SOLVED! Post 2853 Leaking Injectors, Dealer Techs Rock! Extended Cranking after Engine Swap 3.4L 5vz

Does anyone know if the O2 studs are welded in place, or do they screw in place (see pic)? One of ours is broken off. We're considering replacing the O2 sensor, but whether we replace the sensor or just fix the missing bolt issue, we need to know how they fasten on.

Husband is thinking they screw in place, but the other ones are so rusted in place that it's tough to tell.

Or would it be easier/better to just replace that whole section of pipe?

If we do replace the sensor, we'll get the part # from the dealer to avoid confusion (thanks DP!).

 

I have that section ofpipe sitting on the shelf. You want it...and my pipe has no issues worg the studs.

 

Page 18 and 19 of the long version describe how the LC-1 can be wired to the ECM in place of an OEM sensor. So contrary to my initial thoughts it is possible.
Show that section to your guy.

Other than rust, the studs just screw in screw in. It's getting that broken "nub" out that will be the killer.

 

It will have to be drilled out...but the angle is wrong to get a drill in that position.

It is an easy job for an exhaust shop to weld a stud on top of the broke off stud. I would go that route first. I can't imagine what Toyota wants for the down pipe. I bet it ain't cheap. Plus getting that removed from the exhaust manifold will be a pain.not much room up there to work.

 

Good to hear you've finally got your truck running right. I've been following this thread, it's been a heartrending story.

 

Wow, thanks you two! Always can count on helpful input from you guys, really appreciate it! It's so sad what our lives have become - husband's on his computer and I'm on mine, both researching the crap outta all this stuff. And when new posts come up from y'all, I go, "ERIC, so and so posted!! Come read with me!!"

As far as the pipe/broken screw/OEM O2 sensors, I think we're gonna get the dealer part # on the sensors, order 2 of them (hopefully from RA if we can verify correct part #), then order the screw from dealer and just leave the pipe in there. Then have whoever deals with removing MY MOST FAVORITE GAUGE EVER deal with getting the OEM O2 sensors swapped out and replacing the missing bolt however they see best. Thanks for the pipe offer though K!

DP, thanks for reviewing all of that super exciting literature to help us. Will definitely be bringing it along to whoever removes this stupid thing for us, and will point to pgs 18 & 19 per your advice.

Just called Visa to ask if an ASE certified mechanic who works from home would be acceptable in their eyes to essentially clean up this mess, should we need to dispute a portion of charges. They said yes.

 

Gen, let your guy at least look at it first and see what he thinks about the credential thing. If he is ASE and teaches, that should be plenty.

The critical part of "removal" looks to be pretty simple.

 

Yep, I'm now 99.9% sure we'll have him do it all, after just talking to neighbor about his credentials, and talking to Visa about what they'd want if it goes to that point. And I will sleep much better tonight knowing we can just drive to his house when he gets back and say, "we think we figured it out, now you take it from here please!!!"

 

well you better check again, "somehow" one of the earlier posts got "accidentally" deleted so now you do own post #1500

and im putting my chips on the roulette wheel right now and betting its not even the right gage for your truck, im betting its for a different vehicle or engine, and to go farther out on a limb, possibly its not even new and he just had one laying around that he sold to you hoping it would work.

 

My bad. I got the two mixed up. I do that sometimes. Sorry. lol.


Jen, glad to hear you appear to have things fixed. It is always the simple things that cause the big headaches!

 

Both of those sensors placed close together drawing off the same close ground,,for there body grounding. Wondering if that could cause a elec noise upstream into those circuits and also cause this issue with the sensitive aftermaket sensor,,doing ugly stuff to the ecu.

It's driving me nutty,,so I blurt shit out.

Back to reading about Imagrivating Gauges,,and there whole story.


Post thieves,,whatever, steal away!.

 

Well, not sure I understand why an AFR gauge was installed in the first place, but here's my 2 cents. Unless one of its OUTPUTS (brown or yellow) is wired into the vehicle harness, there is NO WAY it could cause any problems. Just providing it power and ground so it can read the sensor and display it on the gauge wouldn't do anything. Now, if somehow they were trying to replace the OEM sensor signal with the AFR kit signal, THAT could be an issue. But a standalone sensor and gauge, no way.

You might be onto something with the #6 item above, though.

 

Elec. noise upstream? You mean literally or figuratively Mod?

Reason I ask is cuz we've noticed ever since the work they did (engine & gauge), when we have a CD in the player, we can hear it spinning in the player. Even when the volume of the music itself is turned up, we hear it spinning. Obviously we don't really care, and who knows, maybe it was like that before. But neither of us remember hearing that spinning noise before, so it's just kinda strange - unless we just didn't notice it before.

Yes, Aggravating Gauges should be the new company name!

