Help....High NOx at 15 MPH on smog (Calif)
10-25-2010, 06:39 PM
#21
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No.....I mean "0" ohms....Nada. Nothing. Heated it to 150 deg. "0".
I did get a 71 code after cleaning the filter in the EGR vacuum Mod on Saturday. I left one of the hoses off. It threw the code after driving for about 2 miles. I put the hose back on, reset the ECU. I driven it about 40 miles since.....and no code.
So.....unless I damaged the temp sensor by just unscrewing it. But like I said. I'm not
getting a reading off the thing.
I did get a 71 code after cleaning the filter in the EGR vacuum Mod on Saturday. I left one of the hoses off. It threw the code after driving for about 2 miles. I put the hose back on, reset the ECU. I driven it about 40 miles since.....and no code.
So.....unless I damaged the temp sensor by just unscrewing it. But like I said. I'm not
getting a reading off the thing.
10-25-2010, 06:54 PM
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0 ohms is a reading; it means it's shorted. (The resistance goes DOWN as you heat it up; it should be 64-97k ohms at 122 degreesF.)
Usually code 71 is thrown when it is "open" (infinite ohms -- same as disconnected).
But as SB5Walker pointed out, that temp sensor is not part of the control system (that's done from regular temp sensor in the water jacket), but is part of the monitor system. It is curious that you're getting those readings, but it is not the cause of your high NOx. You could be having high NOx for any ordinary EGR malfunction, and the bad temp sensor is failing to report it. Or not.
Are you sure you've got the scale on the ohmmeter correct, you didn't touch the probes together ....
You'll make more progress by using a vacuum gauge to run the EGR checks per the FSM, and a voltmeter to check the O2 Sensor (specifically to see if it's pegged due to lean condition.) At least that's what I think.
Usually code 71 is thrown when it is "open" (infinite ohms -- same as disconnected).
But as SB5Walker pointed out, that temp sensor is not part of the control system (that's done from regular temp sensor in the water jacket), but is part of the monitor system. It is curious that you're getting those readings, but it is not the cause of your high NOx. You could be having high NOx for any ordinary EGR malfunction, and the bad temp sensor is failing to report it. Or not.
Are you sure you've got the scale on the ohmmeter correct, you didn't touch the probes together ....
You'll make more progress by using a vacuum gauge to run the EGR checks per the FSM, and a voltmeter to check the O2 Sensor (specifically to see if it's pegged due to lean condition.) At least that's what I think.
Last edited by scope103; 10-25-2010 at 06:56 PM.
11-09-2010, 06:40 PM
#23
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Proper Test?
Same issue as original poster, good CO and HC but high NOx. Was tested on Monday.
But I have a question about the effects of engine RPM on the test.
On the 15 mph test, suppose the tech shifted into 2nd, instead of remaining in 1st?
On my setup (5 spd), at 15 MPH, rpms are 2700 in 1st and about 1500 in 2nd. Similarly, at 25 MPH, rpms are 2400 in 2nd, and 1700 in 3rd.
I am thinking that this would have an effect on EGR operation.
I remember that the tech did kill the engine on the 1st pass as he shifted (maybe I'm wrong). If the tech is driving a Toyota 22re or 3vze like trying to drive a 350, he is not doing it right.
Anyone?????
GG
But I have a question about the effects of engine RPM on the test.
On the 15 mph test, suppose the tech shifted into 2nd, instead of remaining in 1st?
On my setup (5 spd), at 15 MPH, rpms are 2700 in 1st and about 1500 in 2nd. Similarly, at 25 MPH, rpms are 2400 in 2nd, and 1700 in 3rd.
I am thinking that this would have an effect on EGR operation.
I remember that the tech did kill the engine on the 1st pass as he shifted (maybe I'm wrong). If the tech is driving a Toyota 22re or 3vze like trying to drive a 350, he is not doing it right.
Anyone?????
GG
11-22-2010, 04:14 PM
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O.K. ......After getting a extension on my smog. I had to go out of town for a
couple of weeks.
I purchased a vacuum testing kit. And ran the EGR test per the FSM. The EGR Valve
once again seems to be working fine. 0 Vacuum at idle and at 3500rpm when cold.
But I'm getting no readable vacuum at 3500 rpm at operational temp.
Ran VSV test per FSM. working fine.
Ran the vacuum modulator test per FSM. I can blow air threw the Modulator. But I don't know if I would say it's flowing "freely" (per FSM) but air does flow...but not a lot
of air, even with the filter out.
I have nothing to gauge it to.....so is that the way it should be. Or should the air move through it easier?
