S60 2.5T misfire

veektor · Post by **veektor** » 10 Jul 2019, 14:10

Were there other codes in addition to cylinder misfires? I made the mistake of ignoring "IAT sensor circuit" code on my BMW when it started misfiring, thinking it was complaining about the sensor that tells me how hot it is outside. I got busy swapping coils around, then noticed a loose connector. Turned out IAT measures temperature at intake manifold, and is an important input for ECU for ignition timing. All misfires stopped when I reconnected that sensor.

Multiple cylinders misfiring at once, when they all previously worked fine, makes me suspicious that something else is happening. Look around the engine bay for cracked air and vacuum hoses, you may have a vacuum leak. ECU relies on MAF to provide inputs about air flow, and vacuum leaks introduce unmetered air to the system, which mucks up the complex ignition algorithms.

Hawgdalton · Post by **Hawgdalton** » 10 Jul 2019, 16:18

Just an o2 sensor lean on bank 1

Hawgdalton · Post by **Hawgdalton** » 11 Jul 2019, 07:48

Ok so got the cover off to get the coils and the is oil sitting on top of the motor. Look like it coming from the fill neck. Any ideas?

Post by **oragex** » 11 Jul 2019, 08:29

The gasket on the cap may be leaking (pretty common). May try a new cap (I got a similar gasket from a hardware store instead) https://www.fcpeuro.com/products/volvo- ... -8692888oe

Hawgdalton · Post by **Hawgdalton** » 11 Jul 2019, 08:36

In addition to the oil on top of the motor it appeared that the #2 cylinder plug was wet with oil. could this because the car was misfiring or could the oil be leaking down from the top? the gasket on the ignition coil was wet.

veektor · Post by **veektor** » 11 Jul 2019, 10:07

I had to deal with oil on top of the valve cover when I swapped in an engine from a junkyard donor. I actually noticed the same oil pooling when the engine was still in the boneyard, but chalked it off to PO topping off without a funnel. I washed the engine off really good before dropping into Astrid, so I got concerned when I noticed the oil pooling again. Turned out it was missing a couple of bolts that hold down the valve cover to the head. Unless you look very carefully, it is easy to mistake that bolt for one holding the coil pack in place. Also, when the plastic cover is off, you have threaded holes for those bolts, which makes it easy to spot a missing valve cover bolt. Look at the attached picture of my valve cover with oil all over it. I highlighted coil pack bolt in blue, and valve cover bolt in red. Actually, if you look closely, there is a threaded hole in the Y of wiring for coil #5, I think that's the one I was missing.

I don't remember if I was getting any misfire codes at the time, but it is a significant hole in the vacuum system. Whether your problem is a missing bolt (or two), or leaky fill cover gasket, if you are leaking oil over the valve cover, you are also leaking air/vacuum. Find that leak before you start swapping coils and plugs.

: astrid_oil_valvecover_marked.png (931.66 KiB) Viewed 1755 times

Hawgdalton · Post by **Hawgdalton** » 11 Jul 2019, 10:55

Thank you all so much for your help. I replaced the plugs which were very worn and the coils and car runs like a top. Will have to likely replace the PCV system in the near future. Conducted the plastic bag test on the oil fill and it did not suck it in but that will have to be for a another day. As far as the missing bolts I did not find any and it appears the oil is coming from the fill cap or have a new on ordered.

Post by **oragex** » 11 Jul 2019, 11:11

Good news! The PCV on the turbo engine is quite tricky, members here will help you with a few tricks/tools required if needed

veektor · Post by **veektor** » 11 Jul 2019, 12:18

Hawgdalton wrote: ↑11 Jul 2019, 10:55 Will have to likely replace the PCV system in the near future. Conducted the plastic bag test on the oil fill and it did not suck it in but that will have to be for a another day.

I'm glad to hear that plugs and coils solved the misfires. My advice on PCV replacement is don't put it off too long. The reason I had to swap engines was because clogged PCV caused excessive crankcase pressure, which resulted in rod bearing wear, destroying #2, and circulating the metal shavings through the rest of the oil passages. I've posted some gory pictures from my engine tear down last year. Search for my 'project Astrid' posts if you need motivation to expedite PCV replacement. I have read that a common work around to relieve the excessive crankcase pressure is to pull out the dipstick slightly from its tube, allowing some gases to escape that way.

Sorry if I sound like the proverbial ER nurse who won't let her husband ride a motorcycle. I had spent many hours trying to get Astrid running, from inspecting rod bearings underneath the vehicle, then pulling out, tearing down the engine, and ultimately swapping with a junkyard donor. I have looked the Evil in the eye, and it looked like a plug of black soot, clogging the lower PCV orifice. I get easily triggered by those three letter.

Post by **cn90** » 11 Jul 2019, 16:27

Hawgdalton wrote: .......I replaced the plugs which were very worn and the coils and car runs like a top. Will have to likely replace the PCV system in the near future...

- You probably did need to replace the coils. But anyway, now you have 5 spare coils. Keep the old ones as spare or sell on ebay LOL.

- The oil on top of valve cover is likely from oil change fill-up spilling...
This is why I remove the cosmetic cover and store it (along with the Torx bolts) on the shelf of my garage.
This way any oil spill can be seen and cleaned.
Also, any water (do NOT wash engine with a strong water jet!) can also be seen and qiped clean before it ets down to the coil.

So yes, do not re-install the cosmetic cover.

S60 2.5T misfire

Re: S60 2.5T misfire