1999 S70 NA PCV system fix caused misfire

[kyalami321]

You fried ignition coils and who knows what else.
I told you that you messed something up.

How embarassing Ok so other than scrapping the project, and besides replacing the 02 sensor, how can I diagnose the mess I've made? I have a fancy multimeter I could use to diagnose.

[misha]

Replace coils first,then intake gasket,install etm properly.....fix everything.
Bad o2 sensor is not the reason of your symptoms or problems.

[abscate]

Nope. The zzzzt was when you were reconnecting the starter wires and you shorted them to the block. That's really dangerous by the way. The current can weld your wrench to the metal tand then discharge your entire 1kW battery charge in a few seconds

Have a good luck at your wiring looms under the manifold to make sure you didn't damage them

[Sommerfeldt]

Well... The car starts and runs, so the damage can't have been too extensive in the electricals...can it? I hate electricals - it's the only thing which never seems to make sense to me, at least.

Anyway - just to rule out the absolutely most basic thing that could cause your troubles... You're sure that you put coils and plug wires back in the right order...?

- S

[abscate]

The coils need to be tightly screwed down as the 10 mm bolt is the ground point. With the original wiring harness I don't think you can mess up the coil plugs but the looms often self destruct on older cars, so it's worth checking , especially cylinders 4 and 5

[kyalami321]

The coils need to be tightly screwed down as the 10 mm bolt is the ground point. With the original wiring harness I don't think you can mess up the coil plugs but the looms often self destruct on older cars, so it's worth checking , especially cylinders 4 and 5

To what do the looms on the coils connect to? I see that they lead somewhere to the right underside of the engine block ... also, with a multimeter, what's the best way to diagnose whether the coils that don't work are getting power?

[abscate]

Scour threads for 1999 v70 t5 coil measurement where yours truly measured and assigned pins ( I think)

The coils get 12 VDC with the key on, all the time and are fired by the ECU by grounding on command

You need an oscilloscope to diagnose these other than confirming supply voltage and ground

I have cross referenced most of my DIY threads in my maintenance log ( public) for my 1999 V70 T5 Nautical Blue thread

linked here, plus I bumped it by adding pinouts.

https://www.matthewsvolvosite.com/forums ... 45#p375145

[kyalami321]

Scour threads for 1999 v70 t5 coil measurement where yours truly measured and assigned pins ( I think)

The coils get 12 VDC with the key on, all the time and are fired by the ECU by grounding on command

You need an oscilloscope to diagnose these other than confirming supply voltage and ground

I have cross referenced most of my DIY threads in my maintenance log ( public) for my 1999 V70 T5 Nautical Blue thread

linked here, plus I bumped it by adding pinouts.

https://www.matthewsvolvosite.com/forums ... 45#p375145

OK, so I tried two new coils from another S70 and no dice. Coils aren't the problem.

On both one "good" cylinder and one "bad" cylinder, I get the following.

PIN 1 = 0 VDC
PIN 2= about 5 VDC
PIN 3 = 0 VDC
PIN 4 = about 12 VDC

What's my next step? Pin 2 should be ground, meaning 0 volts, right? Are malfunctioning fuel injectors for those 2 bad cylinders a possibility?

Thanks so much to everyone for your help thus far.

[misha]

Since you had "sparkling" adventure in process of pcv replacement,i would not be surprised if you burnt ecu or at least some relays.

[kyalami321]

I'm gonna check the 12V green wire on the injectors as well as the relays that are to the left of the cooling fan. Maybe those are causing the problem.