Intermittent rough idle

[Billy Mild]

It was 64 degrees here in KC, MO today. I decided to take the ZR-1 out to get a bath and stretch her legs a bit. The car ran great almost all day except when I went in the gym. I drove the car maybe 15 miles or 30 minutes. It was fully warmed up, stopped to workout for an hour. Then when I started the car it sorta ran rough and the idle was rough. When I gave it a rev it cleared up. This happened 2 more times on my way home. It is only around idle too.

I have replaced the coils, wires, and plugs(semi recently). Coils are less than a year old, wires/plugs are about 2 years old. I have replaced the injectors about 2 years ago with some Accell units that Haibeck recommends. I currently have 0 vacuum leaks.

Thoughts? Could it be tune related?

[secondchance]

Since it clears up after a couple of revs I wouldn't worry. If it bothers you, try running a can of BG-K44, fuel system/de-carbonizer.
Now that my LT5 has been bored, stroked, ported and cammed, she gets a bit grumpy after a cold start. Takes 2-3 minutes to smooth out. Sorta like me when I wake up.

[Karl]

Originally Posted by Billy Mild

It was 64 degrees here in KC, MO today. I decided to take the ZR-1 out to get a bath and stretch her legs a bit. The car ran great almost all day except when I went in the gym. I drove the car maybe 15 miles or 30 minutes. It was fully warmed up, stopped to workout for an hour. Then when I started the car it sorta ran rough and the idle was rough. When I gave it a rev it cleared up. This happened 2 more times on my way home. It is only around idle too.

I have replaced the coils, wires, and plugs(semi recently). Coils are less than a year old, wires/plugs are about 2 years old. I have replaced the injectors about 2 years ago with some Accell units that Haibeck recommends. I currently have 0 vacuum leaks.

Thoughts? Could it be tune related?

I say check your o2 sensors.

[Paul Workman]

Originally Posted by Karl

I say check your o2 sensors.

I agree. I've had issues like described, twice; both times the O2 was at fault.

Best tool in the box is the scanner I bought that has data-logging capability. I'm told TunerPro and a loptop too is even better - just might not fit in the cubby behind the passenger seat like where my scanner lives.

I tell ya...that scanner has paid for itself many, many times over in frustration alone by pointing to issues instead of having to guess. O2s have had issues that didn't throw codes, on two occasions. But, the scanner pointed to signal issues; once a connector problem, and the other two were outright O2 failures*.

*I'm my own worst enemy sometimes. I installed new O2s and for good measure I sealed the wires entry to the sensor with RTV to keep "whatever" out. However, that led to another problem as the O2s (I found out later) depend on the opening where the wire leads enter the sensor as access to oxygen the sensor depends on to function! $150 and two sensors later I figured that out!

[Billy Mild]

I am going to change the O2 sensors when I swap the headers.