RPM Fluctuations

[FASTEX3508]

Hello Everyone,

I have been a lurker for the past year or so and I have benefited from your posts and comments in relation to the many topics you discussed so thank you very much for that.

Last year I purchased a CPO 2008 EX35 AWD Journey for my wife. She loves the car and she enjoys it tremendously.

Recently (during the last month or so), we noticed that when the car is driven on highway speeds 65-75 miles/hour and then coming off of the highway into a stop sign or a set of lights the RPM will drop from it's normal 600 RPM to 400 RPM for a second or two then goes back to 600 RPM.

We took the car to the dealership and they were able to duplicate the issue but were told that this is normal operation and no need to be concerned. Also they updated the ECM software which it did not make any difference whatsoever.

My take is that the issue did not exist before and this is just started to happen in the last month or so, I believe there might be something wrong and this dealer does not know how to fix it therefore I am tempted to take the car to another dealership or possibly calling into Infiniti to complain, but before I do so I wanted to get your perspective on the issue and if there is a concern that I should pursue at this point.

Thanks and I look forward to your comments and input.

[PapaSmurf2k3]

I would say 400 rpm is NOT normal. Things like alternator output and engine vacuum probably suffer at that point. The check engine light doesn't come on when it happens?
Also, does it do it with the car in neutral, or just while its in gear?

Oh, and Welcome to NICO!

[FASTEX3508]

Thanks for your reply PapaSmurf.

No engine light whatsoever. Also it happens only when in gear. So if I came off a highway and immediately stopped and put it into park it will not do it....again only in gear and in drive mode only as it never does it if I place it in Reverse.

[jmess]

Electric cooling fan comes on?

I think I have noticed something like this with my 08 where the idle seems to wander for few seconds sometimes after coming to a stop. It seems odd when you notices it but it hasn't changed so I wrote it off as being a feature of all the magic taking place with the ECM and emissions controls.

[EXceptional]

Cooling Fan (as mentioned above) or AC comes on ?

Both might put a drag on the RPM.

[FASTEX3508]

When I spoke with the service manager after he experienced the issue he stated that it could be the cooling fan clutch, but later on after the vehicle was worked on, the technician stated that it is normal operation.

As for the A/C it is not being used these days as it is around 40 degrees here in the North East.

I have been doing a lot of research and ask around for the last day or so about this issue and I am finding more and more that it is "normal", this specially after I have spoken with a NISSAN technician and he said it is a common thing among NISSAN vehicles and like my dealer he said not to worry.

Other Nissan/Infiniti Technician went further to explain that it is a software delay in the ECM programming as it takes a second or two to adjust from HIGHWAY driving mode to a STOP mode or even BACK ROAD driving mode (less than 50 miles/hour) unless I have an engine light (CEL) then there is no problem and not to worry about it.

I am not 100% convinced that this issue is normal….I believe there is something that is not operating properly which is causing the RPM fluctuations…..I believe it could be a bad ECM or something electronically like sensors that need replacement and only someone with extensive NISSAN/INFINITI mechanical knowledge can really resolve this issue.

Thanks and please keep your thoughts coming thru.