PDA

View Full Version : Please help me confirm fuel pressure...


nimrod.sixty9
01-08-2015, 11:46 AM
2002 Firebird

https://www.youtube.com/watch?v=scYdYtTk4lA

xpbr2000
01-08-2015, 12:58 PM
well, its doesn't look like you have a problem with the pump. its holds 47psi at WOT thats all its supposed to hold. however when you let off it doesn't drop below 42psi which is required for normal operation.

the system doesn't leak that I can see. but I only saw the 2 second prime at the beginning of the video.

I'd almost be inclined to think that the regulator is beginning to fail. or an injector is leaking. something is letting the pressure drop below 42psi at idle.

nimrod.sixty9
01-08-2015, 02:08 PM
well, its doesn't look like you have a problem with the pump. its holds 47psi at WOT thats all its supposed to hold. however when you let off it doesn't drop below 42psi which is required for normal operation.

the system doesn't leak that I can see. but I only saw the 2 second prime at the beginning of the video.

I'd almost be inclined to think that the regulator is beginning to fail. or an injector is leaking. something is letting the pressure drop below 42psi at idle.

Sorry for the crap video but it is actually dropping lower than 42; it is actually going to 38psi. Pretty much between 38 and 46 at all times.

Also, the pressure only dropped about 5 psi after sitting off for around 30 minutes. Im told that is in spec for a good FPR.

Could it be related to a vacuum leak;

https://www.youtube.com/watch?v=k33taUj4yrQ&feature=youtu.be

xpbr2000
01-08-2015, 03:19 PM
What are the symtoms?

Rough idle and hesitation is what I read from the first video.

A faulty TPS can cause those symptoms.

A vacuum leak can cause rough idle. However IMO hesitation would be unlikely

Are you throwing codes? do you have the ability to scan the sensor values?

nimrod.sixty9
01-08-2015, 03:56 PM
What are the symtoms?

Rough idle and hesitation is what I read from the first video.

A faulty TPS can cause those symptoms.

A vacuum leak can cause rough idle. However IMO hesitation would be unlikely

Are you throwing codes? do you have the ability to scan the sensor values?

No codes, no TPS (2002 drive-by-wire).

Here's threads on it;

http://ls1tech.com/forums/general-maintenance-repairs/1759025-lack-power-hesitation.html

http://forum.camarov6.com/showthread.php?t=107014

I have Torque Pro on my tablet. I can record, just lmk what I need to record.

xpbr2000
01-08-2015, 04:05 PM
You have a tps but its part of the tb assy. You can't replace it like pre-99s can. I'd look at the throttle position, your vacuum values, and maf numbers. Mostly to see if there is any fluctuation on the numbers while its experiencing the issues.

nimrod.sixty9
01-08-2015, 05:02 PM
You have a tps but its part of the tb assy. You can't replace it like pre-99s can. I'd look at the throttle position, your vacuum values, and maf numbers. Mostly to see if there is any fluctuation on the numbers while its experiencing the issues.

Duh, thats right, I did have a shit ton of codes right after I cleaned the TB. Nearly all of which were TPS related. To be fair tho, the car acted exactly the same before I cleaned the TB (maybe not as consistent as it is now). Figured the codes where just cause I cleaned it.

Can you tell me specifically what I have to look for in which? The issue is consistent now. Complete lack of power. Not sure what I have to look for cause I dont know what to compare it too.

xpbr2000
01-08-2015, 05:21 PM
Use torque and look at tps values as you slowly press pedal to the floor. Car does not need to be started. Just in the on position.

As for the maf the you need to make sure the value don't jump around when slowly increasing the throttle. Car needs to be driving in gear (highway is best). As for vacuum list your negative psi at idle.

nimrod.sixty9
01-08-2015, 05:46 PM
Use torque and look at tps values as you slowly press pedal to the floor. Car does not need to be started. Just in the on position.

As for the maf the you need to make sure the value don't jump around when slowly increasing the throttle. Car needs to be driving in gear (highway is best). As for vacuum list your negative psi at idle.

Perfect! Exactly what I was looking for. I will log and post tonight!

nimrod.sixty9
01-08-2015, 07:50 PM
This one is at idle, warm, in drive, on brake; I screenshot MAP as this is the only thing I could find for vacuum, cept of course you see no negative value. What should I use?

http://www.use.com/images/s_3/2015_01_08_380_2ccaedd44e586af9e898.jpg

This shows MAF;

http://www.use.com/images/s_3/2015_01_08_381_e4710243943ea51d66e8.jpg

At start; cruising, on throttle, off throttle, pacing an increase in acceleration.

TPS was perfect with KOEO. On highway it looked good too, tho it seemed to slowly creep down as the car got to speed. That was on a graph tho and couldve just been me.

xpbr2000
01-09-2015, 12:12 PM
Torque has a "torque scan" plugin you can download for free. that will poll all the sensors in a list that you can scroll through to get the actual map value. its looks like it should be -5psi but to be sure you should look at the torque scan plugin. if it shows in/hg goto your preferences>units> and there should be a use psi instead of in/hg or kilopascals check box

I'll look at lunch today inorder to see what my psi is. I'm not sure that there will be much difference. vacuum leaks are usually hard to find. instead of in gear screen shot it while in park. mine is a stick and can't replicate in gear very accurately.

The maf looks to be consistant. I would expect to see spikes if the maf was faulty

can you post codes if you have them? the maf and tps look fine.

The vacuum though I have screen shots when cruising that are -5psi which concerns me. the only screeny that shows me sitting has 13.7 in/hg which is more like -6.7psi

From what I see a vacuum leak is more likely.

