I found a thread on this several months ago and have tried everything to locate it again with no success.. My '04 Z will randomly experience a power loss mainly during the mid-rpm range. There is no CEL coming on. Sometimes the throttle response is amazing and it will chirp tires into 3rd and then sometimes it feels like it is just "lazy". The only thing that I could possibly tie to this is also sometimes during medium acceleration the car will seem to "take a breath" and cause the car to SLIGHTLY jump forward. Again there is no CEL and it seems that this "lazy mode" is more typical than the peppy mode.
As far as mods I have a NISMO CAI and a Motordyne 3/4" spacer. But this problem was apparent before either of those were ever installed. I have tried disconnecting the battery, different gas stations, and letting the car idle before I drive it at start up. But nothing changes it. Does anyone have any ideas? I thought I was just getting used to the power until the "peppy mode" kicked in one day randomly and I knew that there has to be SOMETHING wrong now. But I do not know where to start! Any and all help would be greatly appreciated.

 

Marked for interest.

 

anybody?? nothing? no suggestions? change spark plugs? hire a priest? lol

 

My does this occasionally too. I think its a problem with the TB, try replacing it.

 

Since no one else is jumping in...

I don't see how it could be plugs. Rough idle would be more of a fouled plug sign.

I'm inclined to think there's a problem with the A/F mixture. It's either starving for air or starving for fuel. Because you have a CAI installed, I'd check your O2 sensor first... it's an inexpensive place to start. Should have triggered a CEL, but...

Too, if you have a good scanner or access to one, try running it "live" and monitor A/F ratios...

Also, since you have a spacer, there's always the possibility you have a poor seal between your intake and TB... check to see that all is sealed well.

This advice is worth every penny you paid for it, but that's where I'd start.

 

check for codes anyway. I had the same exact problem and it turned out to be a bad knock sensor. The code does not trigger the CEL but it's there. Get it checked at autozone/advanceauto.

 

Good point.

And BTW, I stated O2 sensor above... brain-cramp. Check your mass airflow sensor, not your O2.

 

if you're not getting any codes.. you also might want to check your battery or battery connections.. since these cars are drive by wire.. they work off the battery also.. i noticed a slight acceleration decline once and i traced it back to my battery ground wasn't strong enough

 

Thanks guys, I figured these were the first places I would start but I wasn't sure if there was something someone else may have known. I will see if there are codes although no CEL and I figured I would check the TB and the 02's. I'm fairly confident that the aftermarket parts are not causing anything because this was a problem beforehand. I appreciate the information and if I find anything out I will post for others reference. Gracias!!
P.S.- I just checked all the bolts on the plenum for the spacer a few days ago and they were snug down good. That was the first thing I did and still the same problem.

 

I'm driving a 04 G35 coupe and have the same annoying issue.
It's like the car gets stuck in 'Econo' mode and the car feels completely lazy and dull.
I’ve spoken to a few techs, but they can never come up with an answer.

One thing that I have found that will snap the car out of its funk is to perform an ecu reset.
The last time I reset the ecu and took it out, it felt like I was driving a completely different car. The car accelerated so much faster/better that I kept bouncing off the rev limiter in first and second. Unfortunately this mode only last for a few trips, then it starts to go back to lazy mode. I wish I could get the car to always run like after the rest. Any fixes that anyone comes up with let me know.

Good advice on checking for codes, I’m going to try that.

 

Thanks for the info iron man that sounds like the quickest thing to try and solve the issue and hope it fixes it for good! At least it's an easy place to start. With my work schedule and volunteering as a firefighter I have no time for sleep much less trying to get it into my garage for a complete diagnostic! I will post my results!

 

P.S.- code 3 in my 350 is the sh*t! I'm definitely the fist responder LOL. With my lightbar in the windshield everyone in my city knows who I am haha

 

Yeah the ecu reset really helps.

In regards to the codes I had autozone run a test and it did not throw any codes.

....but now I have another issue, my clutch is going out so I'm about to replace that.

I think I am going to go with a ACT prolite/clutch combo...anybody have any experience with this combo?

 

I have a '04 Z and after cleaning my pop-charger am experiencing the same "lazy mode" but only between 2-4 k rpms. It feels like the car looses torque for couple of seconds.
While cleaning my engine bay I have:
1)disconnected my battery
2) tried to clean the throttle body

These two things were mentioned above by others, that these things may be causing the problem.

I have also re-directed the Coolant Control Valve because it was hitting my intake pipe.

I will have to check everything over the weekend.

 

Used my scanner today, no codes but I did happen to clean my nismo filter and that seemed to help slightly but not solve the problem. I couldn't put it better myself RAF it's around the 2-4k range and it does feel like it loses torque in that band. Strange... Still diagnosing...

 

Try cleaning,testing, or replacing the Mass Airflow Sensor. If this gets dirty, it will throw your mix off and cause weird stuff like this. Particularly with the oiled filters, the MAF can get gummed up in short order.

 

I have just purchased the MAF cleaner and will give it a try over the weekend. It does make sense to check it and clean it because if the sensor is off, the mixture of air/fuel may be off and have these effects on the accelaration and over all behavior of the car. Thanks.

 

If it was a problem beforehand, did you contact with dealer? Are you the first owner?

chefj

 

I am the second owner, i purchased the car from a dealer. a lady owned it before me. i didnt realize the problem when i first bought the car because the car stayed in this mode for a while and i was'nt used to the power coming from a non-turbo 3000gt. it was faster regardless of what "mode" it is in LOL.

 

Edit: I do recommand Reset your ECU yourself. ( not just disconnect battery.)

https://my350z.com/forum/engine-and-...n-problem.html

Similar issue.

Also, if you keep having a trouble, stop by injectedperformance.com or 350zmod.com, not far from you. great shop.