I have a 1996 Nissan Maxima with the VQ30DE engine. Vehicle has 220k, and while it runs decent, it has some CEL codes related to the EGR and knock sensor. The knock sensor code is self explanatory; I can see a former mouse nest within the lower intake manifold. Some hack mechanic tried to repair a chewed KS wire at some point with speaker wire. The EGR code is a mystery, as it points me to a solenoid (EGRC?) which I've already replaced and yet the code continues, even after a reset.
I pulled the upper intake, it was a treat. I swore loudly at every Japanese engineer within earshot (probably not many present) for the terrible design of this engine's emissions system(s) and how they connect to the UIM. A couple dozen (exaggerated) vacuum hoses going every which way, umpteen solenoids, bolts you can hardly get to... you name it, it's there.
I finally got it off but twisted the EGR pipe that connects to it (didn't realize it was connected and fought the resistance of it). I broke a cooling hose (on purpose, no way to get to the clamps) which should be no big deal to replace with a new one. The EGR tube concerns me-- I believe it can be bent back (it's not broken or cracked), but it won't retain its original diameter where it's been bent. The intake end of the tube is practically blocked with carbon, but I can see how some gases could get through.
I'm not necessarily looking for this vehicle to last another 20 years, but it would be nice if I could get it to 300k. The knock sensor will be replaced the right way, but I want to fix the EGR in a way that it will be reliable with no codes. Has anyone run into this sort of trouble on the VQ30DE engine? I thought about cleaning everything I can get to, hoping it fixes it, but not sure if I should be replacing parts.
The only driveability issue I've had is a miss at idle, and low RPM (under 2k) while under load. This only occurs when the engine is warmed up. That seems to suggest to me that EGR gases are getting into the intake when the solenoid commands them not to... but I'm not sure. Ignition and fuel is okay, I've been watching fuel trims on a scanner. Anyone with experience with this engine, or similar driveability issues, any help would be appreciated.
I pulled the upper intake, it was a treat. I swore loudly at every Japanese engineer within earshot (probably not many present) for the terrible design of this engine's emissions system(s) and how they connect to the UIM. A couple dozen (exaggerated) vacuum hoses going every which way, umpteen solenoids, bolts you can hardly get to... you name it, it's there.
I finally got it off but twisted the EGR pipe that connects to it (didn't realize it was connected and fought the resistance of it). I broke a cooling hose (on purpose, no way to get to the clamps) which should be no big deal to replace with a new one. The EGR tube concerns me-- I believe it can be bent back (it's not broken or cracked), but it won't retain its original diameter where it's been bent. The intake end of the tube is practically blocked with carbon, but I can see how some gases could get through.
I'm not necessarily looking for this vehicle to last another 20 years, but it would be nice if I could get it to 300k. The knock sensor will be replaced the right way, but I want to fix the EGR in a way that it will be reliable with no codes. Has anyone run into this sort of trouble on the VQ30DE engine? I thought about cleaning everything I can get to, hoping it fixes it, but not sure if I should be replacing parts.
The only driveability issue I've had is a miss at idle, and low RPM (under 2k) while under load. This only occurs when the engine is warmed up. That seems to suggest to me that EGR gases are getting into the intake when the solenoid commands them not to... but I'm not sure. Ignition and fuel is okay, I've been watching fuel trims on a scanner. Anyone with experience with this engine, or similar driveability issues, any help would be appreciated.