aidandj

iTrader: (5)

Re O2 sensor: iirc if they aren't powered they die fasterm. Might be worth pulling it out and plugging it when not in use

rwyatt365

Typically they're powered (I have a "magic switch" under the seat that powers the stock sensor heaters when the car is running on the MS). But this is what I found under the car (yeah I know, crimped connections - especially under the car - are not the best thing);

I have no idea how long it's been like that - we'll see how dead the sensor is.

rwyatt365

Fixed the pigtail but car ran like crap. Found out that the O2 signal wire was crossed (WTF?!!). Anyway, running better now, just need for all of the ECU tests to go green.

Running NA for the past couple of days lets me know I don't want to go back THERE again! The car's not a pig but I sure do miss the kick that happens when the turbo spools up.

Soon, very soon...

rwyatt365

DAMMIT!!

It looks like both of the O2 sensors are damaged! The heater wire on the upstream connector (pictured above) had been disconnected for who knows how long and the signal wires were crossed and the heater wire on the downstream connector was pulled out as well. I just ordered 2 new Denso universal sensors...should be here tomorrow. I also got some new waterproof 4-wire connectors from McMaster to (hopefully) eliminate this kind of crap for next year.

I'm thinking of rigging up a switched 12V circuit to the heater circuits for when the MS is back in control. That should prolong the life of these damned O2 sensors during the 50 weeks when they don't do anything but plug holes in the exhaust pipe. Better yet, why not just take out the damned things and put plugs in the bungs instead?

rwyatt365

Still foolin' around trying to get through emissions.

The new Denso O2 sensors did the trick - enough of the OBD monitors went green to go for a test...until I checked the fault codes and saw a P0171 "Bank 1 too lean" code. NOW I have to chase down a vacuum leak.

rwyatt365

NOW I have P0300 and P0141 codes to deal with. I spent most of the day yesterday cleaning the IM (for the P0141), and going through the entire ignition system (for the P0300).

On the drive in this morning both showed back up

DNMakinson

iTrader: (3)

This is what I find on line:

P0300 random misfire
P0141 O2 sensor heater

So, I understand going through ignition system for 300, but not IM for 141.

patsmx5

iTrader: (16)

Just remove the sensors and install a plug if you're not letting the stock ecu control the sensors. You'll kill the heater if you wire them on all the time, and kill the sensor if you leave them unplugged but in the exhaust stream.

Have you checked the grams/sec of the MAF at idle? That's the first place to start if you suspect you have a vacuum leak.

P0141 is a heater circuit problem on an O2 sensor, that has nothing to do with the intake manifold and everything to do with the wiring or sensor for that O2 sensor. Given the amount of wiring problems you posted about, and you said you installed a new sensor, it's probably your wiring.

aidandj

iTrader: (5)

He is letting it control them. This is for emissions.

rwyatt365

Thanks for the assist guys. I've got the stock ECU back in temporarily (as Aidan says) for emissions, so the stock NBO2's are functional and working fine.

I fat-fingered the P0141 - it was is actually P0401 "EGR insufficient flow" code, that's why I was fooling around with cleaning the IM. The EGR module is connected to the wiring harness, but not to the IM (it's just hanging in the breeze and there's a block-off plate on the IM) - and there's no EGR pipe to the exhaust. I got it to pass the OBD check for the last 3 years like this, so I don't know why it's acting up now. What puzzles me is how does the stock ECU know WHAT the "EGR flow" is? Other than the MAF on the intake, there's nothing in the NB2 system that measures flow AFAIK. Maybe that's where I should start looking.

The P0300 is what's driving me crazy! The car is running fine (except for a lopey idle which I think is the result of the exhintake mod) - no hesitations, no stumbles, and smooth as silk above 1000RPM). I pulled the CPS yesterday and noticed that there was a small groove in the face where the nibs on the trigger wheel got a bit too "friendly". I ordered a replacement in the hopes that this is where the problem is.

We'll see...

rwyatt365

Some early-morning research seems to indicate that the P0401 might be related to a clogged, or malfunctioning "EGR DPFE sensor" (Differential Pressure Feedback EGR sensor). AFAIK, this is that damned stock Mazda MAP sensor that sits on the fender well on the cold side of the engine.

I'm gonna clean the pipe today at lunch (sounds kinky!) and see if that makes a difference. If it does then great, I can move on to the P0300.

At least I'll get a squeaky-clean IM and faultless electrical connectors out of this crap.

patsmx5

iTrader: (16)

If it's throwing that code for insufficient egr flow, (that is, the ecu says " there's not enough egr flow") then I'd say the ecu knows how to check the egr system for operation. Well, that and the fact that it does, you can read about the egr system test online for that readiness monitor for exact details on when it test (extended coastdown from above 2,000 RPMs at operating temp or something like that) In short, it's not going to pass an egr readiness monitor for very long without the egr system installed and working.

