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Any ideas of why my 2006 Pontiac Torrent loses acceleration while driving

defiantlysubdefiantlysub Posts: 5
edited February 2017 in Pontiac
I have a 2006 pontiac torrent and I keep having acceleration problems the mechanic keeps saying catalytic converter but I've replaced it 4 times with the same problem returning the check engine light codes says it's running lean with catalytic converter codes as well it will be ok for a few days then start doing it again...when I'm driving it will go into a coast not losing power I'll push on gas car will backfire then eventually will accelerate again but initially with a big surge of gas causing rpm to go 5 then be normal a few more miles and will repeat problem and the problem is getting worse. The dealer sent it to Buick to have a full hour diagnoses and the result was the same a bad catalytic .... As an added note the dealer just put in a remanufactured engine in which the light was on after picking up the car after that was done My car has 119011 miles. My car has an automatic transmission.

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Answers

  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,482
    Well sounds to me like you need to take the vehicle to someone who knows what he's doing.

    Have a look at this website, which lists top-rated, highly trained technicians who can solve this for you---hopefully there is one listed somewhere in your area.

    http://www.iatn.net/

    If everyone has just been chasing codes, that's not going to work. The codes only describe what systems are affected, but it doesn't tell you WHY. If you're running lean, maybe the PCM is compensating for an over-rich condition that is damaging your catalytic--so there's a case of "lean" actually meaning "rich".
  • I just got the result from buick gmc they are saying it's my fuel pump... That was after I paid to get the catalytic converter replaced again.... Could a bad fuel pump totally torch a converter?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 24,999
    What's bad is on the previous referral to the Buick dealer, that dealer's diagnosis was the catalytic converter.

    "Unless the car has age on it, most catalytic converters do not commit suicide. They are murdered by something else that is not right that kills them as the converter tries to do its job."

    --quote from a radio program of a professional and competent car repair shop technician and owner.

    2014 Malibu 2LT, 2008 Cobalt 2LT, 2015 Cruze 2LT,

  • thecardoc3thecardoc3 Posts: 5,329
    edited March 2017
    Every time I see a story like this one, I know that part of the reason this happens is directly related to all of the outside criticism the trade endured for the last few decades. Just take the idea that someone is just supposed to know what is wrong based on the description of a problem, and combine that with all of the suggestions that all someone has to do is put the car on "The Machine" and it will tell them what is wrong and it created a climate where investing the time to really learn how to do this work as well as buy the tooling that we needed to do it was a losing proposition. That's why there are very few people who can efficiently work through complicated problems like this.

    What @defiantlysub has described isn't a single issue and like always the devil is in the details.

    I have a 2006 pontiac torrent and I keep having acceleration problems the mechanic keeps saying catalytic converter but I've replaced it 4 times with the same problem returning.

    Replaced it with what? There are catalysts that can be bought and installed that actually do not meet the emissions systems specifications. The computer tests the catalyst's ability to store oxygen. If someone installs a catalyst that is physically smaller than the original then it only follows that it won't be able to store as much oxygen as the original design did. So that leads us to the question. How many catalysts were replaced because they physically failed and were some of them physically OK but simply unable to pass the onboard test?


    the check engine light codes says it's running lean with catalytic converter codes as well it will be ok for a few days then start doing it again...when I'm driving it will go into a coast not losing power

    Running lean. I could write for a week and not account for every possibility. In general the main causes are
    1. Fuel quality, pressure, and delivery issues.
    2. Computer control input problems which result in injector base pulse width calculation issues.
    3. Feedback control issues.

    The best part here is that for a given trouble code to set, the computer had to run a test and since the catalyst code is mentioned let's use it. For the catalyst test to run there are specific parameters that have to be met. One of those would be that certain codes cannot be set and some of those are (but not limited to);
    Mass air flow sensor codes such as P0101, P0102....
    O2 sensor codes such as P013X, P014X, P015X...
    Fuel trim codes such as P0171,P0172, P0174, P0175
    Misfire codes such as P0300, P030X

    Do you see a problem? The report that the catalyst code is setting as well as lean fuel control is a contradiction.
    The way such a contradiction can occur is that some of those other problems have to be random and not occurring all of the time which could allow for the catalyst test to run. There is also the chance that something is amiss and allows the computer to misinterpret engine operating conditions and that can result in the test running when it should not have. It's anyone's guess what the results of a test that is running incorrectly is going to be.
    This is why it is so important that when a technician begins investigating a vehicle problem he/she has to identify which systems are working correctly as well as in which systems problems currently lie while always keeping in mind something might be working correctly right now but could have a random issue that make time to identify. That's the start, from there when a problem area has been identified then more specific pinpoint testing then can be performed to prove exactly what is causing a given issue.


    I'll push on gas car will backfire then eventually will accelerate again but initially with a big surge of gas causing rpm to go 5 then be normal a few more miles and will repeat problem and the problem is getting worse.

