i just had my engine rebuilt by a shop. now i am having a problem running intermittenly lean. i dont no how it acts under boost because i am still breaking in the engine but it my narrow band O2 gage and my apex i turbo timer both show the engine going off the scale lean every now and then. when those gages show the lean condition the car starts bucking and shaking pretty bad.
the ecu is showing the 55 code for all ok. i tried shaking different parts of the whiring harness and nothing was loose. vacume is 18 at idle and 24 at 2000rpm.the only things that changed during the rebuild were forged pistons(stock compression) and the adition of hks step 1 (264/264) cams. any ideas?

my setup:
91 240 w/redtop
300z maf
t3t04e
fullrace exaust manifold
740cc injectors
300z fuel filter
wolbro 255 fuel pump
nismo adjustable fuel pressure regulator
Enthalpy tuned ecu

all parts have 5k miles or less. this problem did not exist befor engine rebuild.

thanks.

aaron

my web page.
http://www.cardomain.com/memberpage/676406

 

I have $0.25 on dying fuel pump.

 

I also think the fuel pump or some form of fuel system diryness is the cuplrit ..

Change Filter , drain tank and clean it , make sure your 12 volts is constant on the fuel pump and your connections are good at high load ....

 

thanks for the help. i will check over that stuff. i originally did not suspect the fuel pump due to it is only 6 months old but from what i have read lately the wolbro fuel pumps are not that good. i have a feeling the fuel pump is craping out.

as for piston rings and vacume problems i dont understand how one of these would cause an intermitten problem. i figured if it was one of those it would cause a constant problem.

 

how long did your car sit ? how much fuel was in it when it sat ?

water in the fuel ?

 

possibly, the engine rebuild is an entire different story. to keep it short a shop had my car for 4 and a half months at a shop for an engine rebuild and after that they spent two weeks throwing parts at the car tring to get oil pressure. at that point i told them they were out of time and i took the car back and started i working out the rest of the bugs. when the oil pressure was fixed i took the car and topped off the fuel(it was at 1/4 tank). i am going to get a new fuel filter and run some fuel system cleaner through it. hopfully that will work.

thanks,

aaron

 

thats shitty, i'd say take the send line from your fuel pump, pump all the fuel into a bucket, put new fuel in and try it...then pour the gas in the parking lot of the shop that screwed you and spell something dirty along the lines of "chicken fucker" or "Ass Clowns" and set it ablaze.

 

haha, yeah that would be funny but at this point i just want to get my car running again. i cant even work on it this weekend due to it is 35 degrees and raining. i hate being a parking lot mechanic.