Constant coil-pack failure, especially after CNG install.

[Walls]

First off, I'd like to say hello to everyone on here, especially as it's my first time posting. So...

Hello everyone!


So, I'm hoping someone could possibly help me with a problem I'm having with my Serena 7-seater. I should mention it still got an MR20 engine in it, though not the original one it came with. The problem I'm having is with the coil-packs, I keep having to change them constantly, even though It's hardly ever driven.

Recently I installed a CNG kit at Dumore, this seems to have made the issue even worse, as I've come to learn that CNG apparently, is more demanding of coil-packs, and even spark plugs. I've just installed four brand new OEM coil-packs. It drove wonderfully on the way home, didn't use the mini-van the next day. The following day on my way to Penal, I notice a slight momentary stutter with the engine, eventually the check-engine light came on, and the stutter became progressively more pronounced.

I've seen this all before, and I'm dead sure, it's the coil-pack or packs again. Tomorrow I'm heading down to the mechanic to confirm, what I believe I already know. I was even told by a technician at Dumore NOT to install brand new OEM coil-packs, as this exact thing would likely happen. It would fail the next day. But to get them foreign used, as this was his own experience with Serena vehicles.

He was obviously RIGHT!!

So more to the point, my question is about what could possibly be responsible for this constant coil-pack failure? I've heard of heat and faulty spark plugs. However, at no time the temp gauge went above its normal position. After the CNG install, it possibly increased by one bar - I'm not sure though. But I believe I can physically detect that my engine's running considerably hotter, when running CNG, whenever I open the hood to refill. And I think I was told that CNG does in fact run hotter by the technicians.

As far as spark plugs go, I changed them earlier this year, and as I mentioned before, I hardly even drove the van since. If anyone's got any recommendations regarding sark-plugs, brands or specs, I'd be glad to have them, along with any other suggestions regarding this issue.

Thanks!

[Walls]

Oh! One other thing. When running on super (gasoline), that engine burns about a dollar a kilometer. Is this usual for a 2000cc engine?

Thanks again!

[Dave]

Coil pack failure comes from the spark plug.
Generally the combustion chamber runs hotter with CNG and thus needing a colder plug. When the plug cannot fire, the coil pack is loaded and since it cannot discharge to the plug, the pack blows.
Once there is a coil pack issue, plugs must be addressed.

OEM meaning substitute pack was used?
Unless you have an ignition amplifier such as a MSD the same output will always be sent to the plug. When installing a CNG system you should always use new plugs and change them more frequently.

This was discussed here already and afaik there isn't a colder plug option for the MR engine.

[kamakazi]

Could try reducing the spark plug gap

[Walls]

Coil pack failure comes from the spark plug.
Generally the combustion chamber runs hotter with CNG and thus needing a colder plug. When the plug cannot fire, the coil pack is loaded and since it cannot discharge to the plug, the pack blows.
Once there is a coil pack issue, plugs must be addressed.

OEM meaning substitute pack was used?
Unless you have an ignition amplifier such as a MSD the same output will always be sent to the plug. When installing a CNG system you should always use new plugs and change them more frequently.

This was discussed here already and afaik there isn't a colder plug option for the MR engine.

Thanks for the synopsis on coil pack failure, that certainly was helpful to know. And by OEM (Original Equipment Manufacturer), I meant original Nissan branded Coil-packs. I know it sounds weird, but that's what the Dumore technician told me would happen... and that's exactly what seems to have happened. Couldn't confirm it today as my mechanic had some other commitments.

As far as "ignition amplifiers" go, I'm sorry I don't know what those are. So, I'm guessing I don't have any. Would be grateful on a recommendation for a good spark plug for the MR20, as I'm certainly going to change them. Hope it works, as this would be the fifth coil-pack install within a year, on a vehicle that is routinely not driven for days, even weeks at times.

[Walls]

Could try reducing the spark plug gap

Thanks for the reply. But how exactly doe's that work? As, apart from changing oil, a tire, and things of that nature I'm not mechanically inclined at all.

[Dave]

So the stock gap on a MR engine is 1.1mm. It would be experimental but the Dumore personal should know from experience what gap would work.

Also thrown in the mix is Ngks ruthenium plugs which offers longevity of platinum with ignitability of iridiums so basically a more durable plug.
If not financially sustainable, then use platinum plugs or the thicker electrode iridium ones.

[Walls]

So the stock gap on a MR engine is 1.1mm. It would be experimental but the Dumore personal should know from experience what gap would work.

Also thrown in the mix is Ngks ruthenium plugs which offers longevity of platinum with ignitability of iridiums so basically a more durable plug.
If not financially sustainable, then use platinum plugs or the thicker electrode iridium ones.

Thanks a bunch!

[sMASH]

So far good info.


My experience and research is the spark plug blows, which the blows the coil pack.
So, change both st the same time.

I used original Nissan spark plug but the ngk iridium lasts longer.

I will try that ruthenium, next time


What i found out is that the cng burns hotter thsn gasoline, so it needs a different heat range plug. But for my hr16 engine, i only getting the standard heat range for gasoline.


