Help - 2015 Q70 Intermittent Brake Malfunction

[dalap83]

I bought a 2015 Q70 with the 5.6L engine, Technology Package, Deluxe Touring Package, and Performance Tire & Wheel Package, in Hermosa Blue. I have 13,000 miles on it, and after about 10,000 miles the brakes started to intermittently malfunction. When it is normal, the brake pedal is very responsive with little pressure, stops with 1-2 inches of pedal movement, and the seat belt emergency tightening and brake assist engage only in extreme situations. When it begins to malfunction, the brake pedal stops the car with little pressure about 1-2 inches but then after I come to a stop I must continue to slowly depress the pedal to 5-6 inches or else the car will begin to idle forward. It seems to loosen after a while and then it takes 5-6 inches of pedal to slow down or to stop. When it does this, the emergency seat belt tightening and brake assist kick in when there is no emergency, like when I slow down from 30 mph to below 20 to make a calm turn. Of course this is because the pedal is so low that the sensor senses an emergency stop. I've had it to the dealer 3 times already (with my permission, the service guy even took it home and drove in rush hour traffic) but it has not gone into malfunction mode for them. It will go for days for me without acting up, so I believe them. I was thrilled with this car but this is tarnishing what was a great experience because brakes are kind of important. [When they told me that they failed to fix my brakes for the third time, I asked if they could at least make my horn louder....] Any thoughts?

[Ilya]

Hi there, you posted in the older M forum (06-10), moving your post to the 2011+ forum.

In my time on these forums (more than 5 years), can't say I've heard of this issue before on the older cars or the newer ones. Sounds like the dealer needs to sit in the car, in their lot (or on a lift) and just keep messing with the brakes before they replicate it. Even if takes days or weeks. They need to furnish you with a loaner as well.

I honestly would take it to the dealer and tell them to fix it and not call you until it's been found and fixed. If you crash due to brake failure, you will have grounds to go after them HARD in courts...so it's in their best interest to find out a way to not only replicate it, but fix it. They can monitor (I'm sure), the brake pressure via the CONSULT computers they have...make sure they put their senior tech(s) on the issue (call Infiniti corporate if they are not willing to play nice).

------

I had to call corporate on my dealer one time because they were pushing back on a suspension issue I was having with my 2007 M35x and sent some rookie to do a ride-along with me...I knew more about cars than he did and I'm just a systems engineer, not an ASE technician. As soon as I got a case number with Infiniti USA and passed it along to service...I got a call from the GM of that location and he promised his top tech would look at it. Low and behold, the tech found the issue after a 30 mile, 45 minute ride along...bad steering rack. After the ride, he had the car on the lift for literally 5 minutes before he called me in and showed me that the rack was bad and where it was bad.

[AZhitman]

Welcome aboard!

I'd be taking it back to the dealer and leaving it there until they figure it out. Just because they can't replicate it doesn't mean they can't do some diagnostic work and figure out what the hell's wrong. Dealership techs are becoming nothing more than parts-swappers, so speak with the Service Manager and outline your symptoms... you may need to reach out to another dealer or contact Infiniti, but don't let them cop-out on you.

I'm curious to hear what comes of this. My amateur diagnosis is a bad ABS computer.

[Rogue One]

dalap83, please DO NOT create duplicate threads for the same topic. It creates confusion and won't get your problem solved any faster.

[Ilya]

dalap83, please DO NOT create duplicate threads for the same topic. It creates confusion and won't get your problem solved any faster.

He didn't, I moved it and left a shadow topic in place in case he couldn't find it. I was going to delete the shadow topic after a few days. All is well.

But yes, OP, definitely drop it off at either the same dealer or another one and tell them to fix it and you don't want it back until it's been fixed. I wouldn't even give them a choice to say no.

[Rogue One]

Actually he did. I deleted the duplicate before you moved the topic and created the shadow copy (which I also deleted).
Oh well, no harm, no foul.

[dalap83]

Thanks, guys. I won't multiple post again. I'll take your advice and press the dealer. I'm a lawyer and I can be persuasive. I'll update when there's further developments.

[TDot]

When they told me that they failed to fix my brakes for the third time, I asked if they could at least make my horn louder....

Lmao...Well if I cant save my life by stopping I'm going to make damn sure people hear me coming and get the hell out the way to save my life lol.

