Hi All,
First I will introduce myself because I am new on here. My name is Jon, I am a
complete amateur at auto mechanics and I am a first time Volvo owner. I have a 1993
960 wagon with the 2.9 liter straight six. I bought it very used and very cheap and
immediately put about $3,500 into repairing its various issues. Right after it came
out of the shop I started having strange idle surge symptoms and hot start problems
that were occasional at first but have advanced into a constant problem that has left
me stranded for an hour or more several times. Now, when this car is running well it
is a quick, comfortable beast of a machine. However after several misdiagnoses, a lot
more wasted money, and a scalp scratched raw, I am almost regretting this purchase.

I am positive that everyone else on here knows more than I do about these things
so I will detail my problems and ask graciously to borrow your brains. Thanks...

Here are my symptoms:

1. Intermittent Idle Surge: from 750(normal) up to 2K or 2.5K especially when car is
warm at normal running temp. and worse when car is put into park after 15 or so
minutes of driving time.
2. Intermittent Hot Start Problems: (here intermittent means 9 out of 10 times
however recently when car was overheated, run hot for several minutes and then
killed, the engine started right up with no problems) Usually the car will not
start for 20-30 minutes after being driven, if it does crank it will die unless
you floor the accelerator and keep it at 1K to 2K rpm for a minute or so.
3. Oil looks foamy and smells strongly of gasoline: After I recently overheated the
engine I checked the oil and it looked light in color, foamy, and smelled like
gas badly.
4. Runs rough at any RPM above 1700 or so: During normal highway driving the RPMs
will choke back a notch or two as if the car is about to backfire and stall but
it has never stalled while driving nor does it actually backfire. You can just
feel the power surge back and jerk a little and the exhaust may "fart" or "poof".
5. Intermittent Cooling Fan Relay Issues: The cooling fan relay has been very
recently replaced but lately it has been acting up again. Sometimes the fan will
switch on and off appropriately, sometimes it won't cut on at all and will allow
the engine to overheat, and sometimes it will not shut off even after the car has
sat idle for some time and will drain the battery.
6. Loud hissing noise coming from under the car almost dirctly in between the front
rear wheels and slightly to the left of the center (closer to the driver's side).
This may very well be normal because it is not intermittent and I know there are
a lot of vacuum mechanics at work in these Volvos.
7. Intermittent Dash Error Lights: I noticed just recently as the car was running
hot that the transmission error light (the little upward arrow) was flashing on
the display, and the trans. mode switch near the shift stick was flashing back
and forth between "W" and "E". However after killing the engine and turning the
key on and off a few times the dash warning went off and the mode switch stopped
flashing. The check engine light is not on and I have not had codes pulled.
8. Car generally runs a little rich and intermittently blows white exhaust smoke.

Here's what was done to attempt to repair the problems. However none of the attempted
fixes has done anymore than temporarily relieve one or two of the symptoms. After 20
-30 minutes driving time the symptoms always return and sometimes worsen.

1. Replaced cooling fan relay and tightened the ground.
2. Replaced Fuel Pressure Regulator
3. Replaced much of the vacuum hose with silicon hosing and relieved several kinked
hoses with elbows. This was done as a result of a positive smoke test.
4. Replaced Throttle Positioning Switch
5. Replaced air filter and changed oil and filter
6. Replaced ECT sensor (however since the repair was not done by me I am not sure if
it was the front or rear coolant sensor that was replaced)
7. Replaced O2 sensor
8. Flushed out catalytic converter with a little warm water and got a lot of black
sweet smelling black soot and smoke.
9. Sucked a little warm water into the intake which temporarily smoothed out some of
the rough idle issues.
10.Repositioned an improperly placed harness plug going into the ECU. The morons at
the Euro specialty shop I used plugged the harness into the ECU backwards.
11.Listened to the pre-fuel pump in the tank and it sounded like it was working fine.
12.Did the quick gas cap test and didn't hear anything unusual.
13.Unplugged the TPS MAP and FPR while running and observed the expected normal
results.

OK now you know as much as I do. I love this car but its rough running ways have got
me and several others confused. If anyone has any suggestion I would greatly
appreciate it.
Thanks,
Don Jon

 

I would check and see if the ECT on the back of the head has been replaced. If not replace that first. That can almost cause everyone of the problems you have.