NewOrleansLT1

Ok so I was having a stumbling issue upon take off and at low rpm and idle after a hard run on the interstate.. The car barely wanted to make it up the driveway! The next day it didn't want to start.. So I changed the coil and the car started. But it does the same thing? I took the opti off and it didn't look that bad in the inside. Could the optical sensor go bad even tho it looks good? The car revs good in the upper rpm. It mildly back fires through the intake and exhaust sometimes fuel pressure is spot on. I just can't see it being the o2's causing this much havoc! I think it's the opti because the car is acting real load sensitive.. Any help appreciated...

cardo0

Check any codes? Well u got the opti out now - just replace it with a good AC Delco and we will know if it was or not.

NewOrleansLT1

no codes

NewOrleansLT1

if this thing doesn't act right after the opti swap it will be for sale! Asking $3000 not bad for an 11sec car...

fbody_brian

Mines doing the same thing right now, and I know exactly how you feel. If I replace the opti and it still doesn't run right

SS RRR

iTrader: (2)

Usually that is a timing issue. Could also be a vacuum leak.

Adam1203

iTrader: (5)

I agree with SS RRR most times that is a timing issue.

I would go through everything before I just jump on the opti though. I have seen post where guys claim to have gone through 4-5 optis in like 5-10k. I think a lot of people just want to jump on the opti rather then take the time to properly diagnose the problems which results in a lot of lost money and poor results.

http://shbox.com/1/4th_gen_tech2.html#opti_test
http://shbox.com/1/coil_testing.jpg
http://shbox.com/1/4th_gen_tech2.html#ICM_cooling

NewOrleansLT1

Ok so I just scanned the car. I can't start it at the moment but with the key on the intake temp is -40? What y'all think?

BALLSS

this may help diagnosing Opti

http://shbox.com/1/4th_gen_tech2.html#opti_test

I don't think data scan with engine off is accurate so the numbers you are reading may be false

NewOrleansLT1

Ok so I found a short in my IAT sensor's wiring.. It's reading the proper voltage now. I'm still waiting on opti though.. I'll keep you guys posted

F0x Slaughter

Read the no start threads I posted a link how to diagnose a optispark optical sensor

NewOrleansLT1

this is a sticky over at z28.com

Is Your Opti-Spark Failing?

LT1 owners have dealt with the Opti-Spark distributor for 11 years now, but there is still much confusion regarding the causes and symptoms of a failing unit. Tapping into the PCM with a scan tool is a good way to start, but sometimes no codes will be set. Before diving into the Opti-Spark, be sure to verify that your grounds are good and the coil and wires are not the source of the problem, as they are much easier to change.

Symptoms:

* Car suddenly dies and won't restart
* Starts but immediately dies
* Extended cranking to start
* Rough idle
* Sputtering
* Backfiring
* Trouble reaching higher rpm
* Black smoke from exhaust
* Poor performance with car warmed up
* Weak plug wire spark
* Codes 16, 36, and 42 may be set

My car is doing about 7 of the above. I posted this for future searchers..

NewOrleansLT1

It was my opti that was bad! The bearing was shot and the metal pop rivet on the rotor was coming loose. It was hard to tell by just looking at it but once I compared it to the new one I knew the old one was shot. The car is running like a champ again!! Thanks to all who replied and helped me out..

cardo0

Thx for post. Feedback helps us all.

fbody_brian

glad you got it fixed
I'm about to replace my opti also, if it's not the issue I guess I'll have a spare. Can't hurt to have a spare opti!

NewOrleansLT1

Thanks. And your right can't hurt to have a spare. I'm about to take the car down again because I didn't replace the seal and it's trinkling oil. While it's down I'm going to install a heavy duty rotor..

NewOrleansLT1

I'll also add to this thread that before my opti my really took a dump the car had bad torque converter shudder when it locked up with a heavy load. I thought it was TC but now since I have ODB2, new coil, spark plugs and opti it locks up butter smooth.. I don't know which of the above fixed it but it's fixed lol