07-19-2013, 08:26 AM
when you take a head off or expose the deck of any block the 1st test, besides the magic gasoline test to combustion chamber is...
1: head warp test, per the FSM , the mech. steel rule, (flat) and edge down cross wise. feeler gauge in hand, max .002 warp
then same way and same rule, the deck.
the gasket can fail if the deck or head are warped.
i can link the fsm page online for all that. but is SOP all engines.
the rule of thumb is .001" warp per foot. so .002 is on the high side.
keep in mind the bolts get tighter hot , so the head torque is only the starting value, , do not over torque any head.
you car correct the idle works same 89 to 95 on all 8v
the only diff, is the method of setting idle. the 89/90 the Throttle body has no idle bleed screw.
so you mess with the idle stop then the idle switch fails (out of calibr.) you fix that then repeat it all again, again and pull hair out.
that is why they added the bleed, to stop balding suz, mechs. world wide.
it can be real hard, if you have vacuum leaks, near impossible.
one guy here you could block the air horn and motor would run. he told me that was normal. so we gave up.
but you have too little air so is a horse of different color.
low idle on 89, cold is this.
1: IAC not open (TB base air valve dead closed and dead)
2: iSC dead, and or TPS switch stuck open and idle controls are inactive in that state (a lie to the ecu makes ECU mess up)
3: the dash pot must open keyon then retract after 3 to 30sec cold started, if it get stuck retracted, idle will no race at start up.
4: someone closed the TB idle stop screw, or unscrewed it radially.
this assumes spark timing is right. as timing dictates idle speed big time. (retarded = low, too advances too fast)
1: head warp test, per the FSM , the mech. steel rule, (flat) and edge down cross wise. feeler gauge in hand, max .002 warp
then same way and same rule, the deck.
the gasket can fail if the deck or head are warped.
i can link the fsm page online for all that. but is SOP all engines.
the rule of thumb is .001" warp per foot. so .002 is on the high side.
keep in mind the bolts get tighter hot , so the head torque is only the starting value, , do not over torque any head.
you car correct the idle works same 89 to 95 on all 8v
the only diff, is the method of setting idle. the 89/90 the Throttle body has no idle bleed screw.
so you mess with the idle stop then the idle switch fails (out of calibr.) you fix that then repeat it all again, again and pull hair out.
that is why they added the bleed, to stop balding suz, mechs. world wide.
it can be real hard, if you have vacuum leaks, near impossible.
one guy here you could block the air horn and motor would run. he told me that was normal. so we gave up.
but you have too little air so is a horse of different color.
low idle on 89, cold is this.
1: IAC not open (TB base air valve dead closed and dead)
2: iSC dead, and or TPS switch stuck open and idle controls are inactive in that state (a lie to the ecu makes ECU mess up)
3: the dash pot must open keyon then retract after 3 to 30sec cold started, if it get stuck retracted, idle will no race at start up.
4: someone closed the TB idle stop screw, or unscrewed it radially.
this assumes spark timing is right. as timing dictates idle speed big time. (retarded = low, too advances too fast)
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