hi all how is every one doing?

well my problem is that my car has been bogging down alot at slow speeds and when it does and i give it gas to keep it from cutting off it takes a few sec to respond and my rpms went from 2300 to 1900 at 60 MPH but i can tap the gas a bit and it goes up to around 2300 rpms for like 5 sec then goes down again and starts to shutter and stuff..ive been getting bad gas miliage i can fill up right now and go 50 miles and half my tank is gone....so i thought it was my tranny so i got it overhauled and it didnt help well it did since i lost all gears cept for 1st lol...so i had my opti/plugs/wires/fuel filter/both 02 sensors..all changed out but no good...so i thought it could be my (fuel pump) so i went to autozone and got a fuel pressure gauge and hooked it up...and with the key on it reads 38 psi but when the motor is idleing it went down to 32 psi what is it suppose to be at idle ...is that where it is suppose to be??

thanks for the help all,,,cya all soon i hope

edit= it has got a nitrouse TB/lt4 aluminum heads/and a big a$$ cam lol and 4" magnaflows .....ohh and when it starts to bog and i give it half throttle something pops under the hood like on driverside about on the side of motor idk lol

had the computer scanned but no codes or stored codes they said everything is normal that is with 3 diffrent places

 

If possible try to drive the car with the pressure gauge installed. It is tricky but can be routed out by the wiper arms if the hose will reach. You need to confirm that your not losing pressure when the bog happens. The only way to figure this out may be a process of elimination. I also have a 94 z28 and it takes alot to make the check engine light come on- they just aren't that smart. As for the popping sound it could be anything. Is it 1 pop or a series? Backfiring? Have to start somewhere so good luck.

 

With engine running at idle:

1) Disconnect the vacuum line from the pressure regulator, the fuel pressure should be 41-47 PSI.

2) Re-connect the vacuum line to the regulator, fuel pressure should drop by 5-10 PSI.

With engine under load at WOT:

1) Pressure should hold between 41-47 PSI. If not, look for a weak pump or for restricted fuel passages, including the strainer inside the tank.

As Welch said good luck. Be careful of fuel leaks and fires.

 

ok thanks ill go try it out when it bogs and it is only 1 pop .....i just replaced the map sensor like an hour ago and it has helped with the shutter alot ok well be back in a few thanks again

 

well went to test the fuel pressure like both of you said but it started to pour rain lol dont wanna atempt it and get my opti wet lol ill wait till tommorow......

another question> do you think it could be my EGR messed up and if so where the hell is it located lol right below the fuel pressure shroud thingy? looks kinda like a UFO haha gonna be hard to get to but its only $60 might as well try

 

ps.... if it was the fuel pump wouldnt it do this as soon as i drive in the morning like i can crank it in the morning and it runs fine for about 3 min then my rpms will drop like i said above and start to shutter and hesitate like crazy but if i give it gas and it unlocks the converter its all good for about 23 sec lol i counted today think its just the lockup idk....

you know how when u push the brakes in and it unlocks the TC well mine never did that till i got behind slow drivers doing 10MPH in a 35 and kept slamming on brakes i would say in 3 miles they slammed it about 41 times.....well after i passed them and went to cruise my rpms went to 1900 from 2300..my car is pushing 592HP dyno tested before all this happened and got better gas mileage but feels like a dam 4 cylinder when it starts to hesitate and crap.......

BUT i can press the brakes in and hold it and it unlocks the TC and it runs like a champ wounder why..the guy i bought it from raced it professinaly and he showed me paper work that it will go 0-60 in 3 sec without nitrouse at half throttle only had it at full one time lost control in 4th gear lol tires spinning still spinning when shifted to 4th and $hit then i hit a puddle of water and hydroplained and almost hit a highway patrol LMFAO and got a ticket for hytroplaining ??? wtf but it ran fine till i kept pressing the brake in then it ran like poop

 

well at WOT the pressure went to 60 psi is that good or should it be less i guess it aint the fuel pump but after i start it and go about 20 miles an hour in my drive way and it starts to bog like bomp------- bomp---------- bomp------ and the car starts to shake then i let off the gas it sounds like it shuts off for a few seconds then revs back up what could it be? could it be my fuel pressure regulator? i went out to day and started it and unhooked the hose to it and it was sucking air like a jet plain lol and i put my finger over it but it sounded like air was getting sucked maybe replace the hose idk

 

could be a vacumn leak. i was thinkin a sensor out of wack. have u tried unpluggin the map. check the fuel pressure regulator for any leakage gettin into the system throught the vacumn hose.

 

well the hose that connects to the fuel pressure regulator had some electric tape on it the black kind so i unpluged it and it was sucking some good air but when i put my finger over the hose hole it was still sucking a little but you can still hear it over the motor.. might have dry rotted.... um the map sensor i dont think is it cause i just replaced it 3 days ago and only helped with the shuttering back and forth but the shuttering is still there but not as bad....

do you think 60PSI for fuel is to much at WOT ? this aint a factory car the guy i bought it from was a professional driver it even has a roll bar on it and he drove it at the drag strip and he told me the only thing he took off this car was the bottle lol and he prooved it by dyno testing it without the bottle????


edit = all this happened when i was going 60 in a 55 and had to press the brakes in to many times cause of slow drivers doing 35 in 55 and they were regulery slamming on brakes they were from virginia no offence lol... mufflers aint loud at all...... they use to be loud as hell i mean it, but now they are like a 4 banger with twit twit mufflers on it lol

there not as loud i think its my TQ cause i can put a tad bit brake on the brake peddel to unlock the converter and it acts like it use to be BUT why would it start to lock up now after 8 months of driving PLUS had the tranny rebuilt 2 weeks ago???

my car has not been the same after that acks like a 4 banger untill i have to accually floor it and today i had to lol took off from a 65 roll and still burning tires ill be dam lol

 

well the shuttering back and forth is back again but worst this time im thinking it might be a ( IDK ) it never act this way when torque converter didnt lock up but NOW THE TORQUE CONVERTER IS LOCKING UP AND MY CAR IS LIKE TAKING A **** i mean it's taking a **** really bogging down after that and all...ill go 1300 RPMS and it starts to bog my mufflers are 4 times quiter now cause of this i dont have power at all i can floor it and it is like a dam 4 banger when it use to act like a V12 without the nitrouse wtf is wrong ??????????????