Don’t think about it as flow based. It is based on the active adsorption capacity of the catylitic converter. Replace the cat with a straight pipe, and the two will follow close together. Put a good cat in, and you get smoothing based on the surface of the cats storing reactants. Put in a bad cat, and it is somewhere between the two.
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I think you mean 3 O2S on similar sedans…
I don’t follow. The amplitude will be affected by O2 levels in the exhaust stream and little else. The Mazda doc appears to be implying exactly the behavior the other docs are describing: pre-cat will see 0-.5v for lean conditions, as what happens in a coast down, and .5-1.0v for rich conditions, as when under acceleration. Post-cat should be 0-1.0v regardless of situation.
I’m not clear what you’re seeing. From the graphs posted, you appeared to have (had) a “dead” O2s, at about 0.0v. They should be at .45v “base” if they’re working. Then the other graph you posted with all 4 cycling makes it appear the cats are deficient, as noted by the cycling of the post-cat sensors. They should be noticeably slower to cycle, and lower amplitude, as the O2 levels exiting the cat should be fairly steadily low (as the O2 is consumed in the reactions the catalytic converter supports), but with upticks as the stored oxygen is consumed and replenished in the trim cycles. This should be true regardless of where they are hooked up to the ECU (though it certainly might confuse the ECU if they are switched, front to back especially).
I think you’re making stuff up. 
I don’t think the exhaust paths are different lengths, or not significant if so. I also don’t think whether it’s a 4 sensor or 3 sensor system will change the way each O2S should function given its location in the system: post cats’ll always do what post cats do, and pre-cats’ll always do what pre-cats do, regardless of how many of them there are (which DOES leave me wondering, at this point, WHY they choose to use a sensor per bank of cylinders on a single cat system when a single sensor just before the cat would probably work equally well, but that’s really another topic, I think).
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If extra air is seeping around the filter it’s only an issue if that is between the intake sensors and the engine. If the sensors are between the air filter and the engine then it’s not a problem for the ECU.
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OK, I would like to cite general connectivity goofiness as a prime suspect in the previous postings.
So now, O2 sensors are hooked up correctly, and I took the vehicle, now generating no faults, no codes, on a warmup drive. Then I pulled in to gas station, pulled out torque. This is how the O2 sensors are responding at idle in drive now:
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Are your readiness codes now gone as well, or still waiting to see if those are happy?
Those traces make it look like your cats are lazy (the green trace for bank 1 sensor 2 is too active) and the trace on bank 2 sensor 2 is oddly high, but if the readiness goes green, and it passes inspection…
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Have you considered doing a leak-down test to check for any head-gasket funniness?
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I am not getting codes or faults anymore, and I have driven a significant amount, so this is a first. The car runs like a dream now that I got my little wiring concern figured out and have no vacuum or exhaust leaks. I sealed up the oil pan leaks using a felpro gasket, and when I did I changed the oil. The slightly used oil was a beautiful color I would expect to see from a brand new engine. No evidence of any coolant in it, however I did note a slight amount of sparklyness which I presume has to do with the graphite shavings when I scraped head gasket #1 off. I am quite sure the head gasket is sealed nicely due to the way the engine is behaving alongside the color of that oil. The lack of smoke or smells from exhaust is a big clue as well.
The difference is night and day between the felpro MLS in the car now with the prepared surfaces, and the previous head gasket attempt. It clear I’m on path to success this time, just need to get the state inspection to complete now. So I’m just sort of driving around right now waiting for the computer to complete its check cycles. I’ll advise should we see an issue, and my take some more screen shots for you guys to illustrate system health.
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So I had installed a bogus O2 sensor. It was the fat one you see at the auto parts store for cheap. I went back to replace it, and i wanted one I didn’t have to wait for ebay to deliver, so I went to the stores. They were out of these sensors at every auto parts store I tried in Dallas, and internet searches indicating no local stock.
