Well after sitting in the driveway for the last 5 years, I finally decided to get the z going again. I drain the gas, change fuel filter & fluids, and get new plugs. Go to start and wow, it starts right up. The problem is that the exhaust really reeks and has a slight miss. The only code that came up was for the O2 sensor, so I change those and no difference. The Innova scanner that I have does not show counts or detailed info, but it shows the LTFT on bank 1 as -11.7 and bank 2 as -9.3 at idle. It seems to slowly go from -5 & -3 to those numbers as it warms up. The O2 voltage shows .9 at initial start up when cold then fluctuates as normal between .1 to .9 when warm. Is that .9 when cold okay? I pulled the plugs and all the ground straps are white which confirms the lean condition. So what would cause the PCM to pull fuel and let it run lean. False rich maybe? Any ideas would be appreciated.

 

sounds like its running good to me. injectors might be a little dirty, maybe add some injector cleaner.

you probaly have a mouse or something that was living in your exhaust that died in there, i say get it warmed up and take it out on the road and blow it out.

 

The exhaust would be at .9V (900mV) at cold start only if your AIR system is not working or has been deleted. When the O2 sensors are cold, and not working they will read about 0.45V (450mV). With a functioning AIR system, they will gradually drop to .00X V at the sensors heat up and reach operating temperature. Without the flow from the AIR pump, the O2 sensor voltage will rise, to reflect the enriched A/F ratio used for cold start.

What was the exact numerical code for the O2 sensor? Not all codes are the result of faulty O2 sensors?

The fact that is has negative fuel trims indicates that it would be running rich at idle, if the PCM was not reducing the long term fuel trims. -11.7 corresponds to a BLM of 113. -9.3 = 116.

 

Dangalla, when I say reek, I mean being around the car at idle is like a suicidal persons dream! Just breath deeply....

Injuneer, glad to see a familier name from back in the day. The O2 codes were P0135 & P0155 heater circuit. Wasn't sure if they really needed changing, but since they were the original ones, I figured to just change them out. So since I did delete the AIR system, the .9 at cold start would be normal then.
As for the fuel trims, would this mean that it's a false rich condition? Between the smell, the plugs, and the popping of the exhaust during deceleration, makes me think that it's running lean.

 

When you say the exhause "reeks"..... do you mean there is an excessive fuel smell? If not, what does it smell like? Is it s sulfur odor? I'm still trying to figure how you are determining its running lean from the smell.

 

It doesn't really have that smell of fuel, just smells like exhaust but very strong. Hard to expain. I would imagine if you were to run a car in an enclosed garage for a long period of time, that's what it would smell like. Actually, I first thought that it was running rich. Then I pulled the plug after driving it about 100 miles or so and saw that the plugs were very clean, except for the ground straps, which were very white. I just thought since the plugs looked like that, it was lean. So basically I'm just going off of what the plugs look like and could be totally wrong. Could it be running rich and the plugs be in that condition? Any other way to verify that it's running rich? I really appreciate the help!