Need some Advice on possible valve float

[JT'sV6]

Or weak ignition. The issue occurs only at full throttle. I brake boost to 12 psi and go part throttle to 18psi pull all the way to 5800rpm the car pulls strong but at any point I put the pedal all the way down the car will start to shutter and miss almost if there is weak spark. The wideband shows the af does lean out to mid to high 12's when the issue occurs.

At first I thought maybe it was trans related so I had my trans rebuilt over the winter and had my converter freshened with new carbon cluth. Have replaced plugs, wires, and coils. The methanol is unhooked and it has a lt1 maf that is also new. Loaded an old tune that run great on the car and even swaped a stock turbo on the car.

Seems to me it has to be something in the valvetrain and possiblly valve float. The springs come in a hyd roller kit and the entire valvetrain is less than 5yrs old. I guess I could check spring rates but it would be alomst just as easy to just replace the springs.

Just wanted to get some opinions on if this sounds like valve float the way the car will pull at part throttle all the way to redline with mild boost. If not which direction should I take from here?

 

[Chuck Leeper]

What's the tps reading @ WOT?

 

[kidglok]

do you have a log of it?

 

[JT'sV6]

I do have a log but dont know how to upload it. tps reads normal. Even swaped the sensor to make sure that wasnt the issue. As a matter of fact everything in the log looks good. Fuel, spark, and maf readings look as it should. Like I said though it leans out when the issue happens. I even swaped my #60's back to my #42's to make sure I didnt have a bad injector.

I think the reason it's leaning out is due to unburnt air passing through the ex chamber. I may put my wideband in the o2 spot and make a pull for each bank to see what side the issue is coming from.

 

[Phoneguy]

If it is not doing this at part throttle redline, I dont think you have a valvetrain issue. What is your fuel pressure when this happens at WOT ? Fuel filter been replaced? Could be the coils or the module as well. Check the ground to the coil mount.

Bryan

 

[m233roller]

Sounds like it's running out of fuel?? I'd be checking fuel pressure real close at WOT.

 

[TurboDave]

I think these guys have it. You've got a fuel issue. Got a gauge you can monitor while at WOT? Need to know if the fuel pressure is increasing 1 lb with every 1 lb of boost.
Your symptoms sound pretty typical of a fuel delivery issue.

 

[TurboBuRick]

We need more data. Use the "Upload a File" button to attach pl log to your post.

RL

 

[JT'sV6]

At first I thought it was fuel pressure before I rebuilt the trans so I swaped in dual 255's, and bought the adjustable regulator from full throttle. Already had the hotwire. I have confirmed the stumble or studder does occur at 50psi static rail pressure. Have also changed the fuel filter several times. since the issue started.

The coil ground comment has me curious because I do have a mild to rough idle cam in my car and curious to think a ground strap nut has worked loose a bit. I am going to check those today and going to try and find some schematics or break out my voltimeter so I can ground the coil in a different location other than the ground strap. When I swaped this motor in I used a spare engine harness and really dont know the history behind it. another option is this harness could very likelly have a short in it somewhere.

When I try and upload a file that way the file wont come up in my documents page for some reason. Would I have to convert it to excel?? format? Because my laptop does not have that. It is very old and running on it's last leg as well.

 

[Phoneguy]

This is what i did for grounding.

 

[TurboBuRick]

You can't direct it to the folder where the file is or the the file does not show up?

RL

 

[JT'sV6]

The file doesnt show up Rick.

Didnt have time to work on it this past weekend but another detail I forgot to mention was that the headers are glowing after driving around the block a few times. Has been for a while. Fuel trims are excellent and af is 14.5- 15.1. At first I thought it was because i recentlly added header wrap but the more i think about it I think the more I think it has something to do with my current issue.

 

[Phoneguy]

Is there a CAT on this car? Glowing headers is a lean condition or an obstruction.

Bryan

 

[Jerryl]

Lean AF reading combined with glowing headers may very well be a spark issue.
WB reads the unburned air, and unburned fuel burns in the headers.
Changing the coilpack alone may not tell the whole story either.

 

[m233roller]

Or something seriously wrong with the timing ??

 

[cruzn57]

whats the plug gap?
if its over .030, you might wanna tighten it up some.

 

[bison]

probably not float but you need to pull a spring and just get an estimate as to what they are

 

[trbojo]

all i can tell you is i chased an issue EXACTLY like this after i installed champion heads and intake for a year and a half. only difference is my wideband was reading rich. ended up spinning a rod bearing. i dropped the heads off to have checked by my engine guy. found out all the springs were weak.

 

[JT'sV6]

Timing is what it's commanded, nothing funny going on there. Cats are long gone and also has 3" down pipe running through a magnaflow turbo muffler. Dont think there is anything going on with the exhaust because it is all mandrel piping with slip over connectors welded.

There is not enough hours in the day it seems, cant seem to get off of work in time to start tearing into this thing. Another interesting tid bit though, I had the same issue last year but the problemb went away all of a sudden which lead me to believe it was the trans sliping because I added some anti slip trans fluid. I'm sure I'll find the issue, it's probablly something real simple to begin with anyways.

Does anyone know of a tool that will check the strength of the spark or know a method to test it?

 

[kidglok]

casper sells a tester so you can see if theres a miss on one or more of the coils.