Clintb3astwood
Greenie Member
Could you possibly make another one of these and i send you some cash for it?
Drive cycles for emissions
- Thread starter Sho
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BAT-man
BANNED
Hi Jef,
Sorry for the necro, trying to understand the whole picture -
Did this get rid of both P0401 and P0403? I thought P0403 was related to the actual flow of gasses through the engine and monitored by the O2 sensor. I am usually able to get rid of P0401 by plugging in the solenoid, but P0403 comes up unless the pipe is plugged into the manifold.
Are you saying that the rubber hoses stuffed into the EGR solenoid are physically interfering with the valve operation by creating resistance, and this is what the ECU monitors, and this gets rid of P0403?
Sorry for the necro, trying to understand the whole picture -
Did this get rid of both P0401 and P0403? I thought P0403 was related to the actual flow of gasses through the engine and monitored by the O2 sensor. I am usually able to get rid of P0401 by plugging in the solenoid, but P0403 comes up unless the pipe is plugged into the manifold.
Are you saying that the rubber hoses stuffed into the EGR solenoid are physically interfering with the valve operation by creating resistance, and this is what the ECU monitors, and this gets rid of P0403?
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KiwiFlavor
Greenie N00B Member
Emissions testing is for the weak. I have that shit fully deleted.
matt_krebs
Greenie Member
I don't want to be a downer, but I believe the technique of shoving a tube in the EGR is a placebo and it was a completely fluke that it worked. Looking at the Service manual for the Mazdaspeed 6, the two codes P0401 and P0403 have nothing to do with the positioning or backpressure of the EGR valve. I have attached the pages in question that describe the codes and how the ECU tests for them. In summary:
P0401 is measured using the MAP sensor through a process described on this Wikipedia page under the heading "EGR testing".
P0403 is triggered by measuring the voltage across the coils of the EGR valve (therefore something as simple as a resistor network across the EGR pins would trick the ECU). The required sizing and arrangement of these resistors is described in the third document I have attached.
Lastly, one final straw that blows a pothole in this method is that the EGR valve is controlled via a stepper motor. As someone with electronics knowledge, I know that the current through a stepper motor is the same whether it is moving or stalled (not moving) as it would be with a tube shoved into the valve. Here is an article on StackExchange where someone is describing how, without an encoder, there is no reliable way to determine the position of a stepper motor because its stall-current is approximately equal to its operating current when being turned.
TLDR: I believe that by simply plugging the EGR valve the P0403 code will go away and I do not believe the P0401 code will be affected.
P0401 is measured using the MAP sensor through a process described on this Wikipedia page under the heading "EGR testing".
P0403 is triggered by measuring the voltage across the coils of the EGR valve (therefore something as simple as a resistor network across the EGR pins would trick the ECU). The required sizing and arrangement of these resistors is described in the third document I have attached.
Lastly, one final straw that blows a pothole in this method is that the EGR valve is controlled via a stepper motor. As someone with electronics knowledge, I know that the current through a stepper motor is the same whether it is moving or stalled (not moving) as it would be with a tube shoved into the valve. Here is an article on StackExchange where someone is describing how, without an encoder, there is no reliable way to determine the position of a stepper motor because its stall-current is approximately equal to its operating current when being turned.
TLDR: I believe that by simply plugging the EGR valve the P0403 code will go away and I do not believe the P0401 code will be affected.
Cfoldone
Silver Member
I disagree on a couple of your points.
First I agree (maybe) that keeping a good EGR valve plugged in correctly to allow the ECU to verify electrical operation and P0403 will not get triggered, a BIG if is....ECU considers that as a whole system that either code 0401 / 0403 are some how combined, or in a portion of the drive cycle a failure still occurs.
I disagree on the stepper motor presumption that the currents are close. We have no idea how the programmers that created that portion of code decide how to check the electrical operation or failure of the EGR valve. I know of different ways to either move valve to stall (end point) or stroke the position in reverse and back to stall and/or reverse again is a way to validate the operation, percentage of motion, or the other end of the limit.
Correct EGR operation will change directly measurable results of the engine drive cycle, that is how the ECU decides that the emission system as a whole works. By looking at the drive cycle (posted by SHO) you can see it is not a simple cause and effect. This is because spoofing emissions test and verification is a expensive fine ( VW diesel gate) and manufactures want to make sure equipment works correctly.
In the end it worked some and maybe work for others. Emission testing thankfully does not exist...yet in my location.
