honmusa:

Using out-of circuit test like resistance measurement of ignition oil resistance to detect failure cannot be used for definitive diagnosis decision ,most time ,the failure will not manifest until it is put in circuit and fail at a particular temperature .The best method for testing failure and misfiring in coils like ignition and injectors is perform an in-circuit test eg voltage measurement.
When dealing with ignition coil and injectors ,the signals are pulse signals so multimeter is useless in this case .
The best instrument to use in this situation is oscilloscope,from its output ,the misfiring coil and injectors will be clearly seen even if it is a subtle or intermittent failure.
Though an oscilloscope can be an expensive equipment ,it is a necessity for troubleshooting a digital and alternating signal and worth the investment for advance diagnostics.

I should have added - voltage tests and resistance test - both are basic electricity issues.

On that score you are absolutely right! We need both voltage drop and resistance tests, but I to defer to the Factory Service Manual for each vehicle, and in all cases in which I have to do troubleshooting, which is why I said "... without consulting the ultimate reference guide."

So as per the above, you can see that I made reference to Factory Service Manual. There are some vehicles which recommend resistance tests without any study of waveforms, and there are models that include the study of waveforms via an oscilloscope!

For example Honda Civic 2006 - 2009 Factory Service Manual does not suggest the use of a DSO but just a multimeter and the conducting of basic voltage/resistance test to decide whether or not to replace faulty ignition coils and injectors as as simulation tests with HDS, there is no mention of a DSO.

I have attached an example in which the Factory Service Manual makes no reference to the use of a DSO!

In Toyota Avensis Verso 2001 - 2007, both multi-meter and DSO tests are required.

From the above, it is pretty clear that there is no one size fits all, all vehicles should be treated as individuals much in the same way as a parent cannot expect success in child-rearing by treating each child identically.

Wikipedia has this to say about oscilloscopes (so I was not wrong in saying electronics in the first place), I just decided to change it to electrical because of the bolded below:

An oscilloscope, previously called an oscillograph,[1][2] and informally known as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional plot of one or more signals as a function of time. Other signals (such as sound or vibration) can be converted to voltages and displayed.

Oscilloscopes are used to observe the change of an electrical signal over time, such that voltage and time describe a shape which is continuously graphed against a calibrated scale. The observed waveform can be analyzed for such properties as amplitude, frequency, rise time, time interval, distortion and others. Modern digital instruments may calculate and display these properties directly. Originally, calculation of these values required manually measuring the waveform against the scales built into the screen of the instrument.[3]

The oscilloscope can be adjusted so that repetitive signals can be observed as a continuous shape on the screen. A storage oscilloscope allows single events to be captured by the instrument and displayed for a relatively long time, allowing observation of events too fast to be directly perceptible.

Oscilloscopes are used in the sciences, medicine, engineering, automotive and the telecommunications industry. General-purpose instruments are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used for such purposes as analyzing an automotive ignition system or to display the waveform of the heartbeat as an electrocardiogram.

In the institutional automotive repairs class I attended, I was introduced to DSOs, and I absolutely agree that a DSO is a must for the modern automotive workshop, if a repair shop does not have one, they are under equipped so to that extent, I absolutely do agree with the below:

Though an oscilloscope can be an expensive equipment ,it is a necessity for troubleshooting a digital and alternating signal and worth the investment for advance diagnostics.


I guess we are saying the same thing after all, but you called me out that I did not cover all scenarios.


Point taken in good faith

Keep up the good work

This post is a continuation of screenshots from the Factory Service Manual of Toyota Avensis Verso 2001 - 2007 which dictates that both multi-meter and DSO tests are required.

You were right if I had used a proper DSO to diagnose my car's problem, maybe I would have seen exactly what the intermittent or failing components were.

After I failed emission the second time, I went on a short trip with the car before it enters the driving ban and then the dreadful catalytic converter P0420 DTC came.

