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Are the sniffer tests precise enough to catch the conditions EGR operates under?
When I was replacing vacuum hoses, the lower barb on the EGR vacuum modulator crumbled at the slightest pull of the dry rotted hose. I ditched the EGR system at that point, so I don't know what CEL code it would have thrown in such a condition. Hoses and attachments are definitely worth checking, at any rate. Mine had a lot of little air pockets in the plastic where it broke, which inspired very little confidence in the quality of the piece, and presumably, whatever plant/batch it was produced in. I've only seen that one other time: ultra cheap Harbor Freight wire brush handles.
In Califorina, yes the tests actually check for EGR system operation and correct hose routing. It's also part of the visual inspection. Usually it's brief because usually it's working on most cars. If something is obviously missing or not working or the NOx is abnormally high, then it would be checked out thoroughly.
Out here, better to just fix it.
The vacuum modulator is all plastic. Easy to replace but it does make you wonder if it's really worth the $68-$90 asking price for an OEM. The EGR temp sensor seems to come up a bit on SF discussions too. I will check my vac hoses first and I'm going out this afternoon to buy a vacuum test gauge to diagnose the EGR valve and rule that out.
Finally found something to confirm where the EGR VSV is on the 2JZ-GE. This was surprisingly not straightforward to verify when you go into Toyota's current EPC system.
This link below lists VSV's... but I think they are more for the ACIS system rather than EGR:
Well... I ran a vacuum gauge test earlier today between the "Q" connection from the EGR Modulator to the EGR Valve with a T-Tap at both idle with 2K RPM revs and while monitoring it driving around my block and back.
At idle I got what appeared to be correct 5 Hg to 10 Hg readings (I think it was up to 10hg while revving at idle...). This corresponded to what it should have been in the test procedure,
While driving around the block I got what also appeared to be correct operation of the EGR system, registering 0 hg, and 5 Hg to 20 Hg of pressure... just like the test video demonstrations a couple of posts back.
Finally, I picked up a vacuum hand pump tester with pressure gauge at a local auto parts store and ran the vacuum pump test directly to the EGR Valve.
Unfortunately here it seemed not to idle that differently when applying pressure to 5 Hg. There was a bit of change in idle but not much. Upping the vacuum pressure to 10 Hg did not cause the engine to stop.
I put everything back to stock and reset the ECU which cleared the CEL code. I put over ten miles on it since then and still no CEL light. I'll see if it comes back again with more driving.
The EGR valve not responding much to the test with 5-10 Hg of direct vacuum makes me think it might.
I was looking back over my notes and was reminded I also got an occasional code 71, back when I was trying to sort out the knock sensor issues that turned out to be the ECU.
Here's one of the items of interest I turned up at the time, giving an indication in post #1 of why such problems can be so sporadic:
I looked at your thread and it was enlightening for quirks in basic 90's EGR function, thank you!
Unfortunately I think my vacuum test was correct. Some 35 miles after resetting the ECU after my vac tester directly on the EGR valve while the engine was running did not make the engine stall and die at 5 Hg and higher the CEL came back on again.
I didn't run the check engine code yet but I am sure it's Code 71 again.
Last night I tackled the IACV replacement with the SMP AC425 aftermarket model. Absolutely the worst sensor replacement I've ever done, even topping the ECU coolant temp sensor job. The bolts, being seized, required an impact screwdriver. Of course the LOWER of the two bolts was impossible to access without going through the process of staged dismantling of the throttle body to get to that awful coolant bypass hose hiding underneath everything. Which of course spilled and depressurized a bit and required meticulous cleanup even after I made sure the car sat for several hours first.
All to get to one stupid little screw that was seized. I cleaned and wiped every single thing I could and opted not to test start the car until tomorrow, so we'll see if the final culprit for my starting issue was in fact the idle air control. A little bit of the spill got into the end of the intake just behind the throttle body and I wiped every single crevice I could.
