carguy96

OK, my daughter's car, it has been very reliable for many years, 210K miles, Just started to act up...Spark OK, Fuel pressure OK.

What she has is what I would call a weak start, usually takes 2-3 cranks. Engine starts, kinda stumbles and picks up idle, once warm no problem.
Codes just recently set are: P0325 Knock Sensor and P1400 EGR Solenoid Valve fault...

Knock Sensor looks like fun to get to.
EGR is a bit easier, but with this many miles it will certainly be stubborn to remove and repair...

Is there a priority to fix? Does one cause the other ?

Thanks for the input.

jdgrotte

The knock sensor is probably related to the EGR valve solenoid.
If it was my car, I'd pull the EGR solenoid and the valve, beat the heck out of both of them on the ground, clean the valve out really good, work the EGR pintle in and out a bit by hand, maybe take a 12v battery and put power to the EGR solenoid manually, see if it holds air/passes air, double-check the vacuum lines going to and from the solenoid and the valve, put it all back together and see what happens.
With 210K miles, and the problems starting you've got, it sure sounds like a carboned up EGR valve not wanting to seat itself on shutdown all the way to me...although it could just as easily be a weak solenoid.
Disclaimer: I don't own a Maxima, and haven't owned one (yet), so I'm just speaking about EGR systems in general. That's usually the way it works.

JNCoRacer

Just to let you know, the EGR tube gets clogged pretty easily on the 4th gen Maximas, due to a poor design,and its a pain to remove and clean out. If youre up north with lots of road salt in the winters, then I'm fairly certain you have quite a bit of rust. Which will make it even harder to do. You may want to let a mechanic tackle that one.
Now as far as the knock sensor code is concerned...it wont light the check engine light by itself. Its whats referred to as a ghost code. It'll only show up if you actually pull codes. Fuel grade is what most commonly triggers a knock sensor code, such as running regular. Nissan recommends running premium for better performance and mileage. It sucks but well worth it in the end.

jdgrotte

Agreed... I was thinking in terms of...if the EGR sticks open, hot gasses get in the mix, overheat the air/fuel mix, and it's easier to detonate the mix. I didn't know those things 'wanted' higher octane gas.
That's at least 2 things learned today...

__________________
Pointing out the obvious...

JNCoRacer

There's a noticeable difference when you drive with premium as opposed to regular.

carguy96

Looks like I'll do some EGR valve assembly shopping and will install next weekend, I'll post what happens...

JNCoRacer ... I noticed in other threads for hi mileage vehicles you suggest cleaning the crank position sensor , looks easy

Thx for eveyone's comments.

JNCoRacer

Yes those sensors are easy to remove. There's just a magnetic tip on them that needs to be cleaned of any metal debris from time to time. The easiest one to get to would be the cam position sensor. Its located on the timing chain cover towards the top of the motor.
Good luck and keep us updated.

Dan1120

Seeing that your in GA I don't think rust will be too big of a problem. If you want to do the egr guide tube by yourself here are a couple of good walk throughs. Might as well clean the maf, throttle body, and IACV while you have them out.

MAF, TB, IACV, and EGR cleaning for dummies - Maxima Forums
Comprehensive Pictures and Directons - EGR Tube Cleaning P0400 - Maxima Forums

Cutting that bolt to get the nut off on the lower part of the tube was the biggest PIA for me. I used the hacksaw blade method and it took some time. Be sure to use all new gaskets, trust me, I didn't and had to do most of it all over.

The KS isn't too bad. Took me about 20 minutes for my first time. I bought a cheaper one off ebay for about $30 bucks. Autozone wanted a hundred and something. Heres a good video for the KS replacement.

JNCoRacer

Good looking out there, Dan.