On the way into work this morning, cruising around 80mph, wanted to switch lanes and pass a car on the highway. stepped on the gas in 5th gear, started passing the car, then the car felt like it lost all power for a split second, and jolted the car just enough for us to feel it. Literally a split second. What could this have been? First time anything like this has happened, hopefully a fluke.

 

I couldn't tell you what happened, but if it were me I wouldn't worry unless it happened again.

 

If you where at WOT and the car "bucked" then continued on, you are describing fuel cut. Fuel cut occurs at 1700 Hz Karman value, 20°C and 1000 mbar atmospheric pressure (roughly 1.2 bars relative boost). At fuel cut the ECU suspends fuel and spark instantly until the triggers clear. That should occur if you have an aftermarket intake and/or exhaust and/or boost controller with cooler weather.

If you car is stock then it may be bad gas or bad plugs.

Speedlimit..

 

It's about 50 degrees outside, I have a k&n filter, and boost controller set at 16psi. Sound about right? Why does this fuel cut occur?

 

my buddy in the car said it made a clunking sound too.. I didnt realize it, was too busy passing the car and wondering what the hell just happened... would fuel cut off make that sound?

 

Yeah, it was fuel cut.. anything will clunk in the car when you abruptly remove power from the engine.. cold dense air can and a less restrictive/different air filter can definitely cause it..

 

It can't obviously be good for the car.. any way to avoid this?

 

Fuel cut does not do any damage. One way around it is turn boost down. Another way is with some fuel control, higher flow fuel pump, and larger injector. Also some flashes can remove it.

 

I would also check your boost gauge connections; you may find your boost was higher than 16psi. Fuel cut is a safety feature to prevent grenading the turbo/engine should your wastegate/solenoid system fail in the wrong direction. If you bypass it, make sure you have the proper supporting mods to protect your engine. If you continuoulsy hit fuel cut you can stress the drivetrain components over time.

Speedlimit..

 

I actually get this quite often and my car is stock except for the K&N drop in filter. It normally occurs at about 3000 - 3500 RPM with low to moderate load on the engine.

 

So I drove down to springfield yesterday, about 50 miles. On the way down it did it twice. On the way back, I got a "service engine soon" light, drove it home 40 miles with absolutely no problems. I don't know if its related or what. I'll have to drive 60 miles to the nearest mitsu dealer. Anything I should do prior?

 

go to an auto zone or somehting and check the code

if its p0234 then thats the code for a failed wastegate system and it thinks that because the ecu can no longer controll boost

your definately hitting fuel cut

 

If that's what it is, what should I do to remedy?

 

Most likely the code will be the overboost code.

 

Fuel cut will make the CEL come on.

Turn your boost down and see if it goes away.