Friday, June 6, 2014

PCV Valve and Throttle Position Sensor on My 323F Astina

Drove it with broken PCV and TPS socket unplugged for straight two years without major problem

At least, my luck is gradually wornout

The symptoms began the moment I change the broken PCV valve.

After replaced the old broken PCV valve and installed the new one, there's no change at idle.

Another story when I stepped on throttle pedal, the engine is getting hesitant and the rpm didn't rise smoothly and it had tendency to not rise at all.

Hmm, if broken PCV valve and unplugged TPS proved okay, whilst new PCV valve and unplugged TPS result in trouble, then combination of new PCV valve and plugged TPS maybe solving the problem.

The result is I have low idle rpm, so far so good, and I stomped the throttle pedal, the rpm is increasing smoothly, this getting better and better until rpm reach 3000 and suddenly drop to 1000, ...

I press and hold the throttle pedal, hoping it can reach beyond 3000, to no avail. It drop every time it reach 3000 point.

Here, almost without doubt that the TPS is the trouble maker. Almost, since the idle setting and other setting is done with the TPS unplugged, so maybe my engine have wrong setup since begining, still...

Checked TPS with OhmMeter, the result is fine, no problem.

Checked TPS socket (cable to ECU) using voltmeter, the signal is OK, so the TPS isn't the problem.

My TPS is the switch-type-TPS (from many online source including discussion in Mazda Astina Indonesia ), in opposite to potentiometer-type. So it has three switch position mode. (look at the first pic)

Let us name three connector cable in TPS with A, B and C. The first position is when idle, without step on the throttle pedal, A and B is connected. (second pic)

The second position is when we slightly open throttle; A, B and C is connected together. (third pic)

Finally while we are on full throttle, B and C is connected. (4th pic)

I don't really know, maybe because my "exotic" setup since beginning, my 323F couldn't get right rpm while TPS is plugged, so I manually checked by bypassing it function using jumper.

Bypassing A and B through jumper resulted in erratic rpm, it oscilating from 1000 to 3000, ....., ups..., the throttle cable is stuck, make it right...., ok, rpm at idle is 1000, step the throttle, and...., still drop at 3000, duh....

The same with A, B and C connected together.

Don't have a choice, bypassing B and C and... Idle is 1000, step the pedal, it raise smoothly to 3000 and 3500, 4000 and so on..., huray...

Stick with this setting until now, :)