Posted this before. Had no good answers. Motor is a z6 turbocharged.

My z6 wont rev past 4000 rpm. Motor sounds fine. Sometimes it will go past 4000 rpm but most of the time it wont.

It is not an ECU problem. Last time everyone said it was an ECU problem. I have tested it with 4 different ECU. They all wouldnt let me rev past 4000, only sometimes it would go past 4000. Unless all 4 ECU was messed up, but I highly doubt it.

What could cause it to do this? Someone out there has got to have run into this before. Have no check codes or anything. I am confused on what could be the cause. Any help would be appreciated.

 

is your tach busted?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vero &raquo;</TD></TR><TR><TD CLASS="quote">is your tach busted?</TD></TR></TABLE>

Tach is not busted.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flyazzcivic &raquo;</TD></TR><TR><TD CLASS="quote">

Tach is not busted. </TD></TR></TABLE>

how do you know? what have you done to rule out electrical signaling to the tack as well.

 

It cant be broken. I know it works because when I rev from nuetral I can rev past 4000 rpm. I know its working though. No way it can be the tach. I have the OEM Tach and a Monster Tach both with the same readings, unless they are both broken.

 

could it be any sensors, bent valves, anything internally?

 

i had that problem i changed my fuel filter and it worked, but now i got a problem with my fuel pump.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flyazzcivic &raquo;</TD></TR><TR><TD CLASS="quote">It cant be broken. I know it works because when I rev from nuetral I can rev past 4000 rpm. I know its working though. No way it can be the tach. I have the OEM Tach and a Monster Tach both with the same readings, unless they are both broken.</TD></TR></TABLE>

Ok so in nuetral you can go past 4k
But in gear you cannot go past 4k?

 

check your rev limiter. do you have a msd ignition

 

No rev limiter, no msd

 

Does it react like you're hitting a rev limiter, i.e. bouncing violently, or does it just hit about 4 grand and start whimpering? Either your wiring harness and sensors/ECU are severely fucked up or your air/fuel/spark is not what it should be above 4000ish RPM. Check your distributor, check your fuel pump and filter and check your intake piping and throttle body to make sure there are no restrictions.

And Jesus Christ: describe the symptoms better.

EDIT: and I almost feel stupid for asking, but what engine management are you using?

 

EDIT : ^^^ beat me to it

does it sound like a rev limiter type thing(bounces at 4k)? or does it just go to 4k and stop, hold steady? what happens if you get it to 4k and then floor it, does it bog?

describe it a little more

 

It acts like a rev limiter a 4 grand, bounces back and forth. When I floor it at 4 grand it bogs and sometimes it will go past 4 grand if I keep pushing it. Fuel management, Uber tuned w/ 450 injectors. I removed the harness, checked it and seems fine. Never cut the harness before and looks in tact. Will check the rest in the morning. Anyone else with possible causes let me know.