Miata dead. need some help

[Demon I Am]

On the cell, so excuse any misspellings.

Car started bucking/losing power. Pulled into gas station and refilled, checked oil and obd2.
Code p0420.
Left the car parked for 8 hours. Came back to it.
When running sounded like a tractor.
Smoke white coming from rear of motor.
Car drove like shit, to speed maybe 30 with the pedal down. Had to move it from where it was parked.
Checked obd2
P0420
P0300
Barely idles

[tsingson]

From what I was reading, the P0420 is O2 sensor. Are you getting a steady misfire?

[BoBo]

It might be Cat converter or 02 sensor related on (bank1) according to the link I posted.Sucks, a P0300 doesn't tell you specifically which cylinder(s) is/are misfiring, nor why. A buddy of mine had a similar problem he ended up buying another miata since the motor was already 250k+.

According to p0420.com,

"There are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly. The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc".

For more info:http://www.p0420.com/

I hope you get your Roadster back on the road.

[revlimiter]

I wonder if it could be a plugged cat or exhaust? Just pulling at straws here.

[kung fu jesus]

Tony,

List of things to check:

Resistance on the coils
Crank position sensor (dirt/crud build up on the sensor and or plate on crank pulley)
Cam position sensor
Plugs/wires
Loose/frayed broken wires

When the timing goes bad, the O2 starts freaking out.

Another avenue, if you had surging, can be a dirty IAC valve and throttle body.

[Demon I Am]

Ok, I'm going to look at the car again today. Need to tow it from Apex to Raleigh first.
I've had the p0420 for a while, off and on. I believe it might be related to the EGR valve needing a good clean-out. When that code popped up previously, I just reset it and it stayed off until yesterday.

I was told by another friend that the coil packs are notorious for failing on 99-00 Miata. I'll pull the plugs and check for spark. Hopefully this is the case, and I didn't fuck anything up by driving on few cylinders.

I'll start with the easy to look at stuff, coils, wires, check oil for gas, check coolant for oil, CPS, etc and go from there.

Of course this happens as soon as I sell my secondary car...

[Grip Driver]

I'm with Adam, plugged cat or exhaust. Remove the front o2 and see if it runs any better.

[ScratchNSniff]

Hasn't happened to me on a Miata yet, but has on a few of the Proteges with the cat plugged and same symptoms...

[Hyper]

Tony,

List of things to check:

Resistance on the coils
Crank position sensor (dirt/crud build up on the sensor and or plate on crank pulley)
Cam position sensor
Plugs/wires
Loose/frayed broken wires

When the timing goes bad, the O2 starts freaking out.

Another avenue, if you had surging, can be a dirty IAC valve and throttle body.

listen to this guy, he is right in all points.

[Demon I Am]

Barely had enough power to get it on the auto hauler. Got it back to Raleigh. Cranked it to roll of the trailer and it drove fine. I'll start looking at it after some food, and when the sun drops a little

[JLBMX5]

My son bought me a huge canopy for Christmas i can loan you if you think you would need it Tony.

[Agent☣Orange]

Good advice here. I've worked on a couple that were completely dead and it was because they had replaced the crank sensor and didn't tuck away the wiring well enough and a belt ate through the wiring insulation and killed the sensor. If the car is still running, it isn't because of the crank sensor because it just won't run at all in that case, same with the cam sensor. My first guess is also a bad cat and a cat can go bad from a bad EGR or O2 sensor. IAC is a possiblity but it's a reach IMO.

Sorry but I'm not on top of everyone's latest Miata but your info mentions a '90 Miata which you can't be reading any OBD-II info from so what are you driving now?

[tsingson]

2000 NB

[Agent☣Orange]

NB1? Uff, coil pack... Wire gets loose inside the connector on top of the coil and causes misfires.

[Tkblazer]

^ that would be my guess

[mx54life]

Most likely your Cat is gone.

[Demon I Am]

On the cell so I can't get the pix to load...

Pulled all the plugs. #1 normal ashy-ness. #2 and #3 pitch black, crusted electrodes, #4 blackened slightly with normal ash.

Cranked the car with the plugs grounded. No spark on #2 & #3.

