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Thread: California smog analysis, ask a smog tech

  1. #51

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    Oh I know it will fail but does the Weber really run cleaner to the tailpipe? Off to do the $1.98 tuneup. Thanks for the input.

  2. #52

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    Question

    I have failed twice now with the V6 mighty max. I attached the two tests to this post. The first test was before the catalytic convertor replacement.
    High NOX, is failure reason, but O2 is also high. Tech guesses that my combustion temp is too high, due to lean condtion, and that I might have a vacuum leak, and exhaust leak.
    It does run rough before it is warmed up, and has extreme hesitation on acceleration (to the point it sometimes dies when gas pedal is pushed) before warm.
    I did lose a tube that goes from passenger side valve cover to the rubber duct right before the intake manifold. I replaced it with a tube I made myself from an old shower hose. The cover side is really tight, but the duct side is just slid in but not a super tight fit. You can see from the picture that the hard inner plastic tube has no barb. Could that be the reason? I will tape the tube to the intake duct, and see if that helps.
    (Pictures attached)
    There also may be an exhaust leak on driver's side exhaust manifold. Not sure, as oil also drips onto mainfold and pipe from the slow valve cover leak.

    Here is the list of things I have done in the recent past as far as repairs go.
    * Timing belt broke - replaced it as well as water pump, belt tensioner, front cam seals, and front crankshaft seal
    * Replaced serpentine belt at same time as timing belt
    * O2 sensor was giving a code when checked with analog meter. Replaced with new one
    * Catalytic convertor welded in place by muffler guy (CARB compliant Walker model 80904)
    * Exhaust manifold was missing some nuts, so those were installed and existing nuts tightened. Unfortunately sheared off stud closest to driver's side firewall
    * Cleaned out PCV valve with B12 Chemtool, didn't seem too clogged
    * Mass airflow sensor, and throttle postion sensor replaced a couple years ago
    * Spark plugs, wires, and distributor cap and rotor replaced a couple years ago (visually checked plugs right before test, but seemed not very worn, gapped to 40-42 thousandths)
    * Computer capacitors replaced per forum instructions

    Also, I don't think this engine has an exhaust gas recirculation (EGR) system. Am I correct in that conclusion?

    List of problems, that may or may not inlfuence this problem.
    * I think my rear main crankshaft seal is leaking
    * Something in my manual transmission seems to be leaking clutch hydralic fluid (clutch master cylinder has been replaced few years back)
    * Valve cover gasket has slow leak, even though it was already replaced.
    It has been a few months since I paid registration, but have not passed smog, so I'm getting nervous that it may get impounded soon (has happened to me before), as this is my only vehicle.

    Thanks for any help. This forum's members have really helped me to save lots of money, and saved my sanity a couple times already!
    Attached Images

  3. #53

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    Several things come to mind. First is the O2 Sensor. You can get a faulty one and it throws off your readings causing the vehicle to run too lean or rich. Second, is one that I have experienced before on another v6 Mitsubishi in the past. Owner had a friend do the timing belt on his car, but afterward he couldn't get it to smog for the life of him, so he sold it at a loss. Turned out the front cam was off by 2 teeth. Car couldn't run right because of that. I fixed the timing and it worked just fine after. Last might be ECU, but lets not go there just yet.

  4. #54

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    Quote Originally Posted by B-Line View Post
    Several things come to mind. First is the O2 Sensor. You can get a faulty one and it throws off your readings causing the vehicle to run too lean or rich. Second, is one that I have experienced before on another v6 Mitsubishi in the past. Owner had a friend do the timing belt on his car, but afterward he couldn't get it to smog for the life of him, so he sold it at a loss. Turned out the front cam was off by 2 teeth. Car couldn't run right because of that. I fixed the timing and it worked just fine after. Last might be ECU, but lets not go there just yet.
    Thanks for the reply.
    I did replace the O2 sensor, with a walker one just two weeks ago, that had the proper connector already attached, so, it probably is not that.
    Also, I was Very, Very, careful to get the cams and teeth lined up exactly right, so I highly doubt that is the problem.

    I hope it is not the ECU, but a if you guys know of a place where I could have that tested, or repaired, or purchase a new/repaired one, I'm all ears.
    As stated, I did already, recap the ECU, as a preventative measure, and I passed smog once after doing that years ago.

  5. #55

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    Quote Originally Posted by mightymaximus View Post
    As stated, I did already, recap the ECU, as a preventative measure, and I passed smog once after doing that years ago.
    Also, I'm an IT guy with soldering experience, so I was careful when recapping also.

  6. #56

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    Wouldn’t hurt to pop the ecu and see if everything looks ok still. Might try an extra set of injectors too just in case yours might be failing. Or have them cleaned.

  7. #57

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    Quote Originally Posted by mightymaximus View Post
    Also, I don't think this engine has an exhaust gas recirculation (EGR) system. Am I correct in that conclusion?
    The V6 does have an EGR system. After 250K miles it may be plugged or no longer operable and that could cause elevated NO readings.

