Sometimes when in reverse my 07 SRX with a V-6 will surge/buck usually when backing up an incline or when there is more of a load on it. While under a light throttle it can feel like the engine is just surging a little. As you increase the throttle it can be worse even to the extreme of the transmission going into neutral for a split second and slamming back into reverse at 3000 rpm's. The transmission has been rebuilt and it did this before and after the rebuild. No codes in ECM. Anybody have any ideas ???

 

Possibly a misfire. Plugs, carbon build up, cam actuator. There maybe a PCM software update. I would check with dealer for possible special policies that may apply.

 

Thank you for responding to my dilemma. This is an all wheel drive vehicle. No misfire, no codes, engine uses oil due to low friction rings and dumbasses not changing oil in a respectable amount of time ie; every 5000 miles, and relying on the vehicles computer to tell them when to change it. This was bought used. Oil is full and I only use Mobile 1 and A/C filters. I don't see how a software update could help when the vehicle had been fine for thousands of miles then developed the problem. An ECM should not lose part of its programing, should it ?? Educate me if I'm wrong please. Sometimes while under a very light throttle you can feel the engine just start to surge at that time the rpm's will dip down a few hundred rpm's. Also sometimes when under hard acceleration in reverse only the transmission or something will go into a neutral like condition then slam back into reverse and chirp the tires at 3000+ rpm's. Between those two extremes the condition almost feels like the ABS or Traction control is activating but I have turned off the Traction and the scan tool doesn't show any activity with them actuating during this condition either. The engine mount on the drivers side has been replaced and the other side is fine. This has been a thorn in my side for a month now and I do appreciate any help.

 

Just like your phone gets updates there can be updates for the PCM to address different conditions that occur after cars have been out on the road for a while. There were/are concerns with the timing chain and actuator. Carbon can be an especially cold where fuel is absorbed by carbon causing a lean condition. Carbon build up in throttle body can also cause some idle concerns. poor connections are always a cause of intermittent troubles. it's probably going to require a scanner to figure out what is happening. With codes the EPA requires a minimum amount of codes but not a maximum. There can be codes that generic scanner won't pick up. It maybe worthwhile to have it diagnosed, results and recommendations with estimate should be on invoice. don't let shop give you a "Customer Declined Repairs" as cause. If you paying for diagnosis results should be on invoice regardless if it's corrected at that time. Some shops/techs will try not to put what they found on invoice if they don't fix it.

 

Thanks for explaining about the programing but I still don't really understand it. Either way I think that its in the engine or engine control I can get the engine to just barely do it with light throttle and brake torqueing. I don't feel bad about rebuilding the tranny the fluid was horrible, burnt and metal flake. Would the variable valve timing cause an issue like this.

 

Ignition switch? Not much on the key ring.