Should I still go ahead and pay for a professional scan diagnosis to see if there are other problems or just go ahead and change my CAT. The freeze frame data shows the fuel trims during the time of CAT failure were perfect, meaning that it was not destroyed by improper air fuel mixture...like raw fuel getting into the CAT. I guess the CAT was degraded by the previous owner driving the car for so long with faulty oxygen sensors responsible for fuel air mixture.

By the way after I changed to a new thermostat, my engine coolant temperature is now within range instead of the 70degress I had before.

Attached pixs

AutoElectNG, you are really educating us with this thread.

phibetakappa:
AutoElectNG, you are really educating us with this thread.

My pleasure!

That is the purpose of this thread, the application of the scientific method to resolving automotive problems!

It is an honor to have you around!

olaboy1:
You were right if I had used a proper DSO to diagnose my car's problem, maybe I would have seen exactly what the intermittent or failing components were.

After I failed emission the second time, I went on a short trip with the car before it enters the driving ban and then the dreadful catalytic converter P0420 DTC came.

Should I still go ahead and pay for a professional scan diagnosis to see if there are other problems or just go ahead and change my CAT. The freeze frame data shows the fuel trims during the time of CAT failure were perfect, meaning that it was not destroyed by improper air fuel mixture...like raw fuel getting into the CAT. I guess the CAT was degraded by the previous owner driving the car for so long with faulty oxygen sensors responsible for fuel air mixture.

By the way after I changed to a new thermostat, my engine coolant temperature is now within range instead of the 70degress I had before.

Expert opinion will be out in 24 hours or less.

olaboy1:
You were right if I had used a proper DSO to diagnose my car's problem, maybe I would have seen exactly what the intermittent or failing components were.

After I failed emission the second time, I went on a short trip with the car before it enters the driving ban and then the dreadful catalytic converter P0420 DTC came.

Should I still go ahead and pay for a professional scan diagnosis to see if there are other problems or just go ahead and change my CAT. The freeze frame data shows the fuel trims during the time of CAT failure were perfect, meaning that it was not destroyed by improper air fuel mixture...like raw fuel getting into the CAT. I guess the CAT was degraded by the previous owner driving the car for so long with faulty oxygen sensors responsible for fuel air mixture.

By the way after I changed to a new thermostat, my engine coolant temperature is now within range instead of the 70degress I had before.

I have attached FSM explanations for both variations of engines, cannot recall which engine your vehicle uses.

To resolve this, you need a professional scan tool such as Toyota TechStream that can actuate components as well as a study of live data and/or a DSO

The FSM clearly talks above waveforms of the A/F sensor and the Oxygen Sensor

The key to solving this debacle is comparing fuel injection volumes to oxygen sensor output voltage

A professional scan tool preferably with the OEM tool Toyota Techstream is what I would recommend so we can narrow down the options to a faulty CAT or a leaking gas exhaust system, fuel pressure problems or fuel injector problems.

Please ensure you get a comprehensive printout of the state/status of the vehicle

Good DIY with respect to the thermostat

The manual refers to Toyota Intelligent Tester II, its functions have been replaced by Techstream http://alflash.com.ua/testerii.htm

Nothing beats the OEM scan tool when you have to go so deep into the diagnosis and take the time to study the pdfs with the same names as the attached graphics

Thanks for your time, I have ordered for a CAT. I do not have gas and exhaust leakages because these are the two greatest checks from the govt to pass annual MOT, infact no matter how tiny a gas or exhaust leakage is, you will never pass MOT. And my car during the MOT checks does not have any gas or exhaust leakages.
I have replaced all my sensors so I don't think I should worry about those, from what I've read it is stated that 99% of the time one would have to change the CAT when you get P0420.

My original question was considering that my fuel trims are good and no other DTC's, can I conclude that my engine is healthy.
In one of your previous posts you stated a bad CAT as one of the causes of a high HC, and then under high CO a catalytic converter was not listed. Can we assume that a new CAT would fix the high HC and high CO. Because I read somewhere that once you are able to fix the HC then the CO would take care of itself.

http://www.salemboysauto.com/faqs/faq-20.htm

olaboy1:
Thanks for your time, I have ordered for a CAT. I do not have gas and exhaust leakages because these are the two greatest checks from the govt to pass annual MOT, infact no matter how tiny a gas or exhaust leakage is, you will never pass MOT. And my car during the MOT checks does not have any gas or exhaust leakages.
I have replaced all my sensors so I don't think I should worry about those, from what I've read it is stated that 99% of the time one would have to change the CAT when you get P0420.

