Help! No throttle body vacuum

[Dog]

Hi here is my first ever question. I have just reconnected my vacuum hoses. But I don't seen to have any vacuum from the front throttle body male outlet. It go's to the egr solenoid and tees of to the Absolute pressure sensor. Is there any reason I have no vacuum at the throttle body ?

 

[Dog]

No throttle body vacuum

Only problem is my 84 has been converted to a tune port injection motor so I don't think that diagram suits my motor.

 

[vetteoz]

my 84 has been converted to a tune port injection motor .

You did mention the front throttle body which would make one assume you have 2 TB's ;ie a stock 84 CFI engine

Is there any reason I have no vacuum at the throttle body ?

At idle ?
That port is ported vac only

and tees of to the Absolute pressure sensor.

Your MAP sensor is connected wrong ,
it should be connected to one of the 2 vac ports at rear of plenum with as short a line as possible for best response

 

[roger longman]

Hi here is my first ever question. I have just reconnected my vacuum hoses. But I don't seen to have any vacuum from the front throttle body male outlet. It go's to the egr solenoid and tees of to the Absolute pressure sensor. Is there any reason I have no vacuum at the throttle body ?

Your first ?....A bit slow off the mark eh !......Roger..

 

[BRUTE86]

You might have vacuum from all the ports. However, you might be getting confused between Port Vacuum [which occurs at higher throttle opening or acceleration], used for such things as distributor advance {where applicable}, canister purge,], and Manifold Vacuum [which occurs at lower throttle opening or deceleration], used for MAP Sensor, PCV valve, Air Cleaner, Fuel Pressure Regulator {reducing fuel pressure}, Heater and A/C Systems and EGR.

I personally don't like 'T' sections, but do like using vacuum check valves. The ports at the rear of the throttle body should have the following connections:
- The highest port [with a factory bend on it] is port vacuum, and should be used for canister purge.
- Of the rest [all manifold vacuum], the largest one is the PCV Valve port.
- The one closest to the edge of the throttle body and near the large PCV port is the air cleaner port..
- The lower one [towards the centre of throttle body] on the other side of the PCV port, is your EGR port.
- The last one [high and by itself] is for your Manifold Absolute Pressure port.

Make sure all the hoses are intact [not hard or cracked], and are a very tight fit.
Good luck

 

[vetteoz]

- The highest port is port vacuum, and should be used for canister purge.
- Of the rest the largest one is the PCV Valve port.
- The one closest to the edge of the throttle body and near the large PCV port is the air cleaner port..
- The lower one on the other side of the PCV port, is your EGR port.
- The last one [high and by itself] is for your Manifold Absolute Pressure port.

On a MAP TPI TB the Op has installed

The top port ( # 7 ) is the CCV air supply to the pass side rocker cover
The one underneath ( # 8 ) is the CCP vac port from the purge canister
There is a small ported vac outlet underneath the TB that operates the EGR solenoid
The MAF, fuel reg and AIR valves all get their vac from the ports at pass side rear of the plenum

 

[vetteoz]