  8. #58

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    ....edit see post #63 picture went away

    Last edited by claych; 10-23-2019 at 12:59 PM. Reason: picture disapeared

  9. #59

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    Quote Originally Posted by FMS88 View Post
    The V6 does have an EGR system. After 250K miles it may be plugged or no longer operable and that could cause elevated NO readings.
    Ok, here are comparison pics of where my book says the EGR system should be, and what is not there on my engine.
    Also, it appears that I have an engine built to federal smog regulations, and not CA as can be seen on my engine under hood sticker.
    Perhaps that is why I don't have the EGR system?
    If anyone is familiar with an EGR system that is located in a different place, let me know.

    I did notice on the pic of the header, to exhaust, that my gasket looks pretty bad. That may be one of the locations I have an exhaust leak.
    I believe that the gaskets I need for that joint is the one below.
    rock auto gasket link

    If anyone knows a good mechanic that is in the San Diego county area, that works on our older vehicles, I'm willing to take it there, if he/she can fix it. Just went to a place that said they wouldn't fix smog related issues, seemed kinda strange thou

    Thanks again!
    Attached Images

  10. #60

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    Quote Originally Posted by Chargerx3 View Post
    Wouldn’t hurt to pop the ecu and see if everything looks ok still. Might try an extra set of injectors too just in case yours might be failing. Or have them cleaned.
    I know that cleaning injectors, usually involves running the cleaner through the fuel rail on newer vehicles. Do our trucks have the port where we can attach a pressurized cleaner can onto the fuel rail, or is that something done with specialized eqipment that requires removal of the injectors?

  11. #61

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    You clearly dont have the EGR System on yours.

  12. #62

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    Typically you pull them and send to a lab to have cleaned and balanced. Other cleaners are marginal especially in a short amount of time.

  13. #63

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    The above has been around for a long time ,posting here to help Folks understand 5 gas interaction.
    Looking at the 2 V.I.R's & the mentioned severe stumble...
    Have You replaced the fuel filter? I would also perform
    fuel pressure and leakdown tests.
    Granted, the injectors could be suffering from poor spray pattern
    and solenoid wear, but hey simple (cheap) stuff first !!
    Last edited by claych; 10-23-2019 at 01:47 PM.

  14. #64

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    Quote Originally Posted by claych View Post

    Have You replaced the fuel filter? I would also perform
    fuel pressure and leakdown tests.
    Granted, the injectors could be suffering from poor spray pattern
    and solenoid wear, but hey simple (cheap) stuff first !!
    I did replace the fuel filter a few years ago, as well as drop the fuel tank to check out fuel pump. The tank was super clean.

    I will have to get the tools to perform a leakdown, and fuel pressure test.
    It seems a lot of the mechanics in SD, don't want to touch my truck as they can't see high dollar repairs coming from me.

    If I was back in Nevada, I could just ask any number of friends, and take my time fixing it. Here in CA, it feels like the green police are hiding behind every corner to penalize those who don't replace their older vehicle for a Pruis.
    Thanks again for the suggestions.

  15. #65

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    Your Welcome!
    Also forgot to mention,(sorry), replace that 'shower tube' with a correct size piece of vacuum line.
    -The loose fitting is a potential area for 'unmetered' air - read not 'seen' = no signal to ecm= no inj
    pulse width increase net result lean mixture.
    And,
    Repair all exhaust leaks !!! -any- exhaust leak will dilute the machine sample, simply put, sample is lean
    Engine is not running lean.
    Finally,
    Change the fuel filter!!!
    P.s,
    Might be worth a few calls to Your buds in NV( tools etc)

  16. #66

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    OK. I'm trying to figure out how I am supposed to hook up a gauge to the fuel rail to test fuel pressure. Usually there is a port to screw onto the fuel rail to test it. I don't see that on the 6G72 fuel rail.
    Do I need a special tool, that I can put inline with the fuel line or fuel rail to give me a testing port?
    Thanks again.

  17. #67

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    Did a compression test because I already had the tester.
    All cylinders in between 150-160 psi
    1 and 4 - 150
    3,5,6 - 155
    2 - 160
    As soon as I can figure out where to hook up the fuel pressure tester, and borrow or buy a compressor, I'll give results of the fuel pressure, and leakdown tests.
    Can I attach a fuel pressure tester to the high pressure side that I pointed to in the attached picture, with a kit, or adapter?
    Thanks again.
    Attached Images

  18. #68

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    I don’t know of a check valve in the line.

  19. #69

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    Quote Originally Posted by mightymaximus
    I'm trying to figure out how I am supposed to hook up a gauge to the fuel rail to test fuel pressure. Usually there is a port to screw onto the fuel rail to test it. I don't see that on the 6G72 fuel rail.
    Do I need a special tool, that I can put inline with the fuel line or fuel rail to give me a testing port?
    Thanks again.
    MD998700
    MD998753

    Make sure You use a fuel pressure gauge with provision to purge air___

  20. #70

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    Quote Originally Posted by claych View Post
    MD998700
    MD998753

    Make sure You use a fuel pressure gauge with provision to purge air___
    @claych
    Thanks for those part numbers.
    I borrowed a gauge from Oreilly's, and realized that it has no adapter for a mitsu.
    Attached is a picture from an ebay listing of the parts needed.
    Unfortunately they want $70 for it.
    If anyone has another place they have found that part for cheaper, or has one they want to sell, let me know.

