aight...here we go.....i've got an 86 trans am 305 tpi
major hesitation off idle ....aaaalways...in gear or not
put a vacuum gauge on it...15-16 inches of vacuum...and it struggles to stay alive a little bit....then figures out that its having a hard time idling and kicks to a higher idle....giving it about 17 inches of vacuum....
when you snap the throttle....the vacuum drops to 0 and recovers to about 20....then when it idles down it drops back to 16
being an 86 it has a maf....but not a map....so it doesn't code for low vacuum
disconnected the egr sol. - no difference
major exhaust leak just before cat - i'm gonna weld it.when i get time...but could that cause low vacuum?

gimme some idea's on how to fix this...i'm sorta lost

 

A couple of things to check/try:

1) Verify Proper Fuel Pressure (USE A GAUGE)

2) Verify Proper Base Timing

3) Remove the TB and clean it.

4) REMOVE and clean the IAC and the pintle bore while you are there.

3) Set the Minumum Idle Speed (use procedure)

4) Adjust the TPS to .54 Volts.

5) Check Operation Of The MAF Burnoff Relays

6) Install New Air Filter If Necessary


Should take less than an hour to do all the above.
Good luck with it.

 

all those things i have already checked and are good....anymore idea's guys?

 

Connect a timing light and see what the timing is doing when you accelerate. Could be distributor problem.

 

Could be the MAF sensor also, try unplugging it then firing it up.

 

timing is fine 6 degrees base....and advances just fine

runs exactly the same if maf is unplugged or not....


changed plugs and wires cause i noticed two of the wires to have been heat damaged by a broken brace

adjusted the base idle( was way off....but only helped it idle by down quicker since the iac was doing aaaaall the work before)


not quite as bad of a hesitation.....but its still there
the wires fixed the low vacuum...which was odd cause the cylinders weren't misfiring

but it just drops to 0 inches on a throttle snap from idle and stays there for a second or two before it comes back up ...hence the hesitation.....

anymore idea's?