Dealership techs are becoming nothing more than parts-swappers.

Trueer words have never been spoken here smh.

you may need to reach out to another dealer...

I had to do this. I used to always go to Pepe, but lately found them utterly useless, even their "senior foreman/tech"...worthless. Giving me excuses, blaming on none sensical things, justifying. I took my car to Ramsey and they found multiple things Pepe couldnt in one visit, and explained things Pepe BSed about. If you've gone there twice already, I personally would go somewhere else if it's possible.

Anyway, back to the forum I belong in, good luck.

[Ilya]

When they told me that they failed to fix my brakes for the third time, I asked if they could at least make my horn louder....

Lmao...Well if I cant save my life by stopping I'm going to make damn sure people hear me coming and get the hell out the way to save my life lol.

This gave me a chuckle too.

[AZhitman]

I ran into the same issues as TDot with my '95 Q45t. Had a bad miss and rough idle that came on suddenly. Terrified me, because the car was impeccably maintained, low mileage, and perfect.

Scottsdale Infiniti tech, service manager, and foreman all said, "motor's bad - we can put in a takeout motor for $3200."

Uh, no. Why the hell do I want a history-unknown junkyard motor in my 2nd-owner, pristine Q45?

Took it to Midway, where I met their Infiniti Master Tech... within a couple hours, he diagnosed the issue as a bad intake valve. Replacement was done under my extended powertrain warranty in a day, and I still have the damaged valve as a reminder to NEVER take the first opinion as gospel.

That tech and I remain friends to this day, 10 years later.

[BlackCat81]

Thanks, guys. I won't multiple post again. I'll take your advice and press the dealer. I'm a lawyer and I can be persuasive. I'll update when there's further developments.

I'm actually the tech who's worked on your car both times it's been in. It's a beautiful car by the way. trust me when I say I don't doubt you're having an issue, but unfortunately, I can't properly diagnose or replace anything without getting your issue to happen, which is not only frustrating to you, but also to me. I've made a call to technical assistance, who is at a loss as well. Their first question is always "are you able to duplicate the concern?" Me personally, I have no problems starting to replace parts based on an educated guess as to what it could be, but that would take some convincing to the higher ups. You, as the client, have much more pull than I do as a tech. Keep pressing consumer affairs, they'll eventually let me start replacing stuff and we'll get it eventually. I just hope you know that from a dealership level, myself, and Gerard the service consultant have been doing whatever we can to try and remedy this for you. We really appreciate your patience, understanding, and positive attitude even though we know how frustrating the situation is.

[BlackCat81]

Welcome aboard!

I'd be taking it back to the dealer and leaving it there until they figure it out. Just because they can't replicate it doesn't mean they can't do some diagnostic work and figure out what the hell's wrong. Dealership techs are becoming nothing more than parts-swappers, so speak with the Service Manager and outline your symptoms... you may need to reach out to another dealer or contact Infiniti, but don't let them cop-out on you.

I'm curious to hear what comes of this. My amateur diagnosis is a bad ABS computer.

Just an FYI, it's not like I drove the vehicle over 100 miles and said "can't duplicate it, send it on its way!" It involved driving with consult III hooked up and monitoring wheel speed and a host of other things, in real time. If we were just "parts swappers", I would've thrown a bunch of several thousand dollar parts at the car which may or may not have fixed it, and hoped for the best. This isn't a cheap car, nor do I feel comfortable guessing and replacing parts. As the owner of the vehicle, his time is valuable. I'd like the car to be down for the least amount of time possible, and get it fixed and back to him confident it's fixed. I just simply cannot do that until the issue can be duplicated.

[Ilya]

Man, that's awesome. Wish the tech from my dealer was on this forum, lol. Very cool.

[BlackCat81]

Man, that's awesome. Wish the tech from my dealer was on this forum, lol. Very cool.

Haha, I just so happened to glance through the forum and see his thread and it dawned on me it was the same car. I'm just glad he's been so understanding. A lot of times the client thinks we're just zipping the cars around the block and if we can't duplicate it, we ship it. That's not how it works at our store. Even though I haven't been able to track his issue down, it certainly isn't for lack of trying. I'm confident we'll get it sorted out, it's just going to take some time. I'm glad he's been so friendly and understanding about the whole situation. I can't say I wouldn't be a little frustrated if my brand new $70,000+ car was doing something weird, but some repairs can be tricky to pinpoint. And just to add, it's not every day you see a 5.6 Q70 Sport. The car is flipping GORGEOUS, Hermosa Blue is an amazing color.

