Very odd, very specific issue with break in period (more of a PSA for anyone with less than 500 miles)

[obeykube]

Howdy y'all

So, just a PSA. Picked up my 2024 CT4-V B.W. on Friday in Delaware and drove it back to Long Island. I have watched so many reviews and read so many posts on this forum, I'd figure I knew everything about this car and was actually kind of afraid of it not impressing me since nothing was going to be a surprise. My god was I wrong. This car is unbelievable. I love it like a child. ANYWAY...back to the PSA.

For anyone that picks their car up new and has this 500 miles break in period, not sure if it was unique to my car/my driving, but if you have rev match on, and for whatever reason the car thinks you are shifting into a gear low enough that the rev match RPM would exceed the 4.5k limit of the break in procedure, the car will just straight up cut the engine. I replicated this 3 times on accident just because I was trying to break the habit of my GTO where neutral was vague and I shimmied the stick to make sure, doing that made the computer think I was trying to go into 1 or 2 I guess while going 60 and said "no" and just cut power to the engine completely. Only way to get it back online was to stop the car on the shoulder of the road and restart it. I admit it was porbably me with the whole "neutral shake" thing, (which I have now made myself de-learn lol) or maybe it's just a my car thing, but just wanted to share what happend so everyone has a heads up. Steering and braking worked and all systems, just cut engine power. Still pretty scary though!!! Like I said once I learned what was going on I was able to replicate it pretty consistantly, and just turned off rev match and also stopped wiggling the stick like an idiot, but rev match is pretty darn sensitive in these cars. It doesn't trigger when you get into gear, it feels like it triggers as soon as there is even THE SLIGHTEST movement towards that gear.

I could just be an idiot (very real possibility) but wanted to share. NO fault of the car probably, just some funky programing and old driving habits. Thanks!

 

[1Evil55]

You aren't the first to report something like this. Not sure if the shifting you are doing has any similarity to others here. I'm sure they'll be along sooner or later.

 

[rubberduck]

Never had that happen, I guess because I’m deliberate about shifting.

 

[doublethebass]

curious if it'll happen after the 500mi breaking period...

 

[SynisterAZ]

After break in this is how you get the rev match to "double blip" i.e. coming out of a higher gear and moving the stick to the left towards a a lower gear while still in neutral will cause a 1st blip and then a 2nd blip to match whatever gear you actually go in to. I never encountered your example during break in but then again I wasnt wiggling the stick in neutral at highway speeds.

 

[FI Fiend]

Interesting timing, I was recently thinking about this relative to 'money shifting' particularly during the break in period (my car had 200 miles at purchase so started worrying about anything that could've happened). I was curious if it logged that on the ECU, but maybe it just isn't possible during that period.

It does appear it's possibly later though, some folks on here cited damage due to money shifting:

Thread 'Warranty Block on 4BW M6' Warranty Block on 4BW M6

Another user was interested in how to check if that happened if anyone can assist:

Post in thread 'Hello' Hello

 

[JLayer]

I've always wiggled the stick in my other car, so it's natural movement while driving the BW. I agree that It is very sensitive to the movement and it scared the hell out of me when first driving the car.

I've came across that exact scenario a couple of times and the car has never shut down on me. This was all during the 500 mile break in and now past it. I would bring that up to your dealership when you go in for your first maintenance stop or sooner.

 

[DCV]

You stick wigglers!

 

[rubberduck]

The dealer will just tell you not to wiggle your stick when driving.

 

[shbox]

The dealer will just tell you not to wiggle your stick when driving.

That would be good advice.

 

[FLYARMY]

Why did you go to Delaware to get a car ? Paul Conte Cadillac, King O'Rourke and others here on Long Island haven't really had any issues getting deliveries (that I know of). Did you just want a car that was in available inventory rather than special order ?

 

[obeykube]

Fully got the message with stick wiggling guys lol 10-4. I don't think this is a money shift as the engine never actually rev'd up that high. it just cut out. But yes maybe if it didn't it would of. @SynisterAZ I am starting to notice that, where just being in that gate will blip it, not going into a particular gear. @doublethebass I am at 400 miles now so I will let you know, but honestly, I am afraid to do it again lol. @FLYARMY I am not into the business of bad-mouthing people/businesses but I walked into a local dealership of mine wanting to place an order and didn't love the experience. I called Delaware Cadillac as they already had so many in stock and asked if I could place a custom order and it was such a good experience I have no regrets going the 2.5-3 hours down there to get the car.

 

[shbox]

PSA on your PSA...people get confused with the 500 mile tach redline change thinking that is the break-in period, when it is actually 1500 miles as stated in the owners manual.

 

[obeykube]

Agreed!

 

[minn19]

PSA on your PSA...people get confused with the 500 mile tach redline change thinking that is the break-in period, when it is actually 1500 miles as stated in the owners manual.

Yup, 500 for the engine and other things. Then 1500 for the diff from what I’ve read for years. Pretty much the same to similar on most GM performance cars IIRC.

You don’t have to be as cautious with the RPM limit after 500, they just don’t want you racing or doing events until 1500 and differential fluid change before hand.

 

[shbox]

Yup, 500 for the engine and other things. Then 1500 for the diff from what I’ve read for years. Pretty much the same to similar on most GM performance cars IIRC.

You don’t have to be as cautious with the RPM limit after 500, they just don’t want you racing or doing events until 1500 and differential fluid change before hand.

Nope. See, you missed it. 1500 includes the engine. I see no mention of 500 miles.

 

[obeykube]

I don't think he missed it, I think he is just saying in his opinion it's not as necessary to adhere to the 4k RPM limit after 500 miles, as long as you aren't bring it to the track and bouncing off rev limiter. I plan after 500 miles to do a full RPM pull every once in a while, if the engine is completely warmed up.

 

[minn19]

Nope. See, you missed it. 1500 includes the engine. I see no mention of 500 miles.

What the last post said. I know it’s different engines than the LT4/LT6, but everything I’ve read and GM people I’ve talked to is 500 for engine, then 1500 no race etc for diff and or transmission sometimes.

I know break in threads turn into oil threads and everyone has an opinion. This is the best info I’ve gotten for years and followed it and never had a problem. My opinion is engines usually fail because of bad parts/manufacturing error. In the end, I doubt it matters how you break it in or if one does the break in oil change or not. Now the diff is a different story, again my opinion.

Any way, it certainly won’t hurt anything except your patience to drive it under 4K for 1500 miles. I actually followed that pretty close and changed the oil/filter and diff fluid in case I wanted to do an event, I’d be ready.

 

[shbox]

I guess I don't get it. It is right in print above. The first box says do not exceed 4000 RPM for the first 1500 miles. IDK how that is open to interpretation/opinion. Of course, everyone is free to do what they want.

 

[Mutz]

Why did you go to Delaware to get a car ? Paul Conte Cadillac, King O'Rourke and others here on Long Island haven't really had any issues getting deliveries (that I know of). Did you just want a car that was in available inventory rather than special order ?

+1 for King O’Rourke. Bought my 5BW for sticker. Placed order Aug ‘23 and it was delivered Nov ‘23.


Regarding break-in, who can wait 1500 miles? I changed my engine oil at 500 miles and got on it here and there when warmed up. Just changed engine oil and diff fluid at 1500 miles and am excited to get on the car a little harder.