95 Maxima idle and slight missing issue

[lucasjsr]

I bought a 95 Maxima w/155K miles that had been sitting for quite a while. I have been getting it shape (1/2 shafts, spark plugs, oil change, brakes and rotors, new #4 injector and temp sensor and bank 2 #1 O2 sensor). I have a problem with the check eng light flashing then setting a #3 cylinder misfire and a KS code, but I think that the #3 misfire has cleared up after a tank of gas with BG44K cleaner. I still have a slightly rough idle and minor missing but no chk eng light. Will an ODB2 set a KS code without setting the Ck Eng light? Can a KS cause a rough idle? Also I noticed when standing on the driver’s side of the car to the left of the air filter there is a larger hose (aprox 1") and a smaller hose (aprox 1/4"). They are harnessed/clipped together. The smaller hose is not connected to anything and I have not idea if it is supposed to be that way or not. I have discovered the smaller hose has what I believe is a check valve of some sort in it. I am also getting pretty poor gas mileage. At full throttle it runs out fine. Any and all help is appreciated. I do not want to just start throwing parts at it that will not solve or help. Thanks again for reading and offering your help.
Modified by lucasjsr at 8:47 PM 1/25/2008

[NISTECH]

KS will not set the check engine light. KS will not cause a rough idle. The misfire code is of concern, when the check engine light flashes that means catostrphic catalyst damage will occur. Coils tend to be a problem on these cars and being you had an injector issue, you may be looking at another bad injector. Best thing to do is ohm test all your injectors and see if they are all close to the same. Replace any that are mor the a couple ohms difference. usually they read between 12 and 20 ohms. They should all come out very close to each other. If thats not it you may be looking at weak coils.

I really dont know what hoses your talking about. Coukd be the small hose is your transmission vent hose, they usually clip that right near the air flow meter.

[lucasjsr]

Well I am getting no CK eng lite at all now just a rough idle. I think it may have been something sticking and the cleaner and/or driving it cleared it up (I hope). I did notice the idle is around 7-8 RPM and the missing is not noticeable above 2500 RPM. I checked my mileage today and am getting around 15mpg which leads me to believe I still have some sort of minor issue. The rough idle does not feel like it did when I was getting the ck eng lite to set. Other than pulling the intake and checking the injectors or taking it to a shop, can you offer any trouble shooting tips to help narrow my search? Thank you

[NISTECH]

If you have a service manual or at least wiring diagrams for your car you can find the injector connector bulk connector outside the intake and test them from there.

[lucasjsr]

Thank you

[lucasjsr]

I locacted the KS and tested it as detailed on the web site. I have no continuity between either pin and ground. I looked in valley of the emgine at the connection on the KS and there is only 1 (one) wire going into it. Looks to me like someone tried to work on it before and broke the wire off at the KS or it just failed over time. Either way I think I need to replace the KS at this point, am I correct?

[NISTECH]

The knock sensor only has one wire to it. the other wire running down with the signal wire is a sheild wire. The braiding of that wire surrounds the signal wire to keep out interference.

[lucasjsr]

According to these instructions http://www.nicoclub.com/articles.php?id=157926 I should get a reading on one of the two pins, is that correct? I get no reading/resistance from either pin to ground. Thanks again

I checked it again @2000K ohms setting and got a reading of 563. My calculations put that at 1.126 Meg ohms aproximately 2.5 times what the article says is acceptable. Does it sound like a bad KS or am I doing something wrong? Thank you again.

Modified by lucasjsr at 5:20 PM 1/27/2008

Modified by lucasjsr at 5:23 PM 1/27/2008
Modified by lucasjsr at 5:28 PM 1/27/2008

[NISTECH]

The knock sensor is bad, we see it alot in the service arena. When you get it out you will probably see a crack down the body of it. If not it still doesnt mean its ok it just means its not as bad as most of them the go out.

[lucasjsr]

Well that solves that once I get it and put it int THANK YOU SO MUCH. Do you have any suggestions for my engine missing? It feels like a cylinder is misfiring at idle and low speeds. I bought the car after it sat for a year or better. Air filter is good and I have changed the plugs and run BG44K through it. I no longer set codes so I am feeling better that the #3 injector that was giving the codes is either good or at least better than it was. Somone recommended I have the injectors cleaned/flushed. Is that a good thing or is it more a smoke and mirrors, feel good thing? Can cleaning the injectors really help or am I looking in a wrong area, perhaps I bought a bad plug (s)? Can the Idle Air Control cause a rough idle low speed misfire? COuld the KS be retarding the or advancing the timing to cause this problem. I do not get any pinging or valve rattle during any level of acceleration. Would a vaccum leak cause rough idle and low speed misfire. When I open the throttle wide open the car seems to have a lot of pick up. THANK YOU AGAIN.

[3Q Jay]

According to these instructions http://www.nicoclub.com/articles.php?id=157926 I should get a reading on one of the two pins, is that correct? I get no reading/resistance from either pin to ground. Thanks again

I checked it again @2000K ohms setting and got a reading of 563. My calculations put that at 1.126 Meg ohms aproximately 2.5 times what the article says is acceptable. Does it sound like a bad KS or am I doing something wrong? Thank you again.

Modified by lucasjsr at 5:20 PM 1/27/2008

Modified by lucasjsr at 5:23 PM 1/27/2008

Modified by lucasjsr at 5:28 PM 1/27/2008

not to argue with Scott (especially since i think you posted before about code 34--ks), but a reading of 560 (kohms) is in spec. ks still may be bad over the broad spectrum even if it passes the gross check with engine off.ks function is to retard timing when it 'hears' the acoustic signature of detonation. if it hears nothing (including 'normal' engine noises), the ecu will not allow full advance--why we don't recommend to rig a cheater harness in place of the ks. solves only part of the problem, but not the rest.

i think you want to focus on your injectors (is there a sticky for how to ohm them?) and then maybe bad plug/coil.

[lucasjsr]

Thank you for your help. New KS arrived today and I will replace it. I do not suspect that will help the idle but it eliminates any chance it can hurt perforomance. I have had the injectors cleaned and that did little to help. I am going to replace the coils packs to see it that is it (Bidding on a set on Ebay and should win them cheaper than having them diagnosed) If that is not a problem then I have only the injectors to check. I ordered a manual and when it gets here I will check the injectors. Right now it does run and runs well over 2000 RPM and I will live with that and let you know how things turn out. Thanks again for everyones help.