The original IACV unit had a huge amount of carbon buildup. I've kept it to clean and keep for later in case it's still good after reconditioning.
Unfortunately while the throttle body was clean I did notice that the intake plenum "Y" section seemed to have a tremendous amount of carbon buildup. It was nearly pitch black in there. I probably wouldn't be wrong in assuming that the EGR port is probably clogged as well. I'd have pulled that off to clean but I was without any wire brushes, carb, or throttle body cleaner. Also, I'd rather just buy a reman EGR valve off Rockauto to have on standby once all of that stuff is off the car.
I never thought to clean the intake on the two other occasions I did my plugs. And the last time it was my mechanic who did the plugs and the carbon buildup was not even mentioned to me while the piece was off during service.
........
The below text in italics was proven incorrect:
On top of all that, I also noticed that my oil appeared to have become partly sludged. I use only Mobil1 synthetic every 3500 miles with a Mobil1 filter religiously. This is the first time I've noticed this and my last oil change did not show signs of the problem.
I have been driving mostly short distances in the car for the last couple of months. Maybe that's part of the problem.
I hope an immediate oil change with synthetic and a new filter followed by more long drives and yet another change 2,000 miles later cures it. Never had a sludge issue in any of my cars and it's the first time it's happened with this one.
^^ I took my car to my mechanic's this morning and I am both relieved and embarrassed to learn that I was incorrect. I do NOT have sludge. What I have is dark synthetic oil that isn't utterly perfect such that would be found in a much newer engine... but they assured me it isn't actually oil sludge.
I'm not going to lie... lately the SC has really been wearing on me. Not for enjoyment but it seems like every time I get yet another expensive thing repaired another issue shows up.
This still leaves:
-phantom intermittent rough cold start issue (will see if the new IACV fixed this tomorrow)
-leaking PS pump o-ring. Rebuild kit on standby.
-possible worn starter contacts, but so far it seems okay. Rebuild kit on standby.
-Very possibly faulty EGR Valve and plenum carbon buildup. Rest of EGR system appears to be working. Upon mechanic inspection I was completely incorrect about this: -Sludgy oil condition, both in the filler cap over the camshafts and on the dipstick tube. Radiator coolant unaffected.
-Front brake service sometime soon as well.
Absolutely silly, all of this.
I am convinced that other than the sequential turbo side a 2JZGTE or 1JZ-GTE is easier to do basic maintenance on.
.......
Edit: Although this thread sounds close to describing what I have noticed. Maybe what I really have is failing valve stem seals after all and I'm noticing burnt oil in the cam galley... but still... yet another instance of, "Really car? Really? Right now after I just spent even more on you completely unrelated to the new engine?"
Kahn, the vsv towards the front of the engine is for the egr, if you followed the metal tubing under the intake manifold you would see that, I believe its black in color and its on a metal bracket bolted to the front of the intake manifiold right next to the FPR. with a code 71, youeither have a bad vsv, a blocked EGR passage, or a bad egr modulator thing whatever its called. also there are like 3 egr passages and a tube inside the Y pipe (its not exactly easy to clean you need to remove the intake and soak and scrub it even then its quite a task).
its not unusual for the inside of the manifold to look black after alot of miles, thats what the egr does but as long as the buildup isn't too tall or blocking passages its not a huge issue for a n/a car but I have taken it apart and scrubbed it, with doing your swap soon I am not sure its worth it but it could clog in the metal tube with the holes thats in the Y pipe, of it can even clog in the metal pipe that runs from the back of the lower runner up to the egr module or from egr modle to the side of the Y pipe (this passage is rather small and is usually caked in).
also if you had a bad vsv, it could explain why you have bad running at times and the bad running due to that would mean the egr is actually flowing. if the egr was clogged you probably wouldn't get rough running, engine would run good and you get the temp sensor code normally. this is theoretical so take it with agrain of salt I Wouldnt go buying a new vsv without some testing. you can pull the vac lines off that egr vsv and see if its all clogged up as well, that can also do it, but be careful the hose barbs are plastic and can beak on you.
