SoCal Laurel--it Runs!!! Kind of... need a bit of advice RB20DET

[kumasan616]

SoCal C33 Laurel brick now does more than collect dust!!!

Okay so after changing the following out:

new z32 platinum plugs adjusted to 0.8MM gaptested and cleaned all coil packsrebuilt RC engineering stock injectorsnew stock fuel pressure regulatornew vacuum linesreplacement MAFReplacement AAC Valve (thoroughly cleaned and tested with voltmeter)new timing belt/water pump/idler/tensionercleaned up contacts in harnessadjusted throttle cable (cable was causing the throttle blade to not close all the way lol)New Coolant Temp Sensoroil changechecked for intake leaks, all connections are tight

...it runs! RB20s are fun, and plenty of power (coming from an AE86 guy), turbo spools strong and pulls like a freight train when boost kicks in and all 6 cylinders are firing

Now for the issues/bugs:When the engine is cold, it will start, stumble, then find high idle at 1500-2K RPM, runs eye-burning rich, but firing on all cylinders, with a bit of stumble. But during driving, the engine has a bad stumble/hesitation, and sounds like its misfiring until RPMS come up enough to let the engine fire on all 6, and not consistently.

Now here's the weird part-- when I unplug the coolant temp sensor when engine is cold, it runs smooth and smells relatively clean burning, with all 6 cylinders firing. Once it gets hot and I shut it off, the engine will not crank unless the Coolant Temp Sensor is plugged it and when it fires, it stumbles/misfires/sounds like its firing 5 cylinders WTF???

Ideas/Advice would be appreciated, I am STUMPED right now.

BTW, engine is a stock RB20DET in a C33 Laurel (no BOV, internal wastegate, etc.)
Modified by kumasan616 at 6:37 PM 1/12/2009

[USMCgetsome]

look in the above sticky thread. It has all swappable parts including your temp sensor that you can get at the local auto store. Get a new water temp sensor and get going!

[kumasan616]

thanks yeah I've been all over the stickies, scoured the FSM, and already have a new water temp sensor (z32) in there, with no luck. I'm going to check the harness for the WTS to ECU for a bad/distorted signal. I'm starting to question the AAC valve, might check that one over as well. What else, could it be a bad TPS? O2 sensor? Time to play the plug/unplug game...

any other ideas or others who have expereinced this problem? Its GOTT Abe something simple, esp. since the motor is in such good shape...

[kumasan616]

Tried the unplug game, here's the results:

AAC valve: Engine hunts for idle (up, down, rich, lean, etc)02 sensor: Engine barely runs, chugs along (low idle, rich)Water Temp Sensor: Engine has high idle, runs smoothTPS: No change (?)MAF: Engine dies. restart unplugged, engine runs semi smooth (limp mode smooth)

...anyone? CarlH? Note the setup would be about the same as if it was in a 240 (almost everything except its a RHD vehicle)

[sil_eightyRPS13]

throw the rb20 away.... get 26!!!