2016 Mazda CX-9 GT Surging when stopped...

BinDerSmokDat

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2016 CX9 GT AWD
Hello I have a 2016 CX-9 GT with about 15,000 miles on the clock.

Today when coming into work I coasted up to a stop and noticed the engine was surging while stopped with brake applied.
It was surging from idle to a few hundred RPM's over idle in a steady rhythmic pattern. rrrrrrr...rrrrrrrr...rrrrrrr
I had come off a hill and was doing a long slow coast with my foot off the gas, so I chalked it up to that.
When I took my foot off the gas and turned, accelerating up to about 45-50 it was fine, I noticed nothing unusual and no hesitation.

I came to two other stops, with no issues.
When I got to work again I was idling on the long campus drive barely giving it gas and when I was stopped in my parking space, again the surging.
I put it in neutral and the surging stops. I put in gear with foot on the brake and the surging resumes.
I put it in neutral give it a little gas it revs and then put it in gear it surges.

The surge is not strong enough to overcome the brakes nor does it rev more than a couple of hundred RPM's above idle.
It's rhythmic with the brakes depressed and goes away with the brakes released.
No surge at all when in neutral with or without brake depressed.

I checked that the WeatherTech mat hadn't shifted and interfered with the gas pedal.
Other than that, I had to get into work so I didn't check anything else.

Anyone else experienced this?
 
Nothing like that here with only 6,600 miles on the odometer.
Sounds like a sensor of some sort.
I'd have it checked out at the dealer.
 
I was thinking sensor or vacuum leak but I'm baffled as to why it's intermittent.
It was doing it at some stops and then not at others.
 
Mine has done the same since new very occasionally. It happened yesterday and I had the AC on, so I thought it could be the compressor cycling on and off. No idea really...
 
Agreed that a vacuum leak is another likely possibility.
The intermittent issue could be related to a hose crack opening only under specific conditions.
I also agree that a OBDII scan is in order.

Note that a typical scanner will catch most issues, particularly engine and emissions related; but that Mazda also has some modules that aren't read by older units.
(I had an issue with blind spot monitoring on another Mazda. Those modules have code specific to Mazda and the issue clear to them didn't register on my home scanner.)

Since the vehicle is still under warranty I'd have the service department scan the car and then repair the revealed issue.
 
Mine has done the same thing 3 times now. I had to put my car in park, shut it down and restart to make it go away.... seems like a is a mass issue.


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Why hasn't anyone taken it back to Mazda for warranty?

I was a Service Technician for Chevy and if I had this issue I'm still taking it to Mazda for them to fix.

Can answer this question too when they fix it.
 
I am at the dealership now and they are doing a diagnostic and trying to recreate the problem. That is another issue that is so isolated that it is hard to recreate. I'll let everyone know what results from the investigation.


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Yup, as I suspected. Dealership looked at it, tried to 'recreate' the problem. Couldn't. Back to square 1. Next time someone record the problem. Lesson learned for me too.


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Hello, just wanted to provide an update, well an "un-update" as I didn't do anything about the issue. ;)
This problem went away and work got busy so I didn't take it to the dealer.
Recently when decelerating (coasting, foot off gas) and then accelerating there is a harsh surge, almost like the fuel delivery is delayed and there is a slight jerk as the car surges.

I've just hit 20K so I'm taking it to the dealer, I'll report back.
I'm 90% certain they are going to say they can't find anything wrong and then suggest a fuel/intake system cleaning.
 
Dealer looked at it during last service and found no issues and no codes.
It was likely a dirty sensor or some transient issue.
I have not experienced the issue since.

I have been running Top Tier gas recently, that may have helped but not certain.
 
For something as intermittent as this surging, make a video. Have your cell phone at the ready, and when it surges, video the tach. That won't really be enough to diagnose the problem, but at least the service writer will believe there is a problem and maybe inspire the tech to do a thorough diagnosis.
 
I haven't had this yet in the CX9, but in other vehicles its always been a hose or sensor, like a previous comment mentioned. Usually a gummed up solenoid/sensor on the intake manifold. Like a cold start high idle air valve, or air intake temp deal, or something along those lines.

The fact that in this case it goes away in neutral makes me suspect it is related to the transmission ECM.
 
Have a 2013 cx9 and also surges or feel like it wants to turn off only when I'm in gear at a stop light with my foot on the brakes.as soon as I release the brakes the cx9 is fine . Also my cx9 brakes been acting weird the brake pedal sometimes goes all the way down .and the vehicle is hard to make a complete stop.went to mazda dealer bad brake booster causing vacuum leak .which causes engine surging or stalling when in gear waiting for stop light. My cx9 has over 97000 miles and dealer said the cut off mileage for free replacement brake booster was 90000. That the cost will be 1200
Dollars for replacement.i called mazda corporate main # and spoke to a rep in which they worked with me and called the mazda dealer and approved the repair. My cost was only just under 250.00. I didn't mind paying that. The vehicle is running perfect now. If you have a brake booster problem and your vehicle is over the required mileage. 90000. Call mazda corporate. I'm pretty sure they would work something out. It is a safety issue.
 
I am having the same issue. Dealer could not recreate problem, but the service advisor DID see the problem when I took it to the dealer. I told them I will not take the car back until they find and fix the issue. I think what saved me is I have a video of the problem, but it is taken from inside the car and a little hard to see.
 
Reviving this thread.

I wanted to see if anyone was able to get this issue root caused or get this resolved. I've experienced this three times in the 18 months that I owned this car and Mazda dealership can't reproduce and has no clue.

It goes away if I turn off the car and start it again. Three occurrence in 18 months isn't too bad, but would really like to understand what's going on.
 
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