit on me, but it's not really driveable
either.

Timing belt looks great. I put in both sensors new, no change. Swapped
computers with another LHS, the problem didn't move. I'm not sure what to do
next.

Has anybody seen this before? The car's not worth much, so my attempts to
fix it will be very limited. I like it, though, and I'd like to keep it. I
have two 94's so I can test theories at will, if anybody's got one.

 

A couple long shot thoughts since you have replaced both sensors and tried a
new computer too: How good is your battery? Have you cleaned and checked
all the grounds to make sure they are making good connection?

Bob

 

If you've replaced both sensors, check wiring. Another (long shot)
possiblity is that the torque convertor flex plate is cracked and the
vibration is corrupting the crank position sensor reading (which reads
slots in the flex plate).

 

I agree that these are the most promising other possibilities. Thanks for
the replies!

 

try new plug wires and plugs

 

Already did, thanks. It's not that kind of a miss, though. It's like it
shuts completely off for a full revolution, and then it goes again.

I found something else out: As I said in my original post, the diagnosis is
the cam and crank sensors are getting out of sync, and it doesn't know what
to do until it syncs back up. The FSM says it can only sync up on 1 or 4,
which is kind of interesting. That way, if it gets lost, it might have to
wait a while to start running again, which appears to be what I'm seeing.