stuttering at WOT

BlueStreak03 said:

Hey guys, I've had a couple instances of the car stuttering and stammering at WOT. It happens at low and high RPMs and most of the time within a second or so of going to WOT. I just put the JLT on the car a couple weeks ago and haven't had a chance to get it tuned. This is the only problem I've got, no rough idle, no stalling or anything like that. I need some help folks.

Click to expand...

The JLT probably threw your tune off and you are running overly rich at WOT.

BlueStreak03 said:

Think it made it richer?? If anything I would think it leaned it out some. I put in just a touch more fuel with the predator this morning before heading to work. It didn't do it at all since I made that change. I'll keep an eye on it. If it continues I'll probably pull some timing out just to be safe until I can get it tuned.

Click to expand...

I've heard from several people that their car went rich after adding an intake mod like plenum and throttle body on a car with many other bolt-ons and a factory tune. I figure the same thing could happen even with an aftermarket tune that isn't setup to for the new mod. My best guess is that the computer overcompensates for the increased airflow and goes too rich. Had the JLT made it lean, you would be detonating instead of having stuttering problems. It could be something other than the JLT but since its a mod you just recentley did and the adverse side affects happened right after, you've got to think that it is the problem.

But, since you added fuel and the problem has gone away, there is always the possibility that I am a moron and am completely wrong. :eyebulge:

Keep me updated so we can both learn from this. :thumbsup

BlueStreak03 said:

I haven't had a screen on this one since I bought it and put the CAI on there. What's the deal with the MAF position? The JLT places it inside the fenderwell with the filter which makes repositioning the MAF a little tedious because of the wire length. I think I can rotate it some, I'll have to crawl in there and get a good look first.

Oh yeah, I haven't had anymore instances of the stuttering since I put some fuel in the tune. I'll do the MAF thing anyway if possible, just to make sure. I've got some time off over the holidays so I should be able to get a little time on a dyno to check the A/F ratio and get some new numbers for comparison.

Click to expand...

This is actually how John Urist tunes his turbo cars. He rotates the MAF one direction to richen it up and the other to lean it out. Don't know why it works but it does. Don't rotate it until you find out which direction does what, though.