Boost Stutter/Hesitation Problem
 

Saturday at the track I started getting this stutter/hesitation when I was under lets say 75%+ load or so when in boost. Wideband reads the same from what I can tell, boost reads the same from what I can tell, but rpms just drop down to idle almost instantly and then rebound back and then hesitate, etc. Feels like slamming on the brakes for a second. It seems to be getting worse. Was only maybe 1 in 4 times getting into boost. Now its practically 4 out of 4 times. Stutter, then pops/gurgles after, then boost, then stutter then pops. Runs fine out of boost and at low psi/low load.

I am running MSPnP. Ignition problem? I haven't touched anything yet - I got home late last night and everything was super hot.

Is this descriptive enough?

Could you post a data log of this problem happening, along with your MSQ? This'll give me a better idea of what is going on inside the ECU.

going to just guess overboost protection...

Overboost is what I thought too, but my protection is set at like ~16psi and I will get this set in at 5psi+.

My money is on ignition.

Matt, I can try to soon. Maybe over the weekend. Thanks for the extension of help.

then yeah, it's a miss or CAS dropout or something.

Brain, any way to tell in MS or a datalog if it's either of these? Will a CAS dropout create a weird anomaly in the spark angle?

Also, make sure anti-rev is off?

Look for downward spikes in the RPM graph; this is a tip off the CAS is misbehaving.

thanks for the help so far guys. CAS and plugs are cheap and easy enough. I'd say I'm going to order both and see what happens. At the least I can eliminate them. The RPM graph will for sure show downward spikes. Its almost like someone shuts the car off for a second and starts it back up with the foot on the gas in boost.

Thanks Matt. I will still try and get you a data log.

Any luck? I think I'm starting to have the same problem. Just replaced the plugs and still the same issue. Just stutters a bit when jumping on the throttle at about 3.5-4k rpm when I just start to hit boost.

I had a similar issue; mine cropped up seemingly out of the blue. It drove fine out of boost and with light load but over 3-5 psi it would cut out it felt like the someone was slamming on the brakes.
I logged it and was getting occasional resets on the MS when it was misfiring(around ~60% of the time.)
My problem turned out to be the power wire to the starter. I had lost the cap for it about a month before and ended up wrapping it up with tape to keep it from potentially shorting out. I managed to get a little corner of the tape in between the contact and the wire and it managed to corrode enough or wiggle itself a little loose that it didn't get a great connection.
I pulled it off cleaned the connection bolted it down and haven't had a problem since.
I only checked it because I eliminated everything else and that was the last thing I had done the the car before it had issues.

It's worth a shot I suppose.

There may be merit to this. I have had the same problem. Occasionally on the street, and it happened a few times when I took it to the track. Long story short I found my positive terminal on starter is missing the nut. I've never messed with it because it always starts and never thought it would affect anything. Interesting

hrmm i think i'll be checking that out manana :)

so did you find out the problem?

So better really late then never - the issue was that one of the rivots that holds the coil pack to the frame came out. Replaced it with a nut and bolt. Problem gone.