standard thing to do is to take it apart and clean it out, and then do the vsv, but the vsv is considerably easier to change out if you have another SC available you know its good on it takes about 5 minutes to test I would think. if somehow not those it could be the actual EGR module it has a diaphram in it I think and things can get faulty sometimes, tbats pretty much the 3 things it can be, its not a huge system. there is also a temp probe and that triggers the CEL when the pipes clog cause the egr temps shoot up, so since you are getting the code something is stopping it up or the vsv is bad. Im leaning towards the egr being faulty or the pipes being clogged especially since you said you saw alot of carbon. I dont think I have heard of a faulty temp probe but I guess that is a remote possibility as well.
Kahn, the vsv towards the front of the engine is for the egr, if you followed the metal tubing under the intake manifold you would see that, I believe its black in color and its on a metal bracket bolted to the front of the intake manifiold right next to the FPR. with a code 71, you likely just need to replace the vsv,, or have you tried that yet. sometimes they clog and go bad, other times they just fail. you could also have a clogged egr pipe but it would throw the temp sensor code then not the vsv code. change the vsv first they are all mostly the same you can grab a better looking one off another car (I am assuming they are ridiculously priced new but worth a check).
its not unusual for the inside of the manifold to look black after alot of miles, thats what the egr does but as long as the buildup isn't too tall or blocking passages its not a huge issue for a n/a car but I have taken it apart and scrubbed it, with doing your swap soon dont even worry about it. if EGR was actually blocked the temp probe would see much higher temps which trips the other egr code.
also if you had a bad vsv, it could explain why you have bad running at times and the bad running due to that would mean the egr is actually flowing. if the egr was clogged you wouldn't get rough running from the egr, engine runs good and you get the temp sensor code normally.
Thank you for that link! Interesting. It seems like the VSV issue is actually not uncommon.
So EGR Code 71 is mostly related to the VSV failing? And EGR Code 70 would be the EGR temp sensor? Actually, now I'm wondering how "0" for the second digit is flashed on the dash light.
I actually didn't test the EGR VSV yet but I did start doing an inventory of the EGR system as soon as the code came up. Just the same as the 2JZGTE, Toyota has discontinued the EGR VSV for the 92-97 SC300/400 worldwide. And it is the same part for both the 300 and 400.
I don't understand why there are zero aftermarket VSVs available for such a critical function.
I found one off ebay a couple of days ago that just came in the mail. It looks OK but as with the original I haven't tested it yet. I could throw that on and see what happens. The EGR valve failing the hand vacuum pump stall test has me concerned though, so I ordered an aftermarket EGR valve from Rockauto just in case.
Toyota has also discontinued the Cali 2JZ-GE EGR valve (which works on Fed and Cali). Unless there is a different part number for the Supra 2JZ-GE it's aftermarket only but at least there is an aftermarket option. The EGR modulator is available aftermarket too. Same for the EGR temp sensor. It's just the EGR VSV that is used-only.
So you think I shouldn't clean the intake? That was my plan today along with delaying the starting of the car for longer so I can double check all the cylinders in case that bypass hose discharge got anything in there that I might have missed. I checked cylinders #1 and #2 and they were bone dry so maybe I'm just being paranoid about that.
Unfortunately my swap isn't near ready yet and I have to have the stock SC300 emission system working perfectly for my smog test in May. Otherwise I would blow this off :/
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The below text in italics was proven incorrect:
The other thing that has me very surprised and concerned is the oil sludge. It wasn't like that 2500 miles ago and there was no mention of it during my last oil change or my last Blackstone analysis. I always change my oil at 3500 miles and use only synthetic. I'm looking at buying Auto-RX or Gumout to add directly to my oil to see if that helps but I'm also going to get an early oil change asap.