So if your problem is "EGR code" and you don't have the system hooked up, my suggestion is to hook the system up. That should make the egr code go away.

cam is probably causing the P0300 if it's misfiring at idle. Is it misfiring at idle?

rwyatt365

Thanks Pat.

Here in the great state of Georgia, cars of my vintage can squeak through with 2 readiness monitors unset. The EGR monitor is notoriously difficult to reset, but I can get everything else but that one to reset, so if that one doesn't reset...I don't care.

What I do care about is making the freakin' P0401 "insufficient flow" code go away 'cause the testing facility won't go any further if a CEL is set (or pending). That's the one that I've got to "kill".

What I did this afternoon is to clean out the (dreaded) MAP sensor, and the solenoid that "turns on" the flow to it from the IM. I checked the solenoid and it operates w/ 12V applied directly to the terminals and - when open - it "passes gas" quite easily. What I don't know is what triggers the solenoid to open (more research).

In my infinite wisdom I thought, "If the solenoid is a potential problem, why not just hook the MAP sensor directly up to the IM, bypassing the solenoid?" I tried that, and it made the idle REALLY funky (as in, the idle would stick at 1,500 and oscillate for about 30 sec before settling down to normal, and when the fans kicked in the car would die) - so I put it back in the vacuum circuit.

It's not so much misfiring as it has a "blub-blub-blub..." kind of cadence (sort of like a small block Chevy with a big cam in it) at idle. I'm thinking that the stock ECU doesn't know what to do with that. I'm almost thinking about changing the throttle stop screw (OH-NO, NOT THAT!!) to make it stay at 1,000RPM ('cause that's what the state's testing cycle mandates as the upper limit for idling).

We'll see if the new CPS "fixes the problem"

rwyatt365

New CPS should be here tomorrow. I'll also take a look at the MAF tonight (if it doesn't keep raining), clean it up and see if that helps.

I think I have the P0401 solved (and, now that I said that, it'll reappear tomorrow).

If the P0300 doesn't go away, I might be forced to put the stick exhaust cam back in (hoping that might eliminate the lopey idle and satisfy the ECU).

I HATE "OBD-check time"!

patsmx5

iTrader: (16)

I don't remember if you did this already, but I'd throw new stock heatrange plugs in it if you have a misfire code. 1/2 the time that solves a misfire code on miatas and it's cheap/easy/fast to try.

rwyatt365

Oh snap. I still have the cold plugs in. I'll try that.

rwyatt365

Busy day yesterday;
- Installed ARP studs on all 4 corners (all done in-car, the first corner was a bitch 'cause I didn't really know what to expect - that one took almost 2 hours, the rest went in in under 20 min each).

- Flat-rolled the fenders for the VR-1's.

- Fitted the VR-1's and they fit like a champ! The only interference was at full lock in the front - they rub a bit on my aftermarket nose. Other than that, no problems at all, and they look badass on "FrankenMiata"! The wheels are Advanti 15x9 - there's no stretch and the tires sit fairly square on the wheels;

(Yep, it's a "car of many colors". The shell is from a '00 BRG, the front fenders are aftermarket, the doors are from a silver 01', the hood is from a black '99, the nose is aftermarket and the rear bumper cover is from the original 10AE...a true Frankenstein's monster of a Miata!). One day it'll get painted.)

Then came the stuff to try to get rid of the P0300 code;
- Put in stock NGK plugs.
- New CPS, regapped to stock spec's.
- Cleaned the MAF sensor.
- Checked for, and killed, vacuum leaks.
- Swapped in a different coil pack.

Still got the code on the way in to work but I wasn't driving conservatively so that may have "influenced" the code. I'll be a respectable citizen on the way home and see what happens then.

rwyatt365

Saw a thread on m.net where someone suggested checking and tightening the timing belt to spec. The theory is that a timing belt with too much slack will allow the cams and crank to oscillate relative to one another - enough so that the ECU cries "foul" and sets the P0300 code. It kinda makes sense.

Since I have tried just about everything else, it's easy enough to check this out. So I pulled the front of the engine off at lunchtime today. My timing belt WAS a bit loose (slightly more than 1/2-inch play) so I tightened it up. We'll see if that makes any difference. I need this to go away this week so I can get registered (and STOP being NA!!!).

rwyatt365

F-ing P0300 is still there! This is getting ridiculous!!

patsmx5

iTrader: (16)

What on your car is not exactly stock right now?