Low RPM/rough idle when the car is cold and put in reverse

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SilentJay

Member
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CX-5 GT
Not a huge problem, per se, but more curious as to whether this is common.

I park my '17GT in the garage every night. When I start it up and want to reverse it out of the garage, if I don't let it warm up for at least a minute, the RPMs drop and fluctuate significantly enough to feel rough idle. Letting it creep forward in drive is fine.

Before anyone asks, my garage isn't sloped enough that it'll roll out on its own in neutral :p
 
Probably because it's running at high rpms when you first start to warm up the cat converter fast. When you put it in gear the rpms drop back down. That may give the appearance of a rough idle.
 
Check to see if you're getting a trouble code. The first time it got really cold here in Texas, my wife started the CX-5 and I noticed it sort of sounded rough while idling. The Ultragauge reported a trouble code, I don't remember the code exactly but it was a misfire for cylinder 4. I cleared the code and sent my wife on her way. So far it hasn't happened again.
 
This happened to me once as well. I was loading up the grandkids to go somewhere and told them to stay in the front yard until I backed the car out of the garage. I started the car and put it in reverse to back out. The car started running rough as I backed out and one of the girls commented that she could smell gas when she approached the car to get in. This was a few months ago and has not happened since. No errors or warnings on the dash anywhere so I just chalked it up to putting the car in gear too soon after starting it. I do listen for it every time I start the car now but there have been no further issues.
 
Iwannacx5 said:
This happened to me once as well. I was loading up the grandkids to go somewhere and told them to stay in the front yard until I backed the car out of the garage. I started the car and put it in reverse to back out. The car started running rough as I backed out and one of the girls commented that she could smell gas when she approached the car to get in. This was a few months ago and has not happened since. No errors or warnings on the dash anywhere so I just chalked it up to putting the car in gear too soon after starting it. I do listen for it every time I start the car now but there have been no further issues.
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This is actually very normal. Mazda uses an unusually long exhaust header to allow extra cylinder compression which helps with gas efficiency. However, this means on cold starts the catalytic converter stays cold for an extra long time and they don't work well when cold. Their solution is to run the engine rich until its hot enough. This creates a gas smell (sometimes) and a rough idle for ~30 seconds-ish.
 
Iwannacx5 said:
No errors or warnings on the dash anywhere so I just chalked it up to putting the car in gear too soon after starting it. I do listen for it every time I start the car now but there have been no further issues.
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Some trouble codes will not trigger a check engine light on the dash. My wife only noticed it because the Ultragauge installed on her CX-5 alerted her to it.
 
SilentJay said:
Not a huge problem, per se, but more curious as to whether this is common.

I park my '17GT in the garage every night. When I start it up and want to reverse it out of the garage, if I don't let it warm up for at least a minute, the RPMs drop and fluctuate significantly enough to feel rough idle. Letting it creep forward in drive is fine.

Before anyone asks, my garage isn't sloped enough that it'll roll out on its own in neutral :p
Click to expand...
Similar problem for me that turned out to be my air filter. When I changed it, I didn't lock it in completely. The gap was causing rough idle. I reseated it and closed the "lid" which completely fix it.
...Just in case this helps...
 
No check engine light, no heavy gas smell, and the car has 1500km (932mi) on the odometer.

I understand a cold start results in higher RPMs to speed up the warming process, but it's a very pronounced stutter and RPM fluctuation.
 
I found similar problem on my 16CX-9GT. Every time as long as the engine is cold I put the gear to reverse before the RPMs drop down, the car would hesitate to move 2 to 3 times. There is no any significant shaking while the car is not moving. Once I wait for the RPMs drop down a little bit, there is no problem at all.
 
SilentJay said:
Not a huge problem, per se, but more curious as to whether this is common.

I park my '17GT in the garage every night. When I start it up and want to reverse it out of the garage, if I don't let it warm up for at least a minute, the RPMs drop and fluctuate significantly enough to feel rough idle. Letting it creep forward in drive is fine.

Before anyone asks, my garage isn't sloped enough that it'll roll out on its own in neutral :p
Click to expand...

When you start up the car, you need to wait like 20 seconds before you go. CX-5 starts up at a high idle, and over the 20 seconds should start to come down.
 
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