So my service engine light was coming on only when I got to 6th gear, cleaned the air filter and tried that no luck, next day it was running worse and lost lots of power. The car has always had a strong smell of gas since I had it. The third day it was running absolutely horrible. Definitely miss firing. So I changed all the plugs and wires. Once I changed them it ran even worse!?!? Checked the firing order and was wrong. Fixed the firing order and now it wont start, and has a small pudder when trying to start. I have triple checked the plugs to make sure they are in the correct firing order and they are correct! Any Suggestions!

 

What was the code that turned on the SES light? Have you scanned it since?

You cleaned the air filter. Was it a K&N or some other brand that required oiling it? Excess oil can screw up the MAF sensor.

 

Scanned and got no codes. Air filter is after market, honestly, just washed it out, it wasn't that bad. I let it dry over night and put it back on. Could it be the coil? I mean could it progressively go BAD?

The firing order was only wrong on the passenger side! Driver side was good. *correction to previous post.

 

My 93Z use to have the SES light come on at highway speed for 10~20 minutes and go out... Turned out to be the EGR valve... No codes either...

 

If the SES light comes on, the code stays stored in the PCM. How are you checking for codes?

 

My buddy has a code reader (hand held). We checked current and historical and it gave no codes! Check out Shoebox website and it rocks! I checked the voltage on coil and it read good! Very corroded so I might change anyway. Second I really think it is the opti-spark, I looked at the diagram and cant figure out which cable to check? do I get reading directly from the opti spark, do unplug something and get the reading from there? Please help.

 

Have you checked for spark at the coil wire going into the distributor? have you checked to see if you have battery voltage and PCM voltage at the ICM? The opti may be the last thing you want to check!!! because you could do it two ways take the opti off or try and turn the Balancer.

 

How would I check for spark at the coil going to distributor? How do I check voltage to PCM and ICM? What will these things determine? Also I have seen some stuff on recalls for the optispark on the LT1s would I still be able to get this taken care of under the RECALL?

 

have you checked out your fule pump?
it can start going bad ,and just get worse.