1998 Pontiac Firebird low idle wear noise

1998 PONTIAC FIREBIRD
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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
Mar 31, 2008 at 1:36 PM
Advertisement
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
do you know what your fuel pressure is? also check your fuel volume
Mar 31, 2008 at 1:59 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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.
Mar 31, 2008 at 2:29 PM
Advertisement
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
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.
Mar 31, 2008 at 2:35 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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
Mar 31, 2008 at 2:42 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS


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

Mar 31, 2008 at 2:50 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
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
Mar 31, 2008 at 2:56 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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
Mar 31, 2008 at 3:22 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
let me know what happends, i will do my best to help you
Apr 1, 2008 at 7:07 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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?
Apr 2, 2008 at 11:45 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
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.
Apr 2, 2008 at 12:29 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
do you know where it may be located, and how it looks? thanks
Apr 2, 2008 at 12:35 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
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.
Apr 2, 2008 at 1:39 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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?
Apr 2, 2008 at 2:46 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
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?
Apr 2, 2008 at 3:10 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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.
Apr 7, 2008 at 10:55 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
was there any other codes that was in the pcm. if so what are all the codes you have gotten form this.
Apr 7, 2008 at 11:17 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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.
Apr 7, 2008 at 2:43 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
EGR could do it also
Apr 7, 2008 at 3:26 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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.


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

Apr 7, 2008 at 3:51 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
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.
Apr 7, 2008 at 3:57 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
have you checked your IAC (idle air control) to see if it was sticking.
Apr 8, 2008 at 7:50 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I thought that what was wrong, so I bought a new one.. about a month or two ago. I also thought it was the throttle positiion sensor, so I also bought a new one. no dice.
Apr 8, 2008 at 10:04 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
is the only problem now is it has a low idle.
Apr 9, 2008 at 7:45 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
Yes.
Apr 9, 2008 at 8:53 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
can you get me a closer picture of the throttle body when you get a chance i wanna see if we can cheat a little bit.?
Apr 9, 2008 at 9:27 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
is this a good pic I coud remove the air intake, so you could see the whole throttle?


https://www.2carpros.com/forum/automotive_pictures/133498_throttle_1.jpg

Apr 9, 2008 at 11:15 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
this isnt the correct way to fix it, but since i am not there to see what the car is doing you can try this. there should be a stop screw on the throttle cable side that you may be able to turn up to raise your idle. i cant see in the pic if there is one or not.
Apr 9, 2008 at 11:44 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I know what screw that is, how much should I turn it, or how high?
Apr 9, 2008 at 11:52 AM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
i would say just enough to get the idle where you want it and it doesnt interfer with the throttle position sensor reading.
Apr 9, 2008 at 12:29 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I did the throttle stop adjustment. At first I did it too much and the RPM were going up and down erratically at a stop(it would be idling correctly then the rpm would go down slowly, then they would jump into 900, repeatedly. so I lowered it a little and it stopped idling erratically, but the RPM still would drop(500rpm, then it start shaking a lot). What I am thinking it is that vacuum line that I found not connected to any thing, probably the end I can’t find is causing my car to do it. I just need to get a diagram of the vacuum line.... where to look for one? Is there anything else that may cause this?
Apr 14, 2008 at 2:09 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
i looked for a diagram. isnt there one under the hood.
Apr 14, 2008 at 2:31 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
No there isnt one, I also checked in my repair manuel and there was not one on there only the electrical(which does me no good.)
Apr 14, 2008 at 3:03 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
you can call your local dealer and see if they can get you one. i dont think they would charge for it.
Apr 14, 2008 at 3:47 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I bought a manuel online and it had the diagram. I just hope this is the problem. But by the look of it I think it is. Thanks so far for everything I will get back to you with results. laters
Apr 18, 2008 at 1:29 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
well it running better but it the idle just drops. Sometimes when I start the car it starts really weak, like it want to turn off but stays on. I usally just turn it off and start it again and it goes away. maybe it is my fuel pump or something. any ideas?
Apr 21, 2008 at 2:14 PM
Avatar
RHALL77
  • CERTIFIED EXPERT
  • 3,361 POSTS
is it setting any more trouble codes?
Apr 22, 2008 at 7:15 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I havent checked but will go to autozone today to find out.
Apr 22, 2008 at 8:47 AM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I went to Autozone again to do a check for error codes. I found out that I had two new codes. They were p0412 and po418. The po412 was giving ma AIR bypass solenoid malfunction. I think this do to the fact I removed my egr valve. So What I am going to do is reconnect my EGR valve again and see if the codes come out again. It gave me other codes too, but they were the egr valve code and the o2 sensor after the cats (long tube header installed). I will get back to you with result and is there anything else I should do.
These are the codes:
16796 - P0412 Sec.Air Inj.Sys.Switching Valve A Circ Malfunction - AIR bypass solenoid malfunction.
16802 - P0418 Sec. Air Inj. Sys. Relay (A) Contr. Circ Malfunction
Apr 23, 2008 at 2:33 PM
Avatar
TYRANTXZERO
  • MEMBER
  • 33 POSTS
I finally had time to put EGR back on. One I put EGr back Codes went away and only thing showing is O2 sensor 3 and 4. but I idle problem still remains. I just dont know what to do?
Apr 25, 2008 at 11:00 AM