[stang fanatic]

IS there anyone knowledgeable to the design and flow characterisitics of the ford efi upper plenum? suffering from lack of vacuum and believe to be related to vacuum hose setup

[Twist 2 Go]

¿hablas inglés?

[stang fanatic]

for the life of me, i CANNOT find the 6-7" of vacuum loss im experiencing. wild thought was that hose running from main vacum, goes to a 'tee' under the square portion of the manifold and goes to the pcv valve. the square portion of the manifold has no vacuum? 'teeing' into this portion would create a vacuum loss would it not? it sucks, im now grasping at straws here....all compression cks are excellent and show no valve issue whatsoever

[Twist 2 Go]

1st, how are you determining that you are losing 6-7" of vacuum?

Can you hear a leak or does the eng just not produce enough vacuum on a guage? If it's a guage reading, try another port or make sure there isn't a restriction in the hose you're ck'ing it in. 2nd, try isolating the brake booster hose, the cruise control hoses(if equipped) and also the fuel regulator hose. Does it still have the stock cam or one w/ a lot of overlap? What is the timing set at?

[stang fanatic]

ok, using my vacum gauge and tried several places and reading is 10-11" . pinched off hoses to try to isolate...no luck, except for this one hose as i explained...cant get to it. timings a 10 deg. . as for the cam...i dunno. was told by prev. owner he put either B or E series cam, claimed he couldnt remember, but really and truly believe hes full of shit, so id say stock cam...car ran ok before everything ive done (topic: what did i do wrong)anything...all started when i got it all back together.car misfires almost all way to 4k rpm, lumps at idle and runs off ALL the mosquitos and now maybe the neighbors its running so rich (map sensor believes throttle is open due to such low vacuum)

[stang fanatic]

ok....www.autozone.com...on their listing of vacuum diagrams cert. # (forgot) anyways found diagram that even shows the vac line to go from one point of the manifold to the other (was an 87-88) and then on to the pcv valve. only diff. is fitting with two line (emissions solenoids and fpr) ther is a third line going to the vacuum log for the a/c and the brake booster.

[Twist 2 Go]

ok, mass air car or speed density? If speed density, map sensor on the firewall needs a vacuum hose to it, if maf, no vac hose is needed. 1 hose should go to the pcv valve, 1 to the vapor canister, 1 to the junction block on the cowl, 1 for the fp regulator, and 1 more for all the vacuum solenoids for the egr system and thermactor solenoids. Did you have the lower intake off or just the upper? What is the year model and I'll find you a vacuum schematic for it.

[stang fanatic]

first just the upper, but then thought lower might be bad so pulled and replaced gaskets...87 gt w/sdi. hoses ARE correct, thanks though. but answer this, i read 11' vacuum on the mao sensor line, and i got brilliant, and applied 20" vacuum to map sensor and made no difference. EXCEPT for the neighbors bitching about the fuel smell