My 2010 G37 Journey Sedan 7at is having some major issues.

As of right now it will idle in Park and in Neutral, but when I put it in reverse or into drive it will stall the motor. I can get it into gear only if I rev to around 3k rpm or higher and then slam it into gear.

Once I'm driving it, it will often stall at stop lights and stop signs for the same reason. When it stalls and I'm stopping it feels like the transmission doesn't want to disconnect and it stays engaged bogging the engine out.

I personally was thinking torque converter could be stuck locking up. However a couple times it would start in Park and then stall out immediately too, so someone said it could just be that my plugs are over-gapped because of the spirited driving I was doing before this issue.

Any thoughts? Btw once it's up and running it shifts I to all 7 gears without problems, and there's no check engine light. Any help would be appreciated.

My plan is to change the plugs this week, if that doesn't fix it I'm going to get a torque converter and drop the tranny myself, unless y'all have better ideas?

 

Sounds like vacuum leak check all your lines

 

A vacuum leak? Hmm I never thought of that. I'm by no means am expert mechanic. How would a vacuum line potentially have that effect?

 

From my experience, every symptom you describe, leads me to believe there is a issue with the torque converter lockup solenoid not releasing. From the FSM (which mentions nothing about vacuum):


I had this exact issue with my grandmothers old Buick. As soon as you put the car in gear the engine would stall out/same when you came to a full stop. In the end we had to get a new converter.

When was the last time- if ever- the ATF was changed? Not saying it will help your issue but it is a start.

 

I haven't ever changes the trans fluid. I know it's something I should probably do, however I haven't done it yet. I'm pretty strapped for finances so my plan is to do all of this at the beginning of January when I'm paid.

Where did you get that documentation for the 7at?

 

Also if it's the solenoid, wouldn't that throw a check engine light? Or would it not cause a light because it's a trans issue and not engine? Maybe if I had a way to scan the TCM I would find a code?

 

The following link is the for factory service manual for the 2010 Sedan. In this case you will want to download section TM (transmission) though I would recommend downloading the whole manual just to have it:
2010 Sedan FSM

The TCM might not throw a code if the issue is non-electrical. The TCM energizes the solenoid which sends pressurized ATF to the lockup clutch piston (inside the converter). When this signal is cut, the solenoid valve closes and pressure is released. If the piston is stuck or not releasing fully, all the TCM knows is that the solenoid is closed. Still, a good scanner (or even apps like Torque) should be able to check for codes across all systems.

I would be careful when rev'ing the engine and "slamming" the transmission into gear. You will eventually break something big time. I know you need to drive to car, but that continuous "slamming" is not good for the car.

Hopefully other forum members can chime in with more, useful, advice/tips/guidance.

 

I completely agree. I'm trying to drive it as little as possible, however I did want to drive it a bit to identify more of what's going on. Sometimes I can put it into gear from P > D or N > D (or Reverse) and it will go into gear fine. For example this morning it did. However when I began to accelerate there was a bad juddering and it felt like it was locking and unlocking every quarter of a second or so until I got around 5-10mph. (I was basically letting the engine creep and wasn't giving it any gas)

Meanwhile the RPMs were all over the place since one moment the engine was under load and the next it wasn't, and it almost stalled, however the engine was cold and revving a little higher than the standard 500rpm so it stayed running through this juddering process.

It definitely sounds like the torque converter clutch solenoid.

I downloaded that manual, and now I'm trying to do some research on how I would actually replace that part.

If you know, or find out how, let me know! Ty for your help!

 

Replacing the torque converter is relatively easy but for a backyard mechanic it might be difficult. The transmission has to be removed. The FSM will detail everything.

I would diagnose more before jumping in full monty.

Good luck!

 

Have you recently added an intake if so the lines that plug into intakes are the vacuum lines

 

No it's bone stock.

 

Is there any recommendations you have on diagnosing it more completely? Is it possible to scan the TCM with an OBD2 scanner? I'm sure some of my questions sound stupid, I'm still learning here. Lol

Also if I wanted to replace the TCC Solenoid, would I need to drop the whole trans out of the car to replace it?

 

recheck the lines for cracks spray soapy water or window cleaner to look for bubbles

 

A good OBD scanner will be able to check for any codes across most/all systems. Again, if the issue is hydraulic (clutch valve/clutch piston) then there might not be a code.
The solenoid is incorporated into the TCM (Transmission Control Module) and is not serviceable to my knowledge. The whole TCM would have to be replaced. In this case you would only have to drop the transmission pan.

 

Called Infiniti and got the TCM Valve Body part number for my VIN.

It's a $1500 part. I further diagnosed my car (and had to drive it home) and I'm pretty dang sure it's the torque converter clutch solenoid. So in order for me to replace I basically have to buy it from Infiniti, or find another G37 that's being parted out with the same exact part. Even after I replaced it, I would still need to take it to Infiniti to register the TCM to the new VIN.....

Basically it looks like this is a $2-3000 job minimum.

I haven't really decided what to do next.... I still owe like 8k on this car...