My original question was considering that my fuel trims are good and no other DTC's, can I conclude that my engine is healthy.
In one of your previous posts you stated a bad CAT as one of the causes of a high HC, and then under high CO a catalytic converter was not listed. Can we assume that a new CAT would fix the high HC and high CO. Because I read somewhere that once you are able to fix the HC then the CO would take care of itself.

http://www.salemboysauto.com/faqs/faq-20.htm

Your engine is fine except for the throttle body issue which I have not looked into.

If you study the documents, given the cost of a CAT, that is the last thing to do after eliminating every other issue.

So I would say, why not exhaust the diagnostics tree?

All the same since you have already gotten the CAT, install it and do the emission test again.


https://www.youtube.com/watch?v=HADOcrcMikA

I have a vested interest in ensuring that your vehicle passes the emissions test, it will be a fitting demonstration that this method of diagnosing a vehicle is the way forward in modern electrical/computerized vehicles

Ok from the video it looks like my CAT has not been functioning properly to eliminate HC and CO. Kindly check the link below and give your expert advice on this Toyota tech stream reader and software for windows 10. It includes OBD2 cable and software disc

http://www.ebay.com/itm/LATEST-2018-V-2-0-4-ORIGINAL-MINI-VCI-TOYOTA-TECHSTREAM-V-11-30-030-OEM-TIS-/252676155983?hash=item3ad4ac2a4f:g:xNgAAOSwN6JY-yLf

http://www.ebay.com/itm/LATEST-2018-V-11-30-029-TOYOTA-TIS-TECHSTREAM-GTS-MINI-VCI-J2534-DIAGNOSTIC-TOOL-/272628725637?hash=item3f79f03785:g:q0EAAOSwwPhWjQHi

olaboy1:
Ok from the video it looks like my CAT has not been functioning properly to eliminate HC and CO. Kindly check the link below and give your expert advice on this Toyota tech stream reader and software for windows 10. It includes OBD2 cable and software disc

http://www.ebay.com/itm/LATEST-2018-V-2-0-4-ORIGINAL-MINI-VCI-TOYOTA-TECHSTREAM-V-11-30-030-OEM-TIS-/252676155983?hash=item3ad4ac2a4f:g:xNgAAOSwN6JY-yLf

http://www.ebay.com/itm/LATEST-2018-V-11-30-029-TOYOTA-TIS-TECHSTREAM-GTS-MINI-VCI-J2534-DIAGNOSTIC-TOOL-/272628725637?hash=item3f79f03785:g:q0EAAOSwwPhWjQHi

I would not touch those Chinese clones with a ten foot pole

See the price of the item if purchased from the only correct source - Toyota itself!

@AUTOELECTNG,

Please, I will appreciate your input on this issue I posted earlier on:

Hello bro,

I have been having these codes in my Honda Accord 2007 model that uses a drive by wire system for up to a year now:

P0123
P0223
P2101
P2176

The codes have been coming on from time to time, sometimes in a space of one week, sometimes in a space of one month(as the spirit leads).

Each time it comes up, idle becomes erratic,the engine revs on its own without touching the accelerator pedal, very high idle, and sometimes the car stalls. It jerks when I shift from P to D or R, and when if I drive the car, it accelerates on its on up to 40km/Hr. I can only control it with the brakes, as there is usually no throttle response then.

I understand it has to do with the throttle body assembly. I have replaced the throttle body about four or five times.
The latest one, I had to order a new throttle body online which was fixed two weeks ago.
One week later the codes with its attendant issues resurfaced.

I really do not know what else to do.

I am in an area where I do not have access to a variety of mechanics or auto electricians and I'm just wondering if this fault can be fixed for good.

Please, any suggestion on what could be the problem?

