Runs rough when hot from stop at low revs.
Pulls great from 2-5 smooth.
pulled MAF, no difference.
Cleaned IAC and throttle body.
Replaced TPS, thermostat, ECT, voltage regulator.
Can read and reset codes.
Hi all.
long time lurker, first time poster.
Your help has been awesome, and i would like to thank all contributors.
Now my story.
Bought this 96 850 for $500 6 months ago, owner said there was an ABS fault that their mechanic had thrown sensors at and was unable to fix and an acceleration issue that was intermittent.
Had to fix the ABS for RW, found the prob through this site, dry/cracked solder joints, too easy.
Chopped that bad boy apart(someone else had been there before me but didn't do a good job).
Gave it to the junior engineer at work and he fixed it for a carton.
Bought a cheap ODB2 Bluetooth scanner, worked out how to use volvo850Diag.
Read and cleared the codes, light gone on dash, only code was for the ABS.
I'm feeling good, got Vince registered and started to drive him around a bit so i could diagnose this strange acceleration issue.
Vince never got hot enough during these first few months, i didn't know at the time that he was supposed to run at 30'clock on the gauge.
The acceleration issue is strange, during these first moths, heat at 4 or 5, at times when i tried to take off from a stop it felt retarded/held back a little bit missing but not quiet.
Had a look around, found a sensor on the air box, googled, disconnected that guy and drove around, problem still exists.
Next sensor along, the TPS, tested it with my digital multimeter, did not seem to climb smoothly, replaced it, problem still exists.
Tested weather i had a problem with the PVC, glove got sucked into the engine a bit, so good negative pressure.
Cleaned throttle body and IAC, tested IAC operation by running with the tube off, it opened straight up on start, while off the IAC has a small gap.
Battery went flat, someone left they key on while charging a phone.
Got battery replaced, was a bit sad anyway.
Read that the alternator i had should be producing 14V, mine read low 13's.
Bought and fitted new voltage regulator.
Vince hardly started and ran very rough, i had disturbed the ECT connectors, they were in bad shape.
Stripped cleaned and reattached, car went back to normal (still intermittent acceleration)
Tested the ECT, was giving intermittent bad readings on the ohm meter.
Ordered a new ECT and thermostat.
Fitted them today, reset the computer, bled the air (new thermostat didn't have the bleeding thingy)
Started and idel was rough and low 7-800, temp starting to build past what was normal.
Idel smoothed out but wen to nearly 1500.
Im thinking WTF.
hit the accelerator and it dropped back down to ~1000.
Took it for a drive and it ran sweet, no hesitation at all.
Got it hot enough for the fan to come on for a short while.
Stopped the car for about an hour.
Took it out again and it was running very rough, like barely moving from a stop, coughing, spluttering until the revs got up a bit, then pulled normally.
So tomorrow i am going to see how Vince drives from deal cold, and will provide further information if i get any.