First I agree (maybe) that keeping a good EGR valve plugged in correctly to allow the ECU to verify electrical operation and P0403 will not get triggered, a BIG if is....ECU considers that as a whole system that either code 0401 / 0403 are some how combined, or in a portion of the drive cycle a failure still occurs.
I disagree on the stepper motor presumption that the currents are close. We have no idea how the programmers that created that portion of code decide how to check the electrical operation or failure of the EGR valve. I know of different ways to either move valve to stall (end point) or stroke the position in reverse and back to stall and/or reverse again is a way to validate the operation, percentage of motion, or the other end of the limit.
Correct EGR operation will change directly measurable results of the engine drive cycle, that is how the ECU decides that the emission system as a whole works. By looking at the drive cycle (posted by SHO) you can see it is not a simple cause and effect. This is because spoofing emissions test and verification is a expensive fine ( VW diesel gate) and manufactures want to make sure equipment works correctly.
In the end it worked some and maybe work for others. Emission testing thankfully does not exist...yet in my location.
BAT-man
BANNED
So it's possible that the random fluctuations in the IM pressure helped Voodoojeff not light up the P0401 code, and his rubber hose contraption helped with the P0403 code. I can see how avoiding the P0401 condition would not be "imitate able" outside of a logic controller that monitors when the ECU is testing for the differences in the IM pressure due to EGR and send its an expected signal somehow.
The P0403 seems much easier to avoid and apparently the rubber hoses somehow spoof the resistance expected... possibly. But a resistor pack would also be an easy option.
So now it's just about someone trying it and replicating Jeff's approach to see whether the rubber hose and the combination of inputs/output somehow ends up working for us anyway, logic be damned. Testers welcome! I'll try it sometime this year, but if anyone has access to a spare EGR valve and some time... Dewit!
@5doorsoffury how did it end up working out for you?
The P0403 seems much easier to avoid and apparently the rubber hoses somehow spoof the resistance expected... possibly. But a resistor pack would also be an easy option.
So now it's just about someone trying it and replicating Jeff's approach to see whether the rubber hose and the combination of inputs/output somehow ends up working for us anyway, logic be damned. Testers welcome! I'll try it sometime this year, but if anyone has access to a spare EGR valve and some time... Dewit!
@5doorsoffury how did it end up working out for you?
matt_krebs
Greenie Member
@Cfoldone I appreciate the feedback. After further research, I agree that it may be possible to determine if the EGR is working by cycling it between the completely open and closed states assuming that they have a stall detection chip. A regular dc motor is quite simple to detect a stall in because the current spikes, since that does not happen with a stepper I did not think it would be possible. The company Allegro Microsystems seems to sell a series of chips that can sense a stall.
I still have my doubts that putting a tube into the EGR valve would fix anything though. Because all that would do is simulate a stuck valve, which is the entire situation that the ECU is trying to measure for!
I hope I am wrong because I would love for there to be a simple trick. Sadly, I don't think it is that easy.
I still have my doubts that putting a tube into the EGR valve would fix anything though. Because all that would do is simulate a stuck valve, which is the entire situation that the ECU is trying to measure for!
I hope I am wrong because I would love for there to be a simple trick. Sadly, I don't think it is that easy.
tywoodruff
Greenie N00B Member
It's not as simple as putting some resistors into the EGR harness?
I've been trying to pass emissions for 6 months now. Getting tired of driving around with no license plates. Haha
I've been trying to pass emissions for 6 months now. Getting tired of driving around with no license plates. Haha
tywoodruff
Greenie N00B Member
Well, I don't know how or why, but it worked. I bought a used EGR valve. I took the vacuum hose that was on it and stuck it in the last hole. Like the guy did in the pic above, only I didn't have to use two hoses.
After a 3 hour road trip this week I checked and finally got an EGR ready status.
After 6 months of trying to track down a small EVAP leak I'm finally going to get my car inspected first thing in the morning.
After a 3 hour road trip this week I checked and finally got an EGR ready status.
After 6 months of trying to track down a small EVAP leak I'm finally going to get my car inspected first thing in the morning.
TrippyHippy
Greenie N00B Member
I am having trouble with my EGR, It's in Ready mode but before the Evap monitor goes in Ready mode the CEL P0401 Comes up for insufficient flow. Now when you did yours with just the tube you were able to get it to stay in ready without that code coming up? If so i am gonna make a block off plate for EGR and go about it that way. I Have replaced EGR and cleaned the housing very well also. and have a custom return line as of now to the manifold for Emissions Test..
So it's been a while since anybody replied to this thread. I'm just gonna go ahead and share some info on here since I've been dealing with Emissions hell here.
