Pcm & tb issue... Fixed!
01-14-2011, 07:52 PM
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Pcm & tb issue... Fixed!
OK, so about a couple weeks ago i had some trouble w/ the Cobalt, basically when i started the car it had an abrupt rpm change on start up, for one it didnt hop up to about 3krpms like normal and dropped pretty quick, had a low idle tune to it, and i figured, its just cold out(40 degrees F) so i started driving, then as i got down the road, "ENGINE POWER REDUCED" came up on the HUD, so i freaked and didn know what was goin on(this is my ignorant stage to the problem).... so i pulled over and after a few turn off and turn ons w/ the car and it puttering and sounding like it miss fired, it started working outa no where, so i went on about my busines and saw no prob from it for about a week.
A week later, the prob appears again, so i start searching the forums and askin a couple questions, i go to Advanced Auto and get the Check engine Codes that come about, the guy told me 8 codes were showing up, but he only gave me the 2 that he had seen w/ words, which were P2101 and P2135, these were TPS/PCM error(p2101) and TAC/PCM error (p2135), so i proceeded to investigate these two specific errors thinking that if i took it to a dealer it would take a few limbs including my wallet to fix. Well one thread i found gave a step by step technician's process as to diagnose the TB error to rule out a TB issue, i then checked the TB, and found that if i turned the key all the way fwd w/o turning the engine on, the TB fluttered and it sounded like a ratchet, when i turned the car on(looking at the TB w/ the inake off) the TB would open and close on itself, hence the car puttering and jumping from 1200 - 800 rpms until the car was turned off. well when the car was at operating temp (170-181F for me) it would work properly, and no puttering or stalling, but it took alot of turning on and turning off to get it there....
Since i had no idea on exactly how to fix the TB nor did i want to replace it out of pocket, i figured since im at 38 thousand miles, lets see if the Powertrain warranty covers it, so i called the Chevy Dealer and asked them and gave them my information, they told me, if we look at it and its not a Warranty issue, then we will charge you 97.50$(USD) if it is a Warranty issue, we will fix it w/o charge(of course). so because i the car was not gonnna fix itself and it was getting worse i took it in. the morning i was going to take the car in, it took literally 40 mins to actually get it to operating temperature, w/o turning it on and off, it would putter, no gas pedal response, die on me and would constantly **** me off, so i drove to the dealer in engine power reduce mode and they ran diagnostics and thats when i actually foundout that 8 codes were present, and they figured if they cleared them it would work.. temporarily, it did, ran like new had all its power and i was happy, this was fixed at 9 am, when 1pm rolled around i started the car and everything was back, check engine light, power reduce, and 8 codes, took it back to the dealer, they spent 8 hrs of diagnostic check/runs on it, called some people and told me my PCM needed to be replaced, so they did that, after replacing that, they said the TB needed to be replaced as well, and they did that, all of that was covered under the Emissions Control Warranty which is 80,000 miles or 10 years (i think), they said until 2015, that i would be covered for this problem. so today i finally got the car back and it runs perfect, cold started it, and it started fine, not a single prob... so far, knock on wood.... p1681, p2119,1516,2110,2135,p2228, and p0172, these are the CEL codes that came up,so if you receive a flock of these, most likely you have a prob that can be covered under a warranty(pending mileage of vehicle) and if not start w/ TB and work your way to PCM, granted that PCM i think cost a bit, but thats better than not having a car at all... i hope this can help someone if they run into this prob or are having it now.... good luck!
these are some quotes from another post i have... it thought it would be beneficial here..
A week later, the prob appears again, so i start searching the forums and askin a couple questions, i go to Advanced Auto and get the Check engine Codes that come about, the guy told me 8 codes were showing up, but he only gave me the 2 that he had seen w/ words, which were P2101 and P2135, these were TPS/PCM error(p2101) and TAC/PCM error (p2135), so i proceeded to investigate these two specific errors thinking that if i took it to a dealer it would take a few limbs including my wallet to fix. Well one thread i found gave a step by step technician's process as to diagnose the TB error to rule out a TB issue, i then checked the TB, and found that if i turned the key all the way fwd w/o turning the engine on, the TB fluttered and it sounded like a ratchet, when i turned the car on(looking at the TB w/ the inake off) the TB would open and close on itself, hence the car puttering and jumping from 1200 - 800 rpms until the car was turned off. well when the car was at operating temp (170-181F for me) it would work properly, and no puttering or stalling, but it took alot of turning on and turning off to get it there....
