J30 troubles got me going nuts

[cnickk]

94 j30t bone stock besides air filter. ------PROBLEMS-----1. only getting 290-200 total miles to the tank! 2. high idle in Park _(1500-1800rpm);shifting into drive brings rpm back around (900-1000)3. Temp gauge is really going crazy sometimes. stays at nice cool level but the gauge is really speratic.4. when driving if i apply heavy acceleration black or blue (cant tell for sure color) smoke comes out the muffler. (its turning my rear drivers side black and i have to wash it every day) ---CONCLUSION----1. i just want my j-car back the one that idles in park @ 750rpm.2. the black crap on the back of my car (from muffler) keeps jumping on my pants when i walk by and its pissing me off.3. Im clueless someone please help http://www.nicoclub.com/zeromo...15669#
Modified by cnickk at 5:19 AM 10/25/2004

[DAEDALUS]

Hopefully the smoke is black, and is a confirmation that it's running way too rich, which may explain the poor mileage. Could be a fuel leak. The high idle might be a separate problem. Vacuum leak perhaps. It really might might be worth it to take it to a dealer for a Consult diagnosis to see what the ECU sees.

[cnickk]

well i just got it back from Nissan and they said its in perfect shape. i say hell no. spent over 3500.00 on timing belt and other repairs.they say good i say why?

[driverdriver]

1. only getting 290-200 total miles to the tank! ------------------------------------------------------------

Are you using regular gas? If so switch to premium, you'll get better mileage especially in an 10 year old J.

2. high idle in Park _(1500-1800rpm);shifting into drive brings rpm back around (900-1000)------------------------------------------------------------

Is this when you start the car? If it is, its normal. What you need to do is warm the car up for 7-10 minutes or untill the needle drops to 1000 RPM.

3. Temp gauge is really going crazy sometimes. stays at nice cool level but the gauge is really speratic.------------------------------------------------------------

You need a new thermostat

[cnickk]

my car only knows premium never used anything else. yes i can wait till it warms up but i have never had to do this before except maybe a few times in the winter. how much is a themostat, and could i change it myself??

[driverdriver]

how much is a themostat, and could i change it myself??------------------------------------------------------------I would contact Joe at Scottsdale Infiniti (he's one of this boards sponsor), he could probably get you a better price than any Infiniti dealer, the part is expensive. As for doing it yourself, I have no clue. I haven't had to do it myself.

As for your black smoke/soot, it could be your catalytic or a pollution control sensor.

[cnickk]

pollution control may be but i dont want any. lol i live in SC so we dont have emissions standards. can this pollution system be disabled?also under my car coming out of one of the cats or mufflers (under drivers seat) is a metal wire that seems to be off or unhooked. looks as if it was grounding itself on the heatshield...not really sure i just know its hanging now;.

[DAEDALUS]

Thermostats are not expensive. Maybe $8-10? I've never worked on a J, but been inside Qs and 300zx. Probably 3-4 hour job. If you have a bad temp sensor the car might think it's -40*F in the engine and make it run really rich and really fast to warm things up.

[cnickk]

hey man i wanna thank you for your help you have been a cool to bare with me on this. im a newbie but ill learn fast. so...where is the temp sensor located???

[cnickk]

well its all good now but if i admit how i fixed it then someone might talk me into undoing it so......it works now rock on

[MacBg007]

Your j is obviously running extremely rich, if this is happening since you replaced the air filter, you need to check it. I'm guessing because it's not stock it is probably a k&n or something like it that you oil. most people put way too much oil on these and it makes their car run rich due to lack of oxygen.

[metaverse3]

Take out the filter you have and go back to a stock filter. At least for isolating your issue. Nissan has a factory TSB stating K&N filters will leave oil residue on the maf element throwing off readings. Dealership's have been advised of this and any infiniti/nissan tech will advise you the same.

Check the fuel pressure in your system. A faulty Fuel pressure regulator can cause this. Hook up fuel gauge to your system and drive around with it for a day or so. Your local garage can assist with this.

Check the Iac-aac valve. The J30 has a 300zx engine which is notoriously prone for failure of this part. Read this link: http://www.twinturbo.net/ttnettech/iaa/iaa.html

Check your fuel injectors. See if your mechanic can run a "BG quick clean" through the system. This usually helps.

Lastly, have some patience. You mentioned a grounding strap hanging from the bottom of the car, put it back on. Everything on this car is connected for a reason. If something comes off, put it back on. Good luck.