P0300 Battle

[Phone Man]

OK folks I have been having issues with random misfire code. Sometimes it runs good and sometimes I can feel the miss in the drivers seat. Everything has been changed... Plugs (now using copper core ngk's, tried ac and e3's) O2 sensors, Wires (3 types, Accel, MSD and Taylor), Changed cap, rotor, Using Mallory ignition as well as trying stock coil and Another coil just for the heck of it, New spider injector, tps, map, egr, iac, tb etc etc etc.

Runs great on the road, acceleration is great, worse at idle.

Any ideas?

 

[animalfries]

I had the same problem...ran fine except at idle. It ended up being a bad fuel pressure regulator. I have a 2000 but if you pull the vacuum off the regulator you should not smell gas. If it does, replace it.

Don't wait a year like I did, I'm now getting a bad cat code because it ran rich for so long.

 

[Phone Man]

Hmmm my regulator is located on the spider under the manifold. As far as I know there are no vacuum lines

 

[animalfries]

bummer. I'm not familiar with the earlier stuff.

Does this help? http://troubleshootmyvehicle.com/gm_fuel_injector_4.3L_5.0L_5.7L/spider_fuel_injector_1.php

I'm somewhat talking out of my ass here, just letting you know what I went through. On a 2000 if you got a new spider it would have come with a new fuel pressure regulator...I have no idea if yours did or not. Maybe someone else can chime in and eliminate one of the possibilities.

 

[SunlitComet]

Have you actually performed a compression test yet?

 

[Phone Man]

no b/c the motor only has 10,000 on it and I have to remove the headers in order to get the fitting into the spark plug hole. I thought I had found the problem b/c #4 wire had 100% resistance on it. Then O2 code popped up and the plugs look like she was running rich. Changed those and then again p0300

 

[SunlitComet]

this is after you erased the previous occurrences of codes.

 

[Phone Man]

Yup. I have a Scan Gauge II hooked up all the time. When ever the code pops up, I just reset it. Happens just about every time I use the auto starter AFTER driving somewhere. Even though the spider is new, I'm going to check the fuel pressure again to see if it leaks down too quick.

 

[chitown906]

Been getting the same code. Going to keep an eye on your posting

 

[SunlitComet]

Then it has to be an injection or compression issue. at least do the test to rule it out. I would also be interested for technical reasons what the compression is like in the ht383e.