I took my car to the dealer for a surge at idle and random low rpm miss (very random, like 10% of time, if taht) and they said they would do the run down.

Well 53 dollars later they said everything is ok and that all the sensors look fine.

My blms are at 107 on each side and it runs really rich, plus the idle is a little rough and it surges at stoplights after an hour or so of driving on hot days.

When it surges the tach moves really crazy at first, like 500 to 300 to 1200 to 1000ish and then it just keeps suging till it stop, usually a 10 second or so episode. I am thinking opti, but am afrraid to waste the $ if it aint. My Iac counts go way up to 130, but i have replaced the iac three times. Any insight?

 

Kinda sounds like a vacuum leak, maybe around the intake manifold or something.

Mike

 

Check your intake elbow perhaps? Just guessing.... some get rips on the underside and can be really hard to see.

 

i temporarily cured mine by replacing a messed up plug wire. my guess is thats the problem again, im gonna go into this weekend and see if i can get to the bottom of this. my car surges like hell at stoplights, i thought it was gonna die today. my gauges all fell really low(battery, oil pressure, etc.) I am gonna garage it till the weekend to figure out what the hell is going on. Thanks, Michael

 

my car also backfires like hell at like 4500-5k+ rpms. I am gonna buy a scanner cuz im sick and tired of paying the damn dealer to tell me the bull ****. -MIchael

 

all signs point to opti.
The car seems to be running rich because your Hi res sensor is not working properly and that is what the pomputer uses to pinpoint the position of the cam, therefore your computer is trying hard to lean it out by lowering BLMs.

The RPMs If I remember are taken from the low res opti signal which asts like a crankl sensor since there isnt one in 93 -96 LT-1s. The High RPM miss is again the high res sensor. the computer cant advance timing because without that sensor it doesnt know how fast the motor is moving to advance it.

Good noows however, the Distributer part of your opti is probibly working fine, which leads me to believe it could be the optispark harness, It is a 15 insh 4 wire pigtail that couples to the main wiring harness by cyl #6 and goes down to the back of the opti, 2 of the wires are the low res signal the other 2 are the high res. clean the connectors at both ends and look for cuts/ burns on the wires. if that still doesnt fix it you may consider replacing it anyway, I say that is more likely the problem than the opti, it is 40-50 bucks and not too hard to replace. good luck