I got HP tuners today and i just wanted to raise my rev limiter to 7,000. I set every gear to 7,000 under the "normal" / "Fuel Cutoff vs. RPM" menu. and also in the "first gear reduce" menu. However, when my tach hits about and around 6,500-6,700 it feels like the car hits some sort of wall. It almost feels like the fuel is about to cut out like it normaly would, but then continues through to 7,000. I guess I'm just trying to gauge if this is normal or maybe unsafe and or if I missed anything.

Also if anyone has some input, are there some basic things I can tune by myself that would benefit power? I currently have an intake and exhaust.

 

From what I have heard the stock injectors arepretty much maxed out at the 6500 rpm. That could be you "wall" is your computer trying to tell you injectors to put out more fuel than they are designed to.

 

also some have said that it starts to reduce timing about 300 to 400 rpm before redline. i read that somewhere on this here site.

 

could be a few things...do you have any scan's when it happens? Preferably with

mph
rpm
spark
total KR
commanded afr
injector pulse widths
ect
iat
maf hz
etc position

etc, etc.

might help determine if its cutting spark, or if your seeing alot of KR or if its cutting fuel or just adding a ton of it. I know the stock 07 cobalt SS commands 10.8:1 above 5000 rpms which is pretty rich. Add in cat over temp protection and you could see 10.5:1 commanded which is just super rich at that point.

 

i read something very similar on the HP Tuners's forum and it turned out to be the fuel injectors. However, I will find out tommrow when I do some dyno tuning

 

Did you raise the fuel shut off RPM??

 

OK, I had this problem all of last week. The solution I found was NGK BKR7E spark plugs (one step colder), change the coefficent of the a/f table to 1.25 above 4.5k causing the a/f table to read near 11.8, bump that MAF fail signal from 10000 to 12000 (not sure if it's 10000, or 1000, just make change the first two numbers from 10 to 12 in the table). I also bumped my piston protection to 5000. SHe now runs perfectly fine. These are the only changes I have done and my stock injectors are only running at in the 70% range at 7k rpm. This should fix it for you. Once I get Todd to send me the file I can toss it your way Try it out man. Only costs about $10 or less for the one step colder plugs and 5 min of tuning.

 

Why would you rais your piston protection. Its there for a reason. During tunning there should be no reason for raising it.

 

thanks for the input