So I checked my fuel injectors and they are all firing fine. Spray pattern is normal. I also checked for arcing near the wires and there is nothing. One thing I did notice is that it doesn't misfire as soon as I start it up, but after putting it under some load the misfire soon starts to linger and is noticeable as a gentle shake if I just barely let the car start to move (while depressing the brakes). In addition, the car still falls on its face at about 1200 rpms for a split second, and although I didn't check the intake elbow for leaks, it did it several times really bad right after pulling the fuel rails to check the spray pattern. So I assuming it must not be dependent on a leak in the intake elbow. Any thoughts, ideas? Why would it misfire only after going under load? If I let the car idle for a few minutes the misfire almost completely goes away. I'm really hoping it isn't the opti, but it has only gotten better messing with the fuel injectors, etc.

EDIT: Oh yes, here's what's been done so far:
New plugs and wires
New coil
Still no codes for anything

 

Since you replaced half this stuff, it might not apply.

The reason it misfires under a load is that it takes more voltage to fire the plugs under higher pressure, so there is more stress on the electrical system trying to deliver the spark. The higher voltage is trying to find ground through the insulation rather than jump the spark gap, so if there is any weakness that will withstand 10,000 volts, but not 15,000 volts, then it can misfire. This can be a cracked plug, bad plug wire, internal coil problem, etc. Also, heat is greater when the engine is under load, so a coil or ICM that is having a heat related failure can show up then. If your ICM is still mounted directly on the head, you might want to space it out with some washers to cool it down a bit. It may not be related to your problem, but its good to do anyway as long as its still properly grounded.

 

Well the thing is, I just replaced all of them a month ago. And what's weird is I can't even tell it is misfiring while under load, it's only after I slow the car down to about .1 mph (that's right, .1) that I feel the gentle shake from the misfire. I doubt it's heat related because my first low temp fan is out, and so the engine stays cooler while driving than while idling. However, this is not to say that there might not be something else related to the problem. The coil is about one year old and MSD, but I'm not ready to rule that out yet, either.

Any other ideas guys? I know at idle, I'm getting spark, air and fuel. :-/ One of those is still failing after a bit.

 

Please read - and wait 24 hours before doing a "ttt".

https://www.camaroz28.com/forums/lt1-based-engine-tech-9/all-members-read-abuse-%22ttt%22-5485/

 

TTT!!!!!! Didn't know about the 24 hour rule. Sorry.

 

Are you saying it only misfires when you lift off of the throttle ("it's only after I slow the car down to about .1 mph")? And the misfire is characterized by a "gentle shake", and continues until you stop, and let it idle for a while? Then it goes away slowly?

Once it starts to shake on decel, will it continue to shake if you get back on the throttle?

Is this statement still true: "and..... I didn't check the intake elbow for leaks"?

 

Yes, correct. It really is an intermittent if there is a misfire at all. Over at another forum, some people are telling me that the car is just a high torque car and I can expect some shake from the drive train when I am at a crawl and holding the car back. But when I first start up it is rarely there. After driving for 20 minutes, it is definitely more noticeable.

See, it's not decel, it just shakes if I am holding the brakes down and only let it go under one mph. I also notice it if I am driving at 43mph (holding it steady at that speed), just after I shift into my last gear. At that ratio, the car has super low RPMs and so every minor vibration in the engine is transmitted easily to the car. I feel a very gentle shake then, although to an average driver they would probably hardly even notice. So yeah, it's only a very minor problem if any. I

I did check the intake elbow for leaks about 36 hrs ago. I found none and reseated it well on the TB. It hasn't stumbled at all until this morning, when it totally loss power for about 1/2 sec and I thought it might even die, then picked back up again. Besides that....no other problems.

Here's other stuff that might help:

This is a Cylinder Balance Test performed 8 months ago after having the heads refinished due to blown gasket using the Rapid Power Balance system:
Cylinder 1 - 100%
Cylinder 8 - 100%
Cylinder 4 - 100%
Cylinder 3 - 90%
Cylinder 6 - 100%
Cylinder 5 - 89%
Cylinder 7 - 100%
Cylinder 2 - 99%

I also multimetered the injectors. One was 13ohms. The rest were between 15 and 40ohms. I didn't bother with voltage since they were spraying just fine after pulling the fuel rails.

 

What trans do you have (really should be in your signature)? If it's an A4, do you have a locking converter?

The ES poly motor mounts are going to transmit more vibrations than the stock rubber mounts.

 

Ugg, I'm beginning to think it's just me with sports car "jitters," as one other forum member pointed out. I have an A4. By the time you read this the sig will be edited. A locking converter? Oh dang, what's that? I take it I probably don't.

Also, if I really wanted to perform a leak down test is there a decently priced tool you would recommend?