Doppelgänger

iTrader: (12)

So your plugs were causing the ignition cut out? I changed plugs with some I had around this morning (Denso Iridium- not spectacular, but I figured i'd try). I thought there was a difference as I could roll all the way through 2nd gear with no problems, but as soon as I go to 3rd gear I get a bad stumble and the tach needle shakes for a moment. If I touch the throttle before the needled settles, I get multiple backfires of unburnt fuel..like the coils aren't firing and raw fuel is igniting in the exhaust. i'll pick up some 3330's on my way home and hope that helps.

JayL

iTrader: (12)

Yes and I have no idea why, it made no sense to me at the time and I am still clueless about it. They looked perfect and weren't all that old to begin with. New plugs went in with the same gap and all was better.

Doppelgänger

iTrader: (12)

Well, I'll probably replace mine now anyway since they've been in there about a year and a half now.

Also, more clues...On my way to work today, I quick shifted 2nd to 3rd (not hitting the cut problem) and it sputtered and when I went to hit the throttle, I got a bunch of back fires as if I was dumping fuel in , but no spark so all the fuel was hitting the hot exhaust and popping VERY loud and had no power/acceleration.

I noticed that the tach was jumping a bit, not dropping like a complete loss of tach signal/bad ground (seen this happen..this is not the current case)..but dithering quickly within 100rpm of where it was..and while it was doing this, I was getting backfires when throttle was applied. After about 2-3 seconds, the needle stopped twitching and I was able to apply throttle normally.

Something is either interrupting ignition signal or the ECU is cutting signal based on some input....but WHY is the million dollar question and is it related to me replacing the valvecover.... argh.

fooger03

iTrader: (2)

make sure your grounds are tight and clean

BradC

iTrader: (6)

My MSP would do this when the plugs started to get shitty. Get some freshy-fresh NGKs in there.

Doppelgänger

iTrader: (12)

update coming soon ***************

Doppelgänger

iTrader: (12)

OK...i has an update

It turns out that my car actually told me that it didn't like the color of the new valve cover (a kinda smoked metallic black color...looked kinda like cast iron with a bit of flake)


jk

I came home from work and replaced the cover and sanded the seating area to the one ground that I had to remove to put the old cover back on. Then I went over to MazMart and picked up a like-new cam sensor. But before I decided to see if that worked, I stopped by NAPA and picked up some new plugs and installed them on the spot. On my way home, I did a few 2nd and 3rd gear pulls with no harsh ignition cut, though I still got a bit of misfire ~6500-6800rpms. So when I got home I put my Magnacore wires back on and re-loaded my map and went for another drive. Now it's almost perfect. I still got a hiccup or two in 3rd and 4th near redline, I suspect I need to tighten the gap on the plugs just a hair (i'm at .035" and i'll probably go down to .030". Sounds like too tight of a gap, but if it makes the misfire go away..then so be it. Also, with the new old map, the car pulls nice and hard.



I also plugged the lappy toppy back up to see if the AFR issue was still there.... and it is :( 23.8 AFR no matter what setting I touch or play with the harness. So I still need to figure that out. But I have it in open-loop so WB02 isn't being used. It'll be my luck that I need to replace the WB02.....again.



So those who suggested to change the plugs...well, you were right. But to me, the logic of my plugs suddenly needing to be replaced when I didn't even touch them...well... yeah...hard for me to belive.



Anyone have any guesses as to why AFRs read ful lean at all times yet the WB02 gets hot when turned on and it dithers when I start the car and when I disconnect it, readings drop to the Zero Cal setting of 14.7. If the sensor was dead dead, it would read 14.7 at all times with it plugged in.



Anyway.. i'm much happier now.

magnamx-5

iTrader: (7)

nah man it could be dirty, but my gues is you have a bad ground on the WB02 harness that is droping out on you when the **** is vibrating etc at speed. That or the programer is out of whack but if you did a recalibration then i would look for maybe oil in the ehaust masking your readings.

usd2bfst

From looking at your logs it did just look like a spark misfire. I've tried so many plugs, I'd never use anything but good 'ol NGK standards on a turbo Miata.

Also, with your plug wires, make sure to "burp" the air out of the spark plug boot on the coil end when it is pushed on.

Check your WBO2 wiring to make sure it hasn't gotten pinched or melted. If it is hosed, and you have your NBO2 installed still, better to run in NB closed loop than open loop IMO. It has STT & LTT just like factory.

When you're cleaning your ground points, remember the ones under the brake master cylinder area as well as the one on the PPF back by the differential. Also, when the turbine heat shield went on with the FM2 make sure the block ground strap still has good contact under that rear shield mount bolt. When in doubt, sand their surfaces down.

Doppelgänger

iTrader: (12)

Yeah, I sanded the contact area on the grounds by the throttlebody and on that ground strap by the firewall. Also, I currently have the tuning running open loop. Eventually i'll get around to buying a new WB02 to see if it's the sensor or the wiring.

JayL

iTrader: (12)

Do you want to borrow a Hydra sensor for a day to see if that's the cause?