Need some more help Guys! Please!

[LeeS97Z28]

Hi Guys!

Well I changed the fuel injectors and fuel pressure regulator. Believe me the injectors were dirty and the fuel pressure regulator was bad too!

Although this helped a lot, it still studders and pops in the exhaust. But not in the intake.

My car has a new opti that was installed by the dealer!

The dealer also installed AC Delco Plugs and wires. I have put New EGR Valve, Map Sensor, and Intake air charge sensor.

I have cleaned the Mass Airflow sensor and the throttle body ( I put new gaskets in the throttle body.

Is there any way to test the OptiSpark distributor or Can the dealer test it?

Could the O2 sensors be bad and not turn on the light. Would that make it studder and idle strange?

Guys I am open to suggestions!

I am going to get a scanner what would you recommend?

Thanks Lee!

[Craig 94 TA GT]

My recommendation: a laptop, cable and Freescan. You can check your BLMs, and every sensor to see if any are going, or giving bad readings.
A couple questions though...what's and "Intake air charge sensor" The IAT? Also, have you checked your fuel pressure after you changed the injectors and regulator? How about the fuel filter?

I have a similar problem. I replaced everything you have, including springs, roller rockers, and lifters. I have a low end hesitation/stumble problem, and I'm not sure if yours does that too Every tiny replacement has helped about 5%, but it's still there. I already ordered new headers, new O2s and a new cat because those are my last options. Hopefully, yours will be fixed without going that far.

[01SS]

make sure all the plug wires were on the plugs firmly?

[Injuneer]

He can't use FreeScan, its a 97. He needs AutoTap.

Coil? IC Module?

Shoebox has a writeup on how to verify that the Opti is producing the required signals:

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

Also has a mod that shows a way to reduce temperatures on the ICM, spacing it away from the head. That has helped in some cases.

[Craig 94 TA GT]

Oops, sorry, I didn't realize Freescan couldn't handle OBD2
Also, I did the ICM/coil spacing (about 1/4") and did notice an improvement. As Fred mentioned, it's worth a try.

[camaros_rock]

check your timing, thats what it sounds like while changing all that crap it could have gotten knocked out.... never know worth a shot

[Injuneer]

check your timing, thats what it sounds like while changing all that crap it could have gotten knocked out.... never know worth a shot

The timing is controlled by the PCM. There is no way to check it on an LT1. There is no timing mark on the damper, and even if there was, there is no keyway to hold the damper in place on the crank. Nothing that he changed, other than the Optispark distributor could affect the timing. And the only way the Opti could be "off" would be it he had the dowel pin in the wrong hole - difficult to do, and the engine would barely run, since the distribuotr would be 120 cam degrees off the correct position.

[camaros_rock]

I'm sorry, I really dont know a whole lot about ls1/lt1's I'm just trying to pitch any info I might be able to and as far as those damn map sensors go, check the hose line on it my grand prix was doing that and the line broke and had a vaccum leak

[Injuneer]

The LT1 sensor is bolted directly to the intake manifold.... no hose. The rubber seal can leak though.