RB25DET Powered 240sx s13 (89) mid range power loss

Discuss the RB20, RB25 and RB26 series engines.
Ninjaplease41
Posts: 3
Joined: Tue Jun 28, 2016 4:22 pm
Car: Rb25det s2 powered 1989 240sx

Post

I posted about this in the GTR/Skylines section, and posting here just for the chance that it may be seen by more.

I bought this 240sx with the RB already swapped and the wiring is horrendous, but was running fine before a week or 2 ago. Basically it feels like it boosts for a split second and then loses acceleration. But my gauge reads 10lbs of peek boost, and between 6-8lbs under normal conditions. Lower rpm it feels fine, until I start to spool. High end RPMs feel better as well, still not enough power like it should be but it is way better than my mid range. I replaced the fuel pump (Walbro 255), fuel filter and adjusted the regulator to have 43psi (no vac). Checked spark (1 clip on my coil pack was broken and couldn't find another so it's now wired in with electrical tape... but still gets spark). Unplugged MAF to test if it wouldn't like it as much. (Unsurprisingly didn't like it) But recent hunch was TPS sensor. Unplugged both plugs (since this is a series 2 RB25) And it ran slightly better. Still loss of mid range power, but boosts slightly longer. Tested the voltage with a multi meter (didn't check ohms, oops) and had 0.9v-4.9v Closed - Wide Open, respectively. And the transition was smooth as it should be.

Just wondering if that slight bit of voltage being off would create this problem?
How to adjust the TPS?
What else it could be?

Any help would be gratefully appreciated, miss the RB's power. Haha.


Ninjaplease41
Posts: 3
Joined: Tue Jun 28, 2016 4:22 pm
Car: Rb25det s2 powered 1989 240sx

Post

So, just found out that it is actually a Series 1 engine, not series 2. The second connector for the tps was the throttle switch for automatic transmissions? Either way, series 1.


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