Edit; OP, I'm off work until Tuesday, but I'll spend some time racking my brain this weekend and see if I come up with anything. I'll give the tech line data base search another go on Tuesday. If you'd like to speak with me directly, just call the store and ask to speak with the tech Steve. I may be able to ask you some more qualifying questions that the advisors may not think of asking to see if we can't get to the bottom of this ASAP for you.

[TDot]

My suggestion, if your time is flexible and if the problem is persistant until the car is turned off, the next time it begins to happen stop whatever you are doing make a uturn and go straight to the dealer. Stay in the car and call them out and go for that ride. That way your issue isnt subject to appearing the next time or day the car is started. I would think because you've been there so often with no results that you would take priority pulling up like that with the issue happening at the time.

[BlackCat81]

That's a perfect idea, if he comes in and it's happening I'll stop what I'm doing and ride with him.

[dalap83]

First, Steve, it is awesome that you found this and cared enough to speak up! Second, I bought the car at your store because of the service we've received in the past, and specifically Gerard, on my black M45 with black rims and my son's G37s. I drive past Barrington Motor Werks on my way to your shop 15 miles from home to get to your shop because of rude service there a few cars ago. Third, thanks, I agree the car does look awesome and otherwise is the best machine I have ever had the pleasure to use for any task (and the 16-speaker stereo is awesome...once we fix that door rattle).
Now, on more important issues threatening my life, my family's lives, and Infiniti's a** if anything ever happens to this lawyer or his family as a result: Unfortunately the problem has never occurred close to the shop. I work downtown, which is 40 miles from home. Perhaps a clue: it has happened twice since you last saw it before Thanksgiving, once after a 90 minute drive from home to downtown in traffic (I called Gerard pissed off and told him I might take it elsewhere) and again last night after a 60+ minute drive in traffic home from downtown. Both times it happened only in the last 10 minutes of a long drive. After sensing your genuine concern, I will not take my car anywhere else. See you soon.

[dalap83]

...and I'll be sure that folks at Infiniti consumer affairs know that the car seat in the back is used to transport my 18-month old grandson....

[BlackCat81]

Sounds good, I work 7-4 tues through Saturday and I'd like to talk to you next time you bring it in. Hopefully Infinti doesn't monitor this forum, because I'm pretty sure you know as well as I do I won't be able to get it to happen, but I'd like to put a new brake booster/master cylinder in it. I can't guarantee that it'll fix it, but obviously your safety is my biggest concern and it'll be a step in the right direction. The weirdest thing about this whole situation is the car has absolutely 0 codes stored for anything, which is pretty unusual. If it was something weird like air in the system it wouldn't be intermittent, it would do it all the time. One way or another, I'll get to the bottom of it if I have to replace every damn brake component on the car. Look forward to talking with you next time you're in. Oh, and one more thing, if the car seems to do it only after lengthy driving, when you bring it into the service drive, don't shut it off. Maybe after your drive to the store and me taking it out right away we can finally get it to happen. One way or another, it won't leave the shop next time without something being replaced. I'll deal with the repercussions if I have to, I was also the Service Manager for the first year Greg took over the store before I decided to go back to wrenching.

[AZhitman]

Steve, +1 for being here and speaking up. Good to know that you're taking the issue seriously - My comments were from 15 years' experience with service writers and techs, both personally and professionally. Unfortunately, very few techs can think outside the FSM troubleshooting progression - but, in your defense, very few customers are willing to pay for diagnostic time at $130-$150/hr.

A couple anecdotal cases that come to mind right away:

2014 QX60, unusually high pedal pressure to stop the vehicle, and sinking brake pedal at a full stop... dealer replaced BMC (after first claiming 'it's supposed to feel that way"). No improvement. Different dealer, brake controller malfunction identified, issue resolved.

2013 M37X, intermittent spongy pedal and sinking pedal... dealer adjusted the brake pressure switch, then replaced, it, then replaced booster hose (claimed a leak - which wouldn't cause those symptoms). Different dealer identified a faulty BMC and replaced it, issue resolved.

