rough idle 93 850 Topic is solved

93 & 97 850's · Post by **93 & 97 850's** » 07 Nov 2003, 04:41

Unregistered

I have had a rough idle problem with my 93 850
for two years

the following things have been replaced:
fuel pump relay
plugs (oem)
wires (oem)
cap/rotor (oem)
fuel filter
air filter.

cleaned trottle body
check all vacume lines

disconected and reconected all elec. conections 10 times or more

is there any thing else I can try or do, the car is 10 years old w/98k
on it so I dont mind replacing small parts with out proof there are bad.

93 850 glts 98k 5 spd
97 850 sportwagon 70k
00 saab 9-5se 34k

Guest · Post by **Guest** » 07 Nov 2003, 13:16

If your compression is even between all the cylinders I would suggest a good carbon cleaning to remove valve stem buildup. The carbon buildup will soak up the fuel causing uneven fuel mixture. We have found them so carboned up that the valves can no longer seat. Volvo suggests a good hard drive once in a while to clear out the carbon.

93 & 97 VOLVO · Post by **93 & 97 VOLVO** » 07 Nov 2003, 13:29

I did the italian tune up the other day 5000 rpm in second gear
for 5 minutes

still no change,

the car is my comuter and dose not get a lot of highway miles
if any. So every chance I get I rev it high between shifts at least
4500 rpms

Guest · Post by **Guest** » 08 Nov 2003, 05:06

Rough Idle = RPMs go up and down unevenly = car over compensating = Throttle body and Idle Air Control, possible ECU problem like overheating

Rough idle = vibration = uneven fuel or uneven air or uneven power = compression test or clean fuel injectors (go for cheapo solution first like pour bottle of fuel injector cleaner into petrol tank), different level of wear in valves and or spark plugs

quite simple really.

93 * 97 850's · Post by **93 * 97 850's** » 09 Nov 2003, 05:30

I just went through a tank of super with tectron in it still
rough idle,

It feels like the timing is off, I feel vibration at the wheel
while idling, the engine dose not sound super smooth
either, but has been doing that for years

the car has even power, no over heating

changer the thermostat last year

rodsob · Post by **rodsob** » 11 Nov 2003, 21:59

your O2 sensor is sending the wrong signal to the ecu. the rough idle is caused by the ecu telling the injectors to run lean/rich when it shouldn't. does the tach needle move around at idle? if so, the o2 might be the culprit.
my guess is that you used some cleaner (carb cleaner or so) that is not o2 safe. change the the o2 and let me know how it works.

rodsob

93 & 97 850' · Post by **93 & 97 850'** » 12 Nov 2003, 04:42

I have the o2 sensor changed two years ago, durning that time
it still idled rough, I was also careful to use o2 safe carb cleaner,

I did not just spary it in the opening, but soaked a rag and
wiped it out the best I could, at the time I cleaned the flame
trap.

digital2 · Post by **digital2** » 14 Nov 2003, 06:43

excuse me but O2 sensor lasts approx 60K km, if u have used that mileage its time to change, the mass air flow is always the culprit also in idle problems,

1) disconnect and connect back the MAF connector

2) tie up the connector so that it does not flex with tie rods

93 & 97 850's · Post by **93 & 97 850's** » 14 Nov 2003, 10:37

My 93 850 only gets 5000 per year on it the o2 sensor was changed
at 88k the car now has 98k, I did the maf disconnect and zipped
tied as per bay 13, I also disconnected and reconnected all the
connections and add connection grease about a month ago.