Our biggest fear is whether this gauge being faulty/improperly installed has somehow done some kind of permanent damage to something with our truck. Like, at the very least, I'm wondering if we need to have our injectors looked at for a 3rd time if we find that the gauge WAS wired to the ECM. And we're leaning heavily towards replacing both O2 sensors (the downstream and the upstream ones on the exhaust pipe) because if anything might have been f'ed with by that gauge, they sure seem like they'd be likely candidates. Plus we've never replaced them, and we've put the last 120K on the truck, and I don't know if the previous owner ever replaced them. So seems like a good idea anyway. They did test within spec for OHMs yesterday per FSM, but still, if we can find the right ones for cheap enough, seems like good peace of mind - assuming I have an accurate understanding of their function/purpose - see question at bottom of this post

If it is wired into the ECM, and therefore manipulating the air/fuel ratio the ECM is instructing the truck to dispense, that would explain A LOT. Like how our new mechanic kept feeling in his gut that this was a fuel issue, even though he'd combed over the fuel system 100 times. And how holding the throttle open caused a change. And how his 2 separate noid light tests on the injectors were so goofy and had different results.

By the time he was leaving to see his brother, he was saying, "We're almost down to the ECM, because I've almost ruled out everything else. It seems like maybe the ECM is giving those injectors bad info about when/how much fuel to dispense, but why is the question."

He even said once he saw a situation where a injector dying wound up taking out the ECM with it, and wondered if that was what was happening.

Now I'm even wondering (assuming that thing is wired to our ECM) whether it could have led to confusing our throttle position sensor, or somehow have caused that code. Just seems too coincidental that suddenly we get a TPS code. But what do I know? Good thing he knows a whole lot more than me........I'm sure he'll get to the bottom of it all.


EVERYONE - THIS MORNING'S QUESTION, PLEASE AND THANK YOU!

Back to the 2 OEM O2 sensors on the exhaust pipe - can you guys fill me in again on exactly what purpose they serve? Please tell me if my colorful dumbed down version is accurate:

Aren't they basically doing what the AFR gauge does (when it's set up for MONITORING ONLY), meaning they evaluate the air/fuel mix coming out of the tailpipe (which is the consensus info from all 6 cylinders), and decide, hey, this is too rich/too lean/just right?

Then if they decide the mix is too lean or rich, they'd start by hollering the ECM, "Yo! We got a problem over here Mr. Brain Dude!"

Then Mr. Brain Dude (ECM) would try to correct the mix.

But if he's not able to for some reason, and the O2 dudes tell him about the problem enough times, and Mr. Brain Dude still can't get it fixed, then Mr. Brain Dude sets a CEL - right?

Then we'd get a code for "lean" or "rich" or whatever?

If that is all an accurate understanding of how it works, then aren't the 2 OEM O2 sensors giving you the exact same info as the AFR gauge (when its set up for MONITORING ONLY) but they are just presenting it in a different format - meaning ultimately O2s give a CEL when problem occurs and cannot be corrected enough times, vs a gauge that provides constant readings of that mix?

 

Someone on the thread suggested we should consider an AFR gauge, because the death of our old engine was a piston hole, which was thought to be the result of a lean condition. And we did not get a CEL during that event, which was on 11/30. However, we did get a CEL in early August then again in late August, but never checked the codes, so we don't know if they were forewarning of impending doom or not. And unfortunately by December when the truck was looked at by a mechanic (after piston hole occurred), they said the codes were no longer there (apparently they go away if truck is driven enough times after they are set).

Naturally at this point, I wish we'd never gotten the gauge. But I know plenty of people have these gauges, and I've never heard of someone having the issues we've had. And I can certainly see why it was suggested that it could be a good idea for us. Don't have even a teensy bit of bad feelings towards the person who suggested it to us - he was trying to help us navigate through decisions on stuff we'd never even heard of before. Plus, it was just a suggestion on a forum - we were not forced to follow it. It was ultimately our decision to ask our mechanic if he thought an AFR gauge was a good idea for us. And I can see how they can be useful monitoring devices for people - when a properly working gauge is installed properly on a vehicle. But useful or not when done correctly, after this experience, I'll pass

At this point we have no clue how the gauge is wired (to the ECM or not, whether its a ground wire issue or power source issue, or ???). And its going to take the patience of a saint to wait for our mechanic to return and find this out, which sucks, but that is what we are doing, for sure.

But we are 99% certain its the culprit. We repeated our typical hard start scenario 4 times with it unplugged and the crank time had just a slight abnormality to it, maybe an extra second or revolution or so beyond normal. Then after those 4 times, we plugged the gauge back in, waited the same time interval (30 min) as 2 of the previous "test" scenarios - and excessive cranking. Once or twice, I'd be thinking probably a fluke. 3 or 4 times, I'd be thinking maybe this is it, let's hope so. But plugging it back in after all that and the starting issue was IDENTICAL again all of a sudden to the excessive cranking issue we've been chasing all this time - now all of those results together are pretty tough to dispute.