In the Gen2 service manual I found 2 other drivecycles that are slightly different than the one that @Sho posted in this thread.
Following both or either of these, I could not get my Oxygen Sensor to ready up at all. We're allowed 1 not ready here in Az, so I was a little screwed since EGR is deleted on my car. I decided to try hooking up the EGR and doing the trick Voodoojef posted, but unfortunately it did not work for me. What did happen though was even though I threw a P0401, the EGR system still readied up in the readiness monitors. I'm going to do another drive cycle tonight and report back, but my hope is that it readies up after 50ish miles again despite the P0401 being disabled in my tune.
The other interesting thing that you can do that I learned from this drive cycle document is if you go KOEO for 17 seconds, the check engine light will flash 7 times if you have not completed a full drive cycle. It was an interesting thing to check, but even after 500+ miles trying to get the oxygen sensor to ready up, that never went away. One other interesting tidbit is, on the AP my Oxygen Sensor showed not ready, but with a friend's OBDII scanner that was bought on Amazon it actually showed ready, so I wonder if maybe the AP isn't fully accurate. I never did drive through emissions while both EGR and Oxygen Sensor was showing not ready, but tomorrow I will be going in for emissions and I'm very interested to see if Oxygen Sensor is ready and just not lighting up in the AP for whatever reason.
One last thing. Another local Gen1 has tried this EGR trick as well and it did not work for him either. Same thing happened as me. P0401 tripped, but EGR readied up at the same time.
Either way, lots of info here, but figured I'd share my experience so far.
In the Gen2 service manual I found 2 other drivecycles that are slightly different than the one that @Sho posted in this thread.
Following both or either of these, I could not get my Oxygen Sensor to ready up at all. We're allowed 1 not ready here in Az, so I was a little screwed since EGR is deleted on my car. I decided to try hooking up the EGR and doing the trick Voodoojef posted, but unfortunately it did not work for me. What did happen though was even though I threw a P0401, the EGR system still readied up in the readiness monitors. I'm going to do another drive cycle tonight and report back, but my hope is that it readies up after 50ish miles again despite the P0401 being disabled in my tune.
The other interesting thing that you can do that I learned from this drive cycle document is if you go KOEO for 17 seconds, the check engine light will flash 7 times if you have not completed a full drive cycle. It was an interesting thing to check, but even after 500+ miles trying to get the oxygen sensor to ready up, that never went away. One other interesting tidbit is, on the AP my Oxygen Sensor showed not ready, but with a friend's OBDII scanner that was bought on Amazon it actually showed ready, so I wonder if maybe the AP isn't fully accurate. I never did drive through emissions while both EGR and Oxygen Sensor was showing not ready, but tomorrow I will be going in for emissions and I'm very interested to see if Oxygen Sensor is ready and just not lighting up in the AP for whatever reason.
One last thing. Another local Gen1 has tried this EGR trick as well and it did not work for him either. Same thing happened as me. P0401 tripped, but EGR readied up at the same time.
Either way, lots of info here, but figured I'd share my experience so far.
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anthony
Greenie Member
It's weird. My Oxygen Sensor refuses to ready up and will not throw a code, but after the P0401 throws my EGR system readies up. With the P0401 disabled, it will not ready up though. So I cannot pass because if I have the P0401 illuminated I I used a bluetooth OBDII dongle to check out some more info on the self tests and it does show some more info like Voodoojef said.
For the P0401 it's just checking valve pressure. It appears that it requires between 5.5kPa - 655kPa on the valve for it to think it's ready. I'm going to be fabbing up a plate tonight and getting some pressure onto that valve to see if that readies the system up. If it does, that should get me around it. If it does work I'll give some more info on what I'm doing with some pics, but man this is just a huge pain in the ass.
For the P0401 it's just checking valve pressure. It appears that it requires between 5.5kPa - 655kPa on the valve for it to think it's ready. I'm going to be fabbing up a plate tonight and getting some pressure onto that valve to see if that readies the system up. If it does, that should get me around it. If it does work I'll give some more info on what I'm doing with some pics, but man this is just a huge pain in the ass.
BAT-man
BANNED
Any updates, Vash The Delete?
I ended up selling the car after somebody made me an offer I couldn't refuse. They didn't need to worry about emissions crap, so it was the perfect buyer.
I made a plate and applied pressure to the EGR valve directly and that is not actually how it determines pressure on the EGR valve obviously. It uses some combination of the MAP sensor values and RPMs to figure out what the pressure SHOULD be if the EGR was actuating correctly and that's just something I could not figure out how to simulate properly.
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