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
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
Do you know what your fuel pressure is? Also check your fuel volume
March, 31, 2008 AT 2:29 PM
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.
March, 31, 2008 AT 2:35 PM
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.
March, 31, 2008 AT 2:42 PM
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
March, 31, 2008 AT 2:50 PM
March, 31, 2008 AT 2:56 PM
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
March, 31, 2008 AT 3:22 PM
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
April, 1, 2008 AT 7:07 AM
Let me know what happends, I will do my best to help you
April, 2, 2008 AT 11:45 AM
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?
April, 2, 2008 AT 12:29 PM
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.