[kung fu jesus]

2&3 are off the pack on the drivers side, IIRC. I had bought coils on Amazon brand new for ~$90, beck arnley. They were aready mounted in the carrier, just like oem, but no rubber grommet for the third bolt on the bottom.

[Demon I Am]

OK, so I installed the new coil pack, wires, and plugs.Still had the same problem. Rented a compression tester and read 180.180.180.185.
Hooked up my timing gun to each wire and 2&3 are not sending any signal.

So either the brand new coil pack is bad, or my issue lies elsewhere. I reset the CEL, and it didn't come back on, but the car didn't run for long.

Another thing of note: The exhaust seems to be blowing out extra forcefully. Probably due to the whole running on 2 cyl thing?
Tomorrow's plan:
*Check the old Coil Pack with a multimeter, to see if it's bad. Also, check the new one.
*Switch the wires from 1,4 to 2,3.
*Check Cam sensor
*Check the wiring harness connector for broken/loose wires. Apparently, thats a thing.
*Pull the kitty if the code comes back. I know this would not cause the no-fire problem, but better to know.

[Demon I Am]

Think I've narrowed it down a little more. Cranked the car, and pushed hard on the connector, cylinder 2&3 started working. Took it for a 2 mile test drive, cel stated off until the last 1/8 mile. Light began flashing, then turned solid.
Checked codes p0300 random misfire & p0171 system to lean.
No decrease in performance that last mile. This is getting tedious

[Agent☣Orange]

Even though the connector is tight, try wiggling the wires themselves to see if the motor runs right or stumbles. My buddy went through two coils until we identified a loose wire inside the connector. Both coil packs were fine.

[Demon I Am]

OK. I took the 2 coil packs apart, and made 1 out of the known good packs. Clean the connectors with cleaner Hooked everything up and no codes for the last 3 miles

[bslkendall]

OK. I took the 2 coil packs apart, and made 1 out of the known good packs. Clean the connectors with cleaner Hooked everything up and no codes for the last 3 miles

Glad to hear you found a solution.

[Demon I Am]

In not holding my breath

[tsingson]

Still going? Is it running smooth with no codes or no codes but still a bit of problems?

[Demon I Am]

I've put about 20 miles with no issues

[Grip Driver]

sounds to me like you have the issue squared away, good job

[John J]

Chasing ghosts is one of the most difficult things to do when repairing a problem. GREAT JOB hope you have no further issues.

[Packrat456]

Question, does anyone know where I can get the connector going into the coil pack on the drivers side of the car? Mine is missing the latch points, and I think it may be causing the issues that I am having in my car.

[Demon I Am]

I've read online that you can get them through a dealership, and I've found them online. Google search "Miata coil pack pigtail"

[Packrat456]

I've read online that you can get them through a dealership, and I've found them online. Google search "Miata coil pack pigtail"
Thanks 👍

[kung fu jesus]

If the O2s weren't replaced, and the code kept popping for them, 0420, the initial issue wasn't solved. The loose connector was probably unrelated. I would definitely address that first. I personally prefer direct fit plugs on the O2, but if you feel comfortable wiring in universal O2s, go for it.

If you suspect the EGR, pull it and clean it. People have soaked the sensor in a cleaner with good results, from what I read. Cleaning the tube would also be a good idea. The tube can be a little difficult to remove. The fitting on the header is compression and can be sticky from oxidation. Removing the coilpack gives you good access to the fastener (nut or bolt) that secures the tube at the back of the motor.

Running on a lean condition es no bueno.

[Demon I Am]

Lean condition code is gone, misfire code is gone. So the non-drivable issue is no longer occurring. I've put on almost 50 miles with normal operation.
The only code now is either a p0420 or p0402. I'll verify tomorrow, as I'm tired and confused right now. One is the cat (or O2 sensors), the other would be the egr. Both of those are inconvenient, but not dire. I'll be looking at either replacing the sensors or getting a new cat/midpipe (roadstersport), or having Henry's weld me up something, if the cat looks bad when I pull it off.

I have cleaned the upper intake manifold, but have yet to clean the egr valve. That will be an afternoon project.

