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Any ideas of why my 2006 Pontiac Torrent loses acceleration while driving
defiantlysub
Member Posts: 5
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.
0
Answers
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".
"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, 2015 Cruze 2LT,
What @defiantlysub has described isn't a single issue and like always the devil is in the details. 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? 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. 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. 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. 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.
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.
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.
www.iatn.net
PS. The fuel pump ground is G403. G105 is the battery negative cable ground connection to the engine block.