Then I stumbled upon these NTK sensors (formerly a little known company called NGK). They were of solid top shelf Japanese construction and not well advertised on the auto parts stores websites. The person helping me didn’t know much about them, but I was able to go to the shelves in a certain store and there was a whole bunch of these just sitting there. And what’s more, is that they even had the correct plastic connector for my car on them. The wires were too short, but the connector was correct. The pinout, however, was not, but thats an easy fix given I have to lengthen the wires anyhow. Finally, upon careful examination next to one of the OEM sensors, I was able to surmise from the markings on the unit and the exact match mechanically to OEM sensor, that these sensors are in fact the very ones used by Mazda during assembly in Japan.
I installed, and reset my codes. Shortly, the sensor got flagged, but I am experienced and reset again. Now I have been driving for a good bit and I am not getting any fault or CEL code at all. All the diagnostics pass, and I am down to three remaining state inspection tests to pass.
Attached is another Torque plot of the O2 sensors I have currently installed. All of them are now correctly installed and of the OEM type.
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And if that last Torque shot was not enough proof that the Catalyst is good, how about this one I just got in. Notice that the catalyst and all O2 sensors have passed. In the past, I have seen EGR pass with the hardware on the system, but it takes quite a bit of driving around. I would think that it might pass sometime today, at which point I will make a b-line for the inspection shop, solidify things.
The car runs better than ever now. It seems that once I installed that NTK (formerly NGK) O2 sensor, any hesitation I was noticing upon acceleration went away. Furthermore, I had cause, or should I say desire, to go ahead and press the accelerator on down deep from a full stop. Let me tell you, the front wheels spun like a drag racer would his rear, unweighted tires. This went on until I realized my acceleration was minimized due to reduced coefficient of friction, so I let off for the tires to grab and me to take off. One tire is brand new, one is < 10k miles. I think this result is pretty giood for the ole Milly!
Remember that while the short block is new, this car is running with heads that were reconditioned ala myself utilizing knowledge/wisdom of DMS experts combined with a few great web reads. I did go outside the norm by following the youtube guy’s suggestion to resurface heads with large sandpaper on flat surface. Yes, I concur, this works quite well, and I was unable to fit .002 inch feeler under any portion of either head (once all surfaces carefully cleaned of all particles). So while I realize that my victory speech may be short lived, and I may pay the price for my arrogance with unexpected short engine life, I’m feeling pretty good about things at the moment, and not seeing signs of trouble at the moment.
As for most recent fixes, I spent a day earlier this week where I flushed the radiator 3 times using distilled water only. Then I refilled with 50/50 Zerex. This was because I noticed that once I had used the heater, the core let loose its stored sludge fury upon my unsuspecting rebuild, and I saw the temp guage rise during a test drive. Lucky I noticed before it went up much, as I know that overheating is the MOST dangerous scenario for head gasket installations due to the extremely large cylinder pressures.
And finally, I have patched up numerous oil leaks. That stuff just gets everywhere. I had to remove my oil pan because the liquid gasket I had used seemed to soften in contact with the oil and was leaking profusely. I put in felpro gasket and torqued to 13 ft/lbs, forget that 6 I saw somewhere. Consistency is key here, IMO. The oil filter attachment to new block is particulary troublesome. I had to make my own gasket out of that overly thick gasket paper I purchased. And I had leaks at both sets of cams on the side by the timing belts. There are these seals that get stuffed in, and seals around the cams with timing belt pullies. I don’t think I have this one completely resolved, but I think there may be a way to replace these without removing the cams.
And finally, I notced that the bluetooth was not working on the stock stereo in this 01 Mazda. Just because bluetooth wasn’t big back then, and nobody had an android in their pocket is no excuse to omit this important entertainment and cell phone safety consideration. I could literally die without this, or at least that was my justification for the expenditure… of vitally critical importance you see… So I fixed this with a new aftermarket double din 300 watt stereo, which prompted the replacement of the rear speakers (total was about $120 for Pioneer 400 watt speakers AND stereo, can’t believe how cheap stereo stuff is now).