    Now are you ready for the fun part? The description earlier is that the system is running lean. But the report of the backfiring leads to a problem, another contradiction. To backfire there has to be fuel, and specifically the air/fuel ratio that was in the cylinders had to be within a combustible range. So what can cause the correct air/fuel ratio in the cylinder to not ignite when the engine lost power? Ans. It had to have lost spark.

    Now with that perspective in hand the tech has to get the symptom to occur and then prove why.

    By the way, its important to point out that catalyst damage occurs faster when a misfire occurs that allows sufficient air and fuel to be passed into the exhaust system. The greater the engine load during the misfire, the more air and fuel become available for the catalyst to make react and that raises the internal temperature of the catalyst rapidly.


    The dealer sent it to Buick to have a full hour diagnoses and the result was the same a bad catalytic

    More fallout from the legacy of what has been happening regarding diagnostics. Where did "an hour" come from and how is that always supposed to be sufficient? Combine that with not knowing what and how the symptoms were reported to the technician regardless of his/her overall skill set and this may easily have been conveyed as the check engine light catalyst issue and maybe none of the rest of the information was shared, nor the symptoms observed.


    .... As an added note the dealer just put in a remanufactured engine in which the light was on after picking up the car after that was done My car has 119011 miles. My car has an automatic transmission.

    Who is the dealer in this description, a used car outlet? An O.E. dealer that had this used car on their lot that doesn't sell these new? You stated "the dealer sent this to Buick" which is why I am wondering just who the players are. Who is the mechanic you referred to above, an independent? Maybe someone who works at "the dealer referenced? We don't need names, just perspectives.


  • thecardoc3thecardoc3 Posts: 5,329
    edited March 2017
    From the above response. "So what can cause the correct air/fuel ratio in the cylinder to not ignite when the engine lost power? Ans. It had to have lost spark."

    I thought I should be a little more precise on this one. Losing spark does not mean no ignition output at all, it could mean insufficient output to fire the spark plugs under specific conditions. For example.

    Since we have a description of a lean exhaust it is important to understand how the air/fuel ratio in the cylinder impacts the spark plug's ability to fire. Fuel has carbon in it and carbon is a conductor. So, the more fuel that is in the cylinder, the lower the voltage that will be required to get the spark to occur. Meanwhile air is a good insulator, the more air that is in the cylinder the higher the compression and therefore the higher the voltage has to be in order to get spark to occur. Then we have spark timing. The earlier the spark, the lower the compression actually is when the system tries to fire the spark plug which means that it would take less voltage, while the later the spark the higher the compression at that time and the higher the demand voltage.

    OK, got all of that?

    When a technician takes the car out for a road test understanding how changing engine load conditions impacts the spark demand voltage allows for him/her to prove if a given drivability issue is related to spark or not right from the front seat of the car. With enough practice and experience combined with specific product knowledge the technician might even be able to determine if an ignition issue is in the cylinder versus out of the cylinder before any specific testing is actually performed back in the shop.

    If the problem is the engine is leaning out, the spark demand voltage under certain conditions can rise until spark is prevented from occurring in the cylinder. You feel that on the road as the whole engine losing power and not just one or two cylinders going into a misfire. Manipulating the throttle it may be possible to get some of the cylinders to start firing again before some of the others do. If you can feel that, or today see it in scan data misfire counts then you have some direction as to what the problem might be. Meanwhile if scan data is also showing that the fuel trims are having to add fuel trying to compensate for the lean exhaust then you have "A Problem" that must be identified and corrected before anything else can really be proven completely. At this point it is totally random as to whether this is a fuel issue, or a fuel and spark issue and that's why each car has to be evaluated on its own.

    This also explains why a lot of people will resort to just tossing some ignition parts at a given problem. It's so easy to do that in most cases and it might just solve the reported issue. However if you just throw parts at it without learning how to test and prove what is wrong, there will be cars that you won't be able to repair.

