joefuhring

Been having problems with a miss in the engine and also hard starting. Replaced the opti-spark,map,Idle control sensor, plug wires, mass air flow,throttle control sensor, fuel injectors, temp sensor. The only things that I have not replaced are the o2sensors and the knock sensor. Have checked and rechecked for a vacumn leak - no leaks.

Then engine starts in a very advanced timing mode, running extreamely rich condition must run engine at 1500 rpm to keep it running - runs rough with a miss and pings under load. Run out of ideas and parts to replace. Any suggestions? Maybe the Knock sensors? Maybe the o2 sensors?

383vett

Have you checked timing and fuel pressure. What do the plugs look like?

joefuhring

The plugs read very rich, as far as timing goes no real way of checking since it a opti spark. When it starts up it starts very tapical of an engine way too advanced, when running there is a ping that appears when reving up the engine as well it is running very rough.

C409

............. The fuel pressure regulator may be shot ... check for fuel in the vacuum hose ......... Stop replacing parts without a fault code and diagnosis confirming a need ...............

C4vettrn

Did you check the voltage on the idle air control sensor when you replaced it?

bjankuski

Make sure you have the correct firing order on the opti, the cap wire placement is not the same as a sbc. You can make a pointer for tdc and check your timing.

pcolt94

This is where I would start. Fuel in the manifold would make for a hard and rich start.

Is the digital temperature gauge working normal?

Have you tried to isolate a non-firing cylinder?

The PCM sets all timing and cannot really be checked with a light.

Although I don’t think you will solve this checking for codes, it would be a good routine check to see if a code was set.

Have you checked the EGR to see if it is moving freely, not stuck and closing properly.