Oh yeah, here is the promising screen capture telling me that the end of my laborious rebuild is near…
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You’ll be especially happy about this when the outside temp hits 20F in a couple days.
You’ll be especially happy about THIS when you’re 5 years and 100k miles into this overhaul and your radiator hasn’t corroded to death.
I’m curious about this, but yeah. You don’t have to remove the camshafts to replace the seals in modern engines (i.e. anything that’s not using the old “rope” seals, and even THOSE didn’t usually require complete removal of a component). There CAN be a “touch” to it, largely amounting to “don’t roll the lip” and “don’t sprong the spring”.
No argument on consistency.
13ft-lb seems really high, to me. I would expect about 1/2 that, which is more in line with the 6 you saw somewhere (and which I have seen as well).
Here’s my reasoning for why that makes me uncomfortable:
these are usually “junk” bolts (i.e. no “class” or “grade” rating, or at the bottom of that scale, as is usual for automotive industry)
when I look for “standard maximums”, I find 14ft-lb to be about the maximum for the highest class of metric fastener in the size I suspect these are (6x1.0 or 6x1.25).
17.7 lb-ft according to this site
13 lb-ft here, pg 43
14.5 lb-ft here
(Sorry, can’t find my way into the Mechanical Engineer’s Handbook, which should likely be the standard here)
Also, these are threading into aluminum, making it the weak point, I would think, and repairing these threads is a royal pain in the ass.
And my final reason, that just sound high, to me.
But y’know what? If it’s working for you, call it a day! 
Good luck on getting the next Readiness complete!
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Good point about the 6X1.0s I torqued to 13. None of them broke, which seems fortunate to me looking at those numbers you sent, but they didn’t and I don’t think its the thing to do to loosen them.
I may have gotten away with it this time, but it seems I remember breaking some bolts like this off on a job in a previous lifetime somewhere. Or was it a dream?
If a non-mechanic breaks a bolt, but nobody is there to witness it, is he in a forest?
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New issues cropping up yet again.
!. I saw my coolant temp getting toward 212 F (boiling) and actually hit the number while idling. And this is AFTER 3 distilled water flushes. There is still something floating around in there causing blockages? Seems unlikely but possible. Or crappy thermostat that was new just a few weeks ago.
- Im stuck with EGR not being tested. Its been this way for a long bit now, many miles. Here is the listing to tests I just performed. Note that Test 2 CID 11 is missing:
Mode $06 report generated by Torque for Android
Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present
Unit and scaling information are not supplied with the data from the ECU for this type of vehicle. Consulting the manufacturers service book for this information is recommended.
Test report:
TID:$01 CID:$11
- Rich to Lean sensor threshold voltage(constant)
Max: 365
Test result value: 85
PASS
TID:$01 CID:$21
- Rich to Lean sensor threshold voltage(constant)
Max: 365
Test result value: 117
PASS
TID:$02 CID:$21
- Lean to Rich sensor threshold voltage(constant)
Max: 40
Test result value: 1
PASS
TID:$03 CID:$11
- Low sensor Voltage for switch time calculation
Max: 46
Test result value: 1
PASS
TID:$03 CID:$21
- Low sensor Voltage for switch time calculation
Max: 46
Test result value: 3
PASS
TID:$04 CID:$01
- High sensor Voltage for switch time calculation
Min: 0
Test result value: 92
PASS
TID:$04 CID:$02
- High sensor Voltage for switch time calculation
Min: 0
Test result value: 92
PASS
TID:$05 CID:$01
- Rich to Lean sensor switch time(calculated)
Min: 0
Test result value: 72
PASS
TID:$06 CID:$01
- Lean to Rich sensor switch time(calculated)
Min: 0
Test result value: 113
PASS
TID:$11 CID:$11
Min: 34
Test result value: 480
PASS
TID:$11 CID:$21
Min: 34
Test result value: 48
PASS
End of report.
