i ordered the hypertech fuel pressure gauge and the holley afpr from jegs and just got it today

i thought my fpr was bad and my injectors were leaking

so i hooked the the gauge and started the car and it read 35 then unhooked the vac line and it was at 46 lbs then hooked it back up and when i reved it it went back up to 46

then i taped it to the windsheld and started driving and got on it and it never went below 46

so i went home and tured it off to check if would bleed off fast but it stayed at 44lbs while i was looking at it but after 20 mins it went to 40 lbs

after 1 hour and 15 mins it was down to 24 lbs

is this normal drop or no?

thanks alot

joe

 

yes its normal...

 

i just really cant figure out my bad idle and low power problem

idle bounces all over the place and i replaced every ignition peice and checked all the sensors and everything is fine

im at the end of my rope i just dont know what to do now

 

Vacuum lines. Replace your vacuum lines. It costs all of $8 and takes all of a half hour to do (probably not even that long), and if nothing else, its a preventative measure against future failures and other idle problems. Rubber/plastic gets very brittle/dry-rotted after 15-20 years.

 

i checked for vac leaks with propane and could not find any

 

What is the pressure at idle?
Kind of hard to read between the lines, but the FPR operates this way, in case you didnt know:

Under any kind of vacuum, there is less fuel pressure. Examples:
Idle
Cruise (steady throttle, light load)

Under lack of vacuum, there is more fuel pressure. Examples:
Line disconnected
Heavy load
WOT
Key off, system pressurized


Sounds like your fuel system is working ok.

I havent followed your problem. What is the idle issue? Sounds to me like some sort of vacuum leak, as a guess. Does it ever feel like its going to choke or pop through the intake side when you give it a little more throttle at low cruising RPM's? Ever set a MAF code when the car is cold?

 

35 lbs at idle so ya the fpr is working fine

idle it jumps up and down about 100 rpm (600-700)and sometimes goes to stall during warm up and when hot but not as bad

only way i can get it to idle at all is to raise the minimum air to 1000 rpm but i dont think it is the iac that is bad because when the fan goes on or i put some other load on the car it adjusts the idle acordingly and is 2 years old

checked the maf signal and its working fine

also changed the o2 sensor resently

 

Sounds like tps or timing to me.

 

The ecm sets the idle. Do you think it needs to be higher? 6-700 should be ok for most mild cams. Only time you should mess with the throttle plate is if the engine wants you to. I'd suggest setting the minimum idle, reset the IAC, all that jazz... clean out the throttle body (can leave it installed), set the TPS, verify there are no vacuum leaks for the 100th time, and see how it is then.

Have you replaced or looked at the EGR? Thats a vacuum leak you cant detect right there.

 

i checked and adjusted tps and timing and there both fine

thats why i dont know wtf is going on

 

the engine wont run if i set the minimum air to the recomended 450

i will check the egr and check more vac leaks again

im begining to belive that it has to be a vac leak and i ahve missed something because if i move the tps sensor without opening the throttle it runs better so i will have to see tomarrow

im just getting so tired of this

 

Could be the throttle plate is open too far as well. It should be almost completely closed when its set right.

 

Like I said replace your vacuum lines. So what if you don't think they're leaking right now. It costs $8 and takes 30min of your time and then you're guaranteed all the lines you ran will work without issue for years to come...probably the rest of the time you own the vehicle. Its a simple way to eliminate a possible cause to this problem as well as preventing future ones like I said. By the way, when I had issues very similar to yours, it was a broken vacuum line.

 

ok looked at the vac lines again and noticed one that i did not befor and it had a hole and was craked bad and leaking so i replaced all the rubber line that i could i thought it would fix my problem but i was mistaken

started up and still did the same thing now i am getting really pissed

i wanted to see if my car was running rish or lean so i hooked up my volt meter to the o2 sensor like it said in the tech part of this site

as the o2 came up to temp the voltage came up liniarly from 0 mV to 650mV but after it went into closed loop mode it would bounce around volently from 30 mV to 800 mV going from rich to lean and thats when it started to idle worse (the higher the number the richer it is)

but when i took the car out for a ride and got on the car it would go up to 925 mV which is almost right on to what it sould be only a lil rich

but when you got off the gas it would go right back to bouncing up and down

i really am pissed now

 

Change the O2 sensor then. Doesnt matter if its fairly new. Could have ruined it running rich. Did you buy it from some cheap auto parts store? Get one from GM.

 

its a bosch o2 sensor and was changed 2 months ago

im going to pull it tomarrow and see what it looks like and i think i will pick up a ac delco 3 wire 02 sensor from a 92 gm truck and that will work better and less likly to foul with the headers

thats 60 bucks down the toilet

 

And if your still pissed after that then i'll buy the car for 100 bucks...

 

no thats alright man

i will figure it out but these tpi cars suck when if comes to figuring out problems

carb are simple and my ls1 car tells me if it is sick hahaha