So next step is to wait for our angel mechanic to return, then verify what we think, then get that damn thing off our poor truck!!!

 

The two stock O2 sensors are narrowband sensors. This means they can only read a "narrow" range of AFR's. The other thing to note is that the speed at which the readings are read from the stock sensors is much slower than that of a wideband gauge. So back to the first thing to note, in a lean or fat condition it is easier to fall outside of the range of the narrowband sensor than the wideband sensor that comes with an AFR gauge. If the narrowband sensor goes outside of it's range it will throw a lean code, but rarely willl it throw a fat code. I only know that because our trucks at work will throw codes when they are lean due to a dirty MAF, but they won't throw a code when they are fat right away until the catalytic converters plug .

The purpose of the aftermarket gauge is to let you know if you're AFR's are too lean before the truck throws a check engine. For your case the stock setup is FINE. I wouldn't of run an AFR in your truck. If I did I would of hooked up the sensor way further back behind the catalytic converters at the collector where the exhaust from the two banks meets. That way I would of had the average of all 6 cylinders to look at. It's easy to calculate the AFR from a sensor even if it's behind the catalytic converter, you just adjust the AFR by 0.2 and you have a true reading. Most guys on boost will install an AFR gauge because quite often the truck won't throw a code until the damage is done to the catalytic converters if the mixture is WAY to rich. It's also nice to know the engine is running lean so you can take your foot off the gas at WOT in the open loop of the cycle even through the truck should throw a code relatively quickly.

During the open loop, or WOT, the sensors do tell the AFR to the ECU but the ECU doesn't do anything with those numbers. That means it is possible to only run lean on the WOT open loop tables and blow a motor. Again, this is why S/C or heavily modified trucks do run AFR gauges.

You can get your Scangauge II to read AFR's from the stock sensors by using an X-gauge code in the 2nd generation Tacoma, but I don't think it works in the 1st gens. The data off the stock sensors isn't as valuable as data from the aftermarket AFR gauge though, because the Scangauge II is not pulling AFR data fast enough to be useful at WOT.

As for the function of the two stock O2 sensors, yes they feed information back to the ECU when the truck is operating in the closed loop mode. Closed loop occurs basically anytime the truck is not at WOT. The ECU compares the readings from the MAF, O2 sensors, and any other exhaust information it may collect (I don't have a first gen truck) and determines based on a preset table loaded into the ECU whether or not it should add more or less fuel. You never get a perfect mixture with the closed loop, even though you think you would. Instead you get a mixture that fluctuates in a very minor manner between being to lean or to fat that averages out to a near perfect AFR.

You have a V6 so each sensor determines one bank of the engines AFR (3 cylinders). It is very possible to throw a code on only one bank, which can mean a bad sensor, injector, or something else only occurring on that bank of the engine.

 

BTW, again, as tempting as it is Jen I wouldn't blame the gauge. I'd blame the installers. Honestly they are probably used to installing that bung on performance trucks where the O2 sensors are replaced with "dummy" sensors because the catalytic converter has been cut out. They didn't understand you should never put two sensors that close to each other, if for no other reason than you might disturb the exhaust flow to the next sensor with your welding.

If you had of (I know you hate hearing that , but there's not really a better way to say it) installed the gauge at the collector at the end of the y-pipe then I doubt this issue would of occurred.

 

I like that bolded part. I'm going with that. Not that we've really doubted ditching the thing anyway, but good to have more votes saying we don't need it.

Ya lurned me sumthin! Just googled WOT = Wide Open Throttle! Ah, it all makes more sense now.....

Yeah, we looked on the SG II website a while back to see about adding features to monitor additional data on ours, but we aren't able to. Bummer.

OK, starting to understand more about closed loop vs. open loop little by little every day, but still sorta confused. If I'm understanding correctly, then perhaps this had something to do with piston hole. Kinda like what you said:

I was on the interstate, and I'm pretty sure I was laying heavy on the accelerator when that happened, which means I was at WOT, which means I was in open loop, right? So that means even though my AFR mix might have been lean due to bad injector(s), and even though my O2 sensors may have been telling the ECM about this at the time, the ECM wasn't doing anything to correct it because I was in open loop - right? And it's tough to remember exactly what I did, but I remember there was a moderate amount of traffic, and I do remember at one point I looked down at the speedometer and realized I was going kinda slow in relation to it, so I probably laid on the gas pretty heavy then (my mind was on the mudpit in our backyard that my husband was standing in to install french drains - I was headed to pick up rocks for the project). And not sure when the lurch happened in relation to that, but I know the lurching freaked me out, so it's possible I might have suddenly let off the accelerator after being heavy on it/driving fast (which would make the truck go super lean suddenly - right?).

