NousDefions

iTrader: (2)

For the past month or so, my '97 Maxima has been idling extremely lean. When the car first starts up, the wideband A/F sensor (AEM) shows that it is trying to find stoich, and does for about a minute or so, but once the RPMs begin dropping as the IACV closes it leans out to 18:1 (the max of the gauge) and beyond.

I've been trying to diagnose the problem for a little while now, but no result. The car threw two codes after a while: one (0215) for a lean right bank, and the other (0304) for the knock sensor. I replaced the MAF and the lean bank code has not reappeared, but the engine is still idling lean. I haven't been able to change out the KS yet (my hands are just too damned big), but I doubt that would be causing the problem.

I checked all the vacuum lines and made sure there were no intake leaks. The car is running a Vortech V1, a Sard FPR, and a Cartech FMU, but I'm not having any issues with fuel delivery at higher RPM ranges. The ECU is able to achieve near stoich ratios when I am cruising around in closed loop.

The other symptom I have is that the idle is unstable; it dips 50-100 rpms ever 10-15 seconds, sometimes even coming close to dying. In fact, it did stall out on me while coasting to a stop light a week ago. I am also experiencing extremely bad fuel economy, perhaps 70% of what I am used to getting.

Any thoughts?

streetzlegend

iTrader: (8)

Yeah, disconnect your o2 sensors just to see what happens. I used to have a serious leaning condition at idle and low rpms, to the point the a/f went lean off charts and car would stall. disconnected the front o2's, and problem solved. 3 years later I still havent replaced the o2's LOL, I run the car open loop all the time and tune low/idle rpm myself to stoich.

so check o2's, also KS woudlnt affect idle a/f.

NousDefions

iTrader: (2)

That's a good idea. Wouldn't the O2's throw a code if they were malfunctioning?

streetzlegend

iTrader: (8)

Man after working so much on my car and having so many issues, EVERYTHING is possible, you can have no codes and still have messed up sensors. Normally, they SHOULD give out a code. but you never know.

NousDefions

iTrader: (2)

Strangely, I noticed this morning that my car is running extremely rich at WOT. I have an Emanage Blue running along with the Cartech FMU, and I can't imagine that the Greddy would have changed without input, so maybe the FMU got adjusted somehow. The rich condition explains why my fuel consumption has been so bad. I'm tempted to take the car to the tuner again and put it in the dyno, but I would like to get the idle condition taken care of first.

I'll check the o2 sensors later this week. Could the crankcase breather filter cause the lean condition? Since the FMU runs off the vacuum system, perhaps that could be causing the rich condition, but wouldn't a leak lean the fuel delivery out since the FMU wouldn't see boost? My boost gauge is working just fine and reads 20 mm/hg at idle.

NousDefions

iTrader: (2)

I ordered new Denso o2 sensors (they were cheap enough that I just went ahead and got them), and they should be here by Friday. Hopefully that will fix the idle problem.

As for the rich problem, I see that the rich condition only happens once the throttle is open enough for boost to start being seen on the boost gauge. I backed the FMU's needle valve out all the way (which is the minimum amount of gain) and turned it in one full turn. The car is STILL extremely rich, even with a small amount of fuel pressure. WOT is not possible because the car cuts out so bad. A question: could this be a fault of the new MAF interacting with the Emanage? My old MAF could very well have been bad for a while, even when I got the car tuned. Now that it is producing a different voltage, could that change the fuel conditions created by the Emanage injector maps?

maxgtr2000

iTrader: (29)

What you could do is do a run and log it, the log should show you injector duty cycle and maf voltage and you can see what's going on. Open loop could be the issue though with bad o2s and the emanage could be adding to that with the corrections since it's probably in open loop all the time.

NousDefions

iTrader: (2)

Log it with the Emanage, or with an OBDII reader? I've been super busy and haven't had time to open up the Emanage with a laptop.

maxgtr2000

iTrader: (29)

Either way that's easiest to you to get the reading.

NousDefions

iTrader: (2)

Well, the weather has been bad around here and I've been super busy with work, but I finally was able to do a little work on the car. I swapped the O2 sensors, and that didn't seem to do anything with the vehicle.

Furthermore, I noticed that I have developed both a coolant and oil leak. I can't tell where the leaks are coming from, but the oil on the dipstick was super high up when I checked it. After I wiped it down, it still seemed really, really high. Very strange. It seems like it is coming either from the thermostat or the water pump, but I haven't had any issues with cooling. Also, I'm getting a lot of moisture coming from the exhaust, although that could just be a by-product of my test pipes.

I'm still at a loss what is causing the car to run so rich. I haven't been able to hook it up to an ODB II meter yet, but the car goes rich the moment the boost gauge registers any boost, regardless of throttle position or RPM. Very, very strange.

NousDefions

iTrader: (2)

It was super cold this morning, and I almost didn't want to drive the car because there was so much white smoke coming out of the back. I think it was a product of the cold, the moist air, and my test pipes, because it wasn't so bad this afternoon when I fired up the car.

I'm pretty sure my coolant leak is due to a bad water pump, which will be a ***** to replace with the blower. I think I MAY have a faulty injector because it makes a much different sound than all the rest of the injectors. Instead of a fast clicking it sort of makes a slower, deeper sound, which could be causing some of the excessive smoke and would definitely be causing my super rich woes.

What's the best way to check if the injector is truly faulty?

NousDefions

iTrader: (2)

Alright, I was able to check out all the injectors this weekend (they all checked out fine, and didn't seem to be leaking). I replaced all the coil packs and the PCV valve and cleaned the IACV while I was in there.

No the car is running really, REALLY rich. At this point, I'm certain that either the Cartech FMU got screwed up somehow (either mechanically or otherwise) or that the Emanage is acting up. The weird thing is that the car is now running really rich in closed loop too; perhaps the ECU needs some time to relearn now that the coil packs are new.

The spark plugs looked okay, although there was a slight bit of oil on two of them... which is why I replaced the PCV.

Sigh.

maxgtr2000

iTrader: (29)

I'd say it sounds more like the fmu since the emanage fuel corrections in closed loop are usually in conflict with the ecu trying to keep the car at 14.7. As for the spark plugs you need to replace the valve cover spark plug seals. Do you have a breather filter on the valve covers or a catch can?

NousDefions

iTrader: (2)

I have a breather filter.

The car is running a LOT better WOT, and I think the ECU might be having to relearn the long and short term fuel trims at the moment. Another days driving will see if that's the case.

As for the spark plugs being oily, the walls themselves look clean.

NousDefions

iTrader: (2)

It was 2 coil packs, the o2 sensors, and the "new" e-bay MAF. After installing an OEM MAF, the car runs like a top again. Thank goodness.