1998 Pontiac Firebird low idle wear noise

Tiny
TYRANTXZERO
  • 1998 PONTIAC FIREBIRD

Engine Performance problem
1998 Pontiac Firebird V8 Two Wheel Drive 160000 miles

Better description of problem

I have a 98 trans am. 5.7 liter automatic. The problem I am having is it is making weird noise, it idle low(500rpm, it suppose to be around 1000), loss of power, and when at full stop it hesiatate when running again. I started having this problem about a week ago, but the low Idle since I bought the car(about a year ago). At first the idle wasn’t that bad it would shake alittle(low compression because my car would sound quite at a stop light). It only did that in drive, it would not have this problem in reverse nor nueteul. I wanted to fix it so I started fixing thing that would be causing the problem. First I removed throtte body and there was a lot of carbon build up. Nothing, problem remained. Second I changed the Idle air control valve, new MAf sensor, speed sensor. But nothing. Third I gave tune-up, changed oil, sparkplugs(irdium), and wires. When in the process of doing this, I notices oil in the spark plug chamber(a lot). I think that is why I am getting the low Idle. I know that it could be one of 2 things, the pistion rings could be bad or the valve path is leaking oil because of bad seals.(How can I tell?). A month later I stated hearing this noise(bang, bang, like if something is hitting). This only happen in drive, but now even when in park. I just don’t know what to do. I don’t want to take it to a mechanic because where I live(Laredo) no one knows what to do and I also get the run around(like it the fuel filter, Im sure, I put a new one a week after I bought it) any help on this matter, would be great. Oh and it now making a clicking know, I think it’s from a valve.

Mods- egr removed, block off plate.
New headers and y-pipe- slp
New exhaust- flowmasters
Maf-madification
Oil changed – put thicker oil because mechanic told me it would help- 160,000miles, 5w30 to 10w30.
New spark plugs – delco irduim msd wires,
New oil filter –k and n
New air filter – k and n
New temp- 160 degree
New speed sensor
I put some additive in the gas- NOS, etc
Oh and a thrddle body bypass(for coolent)
And also fixed the secondary air system, the smog pump was broken

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Monday, March 31st, 2008 AT 1:36 PM

39 Replies

Tiny
RHALL77
  • MEMBER

Do you know what your fuel pressure is? Also check your fuel volume

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Monday, March 31st, 2008 AT 1:59 PM
Tiny
TYRANTXZERO
  • MEMBER

How would I check the fuel pressure, is there something I could buy.
Oh and I forgot to add something to, I found a vaccum hose with 3 exits disconnected, I tryed finding what they connected to. The leads coming from the passenagers side valve cover. I caped it for the mean time. Could this be the problem.

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Monday, March 31st, 2008 AT 2:29 PM
Tiny
RHALL77
  • MEMBER

It could be the problem there should be a vacuum diagram under the hood to tell you where they go. As for fuel pressure there is a gauge you can buy. Tool trucks for sure have them and some part stores.
There is a valve on the fuel rail that it hooks into. It looks like a valve stem on a tire.

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Monday, March 31st, 2008 AT 2:35 PM
Tiny
TYRANTXZERO
  • MEMBER

I checked my hood there was no diagram anywear, but I well check my car repair book). What are some symptoms of low fuel pressure? I just want to know before I buy one. Thanks

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Monday, March 31st, 2008 AT 2:42 PM
Tiny
TYRANTXZERO
  • MEMBER


http://www.2carpros.com/forum/automotive_pictures/133498_enginemod_1.jpg

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Monday, March 31st, 2008 AT 2:50 PM
Tiny
RHALL77
  • MEMBER

Is there any spots on the intake that you can see where it goes (vacuum lines) If the cap is green no thats not the fuel rail. Thats the EVAP system

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Monday, March 31st, 2008 AT 2:56 PM
Tiny
TYRANTXZERO
  • MEMBER

I looked around and dont see where it connected to. I wll look again today. I think that is the fuel thing, the green one is close to it. Thanks

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Monday, March 31st, 2008 AT 3:22 PM
Tiny
RHALL77
  • MEMBER

Let me know what happends, I will do my best to help you

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Tuesday, April 1st, 2008 AT 7:07 AM
Tiny
TYRANTXZERO
  • MEMBER

I bought the fuel pressure gauge($40). I also found out that my fuel pressure is supposed to be around 60-50psi. I put the gauge on and it read about 50psi when I just turned the key, not on but to where the light turn on. So I started the car and the pressure went down to 10psi. So I had my friend push the gas pedal and it went up to 60psi. After that I checked it about it was kind of staying there, then went down, and then up, back down. Oh and I checked my book to see if there was a vacuum line guide none, only electrical (sucks). Is something wrong with my pump?

