LT1_383_Stroker

Hi everyone-

I've just got my 383 running, I pulled the plugs and noticed that the plugs are progressively dirty towards the rear of the engine. The front plugs look great. Car is running fine but not tuned yet. Any ideas as to the cause? All injectors are new.

Injuneer

How big are the injectors? How far have you driven it? What heat range are the plugs? A short list of major modifications would help. Is the "dirt" carbon?

LT1_383_Stroker

Thank Injuneer!

The dirt is black carbon. It's a fresh 383; forged bottom and the Trick Flow Heads, Cam and Rocker Combo. I match ported the intake to the heads and the throttle body. Injectors are 36lb. I've been driving it around, but haven't romped on it yet. It's either fuel or air related. I'm leaning towards air. I'm going to pull the throttle body back off. I want to make sure everything is okay with the IAC and the small ports in the intake for idle air distribution. I don't think they are working. I know they aren't plugged.

4th Gen 4 Life

Any codes from the SES? Also you should try to get a custom tune from Soloman.

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Injuneer

Let's try again:

What heat range are the plugs?

And to add:

Who tuned it?

How big is the cam?

LT1_383_Stroker

Hi Injuneer-

The cam specs are 220 int./227 exh. .530 lift. It isn't tuned yet. I have a wideband, I was going to tune myself. I put in NGK plugs; the stock substitute. I pulled the throttle body off. This throttle body has a gap from the IAC to the port in the front of the intake. I think it totally bypasses the idle passages in the intake. I don't know why they would do that. I think that would mess up the idle air distribution!

Injuneer

You're kidding, right? Why would you run a 383 with 36# injectors on a stock tune, and then wonder why the plugs are dirty? Makes no sense at all. Get it tuned before you do anything else. Do NOT continue to run the engine.

You are pouring in 50% extra fuel - fouling the plugs, washing the lubrication off the walls, destroying the rings and diluting the oil to the point where you may y destroy the bearings.

Get it tuned!

97WS6SCharged

Stop driving the car until you can at least adjust the injector constant in the PCM. I'm assuming your wideband isn't hooked up since it should be showing the car is incredibly rich with those injectors and a stock tune.

LT1_383_Stroker

Sorry guys, yes it isn't tuned, but I did adjust the fuel injector constant and fuel tables based on some of the tunes I have downloaded. I meant that the tune isn't final, just an initial setup to get the car running. I doubt the car would start or run without the fuel injector constant changed. BLMs aren't pegged full scale and o2 readings are oscillating, so I think I'm okay to do the final tuning. This weekend, I milled a block to fit into the throttle body to cover the air gap. I've run it a bit and pulled the plugs back out. Plugs are the same color everywhere. I think the throttle body was the culprit, I don't know why they would defeat the idle air passages in the intake.