I have an '06 Nissan Xterra off-road that came used and we’ve done a lot of work on, which I’ll list below. After all that, we’re still having a very persistent problem. Sometimes when you start it, it runs extremely rough. Any throttle will kill it right away. After doing this for a minute or two it very abruptly recovers to a normal idle and then drives mostly fine.
We’ve noticed that this seems to happen most when the car has only been off for a fairly short period of time and so is somewhat warm, and it also only seems to happen when the A/C is turned on. But both of these are not high-confidence, it really doesn’t do this very often either way.
Possibly related symptoms:
- We had the SES light turn on with an O2 sensor, bank 1 sensor 1, out of range code on the second sensor. After a while it cleared on its own and hasn’t come back on since.
- Sometimes at high-ish RPMs, say 3k and up, power gets surgey and the SES will flash which I believe indicates a misfire. More often it surges a bit without any flashing SES indication.
- Sometimes right after pumping gas it won’t turn over. If you wait fifteen seconds and try a few times it starts up and runs fine.
Things we’ve done that are related:
- A mechanic replaced all four O2 sensors as part of replacing the primary cats (burned out due to pre-existing MAF problem, see below), and when the SES came on for bank 1 sensor 1 after the replacement he replaced that sensor again. SES came on about this sensor again after that, but then cleared itself and hasn’t returned for a while. I still wonder if there could be a problem there, perhaps wiring or an exhaust leak or something.
- MAF was bad and air intake manifold was leaking slightly when we purchased it, replaced both. Also replaced spark plugs as they were both not OEM-recommended model (NGK Laser) and fowled up, probably due to bad combustion due to bad MAF. Wires looked OK.
- A/C was completely depressurized when we got it, we replaced all O-rings, pumped down, and recharged. But in the process of doing so we found a bit of metal mesh in one of the AC lines, which we think is from an internal failure of the expansion valve. A/C works fine now but we are worried about possible debris in the compressor. Compressor sounds okay, but as said, it’s possible this problem is related to the A/C.
- We suspected the problem starting after pumping gas was related to the canister purge valve, it seemed fine but we “fired the parts canon” and replaced it anyway. That symptom still happens occasionally though.
In almost certainly unrelated service, we’ve also replaced shocks all around and replaced limit switches on the transfer case (but it’s still acting up with slightly different symptoms, possibly wiring? haven’t looked at this yet since it still actually works fine, the dashboard indicator is just wrong. Could be as simple as a loose connector).
I don’t have a ton of theories right now. It seems like the temperature sensor is possibly a suspect if it’s causing weird cold/warm idle detection behavior (would this show up as odd behavior on the temp gauge?), maybe it’s something about the EGR somethings, possibly a lingering problem with the O2 sensor, or something about fuel delivery?
At this point I’m thinking about paying the Nissan dealer for diagnostics to see if their CONSULT II box will tell them anything useful, I’m not seeing anything that strikes me as odd looking at realtime data in Torque but I also haven’t been able to get important things like the fuel pressure. I do have the short-term and long-term trim numbers but to be honest I don’t know enough about fuel injection and ECMs to make much of these. I’d love any ideas.