RB20DET IM SO LOST

[yotik]

So yeah, I searched and searched- but still having 2 issues:

1. I cant figure out where this coolant hose connects to. Its the one under the throttle body going from the plenum towards the back of the block. BTW as far as I know all hoses are hooked up.

2. Engine bogs at around 3500rpm. Im only building boost in 3rd gear going uphill (5lbs). I checked all my vacuum hoses and seems like maybe im missing something?

Any advice and help would be GREATLY appreciated.

[Carl H]

not sure on the coolant line bit...its been ages since i've had my stock plenum.as far as the boost issue goes, it shouldnt be THAT laggy unless you have an rb25 turbo which will run about 5-6psi base off of the actuator and spool around there, without a proper tachometer its hard to tell where the engine is revving just by sound as these engines are high strung and sound like they are revving higher than they are.

does the engine run and idle smoothly?does it free rev smoothly?is there any damage to the ignitor?

in your video you posted it was hard to tell but it sounded like it was missing, might have been the recording or it was indeed missing.

[yotik]

it idles but seems to be a high idle to me (again no tach just yet). seems to be a high idle because the rpms drop when i put it in gear (high idle right?).it does seem to miss a little in low rpms, then cleans up as it accels. other than that smooth accel til it hits the mystery rpm. if i rev it in neutral it cuts out at the mystery rpm and wont go any higher. same thing happens when in drive. boost gauge reads vacuum at all times except in 3rd gear going uphill. is it the maf wiring? help!

[yotik]

I might as well post my specs to save some time..

nothing special:

rb20detstock mafstock ecuwalbro fuel pump 255lphstock turbo with downpipecrapbay same side intercooler and piping

once i getting it running good ill start changing things.

[240daveTX]

make sure your maf is plugged in tightly. then check the wiring where you spliced it. it almost sounds like its running in safe mode cause your maf is unplugged. and if you did splice it, did you make sure to use shielded wire on the two wires that should be shielded?

mine had a slight miss at low rpm as well, then i made a ground for the coilpack and a few other grounds and it went away. making sure the engine is well grounded will be a good way to eliminate alot of your electrical gremlins.

[yotik]

aha! theres a mistake i made. I did not use shielded wire on the splice maf wires. 2 wires get grounded right? so it must be running in safe mode. im going to get the tach resolved + look into this i bet thats the reason why its being so moody. maybe one day ill graduate from rookie.


Modified by yotik at 12:30 AM 6/28/2009

[Carl H]

if you cut and extended the harness further then check the connections, the white sheilded wire is NOT the signal on the rb20 r32 harness but ground...but the black wire is the signal.

[RustspecS13]

I think that throttle body coolant line snakes back to one of the heater hose lines. I don't know how you're not gushing coolant with out it....

~Alex

[yotik]

any idea which hose it connects to? I have everything hooked up as far as i can tell so somethings off.

[lexrob]

I have the same problem no idea where coolant lines go to. I dont even know if i have the right ones.......

[legit240sx]

got my sotck mani off the head and will try to take pics of it manyana

[moso240]

Try to get pics of the collant line so we can see exactly what ur talken about....

The 3500rpm sounds maf related have you checked for any codes at the ecu?

[yotik]

ill post some pics today..

[yotik]

ok so here is the line i cant figure out where it goes:





everythings hooked up but this one is just hanging there. no fluid seems to spurt out with the engine on either, however ive never let the car run long enough to really do much.

anyways if you guys can help with that i would feel like:

and also, i found out today i am def running in limp mode. I was able to start the car with ONLY the shielded wire grounded. any tips on getting the stock rb20det maf to work? there are 2 grounds right? what colors? a diagram would solve this i think. help!

[MATTs14]

thats definitely not a coolant line. Its a vacuum line that can essentially be capped as this is what i did with it. When this motor is swapped into your car there are tons of things that the donor car had that your 240sx does not. Cap it just for giggles and let us know if that helps you out. Good luck!

[yotik]

if thats true then it all makes sense now. thats why i cant build boost. all i can say is:

[RustspecS13]

If that's a vac/boost source just start the car and put your finger over it. If its vacuum source then it'll seal against your finger. If not then that's a coolant line. Which it looks big enough to be a coolant line.

~Alex

[yotik]

yep it was the source. grabbed a cap and now im building full boost! and i shielded the maf and separated it now it works perfect. carlh had the wiring right i shoulda never doubted him.

once again nico saves the day, it was a $3 fix.
Modified by yotik at 6:20 PM 7/1/2009