On top of that.....after getting back in town a driving my truck a little bit. My brake booster seems to have gone out. (re-checked for vacuum leaks. Didn't find any. I have brakes. But not power brakes.
couple of weeks.
I purchased a vacuum testing kit. And ran the EGR test per the FSM. The EGR Valve
once again seems to be working fine. 0 Vacuum at idle and at 3500rpm when cold.
But I'm getting no readable vacuum at 3500 rpm at operational temp.
Ran VSV test per FSM. working fine.
Ran the vacuum modulator test per FSM. I can blow air threw the Modulator. But I don't know if I would say it's flowing "freely" (per FSM) but air does flow...but not a lot
of air, even with the filter out.
I have nothing to gauge it to.....so is that the way it should be. Or should the air move through it easier?
On top of that.....after getting back in town a driving my truck a little bit. My brake booster seems to have gone out. (re-checked for vacuum leaks. Didn't find any. I have brakes. But not power brakes.
11-22-2010, 05:33 PM
#25
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I had a hard time with somg this year for the first time with this truck. I gave my truck a tune up air filter fuel filter plugs wires oil filter new oil new o2 sensor. new cat i did all this this after running sea foam thru the pcv valve and in the oil and a can of sea foam thru the gas tank oh and adjusted the valves. the fuel filter was clogged and can make it run rich. . . a tune up i'm just saying. . .
11-24-2010, 11:42 AM
#26
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After running extensive tests on the whole EGR system per the FSM I couldn't
find a reason for why I'm not getting any vacuum to the EGR at 3500rpm at Op temp.
Tested the VSV per the FSM and it would pass. (Jumped it to the battery, blow air
through the filter. Disconnect the battery, blows the other way. Check for short. Checked for open circuit......passed them all)
Stumped....and no one responding to my last post. I search the net and found a great
article on testing Toyota EGR systems from Motor.com.
http://www.motor.com/magazine/pdfs/082009_04.pdf
http://www.motor.com/magazine/pdfs/092009_04.pdf
Ran their test...and everything was fine until the VSV test. And they have a real easy way to determine if your VSV is bad. You pull the hose off of the "Q" port of your ERG
modulator and apply vacuum. Your VSV should hold the vacuum, if it doesn't.. it bad.
If it does hold a vacuum, then jump the VSV to the battery....once jumped it should release the vacuum. If it releases your VSV is good.
Mine leaks like a sieve! But it will pass all the tests in FSM.
find a reason for why I'm not getting any vacuum to the EGR at 3500rpm at Op temp.
Tested the VSV per the FSM and it would pass. (Jumped it to the battery, blow air
through the filter. Disconnect the battery, blows the other way. Check for short. Checked for open circuit......passed them all)
Stumped....and no one responding to my last post. I search the net and found a great
article on testing Toyota EGR systems from Motor.com.
http://www.motor.com/magazine/pdfs/082009_04.pdf
http://www.motor.com/magazine/pdfs/092009_04.pdf
Ran their test...and everything was fine until the VSV test. And they have a real easy way to determine if your VSV is bad. You pull the hose off of the "Q" port of your ERG
modulator and apply vacuum. Your VSV should hold the vacuum, if it doesn't.. it bad.
If it does hold a vacuum, then jump the VSV to the battery....once jumped it should release the vacuum. If it releases your VSV is good.
Mine leaks like a sieve! But it will pass all the tests in FSM.
11-27-2010, 04:16 PM
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Received the new VSV and installed it. Now I have a new problem.
When running a vacuum test on the EGR. Everything is fine to I get up to operational
temp. When I rev the engine to 3500rpm's I get vacuum for about 1 sec and then
nothing. If I unplug the VSV I get steady vacuum at 3500rpm's.
So obviously my ECM is powering up the VSV.
I tested the VAFM. It's right in spec's.
I tested the TPS. Everything's fine there.
Went to test the Engine coolant temp sensor. But the top broke off when I tried to
remove to connector. Would the ECT cause my problem. Or should I plan on testing
my the connections at the ECM tomorrow?
When running a vacuum test on the EGR. Everything is fine to I get up to operational
temp. When I rev the engine to 3500rpm's I get vacuum for about 1 sec and then
nothing. If I unplug the VSV I get steady vacuum at 3500rpm's.
So obviously my ECM is powering up the VSV.
I tested the VAFM. It's right in spec's.
I tested the TPS. Everything's fine there.
Went to test the Engine coolant temp sensor. But the top broke off when I tried to
remove to connector. Would the ECT cause my problem. Or should I plan on testing
my the connections at the ECM tomorrow?
