Can Not stay at 1,800 rpm

[Lextreme II]

Hey Gang,

Even before the single turbo installation. I knew there is an electrical problem i have in my 1UZFE. I noticed when i drive from idle to 1800 rpm. There is a bog and then over 2k, the car fly. I always curious about this problem.

Today i just press the gas padle at 1,000 and hold it there and so on to 1,800. At 1,800 the engine rpm doesnt stay. It goes down to about 1200 and then to 1800 back and forth. Basically it would not stay at 1800. After 2000 rpm, everything is cool. The rpm jump up and down when i try to keep it at 1800.

Since its rpm dependent, do u think its the TPS? If it is TPS. Would it the primary or secondary? How about the Idle Valve Control?

 

[KDog]

Try swapping your Main TPS for the traction control TPS.
The main TPS can wear out just around the idle position and light throttle. THis is because the sensor spends around 90% of its time there and it wears out quicker than the rest of the sensor.

 

[Lextreme II]

Is the primary and secondary TPS compatible? I will try that.

 

[KDog]

They are the same sensor. You should have no problems swapping them.

 

[Lextreme II]

Took my car to my mechanic earlier today and the OBDI read the following codes:

13 - Crank Sensor (RPM Signal)
25 - Rich
26 - Lean
55 - Knock Sensor Primary
56 - Knock Sensor Secondary

The Crank sensors are being swap out right now. We will see the change if any.

Update:
All crank sensors changed, no improvement. I think the Split Second piggyback ECU interfer the RPM Signal and give the OBD1 a false reading. Wasted 250 USD. Damn.

I change the TPS (used one) and the problem is gone. However, after few 12 psi boosting, the problem is slightly come back. I would like to get a new tps to take care of this problem. The old TPS ohm reading were little off the oem recommedation. The new one is very close to the referrence.