Changed plugs, now have miss at idle...

[Cpt_Impossible]

I just changed the spark plugs from NGK platinum 5 heat range gapped at about 0.9-1.0mm to the recommended NGK BCPR6ES-11's gapped at 0.8mm. Now I am getting a slight missfire at idle every few seconds. It isn't too bad, but you can hear it thudding through the exhaust.

Is there a common mistake I may have made? I just got through searching here and SAU with mixed answers. On SAU they seem to think it is a common problem because the stock coil packs sometimes cant handle the small gap, but as along as the miss goes away when the engine revs, they are saying ignore it. Others are saying faulty coils, faulty igniter, AFM... practically every answer in the book.

I wasn't having any problems from the coils or igniter before this and the miss is only at idle, when I rev the engine it sounds perfectly smooth and powerful as the 20 should.

-RB20det swapped S13-M's K&N filter on stock AFM-Stock BOV plumbed as well as open vented old school HKS super sound vented (ask the crazy japanese guy who had the engine before me...)-3" downpipe back, no Cat-Stock turbo -Stock ECU-No tuning software-Nismo AFPR

Any help would be great

[Cpt_Impossible]

bump to add email update

[DriftingisLame]

I think I have the same issue, does it sound like popcorn popping under your hood?

I run the same plugs but the 7-es's

[Cpt_Impossible]

No, not popping under the hood...

Under the hood you don't really hear it, but you can feel the car thump and hear a deep thump coming out of the exhaust pipe each time.

[DriftingisLame]

okay, yeah.. Its probably the same. It just sounded like that to me because i had a 10" pipe coming off the turbo. Thats probably why it sounded like my engine was popping popcorn. Which would be a sweet invention btw.

I put my turbo back exhaust back on and now it just studders at idle, and revs perfectly and makes power everywhere like normal.

Mine are gapped at .8mm. I'd love to solve this problem as well, and I hope we get some feedback.

[mott6904]

have you tired clean the crud off the spring in the coil that push up against spark plug. Over time it will build up black crud. just a thought

[Cpt_Impossible]

I used electrical cleaner on one, but then thought it might not be a good idea and did the Nintendo cartridge move on the rest. They all looked decent and like I said, I had no problems before.

[Carl H]

did you possibly loose a spring for the coil packs and didnt notice it?

[l0nestar]

I had an issue similar to this on another (non RB) vehicle.

It ended up being the plug-wire had at the boot and was arcing inside the cylinder wall. The hole was where the clip inside the boot clips down to the tip of the spark plug. I noticed it because there was a small white pin-hole / burn mark on the boot. I could hear it arcing, but could not see it because the plug wires had a weather boot around them at the top of the intake manifold (plugs were recessed about 6-8" inside) Engine was a quad cam.

Inspect all around the base of your coils.. just an idea!

[Vkoslak]

Good info. Mine has been doing this as well for a few years now. I've just been living with it. lol

Fortunately I just picked up some coil packs and boots from a ca18det. They look the same. I was planning on swapping some out anyhow.

[daveh93s13]

im glad im not alone with this problem. however i think mine is more serious than your describing. im getting a rough idle, that has that thudding noise, its not a clean smooth idle like a inline 6 should have. it stays this way all through its rev range, when building boost it has a jerky hiccup that dosn't pull hard like it did. the car started to act this way only at full boost. it started two days ago. then today i pulled the plugs, i found out the bcpr5eix-11 iridium ngk plugs were in decent shape, but the connector for #6 cyl coilpack was broken, i super glued the connector untill i get to the dealer to get a new z32 pack. as far as the plugs, i searched and found that the plugs should have 1.1 gap, they were at 1.0. so i set them to the 1.1 and cleaned them. when i reinstalled the plugs and repaired the connector to the coilpack, i started it and now its worse than it was before i started. its got the rough thudding idle and it is falling on its face throughout the rev range. rb20det in s14 with FMIC, 3" exh, test pipe, walbro 255lph.

[daveh93s13]

ive been looking around, i found some info on sites about "rich and retard" function. but its wierd that the car has been running fine for like 2 months and its all of a sudden acting this way, im buying new plugs tomorrow as long as i can find them, i tried napa and vip but they dont have them. then ill test drive at .8 gap instead of 1.1 and im going to replace the coilpacks. i could just do the one that was cracked at its connector but i want the ignition system to be equally new, like i wouldnt replace 1 out of 6 plugs, i realize its going to be pricey but the coils are getting old. the rb20's are getting old now imo.ill keep posted on how i make out with the plugs and coilpacks.

could the 255lph pump be too much with no regulator?and lastly, the other question i had was how do u get the ecu out of rich and retard function?thanks

[MATTs14]

Mine is doing the same thing. Im considering upgrading my coils to just jap racings direct ignition coils. They are basically the same thing as the splitfires and have received nothing but good reviews. And the good thing is is they are only about $350 so you cant complain about that lol. Im just dealing with the misfire cause it still runs like a beast up top and its running better than it ever has. I guess the gap might have something to do with it. I went from a 1.1 to the .8 because i have read around and seen that the 1.1 gap is for higher horsepower around 300 or so and mine is probably around 220. I believe the new coils will help but if not then oh well

[daveh93s13]

im wondering if i made the condition worse when i made the adjustment from 1.0 gap to 1.1, i dont think i mentioned this, but when it was only popping and thudding up top near/at full boost the plugs were at 1.0 gap. when they were taken out and inspected and cleaned i set the gap to 1.1, im wondering if this had a big reason to its worse than original engine performance.

[Cpt_Impossible]

I don't see how a spring would have fallen out. I didn't disassemble the coil packs and they all had the electrical contact in place.

[DriftingisLame]

What plugs did you remove? And what were they gapped at?

[Cpt_Impossible]

Read OP...

NGK Platinum 5's gapped at about 0.9mm, maybe a tad wider.

[daveh93s13]

i just took off the plug cover, found that cyl 2 coil connector wasnt fully clipped. i re-clipped it, and saw that the connector i glued was still in tact, but when in comparison to the other cylinders, the clip wasnt able to be connected fully. as if the glue was in the way, so i shaved down the glue to my best ability without recracking the clip. i left the iridium plugs at 1.1 gap. i also saw the coupling on the intake side of the turbo was sliding off a little bit. not sure if it was also a prob, but sure as hell wouldve been one soon!! after this i test drove it. on start up, it imediatly had a better smoother idle, it reved up smooth and built boost nicely. it still has a slight hiccup pop at full boost but i ordered a new coil today to replace the one that was glued. im hoping that the high rpm hiccup/pop/breakup has to do with the weak connection at the coil. ill keep you guys updated. i also ordered plugs, bcpr6es. ill be gapping those at .8 to see how it runs. im going to install the new coil first, test drive, then do plugs if it still is running sloppy up top.

[DriftingisLame]

My bad.

I was thinking about changing my plugs to the ones you used to run before you had the miss, but there's no way I'll run platinum or iridium plugs in a turbo motor, I'd rather stick with my misfire...

[Cpt_Impossible]

So, I redid the timing last night to 15 btdc and tuned the TPS. Car idles better now but still has the occasional miss. Haven't had a chance to drive it yet since its been snowing here, but it revs great and I can hold a rev with no misses.