1999 S70 NA PCV system fix caused misfire

kyalami321 · Post by **kyalami321** » 11 Aug 2015, 07:36

Hello,

I recently serviced the PCV on my 99 S70 base (230k) using the FCP euro kit. I also changed all 5 spark plugs using Genuine Volvo spark plugs. Right after finishing the PCV service and changing plugs, I had difficulty starting up the car. After getting it started, billows of white smoke came out of the exhaust for about 20 minutes. The engine is also shaking terribly but the idle speed is the correct 850-900rpm. I have codes P0300 (random misfire) and p0135 (02 sensor, bank 1 sensor 1).

During the PCV install, some coolant leaked onto the alternator directly under the hose on the front left side of the engine bay. I let it dry for a day.

Additionally, one of the lower intake manifold screws and two ETM screws split in half and broke meaning they are currently missing from the engine. Battery was disconnected during repair. Pulled ignition coil wires while car was on (after install) and noticed that the two leftmost cylinders have an issue since they don't affect the idle.

Spark plug wells were swimming in unburned oil prior to the PCV service; I dried up most of the oil. Engine has never had shaking problems unless RPMs dropped below 850-900.

What's most likely - vacuum leaks or shorted out/broken ignition coils? Would the O2 sensor malfunction cause engine shake? Looking forward to any possible ideas from you all.

Post by **Clockboy** » 11 Aug 2015, 13:42

I'm not sure if a bad o2 sensor would cause a hard start and the smoke.
If I remember correctly my car continued to smoke a bit on start ups after I did the pcv and that eventually went away.
Did you remove the injectors from the rail when you did the pcv. I know some people leave them in.
If it was a hard start and two cylinders are not working maybe it's fuel/injector related. Usually when I have a seemingly new problem after finishing something it is from something I touched along the way.
I would think the missing bolts could cause vacuum issues and the vacuum issues could in turn cause the o2 sensor to fire off a code. I would definitely get the bolts back in, check all the hoses and then see how it runs.
You could also change the cops to other cylinders and see if the mis follows those two. That would rule out the unlikely event of two cops spontaneously went bad at the same time.
I hate finishing a job only to have something else fail without ever reaping the benefits of the hard work. At least give me a day to enjoy it.
Hopefully someone more knowledgeable will chime in with a more experienced perspective.

Post by **misha** » 11 Aug 2015, 14:17

You messed something up during pcv replacement.
Check everything,especially intake manifold gasket and vacuum lines.
Could be that those ignition coils failed or damaged during pcv system.

kyalami321 · Post by **kyalami321** » 11 Aug 2015, 20:08

I bought some used but guaranteed working ignition coils off eBay that will arrive next week Monday. I will test these and hope that they fix the problem, because refitting all that mess is such a PITA. Thank you guys for your suggestions. Glad to know the O2 system is unlikely to be the culprit; eliminates another possible piece I have to replace.

Post by **abscate** » 11 Aug 2015, 22:25

Additionally, one of the lower intake manifold screws and two ETM screws split in half and broke meaning they are currently missing from the engine. Battery was disconnected during repair. Pulled ignition coil wires while car was on (after install) and noticed that the two leftmost cylinders have an issue since they don't affect the idle.

If the missing screws are near the non-working cylinders then I would get that put right. I would not expect an ETM to work unsealed and improperly mounted either.

Sommerfeldt · Post by **Sommerfeldt** » 12 Aug 2015, 04:22

misha wrote:You messed something up during pcv replacement.
Check everything,especially intake manifold gasket and vacuum lines.
Could be that those ignition coils failed or damaged during pcv system.

This.

- S

kyalami321 · Post by **kyalami321** » 12 Aug 2015, 10:10

I moved some of the coils around to see if it would change, and no dice. After I get out of work I will check all vacuum lines/manifold gasket. I Will report back

If the missing screws are near the non-working cylinders then I would get that put right. I would not expect an ETM to work unsealed and improperly mounted either.

Indeed, it's one lower intake manifold bolt that's near the "dead" cylinders.

Sommerfeldt · Post by **Sommerfeldt** » 12 Aug 2015, 10:29

I don't think I would run the car anymore until you get the gasket checked and that bolt replaced. Also the ETM bolts... All of those should have been in place and torqed down correctly before firing it up in the first place.

- S

kyalami321 · Post by **kyalami321** » 12 Aug 2015, 19:42

Ok I rechecked all my work and replaced all the bolts except two to the ETM, which are broken. No dice.

However, I remember that when I was tightening a bolt right after finishing the PCV replacement, I had forgotten to disconnect the battery. There was visible electricty and a zzzt sound when I struck my ratchet against the engine block. I obviously shorted something out, but could it be the O2 sensor and would that cause misfire through low fuel pressure?

Post by **misha** » 12 Aug 2015, 19:48

You fried ignition coils and who knows what else.

I told you that you messed something up.