Hybrid Misfire

[unclepoo]

I sure people will have discussed or experienced a misfire with a prius or auris hybrid before now....possibly becoming a loud knocking, poor starting of the ICE or a fault light on the dash. So I`d like to share with you guys what I found.

I first noticed the ICE make a sort of !Removed! possibly down the air intake, along with a little stutter in the power, it sounded to come from the front drivers side corner where the air intake is, but I was driving so cant say for certain.

So I ordered some new spark plugs...my logic as a good place to start. 

I removed the engine cover, un-pluged the coils from the loom, removed the bolts holding the coils in place, and started removing the coils....very little room though.

But what I found was number 1 coil was wet and rusty, the other 3 looked perfect. After searching through old posts on here I saw that several people had reported misfires, mostly on number 1 cylinder but obviously not all.

The water drips onto coil 1 from a drain hole in the plastic panel in front of the wipers, drops onto the engine cover, then runs backwards onto number 1 coil. Resulting in a misfire over time.

If the engine cover extended back over the coils to keep then fully dry they`d probably last forever.

I hope this is helpful to others with the same or similar problem.

I`ve ordered a new coil, and I`m going to extend the engine cover to keep the water off.

 

[Gerg]

Great fix!

I'd be interested to know how many miles the car had covered?

Also, how much was the coil?

Did you take the plug(s) out in the end?

Did you get any error codes logged?

I think I might smear some silicone grease on the rubber gasket on ours to try and prevent this.

I found something a bit similar on a Nissan, where a dealer had pressure-washed the engine (not a coil-on-plug engine) and half-filled the plug cavity. I found it before it caused any problems, luckily.

Cheers.

[unclepoo]

I have not changed the plugs yet, I was working in the dark with only a LED lamp to see by. I`ve ordered a 14mm plug socket and room is so tight above the cylinder head I`ll wait until the weekend to get better access and visibility. I`ll fit the new plugs and the new coil.

One thing to note....when I was looking at the failing coil, I found the bottom rubber loose, not bonded to the coil stick like it should be (as well as being wet and rusty). Inside the rubber cover that would sit on top of the spark plug is a spring, a rusty spring in my case. I cleaned up the spring and the contact to bottom of the coil stick the best I could and put it all back together. 

Testing the Auris last night all went well....no misfire or breaking wind noise down the air intake....and from a cold start this morning all has been well all day.

 

[Gerg]

I checked the coils on our Mk 2 a few weeks ago and they don't show any signs of water ingress (yet).

But all the coil tops have had water sitting on them despite the plastic cover on the top of the engine (see water marks on potted upper surface in attached photo), which is a bit odd.

You had probably noticed that the rubber sealing ring has a 'labyrinth'  cast into it (photo), so if the engine was cooling down and the sealing ring was sitting in water, it might get drawn into the plug void. Each of the coils had the opening on this seal pointing in a different direction from new (with all the QC pen marks aligned), so their orientation isn't important(?).

[unclepoo]

I`ve finally got round to changing the spark plug....I`ve had the new Iridium plug a month but not been able to get a plug wrench the correct size.

I ordered a 14mm wrench but received a 21mm....twice, so i ordered this http://www.ebay.co.uk/itm/221995038359?_trksid=p2060353.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT and this http://www.ebay.co.uk/itm/New-3-Pc-Spark-Plug-Socket-T-Bar-Wrench-Sockets-Set-16mm-21mm-3-8inch-Drive-/311712361167?hash=item4893812acf:g:lQsAAOSwDk5UBZTd but had to cut it down and weld on a 19mm nut, as there`s so little space unless you remove the wipers and motor etc. 

With the new plugs in, the engine sounds and feels smoother than ever.

[Konrad C]

On 4/20/2017 at 10:31 PM, unclepoo said:

I`ve finally got round to changing the spark plug....I`ve had the new iridium plug a month but not been able to get a plug wrench the correct size.

I ordered a 14mm wrench but received a 21mm....twice, so i ordered this http://www.ebay.co.uk/itm/221995038359?_trksid=p2060353.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT and this http://www.ebay.co.uk/itm/New-3-Pc-Spark-Plug-Socket-T-Bar-Wrench-Sockets-Set-16mm-21mm-3-8inch-Drive-/311712361167?hash=item4893812acf:g:lQsAAOSwDk5UBZTd but had to cut it down and weld on a 19mm nut, as there`s so little space unless you remove the wipers and motor etc. 

With the new plugs in, the engine sounds and feels smoother than ever.

I bought my spark plug socket from Machine Mart 1½ years ago - https://www.machinemart.co.uk/p/laser-4376-8mm-38-drive-thin-wall-spark-plug/ I was worried about getting the wrong socket and they had it in stock. I did get my spark plugs from a Toyota dealer via eBay. The Avensis 2ZR Valvematic engine use the same plugs as the hybrid.  

 

[unclepoo]

I see your old spark plug has corrosion on it.....one of my coils failed due to water and the same spark plug was rusty and nasty when I removed it. The other three looked the same as in your photo. So it`s worth checking the condition of spark plugs and changing if required.

[PeteB]

I was amazed when my 2002 Gen 1 Prius reached 60k and had it's first set of new plugs in 2005.  All four old ones looked brand new.

Many people since have suggested they only change when they have a problem or they look like the one in the photo above.  But some have reported no problems at 150K or more. 

In 2005 no one really knew just how reliable the Hyrbid system would prove to be, so because the schedule said change at 60K my dealer thought we should and I agreed.

Iridium tipped plus were quite expensive then - a dealer where I lived at the time wanted about £25+vat each plug, but my Norwich dealer charged £15+ vat and the labour was cheaper so it was worth combining with a visit to my parents and getting it done 100 miles away!  The plugs are more reasonable these days.

[kithmo]

On my old 2001 Ford Mondeo V6 with Iridium plugs, the recommended change was at 60K and that's a car with the ICE running all the time. I reckon the Prius could go 100K+ easily one one set of plugs providing no corrosion gets to them.

[unclepoo]

I`m still adamant that my Auris runs better with the new spark plugs in. 

When I removed the old plugs, the earth electrode was eroded, compared to the new plugs that have Iridium pin points on both the centre and earth electrode. Resulting in a wider plug gap.

[PeteB]

1 hour ago, unclepoo said:

I`m still adamant that my Auris runs better with the new spark plugs in...

I don't doubt it - if mine looked anything like the one in the photo, I'd change it now matter how many (or few) miles it had been in use.