Rough idle

[Jefe]

Hi,
I am having a slight problem and it is driving me crazy. First let me give you what i'm working with. It is an 03 Z06 with a modified intake cover, K&N filter, x pipe, and borla stingers. The rest is pure stock. In the last couple of weeks I have noticed that when the coolant temperature is going roughly between 85 to 105 degrees it starts to miss. Its like one of the cylinders is not firing and you can physically feel it in the car. Once it is warmed up, I'd say 115 an above, it appears to stop missing. After it gets to about 180 or so and I go WOT it does not hesitate one bit. As it goes through the RPMs there is no miss that I can tell of. I have received no codes on the DIC. Has anyone had this happen to them and if so, what was it. I hate to take it to the dealer and leave it for 2-3 days and it be something simple. Any advice would be appreciated.

Jefe

 

[c4c5specialist]

Hi there,
It sounds like you have a fuel injector that is partially restricted, which is not giving the correct spray pattern.
Fuel atomization is very critical when cold, because of the volatility of the fuel.
I would start with a GM fuel injection cleaning.
This would seem like the best way to begin.
Allthebest, c4c5

 

[theblackvette]

I have not heard of such a problem. A new one comes up all the time. Have you put some bad gas in it during the past couple of weeks?

On my Z06 I had a temperature bypass put in. It makes my Z06 run a lot cooler. I have not heard any missing.

I wonder if you are running lean during those temps and causing some sort of detonation. I dunno, but it may need to be checked out!

The fuel injector advice is probably the culprit. It can't hurt to clean it out!

I am sure a lot of the Z06 refugees here can give you some insight as well. Keep us posted.

Hi,
I am having a slight problem and it is driving me crazy. First let me give you what i'm working with. It is an 03 Z06 with a modified intake cover, K&N filter, x pipe, and borla stingers. The rest is pure stock. In the last couple of weeks I have noticed that when the coolant temperature is going roughly between 85 to 105 degrees it starts to miss. Its like one of the cylinders is not firing and you can physically feel it in the car. Once it is warmed up, I'd say 115 an above, it appears to stop missing. After it gets to about 180 or so and I go WOT it does not hesitate one bit. As it goes through the RPMs there is no miss that I can tell of. I have received no codes on the DIC. Has anyone had this happen to them and if so, what was it. I hate to take it to the dealer and leave it for 2-3 days and it be something simple. Any advice would be appreciated.

Jefe

 

[JR_Vette]

It could also possibly be a bad/dirty O2 sensor as when the car warms up it goes into closed loop mode and actually starts to 'read' the O2 sensors. Just something else to look at.

 

[Jefe]

C4C5,
When you recommended a "GM injection cleaning", did you mean take to a dealer or just put some GM injector cleaner in the fuel tank?

Thanks,

Jefe

 

[Dave C. '04 Z06]

If it started since you put on the intake manifold, then the first think I'd check is to make sure you don't have a vacuum leak on the manifold. This would make the car run bad until the computer took over in closed loop mode and added the proper amount of fuel.

-Dave C. '04 Z06

 

[TODD L GRIFFITH]

The injector cleaner won't hurt to start. I agree with Dave C., it sounds like the intake could be causing the problem. If the air is turbulant, you will feel a sort of bucking, or surging, like a misfire at low rpm. When you step on it, it's gone.........sounds familiar to me, I had the same problem. I can't imagine it being anything else by what mods. you have. To fix the problem, you are going to have to do something with the arrangement of the intake, to ensure that the flow is not turbulant and linear as possible. Maybe reinstall the filter lid over the intake to minimize any turbulance. Hope this helps.