Let me take note of my vacuum sitting today. hopefully my cam doesn't skew that number too bad. maybe someone with a stock cam would chime in with their Map reading at idle in park. as to make a good comparison as well.

xpbr2000
01-09-2015, 02:05 PM
At idle I'm more like 6.7-7.0 because of the cam. I did put a load of the motor with the clutch it drop down but depending his much I load it I got as low as 4psi

nimrod.sixty9
01-09-2015, 03:08 PM
Torque has a "torque scan" plugin you can download for free. that will poll all the sensors in a list that you can scroll through to get the actual map value. its looks like it should be -5psi but to be sure you should look at the torque scan plugin. if it shows in/hg goto your preferences>units> and there should be a use psi instead of in/hg or kilopascals check box

I'll look at lunch today inorder to see what my psi is. I'm not sure that there will be much difference. vacuum leaks are usually hard to find. instead of in gear screen shot it while in park. mine is a stick and can't replicate in gear very accurately.

The maf looks to be consistant. I would expect to see spikes if the maf was faulty

can you post codes if you have them? the maf and tps look fine.

The vacuum though I have screen shots when cruising that are -5psi which concerns me. the only screeny that shows me sitting has 13.7 in/hg which is more like -6.7psi

From what I see a vacuum leak is more likely.

Let me take note of my vacuum sitting today. hopefully my cam doesn't skew that number too bad. maybe someone with a stock cam would chime in with their Map reading at idle in park. as to make a good comparison as well.


At idle I'm more like 6.7-7.0 because of the cam. I did put a load of the motor with the clutch it drop down but depending his much I load it I got as low as 4psi


OK, updated TP and downloaded ST. Settings are now all American standard. So what do I need to look for now; MAP again (in park)? Was 'Intake: 5.1 psi' not the right line to screenshot?

No codes at all :/

I don't believe I ever saw a negative PSI, assuming I was even looking at the right thing.

Also, what do you think about the harmonic balancer?

I noticed when we went WOT on the FP test video it sounded horrible, metal rattling and such. Thought she was going to implode. Seemed like it always had when let off throttle tho. damned car just turns fuel into noise. Major lack of power. What else could it be? I know there is a vacuum leak, but could that be the source of all my issues? Where are the vacuum lines that I can check?

xpbr2000
01-09-2015, 03:16 PM
the HB should cause anything. I've never heard it causing noise either.

I assume it doesn't misfire and it has the proper oil level. Mine will have a timing chain noise above 1500 RPM. I can only atribute that to the cam and springs though.

The only normal thing that would cause a lot of noise is a collapsed lifter (usually ticking noise) or worn chain and/or bad tensioner. (continuous metal sound)

for vacuum lines, There should be a diagram on the radiator cover that shows the evap system. If not I can probably find on for an 02

nimrod.sixty9
01-09-2015, 03:53 PM
the HB should cause anything. I've never heard it causing noise either.

I assume it doesn't misfire and it has the proper oil level. Mine will have a timing chain noise above 1500 RPM. I can only atribute that to the cam and springs though.

The only normal thing that would cause a lot of noise is a collapsed lifter (usually ticking noise) or worn chain and/or bad tensioner. (continuous metal sound)

for vacuum lines, There should be a diagram on the radiator cover that shows the evap system. If not I can probably find on for an 02

I was thinking HB causing knock retard. It wobbles worse than what the video shows.

Noise was there, just couldn't hear in video. It was random rattling/pinging. It was only at WOT and peak of acceleration (about to level off). Could have deff been a tensioner. Now that I think of it, sounds like a whole lot of exhaust rattle too when first cranked, but only sometimes.

Did I look at the right reading for the vacuum? Are you saying by its reading it is definite vacuum leak and not exhaust?

No active missfires, but sort of feels like a miss (feel it, hard to explain). Oil is good. Again, could have just been the exhaust.

Didn't answer my question about vacuum leak being the true issue. Suppose it's best to track that down first anyway.

xpbr2000
01-09-2015, 04:02 PM
-5.1 is low for me at idle which would point to a vacuum leak. However my engine setup and tune are completely different than your s being stock. I hope someone may have a stock map reading that they could share or at least something closer to stock than mine. I would check the lines and see if there is any broken pieces or bad boots on the ends. you can spray alcohol or starter fluid on the lines and listen for the engine to rev. if it revs where you sprayed has a leak. I've never done it and i'd use caution while spraying a flammable liquid just anywhere.

If you think the balancer is bad i'd have someone look at it. Its hard to tell in a video what something like that is doing.

nimrod.sixty9
01-11-2015, 10:55 AM
Engine bay is covered in starting fluid LOL. No one peep...
This time it just happened to make some of the noise at idle. Looked under the car as I could really hear noise from exhaust; and which I see a crack in the where pass side meets the collector. Ive never seen them break here, and makes me wonder if a bad condition of a CAT could have contributed.

xpbr2000
01-12-2015, 10:35 AM
anything could cause a crack. could have been water splashed on it when it was hot and shunk the metal on part of it causing the tear.

thermal shock or vibration would be my 2 guesses. i doubt the cat could cause a crack.

nimrod.sixty9
01-12-2015, 12:12 PM
Is there a way to test CAT?

xpbr2000
01-12-2015, 12:34 PM
there are a couple ways. one is to measure the back pressure and the other is to take a temp reading from the precat side. I forget the numbers its suppose to be but thats the 2 ways i know to check. I'll tell you now that the temp methed at idle doesn't work. My cat was clogged up to the point that it sounded like a turbo or a diesel while on the gas because the air was blowing out the y pipe connections. but he said that it was within normal.... :-\

nimrod.sixty9
01-12-2015, 02:02 PM
http://www.aa1car.com/library/converter.htm

Looks like intake vacuum could be a possible test.

After htat I have no clue what else could be wrong with this car.