vmok

Hi-

My 1990 SE wouldn't start the other day. After playing with some connectors and such, the car started but smelled really rich (you could smell gas coming out the tail pipe). Also, all the cylinders were not firing. I removed the spark plugs, and they were all covered with black soot, indicating that the car was running rich.

I then put the ECU into diagnostic mode, and drove around. The O2 sensor seemed fine as it would scan from rich to lean (the CEL would light and turn off) quite rapidly. However, I did notice that on deceleration, when the foot was off the accelerator, that the car would run rich a lot of the time (the light was constantly lit). IIRC, fuel injected cars that use TPS are supposed to shut the fuel injectors when the TPS shows that the throttle plate is closed (at least that's what it does in my Miata, the AF meter goes completely lean when the foot is off the gas). It is also running full rich at times at idle, but not all the time. You can blip the throttle and it will start scanning from rich to lean again like it should.

I'm thinking this is what is causing the black soot on the spark plugs. Does anybody know what would cause the car to run rich when the O2 sensor is functioning properly? I'm thinking the TPS right now, but any suggestions would be great. Also, does anybody know what the operating voltage/range is for the TPS? On my SE-R, it's supposed to be between .45v and .55v at idle with the throttle closed, and at 4v during WOT. Thanks!

-V

Kraus91SE

I have the same problem. Did you figure it out? If not, does anyone else no whats going on?

Kraus91SE

onbody has an answer?

eric93SE

iTrader: (1)

Could be leaking injectors. I would reccomend going to nissan for full diagnostics (~~$70) and especially a power balance test.
How many miles do you both have.

male

I don't know if this is fact or not, but if the TPS shows the plat is closed, then the Idle air control or bypass whatever you want to call it, must do it's duty..which is to supply air to the intake charge whit the throttle plate closed. That is the only place for air to enter the intake system with the plate closed..so my intuition tells me that your IAC valve/motor may be taking a sh** on you. Try tapping on it with a plastic handle screwdriver (don't laugh, thisis how we found the prob on my friends BMW!) while monitoring the ECU LEDs at idle..does it change? Try taking it apart and cleaning it real good.I know mine was pretty nasty in there. I think the AIC works off the signal from the TPS (when TPS says closed, ECU tells AIC to open), so the TPS may be faulty too.

male

as stated earlier, could be leaky injectors too, but this would cause cat failure over a relatively short period of time if they are leaking heavily. Power Balance test is a good idea too. Does it run well otherwise? If it runs smooth than you know it's not likely to be ignition prob.

Kraus91SE

I did sef diag and I got 2 codes.

1st Cylinder head temp sensor

2nd ignition signal

for the 2nd one the book say I have to bring it to nissan