    I may just take it to a shop to have the fuel pressure tested as it may actually be cheaper that the adapter. I talked to a friend who also has a early 90s truck about shops he goes to in SD area.
    Attached Images

  21. #71

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    So, I took my truck in and the mechanic had a hard time diagnosing what was the problem as he doesn't see a lot of mitsubishi engines these days.
    It tripped a code, which he could not read as he had no analog volt meter, or OBD 1 scanner. As I left the lot the check engine light went off.
    That was the first visit, for which there was no charge.

    The next visit was set up with a guy the owner called in that travels all around the county whom specializes in diagnosing hard to figure out vehicles.


    He says it was my mass air flow sensor. He could also read the history of the code that tripped and disappeared on the first visit, which was a MAF code. Admittedly, I replaced the original failing MAF with pretty much the cheapest (~$100) remanufactured one I found online two years ago so I could potentially pass smog, which I did.

    They also said their is not really a reliable way to test if the remanufactered MAF is good outside of getting one and installing it, and running it on the dyno to see if the ECU responds as it should. Also they have not had consisent results from remanufactered MAFs. Some are DOA, some work for a while, some a little longer. Is that really the case?
    Is there a remanufacturer that tests their MAFs before shipping them out?
    I believe the one I bought only had a one year warranty, but I'll double check, and post the one I bought for future members to see.

    Now that it has apparently failed, do you guys recommend a certain brand of remaufactured MAF, that has shown to be better than another?
    I can't justify spending the nearly $800 dollar price they want to charge just for the new Mitsubishi original part. Especially since I have so many miles on this engine.
    Thanks again guys for all the help.

  22. #72

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    Found OEM direct replacement new units retailing from about $50 - $200 USD. $50ish are Chinese made on ebay/ $200ish made by Beck Arnley on CARid and Summit Racing. There is always the chance the parts are all coming from the same manufacturing plant and are just jammed in different boxes (happens all the time). For $50 you don't have a lot to lose by trying one out -

    https://www.carid.com/1994-mitsubish...-flow-sensors/

    https://www.summitracing.com/search/...pe/maf-sensors

    https://www.ebay.com/itm/MASS-AIR-FL...e%3AMitsubishi

    If someone has some insight to the MAF situation they'll chime in one thins one. Hope the links are helpful.
    support the forum that supports you - join and donate to MightyRam50.Net today! donations unlock the edit function

  23. #73

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    Go to the junk yard and find one for cheap. Most have a 30 day return policy.

  24. #74

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    Quote Originally Posted by geezer101 View Post
    Found OEM direct replacement new units retailing from about $50 - $200 USD. $50ish are Chinese made on ebay/ $200ish made by Beck Arnley on CARid and Summit Racing. There is always the chance the parts are all coming from the same manufacturing plant and are just jammed in different boxes (happens all the time). For $50 you don't have a lot to lose by trying one out -

    https://www.carid.com/1994-mitsubish...-flow-sensors/

    https://www.summitracing.com/search/...pe/maf-sensors

    https://www.ebay.com/itm/MASS-AIR-FL...e%3AMitsubishi

    If someone has some insight to the MAF situation they'll chime in one thins one. Hope the links are helpful.
    Ok, through some research, I have found that the part sold on carid, is also sold, by Napa, and available from multiple sellers on amazon.
    Here is the Napa link:
    https://www.napaonline.com/en/p/NECX...=mass+air+flow

    Here is the Amazon link:
    https://www.amazon.com/Cardone-74-60...shi+Mighty+Max

    I happened to look at the 'other sellers' that are listed on the amazon product page, and found an open box one for $33 bucks.
    I figured I'd roll the dice, as this is even cheaper than the junkyards wee listing their MAF.

    Here is the link to the one I bought last year around July. Not good buld quality. It didn't even last a year, but I didn't try to get a warranty replacement as this Jun was around the time the timing belt broke, and I was not sure if I was going to keep the truck.
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Just in case I have a bad wiring harness going from the MAF to the ECU, I'm going to check if my Chilton manual has a wiring schematic to see if I have any wiring issues. I don't believe that the mechanic tested the harness from MAF to ECU, because I didn't see him take out the ECU.

    Thanks again for your help. I hope this helps someone else.

  25. #75

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    Quote Originally Posted by Chargerx3 View Post
    Go to the junk yard and find one for cheap. Most have a 30 day return policy.
    Unfortunately nearly all of the junkyards in San Diego are right next to the border, so there is potentially people from two countires pulling parts. When I called a few junk yards they said the MAF is usually one of the first things pulled.
    I may still go down there if my reman MAF doesn't pan out, or if I find I need a replacement wiring harness.

    Oh and I forgot to mention that Amazon would not ship the MAF here, likely because CA thinks the lead will jump off the circuit board and crawl into my skin killing me instantly, or something to that effect

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