i have a 06 wrx with vf39 turbo and some others with tune! i put a new tranny in and everything is connected. now when you rev up the engine without boosting it revs fine but under any boost it misfires and breaks up to about 4k. i just changed the plugs gaped to .029 and no help. coils seem fine. the battery was left out for a lil over a month while doin the tranny can you loose a tune with that. really any ideas will help thanks

 

just throwin this out there but in your intercooler conectedd and tightend all the way?? mine did this after we changed my clutch and forgot to tighten that....

 

Check The connectors on to the tranny something is unplug or miss plug, i change the tranny on mine an was having the same problem that the car would not pas 4k.
2cents

 

i know whats exactly wrong with this! speed sensor isnt connected i bet. either that or a bad coil, check the coil packs. simply pull them out, hold spark plug tip to something metal on the engine, crank it over and you should see a little spark.

 

^ just because the coil sparks doesnt mean it's working properly. Most bad coil packs will spark and work perfectly fine at idle but will break up under load. Thats why so many people have problems diagnosing blown coil packs.

If the speed sensor is not connected then your speedometer will read 0 mph when your driving.


are you throwing misfire codes? any cel?

 

Umm so it's only cutting up to 4k and under load after 4k it's fine?

Are you using a UTEC by chance? If you are re-ground all the wires and check ALL grounds from the MEH. (engine harness)
I always have problems with them and their weak coil signal. :/

I would definitely find someone with a Tactrix cable and log everything once you see a sensor isn't working then it's a gimme. Also run a learning view on the car, it will tell you if the ECU is "thinking" about throwing a code, but the delay has yet to be reached. As I'm Slow above me said check to see if theres CELs. Even if the engine lights isn't on. You'd be amazed how many car i do with the CEL burned out or off with MILs everywhere.

Usually coil-packs will act up under higher loads like up top 5k+ you start to get blowout due to the weak coils and mass amounts of airflow at those levels. You figure a car is doing 270+ grams a sec at that range.

 

^ yay, someone else who knows what they are talking about lol. I've run into the utec corrupting files causing it to burn out coils......usually happens when there is a sudden spike or drop in voltage. Happened on my car and cost me $200 to repair the 2 coil packs that burned out.

 

U r the coolest joe..thats why I love u so much .

 

Yea man....uber common.
I think if it's grounded properly it's less likely to happen. Supposedly from what i've been told. UTEC works about as good as their OL Speed Density does.

 

thanks guy it turned out the maf sensor was inop!!!! thanks for the help