Stock KA24DE Randomly Running Rich... - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

AadosX · 03-04-2005, 12:31 AM

My car has the stock KA24DE in it with and intake, removed emissions crap, and side exit exhaust (no cat, no muffler, nothing).

The exhaust has been on the car for about a month now with no problems. Usually I drive like a woman... shifting by 3k. Well lately I've been driving much more heavily, autocross, drag strip once, etc. Even around on the street I'm known to get on it some times.

Anyways, the other day my car randomly decided to start running rich, or at least it seems. At idle the car shakes but RPM's are the same... almost like a loping from cams. It also shakes more when accelerating. There's a noticable loss of power, and when I get on it, or just take it easy, the exhaust sounds different. If I go WOT and push in clutch to shift it backfires like crazy (more than normal hehe). It did this for about 10 minutes then went back to normal. I drove for another 30 minutes and it started again. This time it continued for a few hours until I stopped driving for the day. Today when I turned the car on it seemed fine for my 2 minute trip down the road... but it was still warming up. A few minutes after that trip I drove some and it was rich again. It was like that the few times I drove all day, but then randomly went back to normal on my way home tonight. I was actually on throttle when it happened too, and there was an obvious bump in power, exhaust note change, and smoothening out of everything.

Any ideas?

Thanks!
John

idlafie · 03-04-2005, 02:49 AM

The wiring harness & plug leading to your Engine Coolant Temperature sensor may have a bad connection or short in it. Test the harness & plug by wiggling it as the engine is running. If the idle starts to fluctuate as you wiggle the wire, then the harness/plug connector is the source of your problem. You'll have to go to the dealer to get the replacement pins & plug so you can fix the harness/connector. Remember, the ECU takes the signal from the Engine Coolant Temperature sensor to adjust the fuel mixture. A short or bad connection will trick your ECU into thinking that the motor is still cold dumping more fuel into your intake.
Anyhow, hope this helps.
ID

AadosX · 03-04-2005, 01:41 PM

Thanks man, I'll look into that. The other things I've thought of are possibly a faulty injector or just bad spark plug.

Thanks again,
John

speeddreamz · 03-04-2005, 01:47 PM

Always check your basics first, Spark plugs, wires, distributor/rotor/cap, oil change, air filter. The reason ur backfiring is becaues either the fuel aint gettin burned up , or theres too much fuel and not enough air for some reason. a little backfiring without a cat is very normal, even a flame once in a while. but, if you say backfiring like crazy i think multiple gunshot like backfires.

phrozen · 03-04-2005, 02:54 PM

is of CEL on? maybe ur knock sensor is causing it

sr240mike · 03-04-2005, 06:05 PM

Im having similar problems with my sr. It seems like at times its pulling timing. Like all of a sudden, it'll be weak, sounds loud, and full boost is reached at 3000rpms. No cels are thrown, and the connections look good too. If detonation is sensed, how long does the ecu read from the knock fuel/timing maps?

03-04-2005, 12:31 AM	#1
AadosX Zilvia Addict Join Date: Dec 2003 Location: Auburn University Posts: 959 Trader Rating: (0) Feedback Score: 0 reviews	Stock KA24DE Randomly Running Rich... My car has the stock KA24DE in it with and intake, removed emissions crap, and side exit exhaust (no cat, no muffler, nothing). The exhaust has been on the car for about a month now with no problems. Usually I drive like a woman... shifting by 3k. Well lately I've been driving much more heavily, autocross, drag strip once, etc. Even around on the street I'm known to get on it some times. Anyways, the other day my car randomly decided to start running rich, or at least it seems. At idle the car shakes but RPM's are the same... almost like a loping from cams. It also shakes more when accelerating. There's a noticable loss of power, and when I get on it, or just take it easy, the exhaust sounds different. If I go WOT and push in clutch to shift it backfires like crazy (more than normal hehe). It did this for about 10 minutes then went back to normal. I drove for another 30 minutes and it started again. This time it continued for a few hours until I stopped driving for the day. Today when I turned the car on it seemed fine for my 2 minute trip down the road... but it was still warming up. A few minutes after that trip I drove some and it was rich again. It was like that the few times I drove all day, but then randomly went back to normal on my way home tonight. I was actually on throttle when it happened too, and there was an obvious bump in power, exhaust note change, and smoothening out of everything. Any ideas? Thanks! John

03-04-2005, 02:49 AM	#2
idlafie Zilvia Addict Join Date: Mar 2004 Location: ..So Cal.... Posts: 940 Trader Rating: (0) Feedback Score: 0 reviews	The wiring harness & plug leading to your Engine Coolant Temperature sensor may have a bad connection or short in it. Test the harness & plug by wiggling it as the engine is running. If the idle starts to fluctuate as you wiggle the wire, then the harness/plug connector is the source of your problem. You'll have to go to the dealer to get the replacement pins & plug so you can fix the harness/connector. Remember, the ECU takes the signal from the Engine Coolant Temperature sensor to adjust the fuel mixture. A short or bad connection will trick your ECU into thinking that the motor is still cold dumping more fuel into your intake. Anyhow, hope this helps. ID __________________ Weekend Mechanic for my Not-So-Mechanically-Inclined buddies....

03-04-2005, 02:54 PM	#5
phrozen Zilvia FREAK! Join Date: Apr 2003 Location: Bay Area Posts: 1,352 Trader Rating: (0) Feedback Score: 0 reviews	is of CEL on? maybe ur knock sensor is causing it __________________ This box is 400x200: Please do not put your sig pic back if it exceeds this. -Moderation

03-04-2005, 06:05 PM	#6
sr240mike Zilvia FREAK! Join Date: Apr 2004 Location: California, Norcal biiaatch Posts: 1,185 Trader Rating: (0) Feedback Score: 0 reviews	Im having similar problems with my sr. It seems like at times its pulling timing. Like all of a sudden, it'll be weak, sounds loud, and full boost is reached at 3000rpms. No cels are thrown, and the connections look good too. If detonation is sensed, how long does the ecu read from the knock fuel/timing maps? __________________ TWO IN THE COOT, ONE IN THE POOT

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

03-04-2005, 01:41 PM	#3
AadosX Zilvia Addict Join Date: Dec 2003 Location: Auburn University Posts: 959 Trader Rating: (0) Feedback Score: 0 reviews	Thanks man, I'll look into that. The other things I've thought of are possibly a faulty injector or just bad spark plug. Thanks again, John

03-04-2005, 01:47 PM	#4
speeddreamz Zilvia FREAK! Join Date: Jan 2003 Location: San Francisco, California Age: 40 Posts: 1,015 Trader Rating: (0) Feedback Score: 0 reviews	Always check your basics first, Spark plugs, wires, distributor/rotor/cap, oil change, air filter. The reason ur backfiring is becaues either the fuel aint gettin burned up , or theres too much fuel and not enough air for some reason. a little backfiring without a cat is very normal, even a flame once in a while. but, if you say backfiring like crazy i think multiple gunshot like backfires.