How does excess fuel degrade your plugs?

[Patman]

I'm just curious, since I recently had a problem with my engine not starting (burnt coil wire) and very likely flooded my engine with fuel in the process. A lot of people are telling me I should change my plugs now, but it's a real big task on the LT1 engine.

I'm just curious though, if the car is now back to normal and is not running rich, wouldn't the plugs clean themselves up after a while? I drive the car hard a lot too, so I would figure this too could help the plugs stay cleaner.

FWIW I'm running NGK G-power platinums.

 

[jason07-1zzfe]

Don't see how it would affect plugs...

Especially with the cause of fuel you had. Shouldn't affect them. Maybe if reason for fuel was extremely rich mix or misfire that caused fouling of plugs.

 

[Patman]

I was thinking that even if the plugs got fuel soaked after all that cranking my engine did (when it would not fire up) then it would go away pretty quickly when the engine did fire up.

I am just trying to trace down why my car lost about 2mph in trap speed in the quarter mile on my last outing, even when weather conditions were more favorable and my race weight was less than it was on my last trip out last fall.

Would misfiring cause plugs to go bad? When my coil wire was burnt it was misfiring badly above 5000rpm. So badly that it would not even shift up into the next gear, it was like I hit a rev limiter.

[ April 26, 2004, 04:32 PM: Message edited by: Patman ]

 

[Jeff in Western WA]

Patman, GM SIGNIFICANTLY upgraded LT-1 coils w/ 1996 vs. earlier versions, get one that's '96 Spec, they are even BETTER than aftermarkets, and wires too!..I'd think of changing plugs/wires much more than the suggested 100K "service interval" cause I've seen the GM plat plugs looking pretty worn at 50K, wires (Delco) are good but 100K miles(?), especially coil wire failures due to those underhood temps....look at Magnecore wires or for even less money Taylors...The GM plat plugs are good but, # of users had many (10%+) "bad", out of the box, so I went w/ Bosch +4's, fresh O2 sensors and of course, clean filters, a clean MAF, clean TB/Intake all contribute...been over/under/through my quite modded 96 Impala SS (lt 10K~ miles) and an active member of our B-Body (LT-1's!) local club so I've seen/wrenched on a few...

pushing 340 flywheel HP at 395 Lb tq w/ just bolt on's on my 4400~ lb "BeaSSt"....just shown and cruised

[ April 26, 2004, 07:48 PM: Message edited by: Jeff in Western WA ]

 

[Patman]

I just had a new coil and coil wire put on by a GM dealer, do you think they would've used the upgraded coil?

The rest of the wires are Neihoff, and as mentioned, the plugs are NGK G-Power platinums, gapped at .050 (these both have about 40k on them now)


My 02 sensors are less than two years old, and my optispark is still original. The car has 101k on it.

 

[DJ]

They would have used the old style coil, the 96+ one uses a different wiring harness plug. On the plugs multiple elecrodes are only good for jacking up the price of the plug, and in the case of Splitfires for breaking off

, platinum is good for longevity but nothing else it will not give any added performance over a copper standard plug, just lasts longer before the gap errodes beyond spec. A missfire like it would have been subject to with failing ignition components will foul the plugs. Don't know much about the underhood of the f-body but a lot of the Caprice/Impala guys swear by pulling the front tires and going through the wheelwell, take a look maybe that would help you

. As much as I hate to say it wires might just be a good idea too, faulty ignition parts downstream(plugs and wires) from the coil are a very common cause of coil failure, trust me I know that is an ugly task and wouldn't recommend it unless I thought it was really a good idea. Taylors are good and only cost say $60 or so as compared to the Magnecores(very nice wires) for $90-100.

 

[Mike_dup1]

Tech Tips


From NKG FAQ

quote:

---

Frequently Asked Questions

Q: What is a "fouled" spark plug?

A: A spark plug is considered fouled when the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil or carbon. This coating makes it easier for the voltage to follow along the insulator nose, leach back down into the metal shell and ground out rather than bridging the gap and firing normally.

Many factors can contribute to spark plug fouling. The air/fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.

Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. In many cases, the spark plug cannot be cleaned sufficiently to restore normal operation. Therefore, it is recommended that a plug be replaced once it is fouled.

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[ April 27, 2004, 09:34 AM: Message edited by: Mike ]

 

[Patman]

quote:

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Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. In many cases, the spark plug cannot be cleaned sufficiently to restore normal operation. Therefore, it is recommended that a plug be replaced once it is fouled.

---

This is an interesting point here. I'm simply curious as to whether or not the plug could eventually get cleaned up if the engine doesn't continue running rich? Since my engine doesn't normally run rich and the plugs may have only gotten a quick dosage of the extra fuel, I just figured they might burn off that fuel pretty quick, unless of course the additives in that fuel (such as the MMT used here in Canada for example) left such a strong coating on them that they never recover.

My engine feels like it's pulling strongly once again, so maybe I should make another dragstrip outing and see if my trap speeds return to normal before I go out and spend $$$ on having these plugs changed. Since I cannot possibly do them myself, my only options are to pay my friend $100 to do them or pay a dealer even more. So as you can see it's not a simple thing, the LT1 plug change is a nightmare. It's times like these I wish I never sold my LS1 Firebird, I could change those plugs in 45 minutes.

