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HwyStar
11-07-2013, 09:01 AM
This may seem like a silly question as far into this car as I have been. But, Im going over any doubt I have and verifying everything right. The illustration in the shop manual didnt match how the firing order was on my last car, or about half of what I have seen on the net. I have seen cars run "ok" with a couple wires crossed.

I just took 1-3 plugs out. 1 and 2 were lean, while 3 wash almost washed down. Im replacing the plugs. But Ive been having a rotten egg smell, lazy o2 sensor on that side at the same time the afr has been what it should be. A little miss fire at part throttle cruise too.

davec73
11-07-2013, 09:24 AM
this may seem like a silly question as far into this car as i have been. But, im going over any doubt i have and verifying everything right. The illustration in the shop manual didnt match how the firing order was on my last car, or about half of what i have seen on the net. I have seen cars run "ok" with a couple wires crossed.

I just took 1-3 plugs out. 1 and 2 were lean, while 3 wash almost washed down. Im replacing the plugs. But ive been having a rotten egg smell, lazy o2 sensor on that side at the same time the afr has been what it should be. A little miss fire at part throttle cruise too.

1-2-3
5-6-4

BLOWN38
11-07-2013, 10:50 AM
1-2-3
5-6-4

Yup that is the plug orientation on the coil pack as you look at the pack from the front of the car.

David Neibert
11-07-2013, 03:53 PM
http://members.tccoa.com/dneibert/PlugandWireLayout.jpg

HwyStar
11-07-2013, 07:05 PM
Thanks! I ended up going to the plug Mike Puckett used. The NGK TR6-IX. Turns out it has the lowest resistance of all the plugs I have seen so far. Lower than the Autolite XP by about .5 kOhm which is a lot. So, I gapped the plugs to .035".

Dave, you ever get your car sorted out??

davec73
11-07-2013, 07:54 PM
Thanks! I ended up going to the plug Mike Puckett used. The NGK TR6-IX. Turns out it has the lowest resistance of all the plugs I have seen so far. Lower than the Autolite XP by about .5 kOhm which is a lot. So, I gapped the plugs to .035".

Dave, you ever get your car sorted out??

Waiting for the 1.7 AR to come back but It ran pretty good the last time I drove it.

decipha
11-08-2013, 12:16 AM
why didn't u slap some app103s in her?

there's a few thousand of us that use those plugs with impeccable results

HwyStar
11-08-2013, 06:59 AM
Wasnt sure what the real problem was at first. Was hoping plug change would do it. Turns out I had a mud dobber nest in my BAP. Problems all fixed! AF where it needs to be at idle and cruise. Feels great, drove the car to work today!

David Neibert
11-08-2013, 12:43 PM
Dave, you ever get your car sorted out??

I have eliminated a few possible causes from the list, but haven't found the actual problem yet. Haven't really been very motivated to mess with it so I've only spent a couple hours checking stuff. Chris Wise is coming over tomorrow to give me a hand trouble shooting the rest of the ignition system and some of the basic mechanical stuff like compression testing. I'm pretty confident we will find the problem tomorrow.

It's a little more complicated on this car because it's running with a standalone aftermarket ECU (FAST XFI), that uses an MSD crank trigger/sensor and a modified MSD distributor (single sync). I also can't bypass the MSD digital 6 ignition because that's the only ignition system on the car.

David

HwyStar
11-08-2013, 03:47 PM
That was the system I was considering for the Mark VIII turbo. Now Im thinking about QH for that car too since I will gain some understanding on this car. Also, save a ton of money using the QH. Any particular reason you went with FAST setup on this car instead of QH?

Micahdogg
11-08-2013, 04:02 PM
http://members.tccoa.com/dneibert/PlugandWireLayout.jpg

I never have quite figured out how the car fires.

When #1 fires, does the coil pack send spark to 1 and 5?
Then when #4 fires, the coil pack sends spark to 3 and 4?
And so on?

And if this is the case, I guess the wasted spark has to hit another cylinder on the exhaust stroke because it would be bad to fire at any other time.

David Neibert
11-08-2013, 04:04 PM
That was the system I was considering for the Mark VIII turbo. Now Im thinking about QH for that car too since I will gain some understanding on this car. Also, save a ton of money using the QH. Any particular reason you went with FAST setup on this car instead of QH?

QH wasn't an option when the car was built in 2004-2005. Tried making it work with a 94-95 mustang 5.0 ECU and Dave Dalke tuned it with SCT. Since the new slot style MAFs didn't exist then either and Pro M had closed their doors I was forced to use a C&L MAF in a blow through configuration. 76 MM worked good but pegged at street gas boost levels, 85MM worked good at WOT but had poor resolution at idle and low rpm. The largest high impedance injectors at the time were 60# and I needed 80# min and ended up using 83# low impedance. Stock computer wont support low impedance injectors, so I used a import trick and wired in a couple resistor packs instead of buying a low imp injector driver. This resulted in poor control of the injectors.

Got tired of fighting it and switched to a standalone that was capable of operating the low impedance injectors and didn't require a MAF (speed density). It works great and I have no regrets about switching. If doing it today I could buy larger high impedance injectors and a good quality blow through MAF, and I probably could run it using QH.

David

David Neibert
11-08-2013, 04:07 PM
I never have quite figured out how the car fires.

When #1 fires, does the coil pack send spark to 1 and 5?
Then when #4 fires, the coil pack sends spark to 3 and 4?
And so on?

And if this is the case, I guess the wasted spark has to hit another cylinder on the exhaust stroke because it would be bad to fire at any other time.

Yes, the two cylinders on the same coil bank are getting spark each time the coil fires.

David

Micahdogg
11-08-2013, 04:29 PM
Thanks, I kinda answered my own question as I sought out a similar configuration in the 3000GT VR4. I got this:


The cylinders are arranged and numbered as shown below. Because each piston begins its combustion stroke 120 before the next numerically successive cylinder, there are three "pairs" of cylinders, 1-4, 2-5, and 3-6. Each cylinder pair moves up and down together and is at top dead center (TDC) at the same time. The firing order is 1-2-3-4-5-6.

http://www.stealth316.com/images/timing-cylconfig.gif

Paired cylinders have pistons at the same relative position, such as both at TDC. However, the paired cylinders are 360 out of phase, such that one is in the exhaust stroke while the other is in the compression stroke. Spark plugs are fired simultaneously in paired cylinders, during the compression stroke for one cylinder and during the exhaust stroke for the other cylinder. The spark during the exhaust stroke is wasted because the basically inert exhaust gas cannot combust. This is called a wasted spark ignition system. An interesting consequence of this system is that the center electrode is positively charged for one spark plug of the pair but is negatively charged for the other spark plug.

What I find interesting about this, is other than Mitsubishi and Ford using different numbering systems, they both appear to have the exact same firing order and same wasted spark system. I always though Ford had some goofy tiring order which is why our exhaust sounded like crap, but the VR4's generally sound pretty good. So maybe it's the 4 cams vs 1....or the 3.0L vs 3.8L that makes the difference?

On second thought, I guess they do sound similar:
http://www.youtube.com/watch?v=grEKEQM5e6M
http://www.youtube.com/watch?v=HPFLP3yIzPM

S_Mazza
11-08-2013, 08:16 PM
I think the waste spark basically gives some of the benefits of individual coils per cylinder while only having 1/2 the coils, and therefore being cheaper. :)

bowez
11-08-2013, 09:28 PM
Also get the same emissions benefits as two plugs per cylinder.