Rough starting | No Related Codes | 1998 V70 N/A 350k km

[yanga001]

Hi everyone,

its been a while. Recently the reliable wagon has developed a bit of an odd behaviour where on startup it sounds very rough and the entire car shakes as if its misfiring. I've checked all fluids (all within spec), have recently changed the ignition coil and did sparks (NGK iridiums) about 60k km back. PCV was done 50-60k km back and i replaced the vacuum line from the intake manifold to the connection by the throttle body. The car runs great when its warm but after i start it, run it for a while, turn it back off it seems more likely to rough start.

Additionally, cold weather seems to make it worse although it is not consistent.

I used VolFCR to monitor while running and check all codes across the system and i ended up with the following:
ABS-141 EBD Pressure Switch Signal Fault
and a emissions related one for catalytic converter efficiency.

I know my distributor cap is fairly old and am going to email a friend to see if he has a spare one along with a spare cam position sensor (took one out of a parts car i might be selling off).

I replaced the airbox recently, cleaned the maf recently, checked all vacuum lines recently, and have switched to full synthetic 5w30 recently.

I have been burning approximately a qt of oil every 3000-4000 km's and filled it recently.

On startup in some weather i have the blue plume but it does not continue after warmup. Additionally it looks like a good amount of condensation but i am not loosing coolant at an equivalent rate nor is the oil chocolate milk looking. I did see some little black spots in the coolant (Zerex G05) however it did not look like the consistency of motor oil. I flushed the coolant partially earlier in the year and will chalk that up to contamination.

My ECT i think is good as it warms up nicely and seems to run strong after the startup.

I am not in a situation where it stalls out, even when it runs rough but i would like to fix it sooner then later.

Thanks for the help everyone!

[yanga001]

Update:

Removed and cleaned idle air control valve. It was original from 1997, had some deposits which i hit with a laser optics cleaner (meant to scrape off burnt on materials from glass). It seemed to fix issues i had with a lot of condensation in the exhaust and the rough idle is still there but far less worse. I am going to check the remainder of the ignition and vacuum lines.

[454cid]

Update:

...some deposits which i hit with a laser optics cleaner (meant to scrape off burnt on materials from glass).

Wow, that's not something typically found in a tool box!

[yanga001]

Update 11/01/2022

Tried starting this morning and the rough idle was back but not as bad. I am thinking its something vacuum related and am looking at replacing a lot of the lines with silicon tubing.

Also looking at pulling a battery + cable out of my wrecked car and swapping it into this one as there is corrosion within the sealed area, it tends to heat up a good amount.

Slated time in the spring to replace the radiator as it has a slow leak (drips or drops come out in certain scenarios) which i think is the reason why the resovoir slowly drains. If i have a blown head gasket then id expect my oil or coolant to have changed colour based on the intervals ive added coolant to it. It has not changed consistency or colour.

Was reading through the forum and had an idea for a variable windshield washer array based on some previous implementations. Digikey sells PWM controlled variable resistors which one could connect to an AVR chip and tap the interval control for taking commands. A certain pattern could trigger the wiper to go slower or faster and another for resetting it. Still in the draft stages.

[yanga001]

Update 17 / 01/ 22

Does not seem to be as temperature related as i thought. seems to be more humidity related.

Sourcing tubing to try and replace all vacuum lines. Will also replace the battery + cable with the one from the pulled car

[tiberious1001]

I'm in the same position as you. Volvo 850 petrol N/A about 450,000km. I've done everything you've suggested and only about 10k back. Replaced/cleaned PCV. All new silicon tubing with PCV and vacuum lines, cleaned MAF etc... Pretty much only happens in the winter and nothing helped. I live about 100 meters from the sea so it can easily get to 100% humidity and extreme weather with 80+mph winds and heavy rain and to me the cold is the biggest issue as during summer the problem pretty much doesn't happen.

Two things I noticed, i have a cement walkway that I park the car under most days. When parked under it, the problem is almost gone. Park it outside with no cover during a frost and it can be so bad it's a struggle to even start the car.

Might be on the wrong path but 2 possibilities I can think of. One a leaking injector flooding one cylinder or maybe a hairline crack in the head gasket. Could both be made worse with temperature.

How is your fuel consumption like?

[abscate]

Tiberious, what’s the condition of your cap, rotor, plugs, and wires?

Any moisture in those parts will cause massive problems when they get old

[tiberious1001]

I forgot to say the only thing I haven't changed is the distributor or leads. Cleaned and sprayed the cap/rotor contacts with contact cleaner then WD40. Plugs are less than 10k old and Volvo brand. Changing them didn't make any difference. Leads are Volvo and haven't changed then since getting the car 7years/ ~160k km ago. Only thing I'm noticing really is fuel economy is not what it was but I don't know if that's just what to expect with the amount of distance done on the motor and nothing to do with the start up and rough-ish idling.

[abscate]

The contacts need to be bright and shiny brass , clean with a sharp scout knife or equivalent

You don’t want any oil on them so clean off thst WD40

[abscate]

The cap and rotor on these cars are such high quality that we forget they are maintenance items. They can go 100k before starting to cause fussiness.

I think we caught Professor Potato with a bad cap earlier last year, too