not running right need help

[camarodriver15]

i have a 91 n/a 5 speed and its running rich cant seem to figure out why and when i drive it it starts acting like its firing on five cylinders it will die at stop signs if you dont give it gas and it lacks power after you drive it for a bit ive checked all the coils theyre brand new but i checked anyways theyre all good all the wires to the coil are getting power the injectors are brand new previous owner replaced them the power transistor unit is brand new cant seem to figure this problem out but im driving a mercury sable that i hate and my truck which gets 8-10 to the gallon so i really need to get this car running right asap and im not exactly a 300zx guru so i figured maybe someone on here has had this same problem and could help me out? i would greatly appreciate any help thanks

[Ace2cool]

Camarodriver15?

Lol, jk man.

Here's a simple test you can perform: While the engine is running, pull coil pack connectors and the idle should change and be very rough on each one. If the idle doesn't change, that is the cylinder with a problem. Could be a broken/loose connection, corrosion on the connectors, or a fuel injector failing.

Sounds to me like it might be a fuel injector issue. Also, you can pull codes from your ECU to find out where the fault is by using this write-up. Faulty injectors would throw a code without throwing a CEL.

[camarodriver15]

thanks for the info on the computer diagnostic testing im going to check it out now

[camarodriver15]

okay i did the diagnostic code 55 which shows no malfunctions but i had some smoke coming through my shift boot so i looked underneath and the pass side cat is glowing orange so im thinking its clogged or its dumping to much fuel on that side i tried the thing with the coils it made a change with each one i pulled off so if the cat isnt clogged which im getting it checked tom. any ideas?

[camarodriver15]

okay the cat was not clogged hopefully someone still looks at this its dumping too much fuel if you take it out and run the s*** out of it it is fine but the second you drive it normal it fouls the plugs out i took it out today and spun the tired all the way through 3rd and went nuts in it and the car was great but the second i drove it normal it was running on 3 cylinders injectors are new but could they be bad and leaking fuel into the cyl? the fuel pressure regulator is good too i checked it injectors is my only theory but i hate to tear it down to change them and that not be the problem

[Ace2cool]

Might be an injector O-ring. Some other tests i would suggest before you look into that (pulling the plenum is a miserable job):

-Compression test (can get one at Auto Zone or anywhere similar for rental)-Injector ohm test (IIRC, should be from 11-14 ohms)

It's not uncommon to find a bad injector in a batch, so ohm them first. Idk about 3 bad ones though. That's what leads me to believe it's the O-rings. They're easily pinched when installing. It's good to put a little vaseline or something similar on them during install to make them easier to get in.

[missThao]

I have a 90' 300zxtt and it is also doing the same thing. Just had an "bad injector" replaced the other day and that's not it either. It dies: when it's idling, at stop signs, sometimes when im at a low speed and step on the clutch.. yeah... its pretty great.. Even my mechanic doesnt know what to check anymore, just tells me all the injectors on the drivers side is not producing as much power as the other side. but they work.. Sooo... please let me know if and when you find out.

[camarodriver15]

alright i will havent been able to do anything for the past few days its been snowing like crazy

[Zwicked]

Did you run o2 diagnostics? That's often the cause of rich condition

[camarodriver15]

no not yet when i was letting it get to operating temperature thats when smoke came through my shift boot and i seen the cat was glowing so i was hoping it was clogged and had it checked and they told me it was flowing good it was running too rich and i havent been able to mess ith it any since then its been snowing for a couple of days:( but i have one question how will i know whether theyre good or bad i understand how to do the check sorta hold it at 2000 for 2 min. and the check engine light will flash? if thats how to do it how what should it flash if its good and what should it flash if its bad? thanks

[Zwicked]

This is the best guide for running ECU diag.

http://www.ttzd.com/tech/diagnostictech.html

"9. Start engine with the ECU in MODE II to enter MODE II - Heated Oxygen Sensor (O2) Monitor . The ECU is now monitoring the left O2 sensor. Warm the engine to normal operating temperature, then run at 2000 rpm for 2 minutes. Check that the LED blinks (or the check engine light) more than 5 times every 10 seconds at 2000 rpm. "

It's a simple but necessary test