90 firebird help!

90firebirdv6 · #1 09-10-2008, 07:34 PM

Hi i have a 1990 firebird v6 with an automatic tranny and 166k miles.

A month or so ago my car started acting weird, when i stopped at intersections, sometimes its would just die. but usually it would start right back up. I thought it might have been my battery cables because they were getting a bad connection and the car would die every once and a while. but i dont think that was it.
I was told to replace the oxygen sensor, so i did. That really seemed to help it. Every once and a while it would idle a little crazy/low when i stopped, but only died like once.

so it was running like that for a few weeks, which was fine for me. But a couple weeks ago i was driving on the highway and while i was accelerating, the engine just cut out. so i immediately took my foot off the gas and it stayed running, but if i tried to give it any gas at all it would immediately cut out and die. so i pulled over and turned it off then back on, and it ran fine again for a few hundred yards then started doing the same thing. It idles, but it idles crazy, from over 1000 to 5-600 rpm and sounds bad too. and as soon as i give it gas it cuts out.

So i got a new battery and wires just incase and that didnt help, i could drive around slowly but it would do the same thing.

So today i replaced the fuel filter, cause i heard that it could just be clogged. I sat it in my driveway in park and revved the engine for about five minutes, going from different rpms, all the way to holding it at 5-6 thousand rpms and it sounded perfectly and didnt stutter or anything.

i took it out for a drive about 10 minutes later and i cruised around 2-3 thousand rpms for about 5 minutes. then i gave it some gas and it cut out and did the same thing. so i let it idle and putted around the corner. I then turned it off then on, and it ran fine again at 2-3 thousand rpms for a few more minutes. so i watched the rpms and floored it and right when it hit 4000 rpms it cut out and did the same thing againnnnn. so i turned it off and back on and it wouldent run good again. i just had to let it idle and in drive let it putt back home.

I got it home and went inside and tried again like 30 mins later, and the car started but it was idling BAD. it was almost dying then i tried giving it gas and it cut out and died. then i turned it back on and then it was idling even WORSE and it died by itself after about 15 seconds.

HELP, i have no idea what to do.

Genopsyde · #2 09-11-2008, 03:18 AM

sounds like failing injectors to me.

FullyAvenged · #3 09-20-2008, 05:36 PM

I have the same car but with a v8. I cant get this car to go past an idle without dying. i have no codes comming up in the computer and I have cleaned the EGR IAC and throttle body with carb cleaner. No luck car runs like shit and is another brick in my back yard. funny thing is is the engines brand new.

Genopsyde · #4 09-20-2008, 09:44 PM

check your fuel pressure then post the results. you could have a fuel pump problem.

FullyAvenged · #5 09-21-2008, 12:06 PM

Already checked it. It's 42 to 45.

Genopsyde · #6 09-21-2008, 02:21 PM

tpi? how is your spark?

Morley · #7 09-23-2008, 01:31 AM

Need to check your cat converters, especially if the car runs fine until you try to put it in gear and go.

FullyAvenged · #8 09-29-2008, 06:04 PM

No Cats Just straight exhaust. Today I put my TPS back on and it ran great for about an hour took it for a drive put gas in and then shut it down. Went to take it back out about an hour and a half later and same boggin effect. The windows were down (get this) I went put the window up with my foot slightly on the gas aas it was bogging down and as soon as i touched the window switch it start revving about to 2500 rpms. let go of the switch it would bog down again. then the car stalled and i got a code 21 which is

:TPS voltage was above 4.3 volts for 10 seconds when the MAP sensor signal showed manifold vacuum above 15 pounds, or TPS signal voltage was over 4.5 volts:

Now is the map sensor in the mass air flow sensor.

WHat could thia be!??!?!

Morley · #9 09-30-2008, 01:33 AM

Quote:

Originally Posted by FullyAvenged

Now is the map sensor in the mass air flow sensor.

WHat could thia be!??!?!

You don't have a MAF sensor, You have a MAP sensor. MAF's (Mass Air Flow) were used from 85-89, MAP's (Manifold Absolute Pressure) were used from 90-92. Check all of your vacuum hoses especially the ones going to the MAP sensor (it is bolted to the right rear of the plenum). If all else fails, you can try a new MAP sensor (costs about $40 at the auto parts store) Also, Get the car warmed up and then check the voltage output of the TPS, it should be the same as when cold. That is, .54v (or so) at idle, and when the throttle is opened it should read increasing voltage, and read it nice and smooth. An analog meter works best for the open & closing checks on the TPS.

FullyAvenged · #10 09-30-2008, 05:18 PM

Well I'm pretty sure this car has a mass air flow sensor. It is bolted above the radiator It has the needle inside of it. Unless this is called something else??

Morley · #11 10-01-2008, 02:18 AM

Quote:

Originally Posted by FullyAvenged

Well I'm pretty sure this car has a mass air flow sensor. It is bolted above the radiator It has the needle inside of it. Unless this is called something else??

If you have a MAF you either have a bastardized system someone put in, or you don't actually have a 1990.

FullyAvenged · #12 10-01-2008, 06:52 PM

I'm sorry I posted on this other guys thread I meant to say it was an 89

Morley · #13 10-02-2008, 01:45 AM

Quote:

Originally Posted by FullyAvenged

I'm sorry I posted on this other guys thread I meant to say it was an 89

Ah, well that's a horse of a different color then. Disconnect the MAF and see if the problem gets better or worse. Do you have any codes stored?

FullyAvenged · #14 10-02-2008, 06:48 PM

Code 21 was the most recent code I got. Something about the TPS. You already answered on it I think. When I disconnect the Mass Airflow from the harness it wont start or stalls when it is running and disconnected whilst running. THe car runs pretty good when its cold but like I said once it starts bogging and running crappy if I push the window switch it will idle a LITTLE better but not much.

It's driving me to the point where I just wanna take it to the junk yard. Brand new engine in it to. lol

Morley · #15 10-03-2008, 01:37 AM

Quote:

Originally Posted by FullyAvenged

Code 21 was the most recent code I got. Something about the TPS. You already answered on it I think. When I disconnect the Mass Airflow from the harness it wont start or stalls when it is running and disconnected whilst running. THe car runs pretty good when its cold but like I said once it starts bogging and running crappy if I push the window switch it will idle a LITTLE better but not much.

OK, the MAF is good then. If it runs better without it then it is bad.
Next you need to ohm out your injectors, cold and hot. They should be 15-17 ohms and have no more than .5 ohms difference between any of them. You have Multec injectors and they are known to be junk. If you need to replace them go here http://www.fiveomotorsport.com/Injec...sTPI.asp#caddy

As to it idling "a little better" when you hit the window switch, it really isn't. What it is doing is idling a little higher. The ECM monitors voltage output from the alt. When it senses that the alt. is under demand it bumps up the idle so the alternator won't drag the engine down below the programmed idle speed.
After checking the injectors, check for vacuum leaks and check for "false air". This is air that is getting into the engine after the maf. This is unmetered air that the ECM isn't seeing and will cause the engine to run like crap when warmed up. One good place to look for false air is from the rubber boot behind the MAF, see if it has a hole worn in it on the under side.

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