11-27-2010, 04:40 PM
#30
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If the ECT doesn't signal operating temp, the ecu will not run the motor in closed loop, and probably it wouldn't open the EGR, either. So, yes, you gotta get the ECT squared away. Plus the motor will run like pants and won't pass the HC portion of emissions without a working ECT.
11-28-2010, 09:03 AM
#31
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Replaced ECT......didn't fix the problem. Still only getting vacuum to the EGR for about 1sec. than nothing at temp. I'm going to start looking for shorts and testing the ECM.
Is there anything else I should be looking at?
Is there anything else I should be looking at?
11-28-2010, 09:57 AM
#32
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My 3.0 failed nox because it had clogged injectors. It eventually passed (barely by 3ppm) with the clogged injectors. They were full of rust.
I've yet to retest it, but that clogged one caused a very lean condition.
I'm not saying that your truck is clogged full of rust like, but i'm thinking you may want to look into it at least.
I've yet to retest it, but that clogged one caused a very lean condition.
I'm not saying that your truck is clogged full of rust like, but i'm thinking you may want to look into it at least.
11-28-2010, 10:22 AM
#33
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Before panic sets in, tee in a vacuum gauge right at the EGR port and drive the truck. See if you get a vacuum reading about 5-7 inches of vacuum rolling about 35-40mph fourth gear/ high gear. If so all is well. If not, you could be losing ground signal from ECM? that completes the circuit for the VSV.
11-30-2010, 02:06 PM
#34
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After all said and done.......It seems my ECM is bad. It's not signaling my VSV to switch.
So I unplugged my VSV. But left the connector on, but not completely plugged in. Keeping the vacuum flowing, and took it to be tested.
Passed with flying colors!!!!!
15mph Test
NOx went from 1247ppm to "5"ppm
25mph Test
NOx went from 676ppm to "86"ppm
All other gases were "0.00"
The only bummer is because I failed 5 previous tests. I was flagged by the Calif smog police. And they won't issue a certificate until I have it tested by the BAR Cal smog
referee.
Has anybody had any experience with them. How hard to they check your system out?
Don't have the money to purchase a new/rebuilt ECM before they're going to test it.
So I unplugged my VSV. But left the connector on, but not completely plugged in. Keeping the vacuum flowing, and took it to be tested.
Passed with flying colors!!!!!
15mph Test
NOx went from 1247ppm to "5"ppm
25mph Test
NOx went from 676ppm to "86"ppm
All other gases were "0.00"
The only bummer is because I failed 5 previous tests. I was flagged by the Calif smog police. And they won't issue a certificate until I have it tested by the BAR Cal smog
referee.
Has anybody had any experience with them. How hard to they check your system out?
Don't have the money to purchase a new/rebuilt ECM before they're going to test it.
12-07-2010, 07:50 AM
#37
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Just an update..........Took it to the BAR Calif Smog referee. Left the VSV connector on
but not completely plugged in.
Passed with flying colors.
The only problem was that my radiator decided to spring a leak in the middle of the test.
but wasn't leaking enough to stop the test. Luckily....it was only a year and half old and
still under warranty. Already exchanged it out.
Still have the bad ECM. But the truck is running fine with the VSV unplugged. Even when cold. So I'm going to leave that way, and take a break and not worry about it
until after the holidays.
Thanks all for all the help and input! Specially...scope103, sb5walker. Thanks for the
help and all the links!
Scott
but not completely plugged in.
Passed with flying colors.
The only problem was that my radiator decided to spring a leak in the middle of the test.
but wasn't leaking enough to stop the test. Luckily....it was only a year and half old and
still under warranty. Already exchanged it out.
Still have the bad ECM. But the truck is running fine with the VSV unplugged. Even when cold. So I'm going to leave that way, and take a break and not worry about it
until after the holidays.
Thanks all for all the help and input! Specially...scope103, sb5walker. Thanks for the
help and all the links!
Scott
12-07-2010, 08:34 AM
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ECMs certainly do go bad, but it is much more likely to be somewhere in the connector string. I'd hate for you to shell out for a replacement that didn't do the trick. This is going to be annoying and boring, but if you could put a voltmeter at each end of the line you might find where the connection goes bad. (Or confirm that it's bad right at the ECM.) You, more than almost anyone else on this list, know what you're looking for!
I'm glad that you stuck it out and reported your results so carefully. Yes, high NOX can be caused by a lot of things, but in your case it was right where it was supposed to be -- the EGR system.