Thank you.


NB:olaboy1 provided some input, which I tried out, but I'm still experiencing the same issue intermittently.
I am thinking of trying another ECU, but i will feel so demoralized if I did and the problem re-surfaces.

I ordered a used CAT, fit it and did the drive cycle to get it ready for emission. I passed emission very good with the result below, but after emission I drove like 40 mins on highway and got P0420 and P0430 codes again.
CO: 0.1 (max0.5)
HC: 2 (max100).
Lambda value 1.01 (max 0.97-1.03)

The car jerks during stop start between (0-40km) intermittently. How do I fix this problem, it's very frustrating.
As per TPS I watched it on my wifi OBD during motion around 110km/h and it never gets above 30%.
My fuel trims look good.

Ok it looks like Dandollar and I have same problem, the difference is that his own TB is a drive by system and mine is a cable system.
I think I may have mistakenly stumbled on my car's problem that has caused me to change parts indiscriminately just like Dandollar changed TB 4 times.

In my engine bar you have a fuse box in the pix attached, I believe previous owner and myself while trying to change spark plugs and get the fuse box out of the way, we may have caused the fuse box to throw the throttle cable out of adjustment base on my observation below.

In case anyone is reading this in future, before you change TB or TPS or IAC, check your throttle cable and find an expert to ascertain its properly adjusted. my car was jerking intermittently before I loosened the engine bay fuse box getting in the way of my IG coil so I could check the coils and plugs, at the completion of this exercise I left the fuse box hanging on the throttle cable and whilst I made a short town driving to the grocery store the jerking repeated itself every 1 minute or so as against the intermittent jerking I had before.

I checked the engine bay after parking and realized I forgot to put the fuse box back in its proper position, although a stupid thing to do but it seem to have pronounced my jerking more and pointed me in the failing component. Also remember I complained about delayed starting, while the fuse box was still hanging on the throttle cable my car would only start at the 3rd attempt and the simplest explanation for this was that my throttle cable adjustment was messed up and supplying more fuel to the combustion chamber than needed for a fresh engine crank up (the cable controls the lever that controls the TPS which sends wrong signal to the ECU which then informs the injectors that the TB needs more fuel), and the car needed 1 or 2 cranks to dry up the excess fuel before it could start with the right amount of fuel. If anyone wants to confirm my assertion take off the plastic boot on your TB and watch excess fuel evaporates from your TB during cranking. If you enlarge the pix below you could see clearly my throttle cable is rusted at the TB end. The cable is the one hanging at that rubber boot, I placed it there when I took out my throttle body for replacement.

The problem is such a simple component will cause you fortune as it makes your TPS and ECU to send too much fuel than needed which can damage your CAT. As in my case a replacement CAT that passed emissions barely 20 mins later threw below efficiency codes which I'm suspecting was as a result of a bad throttle cable or adjustment. I will find a professional to check my cable out. I should have fixed this problem a long time ago because I listed all the components that could cause my car's drivability issues and throttle cable was one of them, and I watched a YouTube video that showed that a throttle cable should retract when you drag the cable in the rubber out, but mine did not retract at all and I overlooked it thinking maybe my own car was not designed that way, so most likely some corrosion in the cable assy is hampering free movement and retraction. This video is exactly a replica of my car's problem, even when I took mine out from the hanger on the car's body where it routes through to the drivers side gas pedal, it still failed the retraction test.

https://www.youtube.com/watch?v=g47G-98iq7Q
As for Dandollar you don't need to replace any further parts, yours is a latest design TB controlled electronically by the ECU, what you are lacking is a professional scan tool to properly program your new TB, take your car to a dealer and have them reprogram your TB.