Hey, I wonder if the lurching on that fateful day was caused by a TPS that was starting to fail?!??!

You lurned me sumthin else! Actually, I kinda remember hearing of this before, about how each side of the "V" is its own bank. But I'm still a bit confused after looking again at the FSM diagram of all the sensors on our truck (see attached file), because the two O2 sensors are labeled:

Bank 1 Sensor 1
Bank 1 Sensor 2

Initially when I read your paragraph above I figured, OK, so each of our O2 sensors corresponds with one "bank" (or side of the V). But then why is the first part of each O2 sensor's name "bank 1"? And which bank is which, anyway? Do I have double O2 sensor coverage on one bank, and none on the other? Although in the first part of your post you mentioned:

So my best guess right now is that Bank 1 Sensor 1 checks bank 1's AFR, then Bank 1 Sensor 2 checks the AFR of all 6 cylinders (or both banks) since it's behind the cat?

Nope, don't hate hearing that at all. I'm much less snarly snappy now that we've very likely identified the culprit behind the issue! And as far as the gauge, I'm not blaming it, or at least not yet. For now, I don't know what to blame, til the thing is properly removed by a professional who can hopefully specify what the heck was wrong about the whole set up. But yeah, the points you are making about how it appears it was improperly installed sure make sense. Seems like that's probably what the issue is.

Another confusing piece to this whole gauge thing is that the gauge APPEARS to be giving us accurate readings of the AFR mix (although I've never had one of these, so have no frame of reference to compare to). It shows rich numbers when started cold; lean numbers when started hot; lean numbers when I'm at WOT and suddenly let off the accelerator (hey, looky there, I just used my newly learned terminology in a sentence!); and even though the numbers are constantly changing when I'm just driving normally, they always seem to be trying to get back to 14.7.

So I'm ASSUMING that supports what you are saying - that the gauge itself is working properly. But the install was somehow done incorrectly.

 

So I don't have the FSM to look at, but my guess would be that you only have O2 sensors on one bank of the engine. The computer assumes that whatever happens on one bank happens on the other. The second generation Tacoma's have 4 sensors, two on each side, but I'm not sure what the setup is like on your truck though you can quickly tell by looking under it.

By the way this next part is only a guess since I can't crawl under your truck, Bama should know for sure.

The first sensor is before the Catalytic Converters and the second one is after the Catalytic Converters. This is so your computer can throw different codes for a possible O2 sensor failure or Catalytic Converter failure if the reading of one sensor is way out from the reading of the other. This is how the sensors are setup on the 2nd generation Tacoma, though it has sensors on both banks for a total of 4 OEM O2 sensors.

If the gauge is the first bung in the chain it should operate properly. That Bosch aftermarket sensor is a very high end sensor self calibrating sensor and it shouldn't be thrown off by the same problems that would throw off a narrowband OEM sensor.

In general wideband sensors are the cats meow because they are tuned towards aftermarket applicaitons and have a wide window of operating conditions. Even if it's not a self cailbrating sensor it probably has some way of balancing itself even if it is getting some "dirty" electrical current. The OEM is mass produced and built only as well as necessary, and is likely unable to deal with extremely turbulent exhaust flow, damage from welding, or "dirty" electrical current.

The funny thing is that Bosch probably makes both the OEM and the aftermarket sensor . They make a lot of the OEM O2 sensors.

 

Well that's kinda dumb on Toyota's part! Why the heck would they set it up to just ASSUME that whatever happens on one bank happens on the other?!??! Silly.

Yep, I know for a fact that my Bank 1 Sensor 1 is just before the cat and my Bank 1 Sensor 2 is just after the cat. Your explanation as to WHY makes sense to me, but as you suggested, let's see what others say.........

Yep, the AFR O2 sensor is the first bung in the chain - assuming you mean it's location on the exhaust pipe. From front of truck to rear, it goes:

AFR gauge O2 sensor
OEM Bank 1 Sensor 1 O2
OEM Bank 1 Sensor 2 O2

Pretty sure the OEMs are made by Denso. Whatevs, I'm going back to trusting them alone. As I said before, if we made it to 195K before piston hole with only those, I'll take my chances.......me and these AFR gauges just don't tango together very well

 

The 1st gen V6 O2 sensors (bank1 sensors 1-2) are located on the single exhaust pipe after the 2 banks join. The first (before cat) does AF monitoring for fuel management, some years and Ca spec engines more than others. The 2nd sensor is after the cat and serves to monitor the effectiveness of the cat.