Engine code 61 help

[Johnny5]

Hey guys so i replaced my injectors, coil packa, wires and a few upgrades but the secondaries arent kicking in. I thought it may be the 2nd fuel pump but i pulled code 61 yesterday which the manual states is either vacuum pump or the vacuum transduser (provides signal to computer). Its hesitating when given heavier throttle and revving slowly. Anyone have experience with this?

[Johnny5]

Or know where the vacuum transducer is? ( not sure if i spelled that right)

[XfireZ51]

The secondary or differential MAP sensor provides a signal to the ECM for adequate vacuum. It's located under the ECM and has a vacuum hose and harness connector on it. If it signals to the ECM that there isn't enough vacuum, the ECM WILL NOT open the secondaries. Now WHY there isn't enough vacuum is another matter.
94-95 motors has sensor under plenum.

[Johnny5]

I am going to see if thr vacuum hose is connected and getting pressure.

[secondchance]

Code 61 is;
61 Secondary Port Throttle System Error

My experience when the differential MAP sensor failed code 56 was thrown. I would check if the secondary fuel pump was working.

[Johnny5]

Hey Young, yea i thought it was the 2nd fuel pump as well than i read that code with a paper clip. I have to test the fuel pumps. Its been 3 months Ive been waiting and I still have yet to feel the LT5 at full power

[Coupe89]

I just replaced a check valve under the plenum.

I wasn't hold vacuum.

I put installed a t and gauge over by the map sensor.
I was the gauge take vacuum. Then the vacuum discharged. Only held for 2-3 seconds.

[mike100]

hook an actual vacuum gauge to tube that goes to the under ecm map sensor for the secondaries. You should get a constant 13 inches of vacuum when you floor it if there isn't a massive vacuum leak somewhere else.

you may have to force the secondary vac solenoid to turn on if it won't activate due to restriction in the ecm with the fault...or clear the code and drive it once.

[Johnny5]

I am going to follow marc heibecks procedure and ground that part in back of the ECM. if the secondaries don't open......it has to be the solenoid, in which case i will have to buy jerrys and alter it or buy a new/used one off a member.

[Johnny5]

thanks for the tip Mike100. I grounded pin C17 on the ECM and heard nothing so the solenoid needs to be replaced. Hopefully that's the only issue. I'll let you guyx know after I replace it tomorrow or Saturday