I'm not sure that bodes well but I'm going off what I've tried to learn about it. I've never had to deal with oil sludge before. I've seen some cases where engines that have rarely had their oil changed have it so bad that they need the pan and pickup vacuumed. That would be an engine pull for an SC, wouldn't it?
I'll try to get some decent pictures of what I'm seeing with the oil. Radiator fluid looks fine btw.
^^ After having taken my car in to my mechanic this morning I learned, to my relief and embarrassment, that I do NOT have an oil sludge condition. I misinterpreted how the oil looked and started making an assumption based on that which was incorrect.
I'm glad. And I feel a bit foolish. But I'm mostly glad I was wrong.
Last edited by KahnBB6; 03-05-16 at 11:18 AM.
Reason: Correction to oil "sludge" assumption
Man oh man, your SC is putting you through the ringer.
Re: EGR tube clogging. The 1UZ intake plenums I've inspected have varied from moderately blocked to almost completely blocked. Depending on how hard the 2JZ intake is to remove, that certainly sounds worth a look to me. I don't know if the tube is a straight shot on yours, but maybe you can clean it out with a wire brush after removing the EGR valve? If so, I would go slow and vacuum it out as soon as you loosen stuff, otherwise you're just pushing chunks of crud out into the intake.
Originally Posted by KahnBB6
So EGR Code 71 is mostly related to the VSV failing? And EGR Code 70 would be the EGR temp sensor? Actually, now I'm wondering how "0" for the second digit is flashed on the dash light.
Uh... I'd never thought of that before. 70 is the only code on the 1UZ lists with a zero, so I'm wondering if it's an old typo that has been repeated over the years?
Man oh man, your SC is putting you through the ringer.
It has, but you know what? My first false alarm (the "sludge" oil condition was deemed an incorrect interpretation by my mechanic) in a while actually makes me pretty happy. It means I might have most of this stuff out of the way soon
Originally Posted by t2d2
Re: EGR tube clogging. The 1UZ intake plenums I've inspected have varied from moderately blocked to almost completely blocked. Depending on how hard the 2JZ intake is to remove, that certainly sounds worth a look to me. I don't know if the tube is a straight shot on yours, but maybe you can clean it out with a wire brush after removing the EGR valve? If so, I would go slow and vacuum it out as soon as you loosen stuff, otherwise you're just pushing chunks of crud out into the intake.
That's good to know about the 1UZ EGR tubes and how they fare with clogging. The 2JZ-GE EGR port on the intake is straight and then takes a sharp 120 degree angle into the main plenum. I've had the plenum off before to do spark plug changes and my valve cover gaskets. It's some work but once it's off I can clean the carbon and EGR port with intake cleaner and a nylon brush. The EGR port I'll just pick away at.
The new EGR valve will arrive on Tuesday. Gasket possibly by then too. Then I just need a large wrench to get at the large nut holding on the cylinder head tube. I might want to locate a spare tube just in case there is the remote chance of it cracking due to fused threads. Probably not but it couldn't hurt.
We'll see if I need the new one after all.
I will try the EGR VSV first while waiting on the parts.
Originally Posted by t2d2
Uh... I'd never thought of that before. 70 is the only code on the 1UZ lists with a zero, so I'm wondering if it's an old typo that has been repeated over the years?
Maybe, but since we're supposed to interpret the flash(es) that come 1.5 seconds after the first flashes, I'm thinking that a "0" as the second number must be the absence of a flash after 1.5 seconds. I can't think of any other way.
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The good news, despite the sudden EGR issue, is that it appears I have normal starting again! Replacing the IACV was apparently the final thing needed to solve the original issue! I have kept my old IACV and I will clean it to keep as a spare but the Standard Motor Products AC425 part seems to work perfectly. It looks and feels just like the OEM valve.
To fix my original condition it took all of:
--New/Reman/Repaired ECU -- due to leaking capacitors and injector drivers
--New Reman OEM injectors -- due to sticking or leaking original injectors
--New Spark plugs/Cap/Rotor/Wires -- due to prematurely worn plugs / cap / rotor
--New Distributor (Possibly) -- O-ring or other leak was present but this did not solve the issue by itself. I noticed a minor difference but I could not verify that the original distributor was actually at fault in this case.
