HEMI Wagon Project Log: Update!

"JGrabowMSt" (jgrabowmst) 05/20/2014 at 10:42 • Filed to: HEMIWagon

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I think its time for new spark plugs...

I managed to get all 16 out in about 45 minutes, give or take, because I was going slow. I used a Craftsman Spark Plug deep socket, and 2 separate 3" 3/8 extensions. I also had a 10mm to get the coils off. Everything went smoothly. Currently, no plugs are in, I just pushed the tubes down so crap doesnt fall into the engine. I need to go get 16 new plugs during my lunch break. Dirtier than I hoped for. Plugs are probably good for lawn mowers or other power tools, but they arent going back into the car.

Shorty wires will go in once the new plugs go in.

offroadkarter > JGrabowMSt 05/20/2014 at 10:52

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it still makes me laugh that the hemi's use 16 plugs

RotaryLover > JGrabowMSt 05/20/2014 at 10:56

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Why in the hell do they need 16 spark plugs???

JGrabowMSt > RotaryLover 05/20/2014 at 11:05

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to meet emissions standards, one plug fires for power, and then on the opposite cylinder, it fires on the down stroke to reburn the gases. Funny enough, it does make a tiny bit more power (only a couple hp).

Since Im putting in shorty wires, both plugs will fire at the same time. I lose about 1hp in the process, but no issues with MDS or emissions. The newer HEMIs all work like this too.

RotaryLover > JGrabowMSt 05/20/2014 at 11:08

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Must be expensive to replace. They use standard plugs, platinum, standard Iridium or Laser Iridium?

JGrabowMSt > RotaryLover 05/20/2014 at 11:19

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these are bosch platinum +4s, but I think Im just going to get coppers, because thats what the engine calls for.

My friend who worked on mopars for a while, and my experience with the neon is that engines sometimes run worse when they dont have the plugs they were designed for. Depending on the cost difference, I may get regular platinums that the gap can be checked, or just get coppers.

I wouldnt be surprised at this point if the slight rough idle goes away with new plugs.

Mattbob > JGrabowMSt 05/20/2014 at 11:23

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1) why dont they just fire the same plug twice?

2) are you saying shorter wires will change the timing on your plugs firing?

RotaryLover > JGrabowMSt 05/20/2014 at 11:25

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Definitely will help. A good throttle body clean up, air filter change and battery reset makes wonders after changing plugs. It will probably get crappy mileage and crazy accelerationat first since the ECU will be learning your driving but after that, it will be alright.

FrederickLawOlmsteez > JGrabowMSt 05/20/2014 at 11:32

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Don't forget the anti-seizure paste, Brah.

BiTurbo228 - Dr Frankenstein of Spitfires > JGrabowMSt 05/20/2014 at 11:35

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Neat :) a twinspark V8.

I wonder if the Alfa Twinspark works the same way.

Cool, if more expensive to maintain.

CAR_IS_MI > JGrabowMSt 05/20/2014 at 11:37

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Wait. What are you driving that has a twin spark V8?

EL_ULY > RotaryLover 05/20/2014 at 11:38

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yup, my w210 uses 12 and it's only V6

JGrabowMSt > CAR_IS_MI 05/20/2014 at 11:40

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2005 Dodge Magnum RT

Stupidru > JGrabowMSt 05/20/2014 at 11:42

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Add this to the myriad of reasons why I will never own a Chrysler product

JGrabowMSt > Mattbob 05/20/2014 at 11:45

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The ignition system takes a little thinking to wrap your head around, so I'll try to simplify it.

There's a coil over pack that fires a spark plug directly under it. At the same time, there's a plug wire that crosses over the plenum, and fires a secondary plug on the cylinder that's on a down stroke for a reburn of the gases.

The short wires change that so both plugs fire on each cylinder at the same time. It removes the need for a reburn, as more gases burn during the power stroke. It doesn't affect emissions, and the MDS system still works properly, which is important. As a bonus, it really cleans up the engine bay.

The newer 2006+ HEMIs moved to a new valve cover with a twin coil pack that fires both and really cleans things up, but I'm not going to buy new valve covers and coil packs when I can just buy a set of wires that does the job.

CAR_IS_MI > JGrabowMSt 05/20/2014 at 11:47

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Thats quite interesting, was unaware that had twin spark.

JGrabowMSt > Stupidru 05/20/2014 at 11:48

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Well, the next "current" V8 wagon would be the CTS-V, and it's just a hair out of my budget. That said, while I thought I would go to a Chevy, the Magnum got my attention, and I am very happy with it. I wouldn't call it strictly a Chrysler product, as it was during the time of Diamler Benz, so it has a little of both in it, and in all honesty, if Chrysler didn't have the help from Benz on the LX platform, it would definitely be way worse than it is.

JGrabowMSt > CAR_IS_MI 05/20/2014 at 11:50

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Yep, all the 2004+ HEMIs have it, to the best of my knowledge.

Mattbob > JGrabowMSt 05/20/2014 at 12:21

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so the wires make both plugs fire off of the same tap? That will reduce the amount of energy in each spark if there is even enough to fire both. Trust me, I can wrap my head around it, I am an electrical engineer.

JGrabowMSt > Mattbob 05/20/2014 at 12:37

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The stock configuration fires two plugs off the same coil. The shorty wires I'm installing only change which two plugs fire at the same time.

Mattbob > JGrabowMSt 05/20/2014 at 13:20

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if they fire off the same coil, without some kind of switching in there, then they fire at the same time anyway. Changing the length of a plug wire will not change the timing. At all. From what I can gather, the stock configuration has the secondary plug wired to the coil of the next cylinder to fire, so you get a delay that way. Of course, I haven't put eyes on it, so I can't say for sure, but I do know that a simple change in the length of your wires won't do anything.

JGrabowMSt > Mattbob 05/20/2014 at 13:39

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The plugs in each cylinder do not fire at the same time. One plug fires during combustion, and when that plug fires, it fires a second plug that's on a different cylinder during the down stroke to reburn gases.

RotaryLover > EL_ULY 05/20/2014 at 14:58

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Damn. What type of spark plugs do you have to use?

EL_ULY > RotaryLover 05/20/2014 at 15:06

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ones here at work (Merc dealer) yay employee discount :]