!. I saw my coolant temp getting toward 212 F (boiling) and actually hit the number while idling. And this is AFTER 3 distilled water flushes. There is still something floating around in there causing blockages? Seems unlikely but possible. Or crappy thermostat that was new just a few weeks ago.
Assuming your coolant loop is holding pressure, and you are using the recommended antifreeze mix, 212F is perfectly normal. Your coolant is not boiling at this point due to both the pressure (think pressure cooker) and the glycol. Of your temp holds the range at about 205-220F during all modes of driving, your thermostat, pump, and radiator are all doing their jobs just fine.
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Zack is right. Straight water boiling point at 15 psi is about 250 degrees. Add glycol in & it will go up some.
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You guys are the experts, and I am just learning, so I am all ears. However, my instinct is that there is still some problem here. I have corrected most issues, but leaving a little bug lurking about can destroy all my hard work prematurely. I want to be very careful that I do not leave things in such a situation as to cause undue wear and tear on the engine, and thusly premature head gasket and engine failure. I have observed that the engine runs quite EXCELLENT until it gets really, really warmed up, and then things seem to degrade.
Let me explain where I am going with this. You see, I have a new engine and it is presently sealed nicely with the felpro MLS gasket. It was a tremendous effort for me, a non-mechanic, to learn enough to be able to properly apply the larning and seal this engine up and reinstall everything so as to make that engine perform so perfectly. I mean for the first 10-15 mins of driving, it runs like I am sure that it did when driven off the new car lot back in the Bush administration.
I saw a video, I think it was a Scotty Kilmer one, about a quick test to determine the effectiveness of catalyst. He pointed out that infared thermometers are cheap (I have a $10 Harbor Freight one) and can be used to do a quick catalyst test. He said that when catalyst is properly working, the pipe before the catalyst will get to about 200 F. And the pipe after the catalyst will get much hotter. However, when you have a catalyst that is really more half-assed, the pipe prior to catalyst will get hot, and may cause overheating issues. Now we have observed previously that perhaps one of my catalysts was not performing as well as the other. The 1 bank catalyst has significantly more rich to lean swing after catalyst than bank 2.
I would like to take more data on this car to prove/disprove my theory. The cat runs as I would expect until it gets really, really warmed up. Then, once warm, the engine is crammed in a tight fit engine bay, and sealed in with protective shielding all around. If something is getting hot in there, on a cool day like yesterday, I noticed the fans were not coming on. There is minimal airflow through that cavity, and so everything heats together. When this happens, the engine quits sounding as perfect, idles a bit rougher, and I notice the temp starting to peak. The thermostat is uspposed to kick on at 180 F.
So let me ask this one, with a 180 F thermostat, what temperature ranges of coolant temp sensor, which is placed at coolant line right as it exits the engine headed for radiator, so what temp ranges are expected for a setup like this? I plan to ensure that my system is cooling properly and all systems are functioning as expected here, as insurance to protect my time and energy investment in that engine.
This is not just something where I plan to drop $350 for new catalysts and then say to myself ‘much better’. I want to catch my bug with data, fix it, then show the improvement in the data. As I understand things, passing emissions is not really the gold standard explaining that everything is working well. It just means that nothing is out of sorts to the point that an obvious emissions problem exists. You can have a problem that will degrade further in the near future and still pass emissions.
This car and its parts have been donated to my little company I am trying to build, 3E8Tech.com, and so I hope to be using it shuttle engineers around, especially this engineer, for hopefully years to come. It would be quite embarrassing for the little engineer shuttle to be so poorly engineered as to break down in front of all the folks wondering, “so are these engineers for this company any good?” And that answer cannot be, “Well I think the engineer has a busted head gasket. Just look at all that white smoke! He should have engineered his car a little bit better, then our engineer would have been here on time! (insert evil mocking laughter here, signifying the end of all hope for the anticipated happily ever after denouement)”
Let me answer the input about the sensor itself:
That article is a good read. And points all well taken.
