Loss Of Vacuum On Idle

[paulr33]

hey ya'll

my rb25det this morning at idle -60mmhg

rebooted car, checked throttle etc, all normal, no error lights, no whack sensors

idle is -60mmhg ish and goes to -10mmhg when you open the throttle

the car drives ok and makes boost but peaks out at 0.40kgcm2 and wont go past

engine seems to run ok, doesnt feel laggy etc, drives normal, no smoke, no bangs etc

the reading is coming from the apexi map sensor which uses the plenum signal that the stock guage uses

the stock guage is unplugged - ill check pressure with that tonight

assuming the sensor isnt whacko and manifold pressure is actually -60mmhg at idle

what does this mean? usually its around -550mmhg and it rises slowly with an even throttle into positive boost pressure

i havent checked anything mechanical / physical yet - will do that tonight

[paulr33]

all sorted - its a split vacuum hose

[Munkyb0y]

rebooted car

haha classic

i had the same thing happen on the road. pulled over, and was extremely grateful to find a split vacuum hose (at the T running to factory/aftermarket boost gauges).

i bet you're relieved

[paulr33]

yeah very

i thought i had lost compression etc but then i realised that probably wasnt possible as it ran reasonable ok and made boost

i was surprised it ran so well and made 0.40kgcm2 boost with a split hose - i thought idle would have been poo, smoke at idle etc and lots of popping farting as its basically atmo mode

[Munkyb0y]

yeah surprisingly, if it wasnt for the strange boost readings, i wouldnt have really noticed a problem. when i checked under the bonnet, motor running, there was quite a bit of pressure coming from the split. it was hissing and carrying on pretty loudly. but idle was fine.

[R33Turbo]

didn't even give no chance for anyone to reply lol

[R31Nismoid]

all sorted - its a split vacuum hose

Could have dropped me an email today man, or called me as ive seen that heaps haha

Used to happen to me all the time as i didnt have a cable tie on my VAC line for ages due to me being lazy

[paulr33]

yeah its cool, was on the way to work and it happened no biggie

im gonna redo all the vac lines, just waiting for the apexi solenoid to arrive so ive got the complete pfc boost kit

[Guilt-Toy]

that happened to me, but the locator on the inlet cam snapped and the bolt worked itself loose and it retarded the inlet cam god knows how much.

Compression test read 30psi in each cyl, and the engine still ran! lol

Replaced the cam and its all good now