ka24de Riddle.....

[trust068]

ok, my 91 240sx has a mystery rich problem and different tuners told me different things. just wondering if any of you guys know what exactly is going on with my ka motor, it is driving me nuts and i need to smog it asap

1991 ka24de 5 speed, 196k

ECU replaced by previous ownerK&N filterRSR Exmag exhaust

Symptom:

1. I observed big black marks all over my back bumper (black substances, cannot wipe off with water but can get rid off by simple green)

2. poeple observe it shoot out black smokes while i gas it hard

3. smell like fuel while idleing

what have i done to fix those problems.

Initially it back fires everytime when i change gears and has CEL on (leaky injector, O2 sensor malfunction, coolant temperature sensor circuit malfunction). I replaced a bosch oem o2 sensor and it gets much better, but it still runs weak. however, CEL go away and never get back again.

So next step, I replaced the MAF, coolant temperature sensor with harness, spark plugs, and the 240sx runs even better. (no more backfires). however, , it still leave black marks on my back bumper and smell like fuel. but at this point, i observed 23mpg on my ka24de. so i guess it was not running rich all the time?

So i ran seafoam in the intake maniford and gas tank. improve a little bit (might be paceblo effect) but still runs rich.

so people suggested1. bad tps2. bad harness3. bad fuel injectors4. bad FPR

@_@ i really have no clue................

HELP..

Thanks

[InsanityInc]

Well, if you're still getting 23mpg, that means your fuel injectors probably aren't straight up leaking. My guess is your TPS is just mis adjusted. It happens over time and even a slight deviation can cause problems. Follow the instructions for adjusting it via the voltage between the two wires on it (NOT THE RESISTANCE ADJUSTMENT), and you'll probably find that it's out of spec.