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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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 Posted: Mon Mar 04, 2019 2:19 am Post subject: Spark Plugs |
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| I am using Denso plugs K16 TR11,, I am not sure if these are appropriate for the 924NA.. the last plug is getting shorted or found wet with petrol.. could I be using the wrong plugs? or is the engine fuel supply too rich? |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Mon Mar 04, 2019 7:42 pm Post subject: Re: Spark Plugs |
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| newbie924 wrote: | | I am using Denso plugs K16 TR11,, I am not sure if these are appropriate for the 924NA.. the last plug is getting shorted or found wet with petrol.. could I be using the wrong plugs? or is the engine fuel supply too rich? |
Without knowing what kind of plugs that is, I would guess that its rich.
Does it smoke and smell rich?
If the plugs has gotten this wet, throw them away and get new ones. Get the recommended Bosch or NGK (from the manual), after that you can adjust the heat range if needed (probably not). |
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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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| Posted: Mon Mar 04, 2019 10:02 pm Post subject: |
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| It does not smell that rich and has stopped smoking, since it was left standing by the previous owner.. I will see what the manual says and test try some plugs i guess... It does start first try working on 3 plugs though which is surprising in a way,, but obviously wont rev up due to the bad wet plug. |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Mon Mar 04, 2019 10:07 pm Post subject: |
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A wet plug will never work good, if at all.
You can have bad spark plug wires too (or plug connectors for that matter), if you have any doubt change them. Generic wires are cheap. |
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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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| Posted: Mon Mar 04, 2019 11:19 pm Post subject: |
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| I have decided to maybe even change to electronic spark too since the distributor has points,,and these seem to clog up in time... the car is a 78 model.... |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Mon Mar 04, 2019 11:32 pm Post subject: |
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| newbie924 wrote: | | I have decided to maybe even change to electronic spark too since the distributor has points,,and these seem to clog up in time... the car is a 78 model.... |
Not sure what the cost would be and if it would be worth it. Points are not that bad, they wear a little but are cheap. They can get dirty but are easy to clean, just remember to NEVER use an abrasive paper on them, that will only work as a quickfix, but will soon cause issues again.
A game changer would be to go to a programmable distributorless system (Mega Jolt for example). This way you can get rid of mechanical issues with worn parts and easily adjust timing precisely. |
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924RACR
Joined: 29 Jul 2001
Posts: 8811
Location: Royal Oak, MI, USA
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| Posted: Tue Mar 05, 2019 12:20 am Post subject: Fouled injector? |
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If it was left sitting for some time - I'd also wonder if perhaps the injector for that cylinder might be clogged a bit and not giving a good even spray... so no good dispersal/atomization of the fuel, just dumping a stream, could act like an over-rich condition, but only that one cylinder... might be worth pulling it out and checking it...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Tue Mar 05, 2019 12:21 am Post subject: |
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Do an injector flow test to determine if they are all delivering an equal amount of fuel.
Do a compression test.
Are you losing any coolant?
Also be aware you probably have a lot of fuel in your oil.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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| Posted: Wed Mar 06, 2019 6:33 am Post subject: Re: Fouled injector? |
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| 924RACR wrote: | | If it was left sitting for some time - I'd also wonder if perhaps the injector for that cylinder might be clogged a bit and not giving a good even spray... so no good dispersal/atomization of the fuel, just dumping a stream, could act like an over-rich condition, but only that one cylinder... might be worth pulling it out and checking it... |
Noted with interest. |
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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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| Posted: Wed Mar 06, 2019 6:43 am Post subject: |
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| Paul wrote: | Do an injector flow test to determine if they are all delivering an equal amount of fuel.
Do a compression test.
Are you losing any coolant?
Also be aware you probably have a lot of fuel in your oil. |
I haven't given it a good run for now since Im still tidying it up a bit and getting the body and interior in order since I need to get it taxed and it needs to go thru a road worthy test before I can tax it. But I do start him up and there is no sign of water loss... though I do suspect that the previous owner might have attempted to start it without success since the cars timing and plug leads were terribly faulty and mixed up, so I do suspect there could be some fuel in the oil. I had in mind to change it once this problem of wetting the plug is resolved though. The car at first was letting up smoke from the exhaust too which has now since stopped also.. I think that the cause of such problems is letting the car standing and best thing to do is go thru the ignition and fuel system as suggested and clean/tidy/change anything or everything. I also intend to put some Lucas injector cleaner in with the fuel once everything is tidy'd up as well. |
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!tom
Joined: 28 Aug 2006
Posts: 1934
Location: Victoria, BC Canada
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| Posted: Wed Mar 06, 2019 8:47 am Post subject: |
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I've gone with plugs 2 hotter than the manual recommends. Otherwise they tend to foul with oil after a while.
I also run a higher octane fuel to be safe with the hotter plugs.
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78 924 NA
5-lug |
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newbie924
Joined: 16 Mar 2016
Posts: 104
Location: EUROPE MALTA
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| Posted: Thu Mar 07, 2019 9:08 pm Post subject: |
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| !tom wrote: | I've gone with plugs 2 hotter than the manual recommends. Otherwise they tend to foul with oil after a while.
I also run a higher octane fuel to be safe with the hotter plugs. |
Can you share the plugs number code? |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Thu Mar 07, 2019 10:16 pm Post subject: |
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| newbie924 wrote: | | !tom wrote: | I've gone with plugs 2 hotter than the manual recommends. Otherwise they tend to foul with oil after a while.
I also run a higher octane fuel to be safe with the hotter plugs. |
Can you share the plugs number code? |
Beware that heat ranges aren't universally exchangeable.
According to design911.co.uk (just googled "924 spark plugs")
The 924 uses Bosch WR5DC or WR5DC+, the 931 the colder WR4DC
Get plugs in a heat range you think good, get one with small thin electrode (Iridium?) they keep themselves cleaner in my experience. Multiple ground electrodes are a waste of money, they are for extended service intervals (100.000 km). |
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924RACR
Joined: 29 Jul 2001
Posts: 8811
Location: Royal Oak, MI, USA
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| Posted: Fri Mar 08, 2019 10:48 pm Post subject: |
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Adding on to this... had a bitch of a time trying to chase the correct new Bosch part #'s down. Seems that Rock Auto have been listing the WR6DC plug for the Turbo... maybe this helps explain why my plugs are fouling constantly, not just maybe some turbo oiling???
OTOH, when I look at the parts manual, I see WR6DS (silver conductor, no big deal) listed for both 924 and Turbo?
Anyway: WR5DC = Bosch 7992 in the new parts numbering scheme.
They're like $1.60 from Rock Auto, so I'll give 'em a shot, see how she goes...
Edit - I got it backwards, the WR6 will be hotter than the WR5... oh well, these'll come in handy when the boost comes up... meantime gotta wait on my turbo rebuild and hope that'll help clean up some of the funk the engine keeps ingesting... and a little more oomph besides!
I also wonder if there's perhaps some variation here EU vs. US spec plugs...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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Fifty50Plus
Joined: 28 Feb 2008
Posts: 1360
Location: Washington DC area
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| Posted: Sat Mar 09, 2019 2:36 am Post subject: |
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I put Bosch plugs in customer engines when they insist. Otherwise I use the No Good Kind. I've had problems with Bosch plugs fouling on all my race cars over 40 years until I switch to NGKs - never had a problem with them.
Just a data point....
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car |
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