My title says it all. All if the sudden, today, my 96 lt4 decided to take a crap on me? I noticed while in the garage warming up, it seemed to wanna hesitate a little. I thought maybe I was hearing things b/c it seemed everytime I leaned in for a closer listen that I didnt hear it. I thought maybe I really wasnt hearing it. So after warming up about 5 minutes, I pull her out and take it down the road. I go around the turn at the bottom of the hill and once I start to accelerate to go up the hill, it starts acting sluggish...like it wants to hesitate. Im like, "wtf...?" So I thought maybe it was a piece of trash in the line or something so I stomped it....just hesitated even harder! I took it around the block per say and when I was coming up on the driveway, I began to notice it was getting worse. When I downshifted into first to pull in my driveway(that goes up hill), it began to hesitate and almost cut off. Thats when I saw the white smoke coming out of the back. I limped it into the garage and shut it off. I got out, popped the hood and began checking for electical connections to verify somethibg hadnt become unplugged. Visually everything looks ok? After about 10 mins, I cranked it up...in neutral, she revved fine and sounded perfectly fine? I didnt chance it by taking it down the road and getting towed.

I did a search and good lord! I read everything from bad/dirty fuel injectors, bad fuel pump, bad fuel filter, dirty maf sensor, bad opti, bad o2 sensor, clogged cats and so on.

Now, Fyi for what its worth, all 4 o2 sensors have been removed as I have hooker headers. I have had car dyno tuned so o2 sensors do not come on as they have been "tricked". I no longer have cats, just true dual exhaust and magnaflow mufflers. I do not know whether injectors are original or faulty. I dont know the age of the opti either or if its ever been replaced. I have an aftetmarket "jet" maf sensor along with the slp cold air intake as well that are both about 2 years old. I always run 93 amoco/bp fuel and mix about a gallon of 100 octane every fill up. And lastly, Im not getting any check engine lights...

Any ideas guys...? Im all ears. I guess whats the easiest, cheapest and first place to start?

 

Check fuel pressure, while driving, tape to windshield.
Check ignition, I like a inline spark checker from coil to coil wire. Obviously, you can only do this at idle or free reving.
Check for low res. signal and high res. signal from Opti-Spark with scan tool.
How old are the plugs, wires?
Check Opti-Spark connectors and the individuals pins for proper tension=pin fit. A small eyeglass screwdriver, the smallest you can get, works ok for this.

If it will miss/act up at idle, diagnose it at idle in your garage or whatever. No sense and getting it towed if you don't have too.

 

Just a side note...new plugs and wires were installed back in Jan...about 150 miles ago, if that.

 

Time for those new heads you wanted back at the beginning of the year.

 

They're already on the way from AFR my friend...estimated delivery date 4/25/2012. AFR 195cc Competition Heads... Still wanna know WTF is wrong in the mean time!!!

 

Had a similar problem with my LT4 last summer - changed plugs (same wires), while driving it would hesitate and "buck" for just a second, then smooth back out. Turned the light off in the garage and looked for sparks, nothing. Turned AC on to put a load on the engine, saw a huge spark from the plug boot to the block - #8 plug wire was not fully seated.. It was random, wouldn't do it every time. Got my habd in there and firmly seated the boot (gotta feel for the click)!

BTW, it never threw a code...I would have figured I would get a misfire code, but no.

 

White smoke makes me think of a head gasket leak....Luckily new heads will fix that -- if it's the problem.

Plug wire short, clogged cat, or failing injectors are other first thoughts though they typically wouldn't cause white smoke.

If it smokes again, pull over and sniff your exhaust. See if you smell antifreeze. I believe you can also test for a head gasket leak thru a pressure test of the coolant system. If it leaks down too quickly (and you don't see the leak anywhere), consider it's going into the motor. You can also check the appearance of your oil.