Hey GM guys.

I am a licenced technician with over 25 years experience. I have searched Mitchel1, Google and any other forums I could find and have seen no other mention of this exact situation.

One of my customers has brought me a 2009 Pontiac Torrent that he picked up at the local dealer auction. Here is what I have found & done up to now.

I have tested the condition he has bought it in for and found that the engine in governed to 4000kms, this is normal for it in park, neutral or reverse, yes, the issue here is that it is governed ALWAYS... I have replaced the MAF sensor and ECM on my journey to this point, I have driven it with the scanner connected and found both the engine & transmission controllers are identifying that the gear selector is in gear and not in one the above mentioned positions. the issue this causes is, if you are heavy on the throttle it will not let the transmission upshift since the engine pulls hard all the way from 0-4000rpm but as soon as it hits 4000rpm it stops accelerating which means it will not upshift until you pull back on the throttle enough to allow it to shift, the rpms then of course drop & you can again accel through to 4000rpm again in the next gear. I have checked the throttle position sensor & can see it sending the full range readings to the computers. I know it isn't a plugged exhaust since it is a STRONG pull right up to 4000 rpm when the computer stops the accel, also, get this, If I shut the car down & disconnect the ECM and reconnect it, When I start the engine & rev it... in park or driving, the engine has FULL range, meaning it will rev passed redline with lots of engine power, however the transmission goes into blackout.... it feels like it is in 4th gear full time, meaning there is no power at take off due to high gear ratio. So back to point, I know the engine is capable of full speed operation if the computer is not limiting it. One point to mention beyond the info above is that the transmission has been replaced before my customer bought it. It appears to be a used transmission by the paint pen writing all over it. All gears are strong & feel normal if you are driving at 3/4 throttle or less. It is only when you floor it that this issue even appears.

I replaced the MAF sensor originally thinking that the reading it was sending at the higher air flow was false causing the computer to miss-control the engine. Once I realized exactly what was happening I replaced the engine controller & had it programed to the car thinking it was not processing the info from the transmission range sensor properly, however, that fixed nothing.

I am hoping someone has experienced this before & can direct me in the right direction. Another thing I can point out is that I do have an Equinox here at the same time with the same drivetrain to compare readings with. Any input to trigger some insight would be greatly appreciated.


Thank You.

FarrouT Farr

Sorry, I put the vehicle specs in the required field in the beginning but I see they did not transfer to the thread.

This is a 2009 Pontiac Torrent with a 3.4L engine with no Mods.

This is a Torrent, not a racing car........If you are at 4000 rpms and the vehicle is not moving fast enough, have you checked slip rpm in the tranny data?

I believe 4K is the max rev limit for this engine....so under normal operation, you should not approach 4k during normal acceleration......

Now from a dead start, if you lay into it and vehicle reaches 3k rpms and doesn't shift, I would be checking back pressure in the exhaust....

Hey Tech II.
Thanks for your thoughts.
As I mentioned in the original post, it isn't a exhaust pressure issue as I can "Trick" the computer into letting the RPM'* past the 4000 benchmark with NO restrictions but then the transmission is in possibly 4th? gear.
Yes it is a Torrent, But when you put your foot into the throttle to pass someone and the tranny downshifts and the engine RPM goes to what should be say 5000 rpm to give you the punch to pass, the computer shuts down the acceleration until it slows to 4000rpm in the lower gear, then maintains the 4000rpm just as if you floored it in park. This causes some serious issues in traffic.

Hello again;
Upon farther investigation... Compared transmission controllers between the 2006 Equinox that I have here that is working properly and the 2009 Torrent that is causing the issues I have found that "Transmission protection mode" Is "ON" on the Torrent causing the trouble, and it is "OFF" on the Equinox that is working properly.
Any thoughts on the cause of "Transmission protection mode ON" ?

Like I said, I would be checking transmission slip data during acceleration.......

Thanks Tech II, That was one of my first thoughts as well. As I drove it more & more with the scanner going through both controllers & finding the input & out put speed sensors are reading properly with the speed & RPM drop of the engine it has become completely clear that it is a rev limiter keeping the engine below 4000 Rpm. There are no codes. It seems as though someone has actually installed a rev limiter on the car. It does have a remote starter installed. If I drive normally in drive, up to 3500rpm in 5th gear & floor it, when it downshifts & the engine revs up, it is an obvious limit condition from 5000 rpm down to exactly 4000 rpm where the engine comes back to full life & maintains the 4000 rpm. as you lift on the pedal at about 3/4 pedal the transmission upshifts again & has full power until EXACTLY 4000rpm. As mentioned, It acts EXACTLY as it does in park when you floor it only in gear.
I was certain it was a ECM issue since this is controlled by the ECM. Problem is, If this was a ECM issue it would have been corrected with the ECM replacement. Also completed a crankshaft sensor learn three times as I have seen that cause similar conditions. There is something causing the 4000rpm REV limit. I will be looking to see if a rev limiter is installed. It is obvious very few people have come across this issue since there is no mention of it on anything newer than 1999. Will advise as to the outcome once resolved.

Does anyone know if this car has a valet key feature? . . . and if it did then what the behavior would be?

Reading this whole thing then searching the interwebs it suddenly occurred to me that a valet key might cause stuff like this, then be programmed the same on other PCMs etc. It is an auction car with unknown history after all. Maybe previous owner lost the other keys, drove it sedately around on the "spare" key then started noticing whenever they push it a little weird stuff happens . . . eventually leading it to us.

I looked in the owners' manual and I didn't find a mention in the likely places. I didn't dig too deeply though.