--New ECU Coolant Temperature Sensor -- Did not solve issue by itself but starting was MUCH improved. This sensor did need replacing anyway.
--New (or cleaned) Idle Air Control Valve -- Due to intermittent sticking or not operating correctly due to carbon buildup
And I think the EGR issue and carbon in the plenum probably contributes to just a bit of idle roughness but it's extremely minor, so fixing that should make for a noticeable difference.
If anything from here on changes with cold start or cooled down start idle I'll update but I think I got it this time
Maybe, but since we're supposed to interpret the flash(es) that come 1.5 seconds after the first flashes, I'm thinking that a "0" as the second number must be the absence of a flash after 1.5 seconds. I can't think of any other way.
Well, there aren't any single digit codes listed, so you may be right.
The good news, despite the sudden EGR issue, is that it appears I have normal starting again! Replacing the IACV was apparently the final thing needed to solve the original issue!
That's what I'm talking about! Still weird that it would change once warm, so maybe the IACV was actually defective, not just gunked up.
Well, there aren't any single digit codes listed, so you may be right.
Oh, there are, but it's suggested as "1-9" with no indication of what flashing represents "0" in the instructions. That's why I thought getting a "Code 70" would mean seven first flashes, pause for 1.5 seconds, then... nothing. So I think we would just assume "0" if there was no flash after the pause.
I used a different guide link but this one is almost the same:
That's what I'm talking about! Still weird that it would change once warm, so maybe the IACV was actually defective, not just gunked up.
It would sometimes give a rough start and sometimes not. Sometimes a mild rough start for three seconds, or 1.5 seconds or 10 seconds. Always the electronics would catch it and cold start idle would suddenly be okay again. Sometimes the rough start was REALLY bad for those few seconds and sometimes it was negligible. It seemed like a mechanical issue in the valve to me but maybe you're right that it was also defective electronically. These were all varying degrees of too little fuel for cold or cooled down starting. I'll clean the old one up and see how it looks later.
I'm very happy to have it solved though. But I do think the ECU coolant temp sensor was also partly to blame originally. I still can't tell if the distributor was really at fault since the new one didn't really change any symptoms. The smoke condition was all plugs, injectors and ECU.
Oh, there are, but it's suggested as "1-9" with no indication of what flashing represents "0" in the instructions. That's why I thought getting a "Code 70" would mean seven first flashes, pause for 1.5 seconds, then... nothing. So I think we would just assume "0" if there was no flash after the pause.
I used a different guide link but this one is almost the same:
Of note, the lexls.com page doesn't list the second EGR code (70). I had previously added it to my in-car notes based on some other list I must have cross-checked with, but that brings me back to wondering if the code 70 isn't just an oft repeated error. You know, like half the stuff on the internet.
Well then maybe there *is* just one code (71) for an EGR system issue in OBD1 Toyotas or at least SC's. Or perhaps it's not the same for all OBD1 Toyotas. For the sake of my own curiosity I'm going to consult the FSM later and see what it says :P
I had updated my post when I wrote the first one I thought 71 was for the vsv then I remembered 71 is just a general code and can be all 3 things. check the edited post of mine above above for what I wrote after, didnt think you would quote it that fast. there is a good chance if you have over 150k that its fully clogged, that is basically what it does over time. it would be worth cleaning it out to fully overhaul the egr system but its a task to say the least. I think there are a few tests you can do with the vsv but start by looking inside the tubes and seeing if they are clogeed, but I think most people have the tube get blocked then the egr temp raises and trips the temp sensor and the code comes on. the vsv failing and the modulator failing are less common but also definite possibilities.
02-29-16, 03:34 PM
70 is the only code on the 1UZ lists with a zero, so I'm wondering if it's an old typo that has been repeated over the years?