z6 turbo'd fresh rebuild on motor and tranny got the turbo installed still lags quite a bit curious if anyone has the same issue or any suggestions for fixin.. its not a all the time lag its just sometimes you hit the gas hard and it wont spool up really lags the motor... i have the stock injectors running off of an fmu with bout 8lbs boost... if that...? any thoughts or suggestions? i have 390 injectors not sure if that'd help? its all obd1 chipped ecu but its not tuned thats why the fmu

 

How big is the turbo?

 

bump

 

its really pretty small maximum maybe like 12 lbs pretty small comes outta a eclipse i think?

 

bump

 

bump

 

thats called a 14b turbo.

your probably using an hf log manifold then too eh?

perhaps the weak point is your choice of fuel management....

i know tuning isnt cheap but you said this was a fresh rebuild, you know?

 

dude get some fuel management before you blow up for freshly rebuilt engine. throw in those 390s and get uberdata and a wideband o2. itll be worth it

 

just simply putting 390cc injectors wont help though. the ecu denst know bigger are installed and you will just run 2x normal fuel(about 2x) so.... dont do that enless you re-rpgram the ecu. how is the shaft play on the turbo?can you wigle it pretty good?

 

you can wiggle it a little but not a ton... As for the "tuning" i can get a chip installed with the 390 injectors for 150 so i get rid of the fmu and just go with the injectors from ecu will this improve the lag and the check engine light at redline?

 

Sounds like you're getting ripped off on just making a chip and shoving it in. Find your closest tuner and take it to them and they'll have it all fixed up like a charm. http://www.pgmfi.org is a good place to find the DIY knowledge and good tuners.

 

I don't know why everyone immediately blames the FMU...in this case having the FMU has nothing to do with a non responsive turbo. It could actually be something very simple like a loose coupler causing a boost leak not letting the pressure circulate. The FMU doesn't actually do anything until the onset of boost.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autoworks &raquo;</TD></TR><TR><TD CLASS="quote">I don't know why everyone immediately blames the FMU...in this case having the FMU has nothing to do with a non responsive turbo. It could actually be something very simple like a loose coupler causing a boost leak not letting the pressure circulate. The FMU doesn't actually do anything until the onset of boost.</TD></TR></TABLE>



FMU is fine for low boost, seems like the OP knows what he is doing has the fmu untill he can get the ecu tuned...as for the lag I would look for any vac leaks, loose couplers and pre-turbo exhaust leaks my money is on the last one...also if you are using an internal wastegate check to make sure the flapper is saying closed all the way or if there is any cracks around the whole

 

i dont like fmu either way because its like a jimmy rig to boost. and y es its ok for low boost but im just curious if maybe it gets too much gas or something like that? i have checked and re checked all the fittings and everything they're all tight and as for pre turbo exhaust leak i doubt thats an issue although i do have a major leak coming from my cat could that have anything to do with it? and the lag is not something that happens all the time it just happens occasionally like i hit the gas real hard and sometimes it spools up fine takes off like a champ and sometimes it'll lag a bit and then kick in really hard as if it were missmissing fuel or something..

 

Going by your cardomain pic it looks like you have a Greddy mani. and a 15G turbo. Are you not getting the response when you hit the gas at an already high speed or cruising RPM?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cor4ey &raquo;</TD></TR><TR><TD CLASS="quote">i dont like fmu either way because its like a jimmy rig to boost. and y es its ok for low boost but im just curious if maybe it gets too much gas or something like that? i have checked and re checked all the fittings and everything they're all tight and as for pre turbo exhaust leak i doubt thats an issue although i do have a major leak coming from my cat could that have anything to do with it? and the lag is not something that happens all the time it just happens occasionally like i hit the gas real hard and sometimes it spools up fine takes off like a champ and sometimes it'll lag a bit and then kick in really hard as if it were missmissing fuel or something.. </TD></TR></TABLE>
Leak at the cat won't cause a problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autoworks &raquo;</TD></TR><TR><TD CLASS="quote">
Leak at the cat won't cause a problem.</TD></TR></TABLE>

Yea acctually a leak at the cat should help you spool quicker

I gained 2 psi and a much quicker spool time, maybe 1500rpms, by unbolting my stock cat and exhaust

 

definitly get a chipped/tuned ecu or get that and tune it, before you lean that motor and and blow it. its better safe than sorry, and a fmu can definitly make you sorry

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18sihatch &raquo;</TD></TR><TR><TD CLASS="quote">definitly get a chipped/tuned ecu or get that and tune it, before you lean that motor and and blow it. its better safe than sorry, and a fmu can definitly make you sorry</TD></TR></TABLE>

Yea FMU isn't the greatest but it has been proven to work, yea there are many better alternatives but he is running low boost time he can get tuned...i think he is smarter for running an FMU on low boost than rocking a basemap for a wfew moths or something....

If you don't have any bost or exhaust leaks maybe you are leaning out in some certain condition causeing a lagish situation...do you have a a/f guage? Narrowbands are worthless but in this case it might show you atleast if you are leaning out when you feel the lag

 

ive got nothing against an fmu. its a great way to start. specialy for someone in my area. no dyno within 300 miles. and i still fight with the people here.they dont even think you need fuel.

 

wait. what does your chip consist of. whats on he map? mabye there is a lean spot at certain vac or something. see if someone has another one you can borrow for 20 mins. check it out. there are chances its the chip :D good luck keep us updated

 

Well it is a chipped ecu but has a stock fuelmap on it thats why im curious as to why it does the lagging thing.. as for fmu i just dont like it... yeah obviously its needed for boost unless i have it tuned i just dont like it in general ya know? i think it wastes alot o gas and isnt like right for the application but it works for now... from here its just a money situation to get the rest all done... But the chipped thing i went to idahospeed center and they have preprogrammed chips for 150 and it will let me get rid of the fmu and run how a car thats turbo'd would run smoothly? And its usually a high rpm like ill leave it in second doin like 40mph at 4 grand? and slam it and sometimes it'll really take off nicely and sometimes like i kick forward as if it wanted to die ya know?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cor4ey &raquo;</TD></TR><TR><TD CLASS="quote">Well it is a chipped ecu but has a stock fuelmap on it thats why im curious as to why it does the lagging thing.. as for fmu i just dont like it... yeah obviously its needed for boost unless i have it tuned i just dont like it in general ya know? i think it wastes alot o gas and isnt like right for the application but it works for now... from here its just a money situation to get the rest all done... But the chipped thing i went to idahospeed center and they have preprogrammed chips for 150 and it will let me get rid of the fmu and run how a car thats turbo'd would run smoothly? And its usually a high rpm like ill leave it in second doin like 40mph at 4 grand? and slam it and sometimes it'll really take off nicely and sometimes like i kick forward as if it wanted to die ya know?</TD></TR></TABLE>
Sounds like a mix between a small turbo and the FMU.
With a 15G don't expect much "kick" when you are already up into the RPM range. That mixed with the mechanical FMU just probably not making a smooth transition under such a load...moreso the turbo