What i find works is to only use the cng when u don't need power. Like if ur only mashing 1/4 of the x.

If i need power, any slight power, to go up slight hill or to speed up, i switch to gas.
Snd when i dont need any power at all, switchback to cng.

This works best. I tried gapping, original plugs, original coil pack, rich cng setting, lean cng setting, changing plug regularly ... Snd the only thing that saving the plug/coil pack is petting the engine on cng, and switching if i need power.

When i get the misfire indicating that either plug or coil going, i jess run it till it gone or get bad and change that combination together.



Is a pain to do, but i get accustomed to doing it.. Like driving manual.

So far i went from changing every 5 months average to a whole year without changing.

[Dave]

Interesting point with the HR and modern engines.

If you use thin oil, you are gonna have huge amounts of blow by so use of a catch can, combustion chamber temps are kept low from lack of oil presence will also go a long way especially given how CNG burns.

[kamakazi]

Could try reducing the spark plug gap

Thanks for the reply. But how exactly doe's that work? As, apart from changing oil, a tire, and things of that nature I'm not mechanically inclined at all.

Smaller gap requires less voltage from the coil to spark (jump the gap)

Could try down to 0.8-0.9mm

I saw that ruthenium was a bit of a marketing cash grab by ngk.

[Walls]

Could try reducing the spark plug gap

Thanks for the reply. But how exactly doe's that work? As, apart from changing oil, a tire, and things of that nature I'm not mechanically inclined at all.

Smaller gap requires less voltage from the coil to spark (jump the gap)

Could try down to 0.8-0.9mm

I saw that ruthenium was a bit of a marketing cash grab by ngk.

Okay... great info, thanks.

[Walls]

So far good info.


My experience and research is the spark plug blows, which the blows the coil pack.
So, change both st the same time.

I used original Nissan spark plug but the ngk iridium lasts longer.

I will try that ruthenium, next time


What i found out is that the cng burns hotter thsn gasoline, so it needs a different heat range plug. But for my hr16 engine, i only getting the standard heat range for gasoline.


What i find works is to only use the cng when u don't need power. Like if ur only mashing 1/4 of the x.

If i need power, any slight power, to go up slight hill or to speed up, i switch to gas.
Snd when i dont need any power at all, switchback to cng.

This works best. I tried gapping, original plugs, original coil pack, rich cng setting, lean cng setting, changing plug regularly ... Snd the only thing that saving the plug/coil pack is petting the engine on cng, and switching if i need power.

When i get the misfire indicating that either plug or coil going, i jess run it till it gone or get bad and change that combination together.



Is a pain to do, but i get accustomed to doing it.. Like driving manual.

So far i went from changing every 5 months average to a whole year without changing.

Link:
https://carfromjapan.com/wp-content/upl ... 24x652.jpg

Great info. Thanks!

[Walls]

Interesting point with the HR and modern engines.

If you use thin oil, you are gonna have huge amounts of blow by so use of a catch can, combustion chamber temps are kept low from lack of oil presence will also go a long way especially given how CNG burns.

Um... Would the oil catch suggestion also be pertinent to my MR20 engine. Also, with respect to the spark plug temperature rating, any suggestions as to much colder I should go.

I found these NGK iridium plugs on Amazon: https://www.amazon.com/22401-ED816-LZKA ... 216&sr=8-1

They're the LZKAR7AP-11's (as opposed to the standard LZKAR6AP-11), and they're apparently one point colder than the standard ones, as seen here: https://carfromjapan.com/wp-content/upl ... 24x652.jpg

Barring any suggestions, I'm planning to install these, after gapping to 0.9mm as suggested. Hope I'm on the right track?

[1800GSRLANCER]

I run cng on a y11 Ad wagon, manual qg15 E-throttle. Had a misfire from the initial install at burmac in 2020, tried platinum plugs it lasted about 2 months, tried some foreign used ngk iridium I had in a head and block and that sloved my problem. I might get over a year misfire free and if I does occur I have spare coilpacks I roll around with, that engine however eventually valve seals went was smoking and burning oil I drove it until it gave out lol, changed head and block and bought denso iridium this time and I was misfire free for about 2 years! Until a few months ago the misfire came back and I decided to try something so instead of foreign used coil packs I tired a brand new one and it didn't work as it usually would have then I changed all 4 new packs and then tried the original ngk plugs and I noticed a difference the misfire is usually on a cold start and when it's at optimal temperature there is no misfire... tried a liqui moly fuel injector cleaner and the rough idling died out so a full injector clean is necessary.

[Dave]

If the mileage is high, try replacing the in tank fuel filter.

[Noelrags1234]

Since the issue keeps happening, check for overall ignition and fuel system problems. Make sure your CNG system is tuned right. For spark plugs, use ones suited for CNG, NGK or Denso are good brands.

[Thomas 007]

Yep, I agree with Noelrags. Keep an eye on engine heat and consider adding heat shields.