88fox50

sometimes when returning to idle while driving the engine drops from 1000 rpm down to about 500 along with the voltage ..then back up repeatedly... ...sometimes it runs great then sometimes it hesitates in lower rpms and sorta pops like an internal backfire but i get pissed and mash the throttle and it returns to normal... i have replaced plugs, wires, cap rotor, new msd blaster 2 coil be here tomorrow, replaced EGR, still doing it ...any ideas?? oh and replaced fuel filter...

1988 5.0 GT
M/T

PRO50SC

Try cleaning the iac and the throttle body.

brentloftis

Check or replace the vac line from below the upper intake plenum to the MAP sensor.

Joel5.0

Is it a MAF conversion?.... if so, did you install and wire the VSS sensor?

88fox50

ok i googled and looked thru the haynes book...i will replace the IAC tomorrow (52.00) and i will let u know...but as far as the MAP sensor hose..is there anyway to replace the hose without pulling the intake off? because the hose is definatly in need of replacing..its not cracked but it is dry rotting ....thanks for your help and patience

mjr46

voltage will drop as rpm drops cause the alt output is based on rpm so I wouldn't focus to much on that issue more so the idle issue... after cleaning throttle body and iac..has the car been tuned up lately.

88fox50

i bought it 2 weeks ago....since then i have replaced the cap, rotor, plugs, wires, fuel filter, coil....c'mon man...gimme some credit.

mjr46

how am I suppose to know you have done all that stuff??.........anyway check for vaccum leaks and run a loeo/koer test and verify there are no codes

88fox50

just messin with ya man!...lol ....anyways i appriciate the info...

brentloftis

To replace the hose you only need to remove the upper plenum, and most of the time not all the way off, just enough to get access.