As for my TPS reading I have now done the proper check with KOEO and gas pedal fully depressed my TPS gets to 80% max incrementally and it's within manufacturers spec of 64%-98%, but I'm sure with a new throttle cable I should be able to get it up to 90%, either way my TPS seems to be fine. At 80% TPS translates to 4v by my calculation, so I'm looking at around 90% or 4.5v.
As explained in the video below the gas pedal and throttle cable are equally responsible for air fuel stoichometry ratio and a failure of one or both would cause same problems of air fuel ratio sensors, but this time since they are only mechanically controlled they would not throw any DTC as it looks like it's only my brake pedal that has a monitoring sensor and not clutch and gas pedal.

https://www.youtube.com/watch?v=smI2ijg4KcM
I will update on my final fix.
Dandollar you might want to see the videos below also.

https://www.youtube.com/watch?v=FJobCD6y8fk

https://www.youtube.com/watch?v=Pgln9L5Y7sQ

Update: my mechanic and Toyota company guys said my accelerator cable is not designed to retract and the retraction is done by the lever on the TB, however after we unbolted the cable from the TB and put it back again I noticed some improvements in my drivability. Prior to this I had "hesitation" and "jerking" problems, the hesitation was more like a sluggish movement from dead stop and higher gears, but now ONLY hesitation has disappeared as the car's movement is very smart now with a very good throttle response time. I also noticed watching my OBD2 that my BTDC has increased immediately after throttle cable adjustment from around 10.5 degrees at idle to 12-13.5 degrees at idle, FSM specifies 5-15 degrees and as you know ignition timing is critical to full combustion, and that explains why I had engine sluggish movement and poor MPG due to retarded ignition degree. From 5-15 degrees specified, what is the best ignition advance degree one should aim for that supports full combustion?
I looked at another Toyota's gas pedal and acccelerator cable mechanism and noticed it has some free play or loosen tension in the cable if you drag the cable up from the point it's attached to the gas pedal inside the car before it even controls the throttle body lever, something around 2-3mm, but mine has almost zero free play/tension and you can't drag the cable up as once you depress the gas pedal it controls the throttle body lever immediately. I am trying to convince myself that the fix to hesitation and jerking lies in the accelerator cable and gas pedal.

https://www.youtube.com/watch?v=R1tPT7anjwk
The only problem left to fix is the jerking, like I said the jerking is more now than before, and I'm trying to remember exactly what I may have done that could cause the increase in jerking now because that may lead me to the root cause of the prior intermittent jerking. Judging by my driving experience this jerking is a complete simulation of a dirty/clogged carburetor spray jet, and in this case the injector nozzles.

dandollar1:
@AUTOELECTNG,

Please, I will appreciate your input on this issue I posted earlier on:

Hello bro,

I have been having these codes in my Honda Accord 2007 model that uses a drive by wire system for up to a year now:

P0123
P0223
P2101
P2176

The codes have been coming on from time to time, sometimes in a space of one week, sometimes in a space of one month(as the spirit leads).

Each time it comes up, idle becomes erratic,the engine revs on its own without touching the accelerator pedal, very high idle, and sometimes the car stalls. It jerks when I shift from P to D or R, and when if I drive the car, it accelerates on its on up to 40km/Hr. I can only control it with the brakes, as there is usually no throttle response then.

I understand it has to do with the throttle body assembly. I have replaced the throttle body about four or five times.
The latest one, I had to order a new throttle body online which was fixed two weeks ago.
One week later the codes with its attendant issues resurfaced.

I really do not know what else to do.

I am in an area where I do not have access to a variety of mechanics or auto electricians and I'm just wondering if this fault can be fixed for good.

Please, any suggestion on what could be the problem?

Thank you.


NB:olaboy1 provided some input, which I tried out, but I'm still experiencing the same issue intermittently.
I am thinking of trying another ECU, but i will feel so demoralized if I did and the problem re-surfaces.

I will look into your issue and provide you feedback soon!

@AutoElectNG

Kindly help out. P0725 and P0448 DTCs on a 2008 Nissan Sentra Se-R.

Any advice or referral to a reputable auto electrician would be helpful.

thanks

Lexmeizta:
@AutoElectNG

Kindly help out. P0725 and P0448 DTCs on a 2008 Nissan Sentra Se-R.

Any advice or referral to a reputable auto electrician would be helpful.

thanks

I have already told you the solution for the first code, I have been too busy to work on the second code!

I would recommend GAZZUZZ.

