1998 Monte Carlo Z34 Idle Problems?

[edstace]

Hi, I have a 1998 Chevrolet Monte Carlo Z34. This car has not given myself or the previous owner (my mother) any problems until the past couple of weeks. Originally about 2 weeks ago I started my car in the morning and made it about 5-6 miles down the road and it stalled out (everything instantly shuts down and the dash lit up like a christmas tree) on me as braking. I would go to start it again and it would do the same thing. I had a diagnostic performed at Firestone, nothing came up. The car actually worked fine after this until last Tuesday. I tried to start it first thing in the morning and it would try to turn over but failed miserably. Had it towed to Firestone, diagnostic performed, they SAID it was a bad computer module (?) and they also cleaned my fuel system. Everything worked fine afterwards until yesterday when it would actually crank but then gradually die. The only way to keep the car alive was to constantly apply the gas. I took it back to Firestone, they ran a diagnostic, came back clean, they told me it was a shot in the dark but they can try changing my spark plug wires. The car worked fine afterwards, until it started losing gas/power towards the end of the day. The next morning, the same events happened again, except I left it in my parking garage and hitched a ride with a friend to work.

Sorry this was so long, but this car is about to break me, I've spent $700 thus far. Any ideas what could be the problem?

Thanks.
Eric

[richtazz]

I would do a fuel pressure test and compression test. It sounds to me that either the fuel pressure regulator is bleeding off and not supplying enough fuel to keep the injectors firing, or you have a head gasket going or some burnt valves thats bleeding off compression not allowing the cylinders to produce power.

[Rjevon77]

I have 165k miles on it I just had my intake cleaned out and after my car sits for 8 or more hours when started it idles up and down until it finally dies. After about 3 or 4 times it starts fine. My light isnt on so I dont know what it cuold be. Ive invested @2k in overall repairs so far. I was wondering did u find out what youre problem was.

[kamikaze_k77]

Originally Posted by Rjevon77

I have 165k miles on it I just had my intake cleaned out and after my car sits for 8 or more hours when started it idles up and down until it finally dies. After about 3 or 4 times it starts fine. My light isnt on so I dont know what it cuold be. Ive invested @2k in overall repairs so far. I was wondering did u find out what youre problem was.

Get both upper and lower manifold intake gaskets checked. Had same problem. One gasket had slight leak, only noticed problem on startup with same symptoms. had gaskets replaced ($300 for both including labor) and it runs great!

[ulies8]

Check your MAF sensor located between your air filter unplug the electical plug then drive it see how it reacts. if the car runs after a couple of hours it may be the Mass Airflow Sensor.,

[ulies8]

Also check your throttle position sensor they cost about 32.00 dollars. replace the old one. Its located on th throttle body beneath the air flow valve.

[ricebike]

hmm... those 2 sensors mentioned previously should have set a trouble code soo that may not be the problem...

the gaskets K mentioned are notorious for that... so u may haveta hunt towards that direction

don't go back to that Firestone since the technicians there don't know much about this particular GM vehicle... find another shop!

If you live close to an Autozone, they can plug an OBD II scanner & check to see if you have any troublecodes for free! in the parking lot!

and, here's a list of trouble codes for your vehicle:
BOOYAH!

[ulies8]

Did you change the oxygen sensor that could be the problem

[ricebike]

Originally Posted by ulies8

Did you change the oxygen sensor that could be the problem

umm, i guess my post flew by you, ulies8...

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hmm... those 2 sensors mentioned previously should have set a trouble code soo that may not be the problem... etc.

[ffgus]

Try cleaning the Intake air control valve. It worked for me on my 2002 monte ss, 3.8. Use carb'choke cleaner. Do not get the electronic contacts wet.