Hey, thanks in advance for reading this. Recently I just put a rebuilt 305 TBI engine back into my 91 RS and I am in the process of getting it to run right, right now it will stall out when I put it in reverse,drive or any gear, any ways I pulled the codes off of my car and it had a code 12 and a code 34 the code 34 says that the MAP sensor has low vacuum, I am not sure where the MAP sensor is, I have a vacuum hose that comes out of my wiring harness hooked up to the back of the TBI unit where the vacuum hose should be running to the MAP sensor. Anyways my main question is where is the MAP sensor, or is this the right hose I have it hooked to? I can take some pics if need be. Sorry if I posted this in the wrong spot not really sure where to put it. Thanks again for taking the time to read this and any input you guys have.

Codey

 

Codey

If you are pulling Code 34 you should make the following basic checks.

Get a vacuum gauge and measure vacuum at idle by disconnecting vacuum hose right at the MAP sensor nipple. (hmm). You should be seeing idle vacuum of your engine and depending on your engine combination it can very significantly. With a factory cams 16 to 20 in-Hg can be expected. With engine RPM below 1200 RPM Code 34 will be set if MAP sensor voltage is too low – very high vacuum ~ 25 In-Hg (0.25Vdc).

Check MAP voltages, with a DVM, pin B, at idle it should be around 1 to 1.5 Vdc. If pin B reads around 0.25 volts check + 5Volt reference supply, at pin C of MAP sensor – it should read close to +5 Vdc. Pin A is ground – it is very common during rebuilds to forget to connect ground!

MAP sensor can be damaged by moisture accumulation if improperly mounted. MAP should be mounted with inlet nipple mounted downward. Dead MAP sensors will have near zero output voltage at Pin B.

//RF