BTW, lots of Corporate folks check in here regularly... Hell, we had the former Chairman (Palmer) posting here, we get lots of views from the IP in Franklin, and some of our staffers and regular contributors are employed by the company (from line staff to product planners to management).

[BlackCat81]

Steve, +1 for being here and speaking up. Good to know that you're taking the issue seriously - My comments were from 15 years' experience with service writers and techs, both personally and professionally. Unfortunately, very few techs can think outside the FSM troubleshooting progression - but, in your defense, very few customers are willing to pay for diagnostic time at $130-$150/hr.

A couple anecdotal cases that come to mind right away:

2014 QX60, unusually high pedal pressure to stop the vehicle, and sinking brake pedal at a full stop... dealer replaced BMC (after first claiming 'it's supposed to feel that way"). No improvement. Different dealer, brake controller malfunction identified, issue resolved.

2013 M37X, intermittent spongy pedal and sinking pedal... dealer adjusted the brake pressure switch, then replaced, it, then replaced booster hose (claimed a leak - which wouldn't cause those symptoms). Different dealer identified a faulty BMC and replaced it, issue resolved.

BTW, lots of Corporate folks check in here regularly... Hell, we had the former Chairman (Palmer) posting here, we get lots of views from the IP in Franklin, and some of our staffers and regular contributors are employed by the company (from line staff to product planners to management).

Ya, I have a feeling a master cylinder and booster will fix it, but again, being unable to duplicate the concern doesn't leave me 100% confident. His car is new, so him paying diag time doesn't apply in this situation. I have several hours of driving and data monitoring with his car, and I've never been paid for any of that time. There's still a few of us techs out there that genuinely care about fixing cars, regardless of if we get paid to do it. Yes, I need to make a living just like anyone else, but I won't sacrifice someone's safety by blowing off a concern knowing I may not get paid if I can't find anything wrong. While I'm not married nor do I have kids, I would feel absolutely terrible if something happened because I chose to blow off a concern because I wasn't going to get reimbursed for my time. I'm proud of what I do, and I attribute my attention to detail from my time in the Marine Corps. I appreciate the heads up on some similar issues and resolutions you posted. I'll get the car fixed one way or another, that I can guarantee. Thanks for the kind words.

[AZhitman]

Roger that - Keep up the great work. Glad to have you around... it's definitely a step in the right direction for the community.

[Ilya]

Roger that - Keep up the great work. Glad to have you around... it's definitely a step in the right direction for the community.

I second this.

[BlackCat81]

I ordered the booster this morning. As an added bonus it comes with a new pressure sensor switch so it'll be two birds with one stone and hopefully we'll get it fixed. Gerard will call you and follow up, the part is 3-5 days out.

[kmk786]

Guys, this is a beautiful thread. I am touched and a little jealous.

Steve - you rock. And, are my hero! There should be more people like you in this world.
Dalap83 - I hope things work out with the next trip in.

Keep hope alive! Sorry for getting all sentimental.

Back to brake grinder, cylinder, calibrator, transformer discussions!

[dalap83]

I'm very hopeful. Day three with a loaner (a Q70 too) while the guys test, replace parts, and check the results. I even got to shake the hand of Steve, the United States Marine I am honored to entrust with my car. I'll hopefully be able to write a positive final chapter soon.

[Ilya]

And he's a marine? Man, good stuff.

Steve, thank you for your service.

[AZhitman]

SALUTE!

[BlackCat81]

Thanks guys! I'll post the update; I finished the car yesterday morning. When I pulled the master cylinder off the car I happened to hold it a weird way and noticed brake fluid leaking past the seal and down the piston (externally). I looked inside the booster and there was brake fluid inside it, obviously where it shouldn't be. I'm glad I could actually see something physically wrong with the car. It got a new booster and pressure switch, and a new master cylinder. Spent more time bleeding the brakes than I did doing the actual repairs, haha. I have a feeling we'll be good to go!

[Ilya]

Nice! Yeah, sometimes bleeding can take forever. I had to bleed my motorcycle for like an hour before I got the air out, not sure why. That was after I thought I got the air out and go to my first corner and had no rear brake lol.