Nissan Sentra 1992 EngineOne of the fears I had with getting a old car that dates back just when EFI systems were just going standard is that the electronics might give up on me one day or the next. And I’m fearing just that until me and my mechanic gets to the bottom of it, I might be looking at a lot of replacements for the fuel control system.

Last time, I shared that I’m having some problems with erratic idling. Then the engine struggles to get to a stable RPM (which with the B13 with a GA16DE engine is 750 RPM +/- 50) coming from a cold start. This is accompanied by several RPM dive bombs that sometime would lead to the engine sputtering and dying out. I had to mix it up with a few soft punches of the accelerator pedal just to keep the engine alive.

Since my mechanic didn’t have a CONSULT module that checks the sensors and the ECU for any error codes, we resorted some good old mechanical approach (which are also featured in Nissan’s service manual for the B13). First, we decided to clean all the sensors free from soot, starting with the MAP sensor, then to the 02 sensor, and the idle adjustment valve. We took care to disconnect the battery prior to it so that no voltage spikes may damage the ECU.

First, we checked the ignition timing if it was set to the specified degree. Next, we checked the idle valve to make sure that the proper engine speed is reached while idling. Still no progress. One thing we noticed though, is when we tug on the throttle cable, the RPM stabilizes quickly so we adjusted the throttle cable settings to get rid off the slack. After doing so, the RPM seems great. Tried coming from a start and the engine came to life and almost straight to the specified RPM.

So I went home, happy that the car’s supposedly in tip-top shape mechanically… finally.

Then the next day, I tried starting the car and experienced a hard start. Took me 5 seconds of cranking and the RPM still dove and the engine died. Cranked it again and it came to life, RPM dove to critical but erratically managed to get itself to normal RPM. Tried it out a few more times throughout the day and had a mix some good starts and hard ones. Quite puzzling.

Generally, I don’t have any problems now when the idling’s stable and is good to go. On the road, I have no complaints whatsoever, only that when I cruise down to a halt, depressing my clutch, several close-to-dying RPM divebombs still happen.

I’m just giving the ECU time to remap new driving data (and the prior adjustments that we made) for a few days, if all else fails, I might be force to go to a Nissan d(st)ealership and have the darned ECU nitpicked using their CONSULT diagnostic module. But as with dealerships, they’d push you to replace everything with brand new parts that we all know, that coming from a dealership, would cost a fortune.