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Spark Plugs

Discussion in 'Gen 2 Prius Technical Discussion' started by mbooth62, Jul 17, 2012.

  1. mbooth62

    mbooth62 Junior Member

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    My 2005 has 93K miles - almost 7 years old so decided to change plugs. Bosch had rebate on Iridium Fusion Plugs (purchased for <$2 ea at rockautoparts) so I decided to try - despite some comments about Bosch and Toyota not mixing well. Old plugs came out very easily (NGK) and looked worn but still basically OK (see pic). I had noticed more shuddering on start-up and shut down of ICE in last 10K miles or so - which improved a bit after running a couple of tanks of Techron through the system - but still not as smooth as new. DIY's on removing plugs were very useful (especially the one where the guy uses some twine in the plug socket to remove the plug from the hole (I didn't have magnetic socket). The connector for the coil on plug #4 is a bit*ch to get off - I sprayed some WD40 on it, pressed the tab down with a screwdriver (be careful not to slip since the coolant hose is right behind here) and eventually managed to push it off (this probably took the most time of the whole job). Putting the connector back in is so easy - it slides in and locks into position with almost no force ! Torquing the plugs down to correct spec is very important (too loose and the plug may run too hot and too tight you may damage the head) (13Lbs/ft).

    Fired up the new plugs today and commuted to work. ICE seems to start and shut down slightly smoother and accelerates more smoothly (so I think the NGK Iridiums will last 120Km/7 years - but are maybe not at peak performance anymore at that point) - maybe some of that is physcological ! But so far, no problems with the Bosch plugs. Let's see if there is any difference in gas mileage over the next few tanks. (If the Denso or NGK Iridiums were close in price, I probably would have gone with those - maybe at $6 per plug that should not be an issue - but I guess the Bosch marketing dep't did a good job convincing me ! )

    Anyone else running Bosch IF plugs ?

    plugs low res.jpg
     
    #1 mbooth62, Jul 17, 2012
  2. Landj

    Landj Junior Member

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    From your pictures the 'gap' looks very wide. Usually the gap should be (in the order of) 25 thou. I think you were right to junk these plugs.
     
    #2 Landj, Jul 17, 2012
  3. edthefox5

    edthefox5 Senior Member

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    Bosch makes a lousy plug. Shuddering is probably more from throttle body needing cleaning. Hoped you use some dielectric grease on the cop connector.
     
    #3 edthefox5, Jul 17, 2012
  4. mbooth62

    mbooth62 Junior Member

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    Throttle body was done at 60K - but I will check again when I change air filter. Yes, used anti-sieze. Yeah, I'm not sure where the data comes from that says Bosch is bad - only anecdotal ? , or can someone point to a real study - but given the rebate, I though I'd give them a try - and like I said so far happy. Let's see how they hold up after 60K miles. BTW never had any issues with Bosch plugs in previous cars. My Porsche mechanic used NGK on my other car - he would not use Bosch there !
     
    #4 mbooth62, Jul 17, 2012
  5. edthefox5

    edthefox5 Senior Member

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    No not anti seize..... dielectric grease. Anti-seize is used on the plug threads. DG is used in the coil over plug ignitor socket where it plugs onto the top of of the plug. Prevents it from corroding and keeps moisture out of the connection and makes it possible to unplug it 100K later.
    This:
    www.TechGuys.ca | How to: Change and inspect spark plugs
     
    #5 edthefox5, Jul 17, 2012
  6. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    The plugs you took out show virtually no wear (just slight carbon deposits). I would have cleaned them up and reinstalled them for another 100k miles. Yours look the same as mine after 100k miles. If you wire brush them, and re-gap them, they will be good as new. Irridium is very hard and corrosion resistant.
     
    #6 usnavystgc, Jul 17, 2012
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I would not recommend regapping used plugs, on the basis that the ground electrode may weaken and fall off into the combustion chamber. You're not married to the plugs, after all - it is OK to replace them per the maintenance schedule.
     
    #7 Patrick Wong, Jul 17, 2012
  8. bedrock8x

    bedrock8x Senior Member

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    Incorrect, the gap should be 1mm or ~40 thou.
     
    #8 bedrock8x, Jul 17, 2012
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  9. mbooth62

    mbooth62 Junior Member

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    At $2 a plug ... not worth regapping ...
     
    #9 mbooth62, Jul 17, 2012
  10. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    I know, I know. Everyone is not as cheap as I am but, to me, its worth it. Especially when they show no wear. But, that's just me.
     
    #10 usnavystgc, Jul 18, 2012
  11. mbooth62

    mbooth62 Junior Member

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    My friend's wife would hang up kitchen paper towels to dry - so she could use again - I think that takes the prize !
     
    #11 mbooth62, Jul 18, 2012
    usnavystgc likes this.
  12. wjtracy

    wjtracy Senior Member

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    ...do they save the old plugs for iridium recycling? Gotta do mine soon...
     
    #12 wjtracy, Jul 18, 2012
  13. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    Not that I'm aware of. They only have a very small amount of iridium in them but, it is a very rare metal (at least according to Wikipedia).
     
    #13 usnavystgc, Jul 19, 2012
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