In this situation, I have a new coolant sensor that I installed a few weeks ago. On this design, it is located on a piece of piping just right as coolant leaves the engine on its way to the radiator via upper radiator hose. The fact that I am able to always see the temperature when running the engine via Torque, I think, is a clear indication that this sensor is reporting temperature data appropriately. This is not to say that the correct things are happening as a result of the readings. It just means that the temp sensor itself is properly functioning.
So have a section in my service manual on “Fuel and Emissions Systems”. This is the most useful and applicable section that I have seen in the service manual. Mazda is great for documenting thoroughly appropriate procedures for pretty much the entire range of issues one might expect for a car like mine that is built to be 100% Mazda spec compliant.
In this chapter, there are extensive procedures documented that can be used to validate proper operation of the key systems in play during engine operation. For example, there is a section on EGR, and exactly how to verify that it is properly actuating and functioning when using the car. A lot of the checks are things like measuring coil resistance for solenoids to be sure that there truly is a load for the control circuit to drive. Some of the checks include things like: “use this certain PID and switch it to XXX and verify that the solenoid actuates”.
Thing is, I have not, so far, been able to figure out how to do this PID switching trick with Torque. I have noticed that this mode exists with the Actron scanner at DMS.
I would like to walk through all of these tests with this Mazda to ensure that all these control switches and solenoids are properly functioning. I can come and do this at DMS and hog a bay for hours. On the other hand, I can hog my own bay at home and have access to my refrigerator and its contents should I be able to figure out how to use Torque with ELM327 to do the same thing. Anyone know how to use Torque to manually toggle PID stuff?
I just had two thoughts.
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I could do this out back at DMS, no bay required.
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I remember that both Flepro and Beck Arnley’s MLS head gaskets for this application have been modified to remove coolant holes on one part of the engine. In other words, someone has noticed that this engine, used in 5 production Ford and Mazda models, has an inherent cooling issue. The issue is that coolant does not properly flow through the engine, as flow forms a loop closest to water pump and therefor provides inadequate circulation to the portions of the engine furthest from the water pump. So these aftermarket gasket companies, which are the better ones IMO, have attempted to improve things by forcing this circulation to a more central spot in the engine in hopes of better cooling at the extremities. Here is a photo, notice that at the bottom of left head gasket, holes are not present for coolant flow as they are in the cheapie head gaskets.
So let me formalize thee questions on my mind in hopes that someone may read through this and have answers come to mind:
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Can you use Torque to set individual PID bits as suggested by Mazda service manual to manually actuate solenoids and what not?
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My engine has a 180 degree thermostat. I saw it peak at 212 during idle yesterday after a 10-20 mile drive set. I felt it was overheating, as this is a 32 degree F departure from the 180. What is acceptable range of temperatures for 180 system like mine with 180 degree thermostat?
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Given the situation where I have noticed that the aftermarket head gasket manufacturers have altered their head gasket designs illuminating a cooling flow problem, what recommendations do experts have for me to ensure robust engine life for this rebuild?
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I believe that this engine still has a bug, and the bug is related to overheating. it is not an overwhelming overheating, it is more subtle than that. But my car has it, and it is not properly addressed. I believe that this issue led to the early demise of the engine the first time, as 115k miles is too short for Jap designed engine. The engine suffers mild overheating, wears on MLS gaskets, they start leaking early, water gets in cylinders, and we wind up where I started with this project. What data/testing is recommended to highlight this issue to all on this board where we can clearly see the issue so that we can apply a clever solution and see the improvement in a subsequently taken data set?
#2 - What is the temperature of the OEM thermostat? Trying to substitute in a lower temperature range will throw off your ECU/PCM and will not fix a broken cooling system (obstruction, etc.)
There is no advantage to running a lower temperature thermostat, and it may actually cause drivability issues
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Make sure you’re looking at the right thing too. On all of my MX-5s there was a separate thermal switch for activating the electric cooling fans on the front of the engine vs. the temperature sensor for the ECU on the back of it.
Are your fans turning on to cool things down? If not, look there first.
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