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Wednesday, April 2nd, 2008 AT 11:45 AM
Tiny
RHALL77
  • MEMBER

Disconnect the fuel pressure regulator with it running and see what your pressure is, but to me it sounds like you need a fuel pump.

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Wednesday, April 2nd, 2008 AT 12:29 PM
Tiny
TYRANTXZERO
  • MEMBER

Do you know where it may be located, and how it looks? Thanks

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Wednesday, April 2nd, 2008 AT 12:35 PM
Tiny
RHALL77
  • MEMBER

Its a round shape cylinder, it should be around the same location as where you tested fuel pressure or somewhere on the fuel rail. It will have a vacuum hose on it. In your picture, it looks like it is next to the red hose.

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Wednesday, April 2nd, 2008 AT 1:39 PM
Tiny
TYRANTXZERO
  • MEMBER

I will check it when I get home. How would I know if there something wrong with it? Also I have a question. That noise it making sounds like it coming from somewhere in between the tranny and the engines. Better yet if there something wrong with the tranny(like torque converter) could that be contributing to my car problem?

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Wednesday, April 2nd, 2008 AT 2:46 PM
Tiny
RHALL77
  • MEMBER

In some cases there will be fuel coming out when you pull the vacuum line. As for the noise, it could be setting off a knock sensor and causing the low power. Check and see it your torque converter bolts are tight. Is the noise there all the time?

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Wednesday, April 2nd, 2008 AT 3:10 PM
Tiny
TYRANTXZERO
  • MEMBER

I notice that my check engine light started blinking on and off on Friday. So the next morning I went to AutoZone and they told me it was a second cylinder misfire. So I went home and checked the coil and spark plug on the second cylinder. Nothing, but when I looked at the spark plug wire I notice it was burn (it looks like it was rubbing against the headers; I forgot to take a picture so I could show you). So I bought a set and replace that one, and wow! It stopped making the noise and my car feels and drives better. The low idle still remains. Can a bad fuel pump or regulator contributes to that.
This is what my car does now. The car starts, it sounds great but a few seconds later in drops.( Noise ex - loud, loud, loud, quiet quiet, quiet) kind of like it loses power. When I a drive and stop at a light. The idle is good for 3 - 4 seconds but then it slowly goes down to 500 RPM. (From 1000-900). So I often put in neutral to avoid this(700-600 rpm stil low but better). Also if I step on it (floor it) it runs good. But then it starts acting weird when I stop. Idle goes low even before I stop, my cars sound really weak also. Another thing it does, if I turn on my air con or heater. The idle jumps, then it goes down, then up, till idle range. Weird, right? Thanks so far.

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Monday, April 7th, 2008 AT 10:55 AM
Tiny
RHALL77
  • MEMBER

Was there any other codes that was in the pcm. If so what are all the codes you have gotten form this.

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Monday, April 7th, 2008 AT 11:17 AM
Tiny
TYRANTXZERO
  • MEMBER

There was other codes: egr valve code( I removed it but it having the problem before). Also a oxygen sensor(removed cats, long tube headers. But still have the ones before the cats). Those were only two. But I will have then check again today.

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Monday, April 7th, 2008 AT 2:43 PM
Tiny
RHALL77
  • MEMBER

EGR could do it also

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Monday, April 7th, 2008 AT 3:26 PM
Tiny
TYRANTXZERO
  • MEMBER

I have it on but it wasnt giving me the code before. I just removed because it just recycle exhaust into the vehicle. So I removed it.


http://www.2carpros.com/forum/automotive_pictures/133498_engine_2_1.jpg

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Monday, April 7th, 2008 AT 3:51 PM
Tiny
TYRANTXZERO
  • MEMBER

Sorry about pic. I just wanted to show you were the egr was and the fuel regulator.
Even withthe egr on it was still giving me the low idle.

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Monday, April 7th, 2008 AT 3:57 PM

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