[Demon I Am]

... And the cat came back, the very next day


Cleared the p0420 code this morning, drove 35r miles to work with no issue. 2 miles from home and it all came back. P0300, flashing cel, no power. Limped it the 2 miles home. Looking under the hood I noticed the VICS solenoid is broken at one of the nipples. I can pick up a good one tomorrow afternoon from a parts scrapper. A vacuum leak wouldn't cause all this headache, would it?

I'm tempted to buy a cops setup, if this coil pack is the problem. I want to try wiggling the wires again, and see if it does anything. No clue how the wiring would have become errant.

At this point I'm almost ready to walk away from the car, sell it at a loss or something

[Grip Driver]

A large enough vacuum leak will cause all sorts of issues, especially drive ability. Vacuum leaks however don't typically come and go.

[revlimiter]

A truly huge vacuum leak will make life suck. A small one will just make a sucking noise and give you some sort of OBD code about the air meter.

I still think a good 90% of the exhaust needs to be removed and checked for plugging.

[Demon I Am]

Well I can't get to work tomorrow, so I'll be looking at what I can. How explain how a clogged exhaust would cause the 2-3 cylinders to not pulse.I have read that misfires kill cats, but not the other way around.

[Demon I Am]

So after more monkeying around today, I believe my problem is related to the wiring harness. with the car cranked and running smoothly, I can make it misfire by pushing the wiring harness against the coil pack housing ( front of the car). if I pull it back, the misfire goes away.


I checked the crank sensor, it was cruddy, so I cleaned and reinstalled. I've cleaned the upper intake mani. If I can figure out a way to do so, I'll pull the egr pipe. I don't have a 22mm wrench handy. Once the miata breaker is home, i'll go get that solenoid and probably a 3rd coil pack, just to have a spare.

Ordered 2 pigtails from Ballenger. I have on clue how to, and no tools to solder. Should I be OK with crimping the wires, or am I going to need to buy a soldering gun and other stuff?

[tsingson]

Was the harness possibly pinched at some time back there?

[kung fu jesus]

That was my guess. There are some sharp edges back there. If the coilpack connector is messed up, I suggest looking for a weatherpack connector. You may be able to find them locally. if you do that, it might be a great time to sheath the harness with the connectors cut off to insulate them further.

[Demon I Am]

Does not look like it. one wire is bent at a 90* angle at the connector. Maybe the crimping on the inside is wacky? There are no cuts in the sheathing at all.

[kung fu jesus]

Tony, help me remember...

Does your FUBAR coil pack connector connect at the coils themselves (fixed to the back) or at a pigtail away from the coilpack?

I have used two-part epoxy in the back of OE connectors to stabilize aging wires going into brittle OE connectors. Just need to be sure the wires aren't frayed or corroded. Just a little epoxy helps brace the wires going into the connector, seals out weather. You don't want it to get into the male/female physical connection itself, or that connection become permanent. :) The two-part epoxy hardens fast, too.

If the detent on the connectors is broken or worn off, I have had some luck building up a new detent using a drop of superglue in that spot (connection apart of course). Sometimes 1 drop, wait for it to harden, then another drop, etc. builds up the surface so the connector with the latch can grab on to it.

[kung fu jesus]

I don't remember how many pins the NB1 coilpacks have, but this is an example of the Weather Pack connectors I mentioned in the previous post. Not cheap, (<$10), but they are something that is pretty 'bomb-proof' They seal so well, that sometimes they are hard to get apart.

http://mazdaroadster.net/attachment.php?attachmentid=14242&stc=1

[Demon I Am]

I ordered these http://www.bmotorsports.com/shop/product_info.php/products_id/2076

I don't have the tools required to crimp those, so I thought the pigtail would be easiest.

The coils themselves have the connector built on

[Grip Driver]

Look at the pins in the connector and see if they have spread out. You could be getting an intermittentent connection caused by a loose or spread out pin.

[Demon I Am]

OK, so I ordered the wrong connectors. But we were able to save the day by cutting the bad wires (there were 2) and splicing the wires and pins from one of the new connectors. After going everything up she is sounding good, and I can no longer duplicate the problem. Hopefully this is it for now.

Thanks for all the help and encouragement!