He hates Nissans though, so I don't know if he would love to deal.

Your issue is rather minor especially the first code, the second code might be more involved.

The issue is to repair modern cars right:

1. You want someone who has a post-secondary education, he is a graduate.

2. You want someone familiar with computers, he used to work with computers before, so he is.

3. You want someone who knows his way around, electronics, he does.

4. And you want someone who knows old-school troubleshooting, he does.

5. You want demonstrable expertise, he has got that too.

So whatever he tells you, should be well-considered professional advice that you can rely on.

Have a nice day!

Thanks for the response. Sadly, i tried and like you said, its a Nissan.

Actually more worried about getting an expert hand to help me sort it out. Don't want to end up worsening issues in a bid to solve one issue.

AutoElectNG:


I have already told you the solution for the first code, I have been too busy to work on the second code!

I would recommend GAZZUZZ.

He hates Nissans though, so I don't know if he would love to deal.

Your issue is rather minor especially the first code, the second code might be more involved.

The issue is to repair modern cars right:

1. You want someone who has a post-secondary education, he is a graduate.

2. You want someone familiar with computers, he used to work with computers before, so he is.

3. You want someone who knows his way around, electronics, he does.

4. And you want someone who knows old-school troubleshooting, he does.

5. You want demonstrable expertise, he has got that too.

So whatever he tells you, should be well-considered professional advice that you can rely on.

Have a nice day!

Lexmeizta:
Thanks for the response. Sadly, i tried and like you said, its a Nissan.

Actually more worried about getting an expert hand to help me sort it out. Don't want to end up worsening issues in a bid to solve one issue.

take it to autologic @gbagada ,nissan is part of of our specialty!!! call 08061166316

honmusa:

take it to autologic @gbagada ,nissan is part of of our specialty!!! call 08061166316

Okay sure! This is what I've been looking for
Thanks

Did you know that as far back as 2012, a Ford Fusion had 70 on-board computers?

And that that data on the Ford Fusion vehicle computer network [controller area network (CAN)] flowed at the rate of 25 gigabytes per hour!

Little wonder then that if you drive a modern car, you want a repair man that understands and appreciates computers and respects (read that to mean does not abuse) electrical/electronic systems!!

You can read more here: https://www.usatoday.com/story/driveon/2012/12/22/ford-fusion-computers/1786297/

AutoElectNG:


Any updates?

Have the codes gone for good?

Yes, all codes have gone, get as high as 21mpg on highway and fires well.
Thanks.

tunde783:


Yes, all codes have gone, get as high as 21mpg on highway and fires well.
Thanks.

Good to know everything is working like it should!

dandollar1:
@AUTOELECTNG,

Please, I will appreciate your input on this issue I posted earlier on:

Hello bro,

I have been having these codes in my Honda Accord 2007 model that uses a drive by wire system for up to a year now:

P0123
P0223
P2101
P2176

The codes have been coming on from time to time, sometimes in a space of one week, sometimes in a space of one month(as the spirit leads).

Each time it comes up, idle becomes erratic,the engine revs on its own without touching the accelerator pedal, very high idle, and sometimes the car stalls. It jerks when I shift from P to D or R, and when if I drive the car, it accelerates on its on up to 40km/Hr. I can only control it with the brakes, as there is usually no throttle response then.

I understand it has to do with the throttle body assembly. I have replaced the throttle body about four or five times.
The latest one, I had to order a new throttle body online which was fixed two weeks ago.
One week later the codes with its attendant issues resurfaced.

I really do not know what else to do.

I am in an area where I do not have access to a variety of mechanics or auto electricians and I'm just wondering if this fault can be fixed for good.

Please, any suggestion on what could be the problem?

Thank you.


NB:olaboy1 provided some input, which I tried out, but I'm still experiencing the same issue intermittently.
I am thinking of trying another ECU, but i will feel so demoralized if I did and the problem re-surfaces.

I am ready and available to take this on.

Let me know if you are still interested.

Several versions of Honda Accord exist - American, Canadian, European,Japanese, 2 door, 4 door, coupe, Auto, Manual, CVT.