 

[36coupe]

I would definetly consider changing the oil. If you gas fouled the plugs, a substantial amount of gas would drain to the oil pan.

 

[Virtuoso]

I don't see how fuel could continue to foul a plug if it starts firing properly again.. I mean, fuel burns right?
Change the oil but leave them plugs in.

 

[jsharp]

Long term rich running will cause carbon buildup on the plugs and sooner or later one will likely foul. Your one time flooding will probably have no effect on them. If it's running fine now with no missing, I'd say don't worry about it...

 

[crashz]

OT - Patman, you may have mentioned it before, but I missed it. Why did you get rid of the LS1? Was it giving you trouble?

 

[Patman]

quote:

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Originally posted by crashz:
OT - Patman, you may have mentioned it before, but I missed it. Why did you get rid of the LS1? Was it giving you trouble?

---

Not at all, in fact it had to be the most reliable LS1 on the planet, no piston slap, no oil consumption at all (maybe 1/8th of a quart every 3k if that) and it never went back to the dealer once for any kind of warranty work.

I ordered it brand new from the factory and drove it for 2 1/2 years and 27,000 miles. At the time it was my "nice weather car" only and I never took it out in the rain, let alone the snow.

Then my wife got her licence so she took over the 2000 Civic as her own car. So I was faced with the thought of driving this perfect LS1 Formula through the winter and I just couldn't bring myself to do it. Add that to the fact that I wanted an automatic again as I was tired of shifting the 6 speed (and tired of missing shifts at the dragstrip all the time) and started getting interested in having a Grand Prix GTP, and the next thing you know I went to a dealer and traded it in for a 97 GTP. Big mistake. The GTP was very nice but I missed my Formula the moment I turned over the keys to the dealer.

So less than a year later I decided to get another Firebird, but couldn't find any affordable LS1 Firebirds, so I ended up trading the GTP straight up for the 95 Formula I have now. It is a very nice car, but just isn't the same as my LS1 was.

 

[DJ]

I was saying do the plugs based more on the missing you had experianced than on the flooding, if it feels good now then by all means test it out again and see if it got better. Maybe it was something simple like some bad gas and it was pulling timing, the knock sensor will "hear" pinging long before it is bad enough for you to hear it, so unless you have a scantool you might never know? If you are interested in a laptop based scantool let me know and I can point you at a few for the OBD1 LT1 cars.
I also understand what you are saying about not wanting to change them unless you are sure, I am able to do all my own work so with cheap things like plugs I don't hesitate since the labor is free.

 

[Patman]

A friend of mine has the Datamaster scan tool software and a laptop, and we've run it on my car in the past (it didn't show too much timing being pulled out at that time), so I should get him to come over sometime (although it's the same guy who does my plugs, so like I mentioned he's pretty busy lately)

 

[Patman]

I'm going to be changing the oil soon. I was originally going to do a 10,000km interval with it, but now am going to cut it short to 5,000km, which will be in about 3 weeks.

 

[Jeff in Western WA]

Patman, typically "fuel fouled plugs" are "junk" at 40K I'd replace anyway, the LT-1's (IMO) seems to be great running engines but, a bit "hard" on plugs, for performance, I'd change at 25K intervals and wires at 50K, most everybody else will do fine on 50K plugs/100K wires but, 100K plugs (?

), they be "welded to the heads!"

, an upgraded coil/system should help A LOT, but, I'd shy away from the MSD's, etc, seem to fail oftenm and provide no benefits over the '96 GM coil, a nice catback exhaust helps tons', the Throtle body cooolant bypass is free upgrade and a less restrictive air induction set up will gain nice HP over stock, all of these add mpg's too........Jeff '96 DGGM (Impala SS), 9585 miles, many mods, 9 show trophies

"used mostly for parking"

 

[Patman]

I've got one of the best catbacks on the market on my car actually, SLP's "2 on the left", which is the optional exhaust on the 96-97 Camaro SS. Great flow, great sound, amazing quality for such a low price too (lowest priced stainless steel system out there)

I don't want to do the throttle body bypass due to me driving my car all year round. It is parked outside overnight, so it will see below zero temps in the winter sometimes.

As far as the air induction, I've been hesitant to replace the factory airbox since everything else out there uses a K&N air filter or other cotton gauze type filter. But if I could find a used K&N FIPK and then replace the K&N cone with a similar sized paper cone filter that would work. Or I could also get the K&N filter wrap to cut down on the amount of dirt getting through.

 

[Jeff in Western WA]

A comon B-Body mod is to "swiss cheese drill" the air filter box to let in more air, remove the "second base" silencer, and, remove the MAF screen...this has a proven effect in the B's highly restrictive factory air induction system..and you can use the stock type paper filters...doubt the TB bypass will cause the TB to "ice" in the cold, just not like the old carb cars but...enjoy!

 

[DJ]

I have driven a lot in zub-zero weather with the TB bypass and never a problem, snow freezing rain, teens below zero the whole works.
Datamaster is my favorite, and did you know the cable it uses to connect to the car can be used to reflash the pcm? If you haven't had the car reprogrammed yet I highly suggest it, you will swear it is a new car.