    Do you know what the difference is between "A Problem" and "The Problem"? "The Problem" is always the last "A Problem" that someone identifies and corrects. Oh, and remember every time you have heard a story or seen a report about a car being road tested? Bad apples spoil it for everyone and you cannot learn let alone use the information above unless you are performing a proper road test at the beginning of each and every diagnostic as well as after the repair is completed to prove that the car is in fact completely repaired and that there are no more "A Problems" left undiscovered.
  • First off I want to thank you guys for commenting..... Here is a update and info.... The car dealership I bought the car from is Mini Cooper/AutoNation here in Las Vegas...that is who I was referring to as they.... So I replaced the catalytic convertor  and Mini Coop then reffered the SUV to Buick for a diagnostic ...3 times because Mini did not agree with the diagnoses that it was indeed fuel pump ... It was to be sure (they said) Buick Gmc said yes for sure....well Mini coop told them to do the repairs.... I picked up my Pontiac and it did the same hesitation thing ( no backfire just hesitation) while driving on the highway .... However no check engine light (lean code) came on .....I returned to the dealer (Buick Gmc) they then called me next day and said the ground 105 was loose on the newly installed fuel pump and to return next day to get my truck..... I drove 1.6 miles from dealership my check engine light came on I immediately returned to dealership (Gmc) they ran the comptuer check for code it was the lean code yet once again.. I refused to drive the car until something was figured out they gave me a loaner car... That next day they called me and said the problem was the mass air flow... And they cleaned it out reset codes and it was good ...to come for my truck ... On the way home my check engine light yet again came on.. I keep telling everyone that I never had a problem with check engine light with lean codes coming on until new remanufactured engine was put in... I havent been able to tell if hesitation has been fixed while driving on the highway yet because of me not being able to drive it longer than a day. I brought out this discussion to the mechanics at the dealership .... One said we already know it's running rich not lean or it wouldn't keep torching the insides of the catalytic convertor.... Extremely frustrated I said well no one seems to know what in the he##  is wrong after seeing teo dealership shops and two other shops (meinke and a mechanic at a local repair shop with high reviews on yelp) I have to much negative equity to trade in and it has been a total nightmare since I bought it...unfortunately in Nevada there is only a lemon law on brand new vehicles
  • defiantlysubdefiantlysub Posts: 5
    edited March 2017
    As an added note I had went to auto zone awhile back to see what the code was before returning to the dealership just for my own records it was PO171 Fuel Trim System Lean (Bank 1) I understand AutoZone isnt a mechanic but oddly enough whats weird is the paper states suggested parts which are: either Fuel Injector or Intake Manifold which no one at any mechanic dealership has said was possible cause....
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,482
    There's no one, and not even any 5 "causes" for this code. All it means is that the engine is running lean. That can be caused by as many items as you could list on the right sleeve of a long-sleeve shirt.

    The only real solution is a methodical diagnosis. If you're getting suggestions from someone who has not plugged in a pro scanner and drilled down through all the sensor and module inputs, then they are only guessing, using your wallet to fund their speculations.

    Here's a pretty good tutorial that might give you some ideas, or at least a "language" that you can use to discuss things with a technician.

    http://www.engine-misfire.com/p0171/

    Good luck tracking this down--and sure, if you want to test for a manifold or vacuum hose leak, that's not a bad place to start.
  • thecardoc3thecardoc3 Posts: 5,329

    As an added note I had went to auto zone awhile back to see what the code was before returning to the dealership just for my own records it was PO171 Fuel Trim System Lean (Bank 1) I understand AutoZone isnt a mechanic but oddly enough whats weird is the paper states suggested parts which are: either Fuel Injector or Intake Manifold which no one at any mechanic dealership has said was possible cause....

    If your car had only one fuel injector, then there would be a remote possibility that it could be to blame. But you have an injector for each cylinder so if one of them was failing you would get a cylinder specific misfire. As far as the intake manifold causing a P0171, it would be plausible to have an intake manifold gasket cause a problem like that, but not the manifold. Even so you would be referring to a lean engine at times when intake manifold vacuum is high such as at a no load idle. You described a loss of power on the road under heavier loads which rules out a vacuum leak. So much for generic canned answers.

    I refused to drive the car until something was figured out they gave me a loaner car... That next day they called me and said the problem was the mass air flow... And they cleaned it out reset codes and it was good ...to come for my truck ...

    Top techs do not condone cleaning the MAF sensor as a repair. There can be an argument made for a conformation test where the sensor is cleaned if the sensor is suspect, but it should then be replaced if it is proven to be faulty. However there will be no shortage of people who disagree with that who are basing their argument primarily on the cost of the two different approaches, since they don't know any other way.


    On the way home my check engine light yet again came on.. I keep telling everyone that I never had a problem with check engine light with lean codes coming on until new remanufactured engine was put in...

    That might be good information and it might be totally misleading. Either way it is unnecessary information. A proper diagnostic approach concentrates on what the car is ding right now.



    I havent been able to tell if hesitation has been fixed while driving on the highway yet because of me not being able to drive it longer than a day.

    You have to drive it how long to get it to act up?



    I brought out this discussion to the mechanics at the dealership .... One said we already know it's running rich not lean or it wouldn't keep torching the insides of the catalytic convertor....

    Running rich would have the vehicle set code P0172 and the fuel trims would have been taking injector pulse away from the base calculation. P0171 is lean and the fuel trims have to add fuel to try and correct for the lean condition. BTW running rich will not damage the convertor any where near as fast as what running lean can. When an engine is too rich all of the O2 the engine breathes is used up in the combustion process and for the catalyst to do its job, O2 has to make it to the exhaust. When testing if I want to turn the catalyst off, I can physically cool it off with water on the outside shell, or I can drive the system out of control rich.


    Extremely frustrated I said well no one seems to know what in the he##  is wrong after seeing teo dealership shops and two other shops (meinke and a mechanic at a local repair shop with high reviews on yelp) I have to much negative equity to trade in and it has been a total nightmare since I bought it...unfortunately in Nevada there is only a lemon law on brand new vehicles

    Use the iATN shop finder to find a qualified technician that has the skills and training to solve this for you.
    www.iatn.net

    PS. The fuel pump ground is G403. G105 is the battery negative cable ground connection to the engine block.
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