i recently noticed that lately my car at wot and under boost at around 4500rpm my car begins to bog out and i believe its detonating (not sure what this should feel or sound like since it never happened to me before) and my wastegate is so freakin loud that i can't really hear that good. my air fuel gauge is showing that its running lean at WOT while boosting but it runs fine when driving it on the street and even when the boost first kicks in but as the rpms increase it starts to bog out. i also notice a huge decrease in power from when i first installed the kit. i have a drag 3 kit with an fmu, stock injectors, and an inline fuel pump with no fuel pressure regulator or gauge on an ls motor. what do u guys think from what i described? the fuel pump seems to be working fine and the fuel filter is about 2000 miles old. besides getting a fpr which i am gonna do what do you guys think it could be. remember that at first the car run hard while in boost no leaning out. could the fmu have gone bad? the kit was installed under 1500 miles ago. i'm also running the stock ls ecu. thanks in advance.

 

Fuel Pressure gauge would be a very nice start as well as bigger injectors and some tuning...(S-AFC, Hondata, Uberdata, Aem EMS, Motec, Haltech...ETC)

 

anybody have a clue... c'mon turbo experts... do u guys think a fuel pressure regulator and gauge will help my problem?


bump for some help

 

you're main fuel pump might be taking a ****.. maybe

 

he just told you what to do....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tchleung &raquo;</TD></TR><TR><TD CLASS="quote">you're main fuel pump might be taking a ****.. maybe</TD></TR></TABLE>

how come the car runs fine when not in boost and even when in early boost... its when the car hits about 4500 rpm or so that it starts to bog out. should it still make a difference at low rpms? thanks for the help. should i replace the stock one with a walbro 255 high pressure one even though i have the inline fuel pump too? will this cause it to run rich?

 

sounds like it might be the spark plugs!
they foul out pretty fast on those kinda of setups. pop new plugs in and gap em to .028

also could be plug wires, i recently experienced that, under boost it would miss like how ur stating, tried everything, then tried the plug wires, was soo happy it was that.

try the plugs first, then the wires. let us know how it goes. while u at it, minus as well do a compression check.

 

If .028 is too much try .030, don't want it to blow that spark out. Also it might be the FMU, but I would go with a little bigger injectors. A stock ecu and an FMU can handle like 310cc. That would be the best bet. Also, how much boost are you running?

 

I basicly had the same problem, I got NGK BKR7E and gaped at .35. Ill proly go down to .32 once I get the fuel system at proper pressure.

 

i'm running 6psi on my greddy profec b2. i have set it as best as i can and it seems to be running pretty well and spooling up quick.

 

Ick, FMU.

If you were knocking bad, you would know. It feels like Normandy in your catalytic converter.

Oddly, this is the reverse from what an FMU typically does (bogs like hell under low load, or knocks like hell up high). 6Psi on a Drag kit is not enough to blow out spark, unless your gap is rediculously huge.

My diagnosis:

Because FMUs have to make you run hella rich in the middle, you've probably fouled your plugs pretty badly. Swap them out and see if the performance feels "like it did when you first installed the kit".

If you run an FMU, you should change your plugs when you change your oil.