Trying to pinpoint the problem where my car started running crappy.

Basics: '97 LT1, Base tune & OBD-1 conversion via MadZ28, 383 ci, Advanced Induction Full Port heads, ported intake, Delteq, 42# injectors, Jet Hot Long Tubes...and a ton more, but that should cover the essentials. Supposed to be a 425-445 rwhp setup.

This first night it ran pretty darn good. Today it started stumbling/missing/running like crap.

I saw a melted wire loom, so I figured I had some melted wires (I was hoping), but they all look OK.

I have my old O2 sensors in still since I am running Jet Hot headers, and I read hear to run my old sensors while those were heated up the first couple times. They've gone through a few heat cycles, I should be OK to put the new O2 sensors in now, no?

I decided to pull a plug out, I think it's #4...2nd one back on the pass side. It's covered in black/sooty/carbon. I'm wondering if this is what's causing all the misfires, or if the problem lies deeper. I'm running NGK TR-55's based on popular opinion of this forum, but then again, doesn't mean it's specific to MY engine.

I don't know if I should just go with a different plug, or try another set of the same plugs since the engine's now broken in, or if I should get a datalogger and a more precise tune...not sure which direction to go here.

Going to pull the rest of the plugs and see how they look too. I don't know if it's fouled because of something ELSE going wrong, and making it run bad, or if it's running the way it is because of it fouling and something awry in the tune...

Thanks for any advice...
Dave

 

What kind of looms do you have and where did it melt? Sometimes you can damage the wire on the inside with the outside looking OK. I wouldn't rule out plug wires yet.

--Alan

 

The looms are just the split-loom convoluted tubing stuff. I went and got some heat wrap and I'm wrapping that part of the harness up as we speak.

The wires in that bundle are for the front crank position sensor (which I'm not even using), the passenger side O2 sensor(s), and the starter wires...

I took the rest of my plugs out and they're all fouled too. I have some new plugs I'm going to put in, as well as the new O2 sensors, and see what it does I guess...see if it runs right, or if they foul again or what. Plug wires are brand new, and they're not melted.

 

Well got the plugs changed out. Went to change out the O2 sensors, and the passenger side was galled and stuck inside the header. Fought with that for a while trying to find a 18-1.5 thread chaser/tap. Got it running again with new plugs and new O2's, same crap, runs like total crap. It literally sputtered down the street. Headers were bright orange when I got home, and the coating looks like a bag of *** now I think. Not shiny any more. Glowing headers as far as I know is usually due to a lean condition, or too retarded timing, correct me if I'm wrong. I'm going to replace the fuel filter too, to see what happens there. I'll re-adjust the valve lash tomorrow as well and hope that clears everything up.

Any other advice/comments/prayers welcome!

 

Dave, Glowing headers means that there is fuel burning in the headers which is too Rich. Something is telling the computer to add more fuel than it needs because it should correct that problem by itself at idle/cruise.

Bret

 

Oh OK, I guess that too then. :/ I can't figure out why it would run OK, then just turn to crap...if it's the tune. I really need a datalogger I guess.

So lean causes glowing headers, but rich causes it too? Oh great.

 

Nope just too rich causes the headers to glow.

Bret

 

Check the other thread in here on the glowing headers.

Altitude and a tune not checked on a A/F meter and dyno would be things you two have in common.

Bret