no boost while reving

[5M-GECelica]

well first of all i just bought this car and i have never owned a turbo vehicle before. but while in nuetral just sitting there and reving it doesnt produce boost. it does take a second when you put it to the floor to achiev boost, but i'm not sure if it is related. and i am getting 6 or 7 psi (whatever is stock) thanks for any help.

[jefe_not]

I don't think you'll get boost unless the engine is under load - i.e. not sitting there in neutral. Don't ask me why, just take the car for a drive...

[4SFED]

What he said. And turbo lag probably accounts for the one second wait. Got any long incline hills around? Check your boost on a steady hill climb.

[5M-GECelica]

hmm ok. well thats weird. my duddie had a 7m-gte also and it would build boost pretty easily while in neutral. it was stock and i dont know if an 87 comes with a different turbo than an 88 or not.

[SolidStateS15]

it won't build any real boost not being under load, but depending on what turbo or system you have going some can see a few psi in neutral. enough to shoot off the bov at least if you have a quick spooling setup. usually a stock turbo isn't going to do it for you, but i haven't driven a 7m yet.

[5M-GECelica]

hmm. ok ill take your word for it i just remember my friend had a 7m and he could rev it in the paking lot and shoot off the BOV. oh well

[SolidStateS15]

it prolly wasn't stock.

[4SFED]

My white 85 with 7mgte has a speed/density engine management system (SDS EM-4) which eliminates the AFM. Therefore, there is only a short pipe between the airfilter and the turbo inlet and the BOV vents to the atmosphere. It boosts and you can hear the turbo spool up and hear the BOV vent even when revving up from idle while the car sits. I currently have a Bosch BOV on it but am switching to a Greddy. It sounds very mean - sorta like the whine of a Cummins turbo diesel but louder and throatier.
My black 85 with 7mgte has a stock markIII Toyota ECU and AFM, etc. It will spool up just fine under load, but while sitting there and revving it does not and neither has any of my stock markIIIs that I've owned in the past. My 91 would boost at high revs after I'd put a HKS Dual Drager exhaust on it and shimmed the wastegate and put a Bosch BOV on and cone filter, etc on it.

[WadeT]

Nice way to abuse an engine...

It's not good for an engine hit boost w/ no load. And yes, most BOVs will open and make some noise before actuall boost hits.

[4SFED]

I agree with Wade, that's why I suggested a long steep hill for a load to check your boost.