I need to be sure which one you drive

There are scanners and there are scanners.

Any autoist worth his salt will tell you that there is a marked difference between what an aftermarket tool can access and what a factory scan tool can access, actuate and generally do.

The reason is not far-fetched. The technology has to be licensed from the auto manufacturers and their is no incentive on the part of the third-party guys to license everything that can be licensed because it was greatly increase how long it takes to break even.

Now the question is - Given the cash crunch Nigeria faces, what would you consider a reasonable and appropriate pricing and affordable price point for factory level aka dealership grade scanning?

Please provide your input so we can determine what the market is comfortable with.

I was monitoring a radio program yesterday and several callers complained that they want to patronize the educated techs but their charges are so unwelcoming so they run to the roadside guys and hope and pray for the best.

I will appreciate your input into this market research.

If you provide reasons to back up your positions, it will be all the more helpful as we gauge the feel of the market.

Lexmeizta:
@AutoElectNG

Kindly help out. P0725 and P0448 DTCs on a 2008 Nissan Sentra Se-R.

Any advice or referral to a reputable auto electrician would be helpful.

thanks

Has this been fixed? If no, here is my second recommendation: LeJeun3. I have not met him , but I have studied him and his methods, and I can wholeheartedly say, you would be in safe hands and the experience you communicated to me via email cannot happen with him!

Let me know how it goes.

AutoElectNG:


Has this been fixed? If no, here is my second recommendation: LeJeun3. I have not met him , but I have studied him and his methods, and I can wholeheartedly say, you would be in safe hands and the experience you communicated to me via email cannot happen with him!

Let me know how it goes.

would contact him and get back to you on it.
Hasn't been fixed. Parked the car for a while pending when I get the time to fix.
Thanks a lot..cheers

OBD II DTCs tell you where a problem is, they don't tell you what the problem is.

There are no different from you going to a doctor and telling him "my shoulder hurts"

The doctor still has to do diagnostic tests to figure out if your shoulder hurts because of turn rotator cuff, arthritis, neuropathy, etc

Above modified from JimZ comments on thetruthaboutcars website posted September 15, 2017 11:35 am

OBD II DTCs also help with starting to figure things out or with determing the severity of the issue
Above modified from gtemnykh comments on thetruthaboutcars website posted September 15, 2017 12:28 pm


So while a few mechanics may dismiss OBD II DTC codes as being irrelevant and a technician's physical checks as being relevant, the truth of the matter is that just as a doctor asks you how you feel and uses that as a guide to narrow down possibilities and courses of action, it is a combination of DTC codes and the expertise of a trained techie that is required to complete the diagnostic process which explains why so many times the question is asked: "Scan and post codes"

I have been in contact on WhatsApp with AutoElectNG, such a fantastic guy with a huge wealth of experience in automotive diagnosis.
I followed all the vital information he outlined in his last post to the last letter.
My personal advice in case a car DIY enthusiast is reading this is to get these two things before proceeding with any troubleshooting.
1. Technical bulletins on your car factory service manual. This will give you a comprehensive lists of all the parameters and values your car should meet.
2. A reliable scan tool that can read all the information derived from point 1 above.

AutoEletNG streamlined the troubleshooting to oxygen sensors behaviors (upstream and downstream), and his reason was because of OBD monitor test for CAT not completed. The oxygen sensors were behaving erratically, and he advice I do an engine/ECU software update.

The ECU software update fixed all my fuel trims within spec and car drives smoother, and whilst comparing all technical data from FSM with live data on the scantool, I realized Evap VSV was OFF instead of ON, and that may probably be the cause of what has been damaging my CAT by causing my A/F and oxygen sensors to behave erratic, unfortunately no DTC was set for this Evap VSV (http://alflash.com.ua/evap.htm).

I shall give more update here on the final fix whilst I work closely with AutoElectNG.

I do still have pending CAT codes P0420 and P0430, which I believe the Evap system is the culprit.
My only confusion right now is Evap monitor is showing complete while CAT monitor shows incomplete.