HELP !!!! Whats wrong with my engine??
 

Ok so i have been having troubles with my 2.0 beta engine lately.. When i drag race or just floor it.. When I reach 4000 RPM I lose ALOT of power !!



Probably around 20 to 25 hp.. Then when I reach 5000 RPM.. I gain the power Back ( and meaby a little more ) ?? My mechanics told me to put a product in my gas that would clean out the injectors.. it did not do anything.. I then installed headers. thinking meaby my Cat might be cloged.. I helped for a few months meaby but still it stays there..



This is so bad it probably adds 0,5 to 0,8 seconds to my quarter mile time and I would really like to fix it... Thanks guys

That sounds like maybe a MAF issue?



If you have an OBDII scanner that will show you realtime data you can probably see what the issue is.

Reset your ECU.

already tried that !

how are your o2s installed

I am going to guess coil

I have one O2 NOT installed.. the one on the headers.. But it was doing it before I took it off !

how old are your spark plugs, wires, coils?

Spark plugs I just changed thinking it might be the prob ! Put in NGK irigium and nothing changed !!..

So if I understand what you're saying, you have a engine "stumble" that starts around 4000rpm but clears by 5000 rpm.

You can rule out cat converter. If the cat converter were clogged, the performance would get worse the higher the rpm goes (and exhaust flow increases).

You can rule out clogged injectors. If they are clogged @ 4000rpm, they should be just as clogged @ 5000rpm. So the problem would get worse, not better.



Are any check engine lights triggered? If so, what is the code? If the problem is bad enough for you to feel, then it SHOULD be triggering a check engine light.



My guesses would be...

I'm guessing you've got a bad plug wire or coil, or a sensor problem with the cam/crank sensor. Any of these should trigger a check engine light though.

At full throttle the 02 sensor data is ignored by the engine management system. I think the threshold is 90% or 85%. Anything over that TPS signal the ECU simply dumps fuel and the o2 sensors are ignored by the ECU because the ECU told the injectors to dump loads of fuel.



Check your Coils and your plug wires, and if possible with a multimeter and check Cam/Crank position sensor data with a ODB2 reader.