I have two codes.
One is the Knock sensor
second is system too lean (bank 1)


I cant seem to find the problem at the moment for my p0171.
I`ve checked for vac leaks with a smoke machine. (nothing)
I cleaned the MAF sensor as well.
I did have an 02 sensor code pop up a while before this code was set. Rainy day and I hit a large puddle of water. I cleared the code and O2 sensor isn`t coding anymore. I tend to think it`s working properly.
I haven`t checked my fuel pressure yet. Trying to find time in the garage between repair jobs (I work at mazda)


My question simply.. are there any usual suspect on 4th gen maximas for this code?


My second problem... I drive about 30 minutes on the highway and when I take the exit and come to a stop my RPM stays between 1500 and 2000 RPM. If I shut the engine off and restart it usually goes back to normal. Am I looking at an IAC cleaning?


Don`t spare the technical terms. I`ve been a tech for a while now. I can post freeze frame data if anyone wants to have a look with me. Thx guys


BTW 96 max. Manual TM

 

High idle is often due to a vaccuum leak.

You have a lean code in bank one.

I believe that the two might be related.

Another member had a vaccuum leak which was traced to air leaks where the uim bolts onot the engine. Also a vaccum leak at the injectors.

You might try spraying something combustible at the base of the uim and the at the injectors.

The 325 code is usually just along for the ride.

 

I checked with a smoke machine and didnt see any vac leaks. I did focus my smoke test on the front valve cover given the code. My high idle only happens when rolling on the highway (interstate) maybe related.. ill check again. I did however find a small exhaust leak after the upstream o2 sensor right before the flexpipe. I figure that exhaust leak would affect both banks. I need to pull out the freeze frame data again and look at the numbers if someone would like to look at it with me. Logically speaking if i had a fuel pressure problem i should be getting a lean mixture on both banks. By deduction i thonk i can rule out my fuel delivery.

 

Freeze frame data.. thats all the genesys was able to give me

 

Live data

 

In all cases i dont see any change in my o2 sensor B1S1. IT stays at 0 volts in closed loop. Looks like my problem. Second opinion anyone?

 

Hi SSC, I have a very similar issue with my max but mine seem to be intermittent, I get high idle on start up at about 1800 rpm which only last a couple of seconds then it drops straight down to about 1400 rpm and seems to behave it's self and engine idle is normal at about 700 rpm but I'm getting a very slight increase in revs at idle when warm, it's only small increase of 20 to 30 rpm but it's noticeable, I have had the same problem with fast idle while driving as you have it feels like the cruise control is on but mine has also done it while city driving, I went straight to the throttle body and cleaned it as well as the egr which was blocked up, i cleaned and test the IAC which was out of speck so I replaced it with a good second hand unit, this made the engine easier to start but didn't fix the high idle at start up, then I did a smoke test thinking it may be a vacuum leak, no leaks found. I'm started to suspect a leaking fuel injector. Now after reading JvG comments " Another member had a vaccuum leak which was traced to air leaks where the uim bolts onto the engine. Also a vacuum leak at the injectors.
You might try spraying something combustible at the base of the uim and the at the injectors." this will be my next check, which will be tomorrow as I plan on doing a full service on the max. will let you know what I find.

Cheers Chris72

 

You have any codes with that? A vac leak would provoke a p0171 or possibly a p0300. Do you have access to a scanner that does live data? IF you do might be a good idea to look at the sensor readings. Generally spraying something onto a vaccum leak will make a difference in the way the engine runs. IF you do notice a difference then you zero in on your problem. Dont confuse high idle with fast idle though. If your car is cold its normal for it to idle high for a few minutes. Let me know what you find. Ill be happy to help

 

Just a quick item to note SSC, I think you have a 5th gen. You might get better information in the 5th gen group.

As a side note, there is a significant difference in the ECU between the 4th and 5th gens. Also, the ability to use an OBD2 scanner for full diagnostics between the 4th and 5th gens is very different.

A friend of mine has a 2000 model. For that car I was able to use NDS2 on the OBD2 port with a VAG KKL 409.1 adapter. The OBD2 port on a 4th gen is provides basic code reading and reset capability.

Us 4th generation owners just do not have the same functionality with the OBD2 port as the 5th gen owners. For all of my serious 4th gen diagnostics, I have to use the older 14 pin consult interface with a tool that communicates with the ECU for older Nissans.

 

I just didnt update my car in my profile. I have a 96 now. Its been a while i havent been on the forum im using an old genesys evo as thats the only scan tool we have capable of giving us live data on our used cars

 

Cool. You've got a pro shop tool there to work with.



I have a 99 model with a little bit of the high rpm issue on occasion. Though it comes and goes. Not bad enough to get concerned about at this point. I'm planning to move the TPS to the 98 model that I'm refreshing. If the problem moves to the 98, then I'll know it is the TPS.