Since i had no idea on exactly how to fix the TB nor did i want to replace it out of pocket, i figured since im at 38 thousand miles, lets see if the Powertrain warranty covers it, so i called the Chevy Dealer and asked them and gave them my information, they told me, if we look at it and its not a Warranty issue, then we will charge you 97.50$(USD) if it is a Warranty issue, we will fix it w/o charge(of course). so because i the car was not gonnna fix itself and it was getting worse i took it in. the morning i was going to take the car in, it took literally 40 mins to actually get it to operating temperature, w/o turning it on and off, it would putter, no gas pedal response, die on me and would constantly **** me off, so i drove to the dealer in engine power reduce mode and they ran diagnostics and thats when i actually foundout that 8 codes were present, and they figured if they cleared them it would work.. temporarily, it did, ran like new had all its power and i was happy, this was fixed at 9 am, when 1pm rolled around i started the car and everything was back, check engine light, power reduce, and 8 codes, took it back to the dealer, they spent 8 hrs of diagnostic check/runs on it, called some people and told me my PCM needed to be replaced, so they did that, after replacing that, they said the TB needed to be replaced as well, and they did that, all of that was covered under the Emissions Control Warranty which is 80,000 miles or 10 years (i think), they said until 2015, that i would be covered for this problem. so today i finally got the car back and it runs perfect, cold started it, and it started fine, not a single prob... so far, knock on wood.... p1681, p2119,1516,2110,2135,p2228, and p0172, these are the CEL codes that came up,so if you receive a flock of these, most likely you have a prob that can be covered under a warranty(pending mileage of vehicle) and if not start w/ TB and work your way to PCM, granted that PCM i think cost a bit, but thats better than not having a car at all... i hope this can help someone if they run into this prob or are having it now.... good luck!
P0172 Fuel Trim System Rich ECM, PCM
P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance- ECM, PCM
P1681 Control Module Throttle Position (TP) System Performance PCM
P2119 Throttle Closed Position Performance ECM, PCM
P2135 Throttle Position (TP) Sensor 1-2 Correlation ECM, PCM
P2228 Barometric Pressure (BARO) Sensor Circuit Low Voltage PCM
I am still guessing a bad TB. Could be a bad ECU as well, but that is less likely than the TB actually being bad. The BARO and Rich codes are usually caused by an intake leak, though they could be caused by a TB problem with the boost bypass.
P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance- ECM, PCM
P1681 Control Module Throttle Position (TP) System Performance PCM
P2119 Throttle Closed Position Performance ECM, PCM
P2135 Throttle Position (TP) Sensor 1-2 Correlation ECM, PCM
P2228 Barometric Pressure (BARO) Sensor Circuit Low Voltage PCM
I am still guessing a bad TB. Could be a bad ECU as well, but that is less likely than the TB actually being bad. The BARO and Rich codes are usually caused by an intake leak, though they could be caused by a TB problem with the boost bypass.
I had those same codes and i have seen a few other post where people had the same codes too. It always turned out to be the throttle body. I even replaced my pcm first as I got a cheap one locally and the problem persisted.
Bring it back to the place you bought it as the part is usually $50-100. Unless it turns out to be ur pcm. All you have to do is unbolt/plug the old one and bolt/plug the new one back in. Mine gradually got worse over time to where I couldnt even get a block away before it went into reduced power and clearing the code it would come back up 10 sec later. I cleared to codes with my interceptor but it always came back.
Bring it back to the place you bought it as the part is usually $50-100. Unless it turns out to be ur pcm. All you have to do is unbolt/plug the old one and bolt/plug the new one back in. Mine gradually got worse over time to where I couldnt even get a block away before it went into reduced power and clearing the code it would come back up 10 sec later. I cleared to codes with my interceptor but it always came back.
Last edited by MoJoJoSSsc03; 01-14-2011 at 08:01 PM. Reason: add on
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