Rough Idle - Page 2

BlazerLT · #16 05-06-2005, 01:05 AM

TB Cleaner

freddie cosme · #17 05-08-2005, 03:56 PM

Well replaced all that was mentioned before (major tune up) cap rotor wires pcv fuel filter air filter cleaned EGR and throttle body even added a 20 oz bottle of techron and still have a rough idle.I dont know whats next I have no codes and Im running out of patience.... Im ready to trade it in

blazer94 · #18 05-08-2005, 04:03 PM

Quote:

Originally Posted by freddie cosme

Well replaced all that was mentioned before (major tune up) cap rotor wires pcv fuel filter air filter cleaned EGR and throttle body even added a 20 oz bottle of techron and still have a rough idle.I dont know whats next I have no codes and Im running out of patience.... Im ready to trade it in

just a thought... how were your plugs when you changed them? any glazing, burned deposits? How is your coolant level? Is it low, or is it where it should be? Any puddles under your vehicle?

freddie cosme · #19 05-08-2005, 04:12 PM

When I removed the plugs they did not look that bad.The tip of the electrode of the plug was a little worn but I would chaulk that up to normal wear and tear. as for my coolant I have not checked it.Do you think that may cause the rough idlle? I am not running hot and I have no puddles under my car......

blazee · #20 05-08-2005, 04:21 PM

That covers all the normal maintenance items. If the rough idle persisted, that would indicate that you may have a real problem. I would check the fuel pressure. Your local Autozone should have a fuel pressure gauge as a loaner tool. You just pay for the tool, return it within 3 days and they give your money back.

The gauge attaches to the schrader valve, it is at the back of the intake on the driver's side, it looks like a big tire valve with a black cap on it:

When you turn the key on, the pump runs for 2 seconds. While the pump is running the pressure should be 60-66psi.

When the pump primes and shuts off (engine still off) the pressure should hold steady between 55-60psi.

With the engine running the pressure should drop 3-10psi depending on engine speed due to vacuum on the regulator.

freddie cosme · #21 05-08-2005, 04:25 PM

I have a fuel pressure guage and I will hook it up. Is it ajustable via a pressue regulator?

freddie cosme · #22 05-08-2005, 06:29 PM

fuel pressure right on 55psi

freddie cosme · #23 05-08-2005, 06:51 PM

Just a tidbit of info the vehicle runs good while normal driving....its when you come to a stop you feel the crappy idle.

s10blazerman4x4 · #24 05-08-2005, 07:13 PM

does it shake like a dog would when you give them a bath and they want to shake water off? Mine does that since i bought it and it seems normal because my uncle's 91 does the same.

Just my99

freddie cosme · #25 05-08-2005, 07:37 PM

Quote:

Originally Posted by blazer94

just a thought... how were your plugs when you changed them? any glazing, burned deposits? How is your coolant level? Is it low, or is it where it should be? Any puddles under your vehicle?

I was just curious... Why would you ask about my coolant? I was checking it out & it needs to be changed (flushed).

freddie cosme · #26 05-08-2005, 07:44 PM

I was checking to see if I was getting any voltage to my EGR. I put my test light to the connector and I got was a weak lit test light, I checked other sensors and my test light is brightly lit. I think I may have a EGR circut problem.

blazee · #27 05-08-2005, 08:16 PM

What was your fuel pressure for each of the following situations:

1)KEY ON, ENGINE OFF, PUMP RUNNING.

2)KEY ON, ENGINE OFF, PUMP OFF. (DOES IT REMAIN CONSTANT?)

3)KEY ON, ENGINE RUNNING.

He was probably asking about the coolant due to the notorious leaking Chevy intake gasket. Let's hope that isn't the problem. If it were leaking you should have seen deposits on the plugs and the idle would have improved briefly after changing the plugs.

I believe the EGR valve should only have voltage when it is being commanded to open and the voltage will depend on how far the ECM wants it open.

And no it isn't normal for these engines to shake like a mad dog.

After looking back over this thread, I just realized we didn't have you try cleaning the IAC valve. That would be another easy thing you could try.

freddie cosme · #28 05-08-2005, 09:13 PM

Quote:

Originally Posted by blazee

What was your fuel pressure for each of the following situations:

1)KEY ON, ENGINE OFF, PUMP RUNNING.

2)KEY ON, ENGINE OFF, PUMP OFF. (DOES IT REMAIN CONSTANT?)

3)KEY ON, ENGINE RUNNING.

He was probably asking about the coolant due to the notorious leaking Chevy intake gasket. Let's hope that isn't the problem. If it were leaking you should have seen deposits on the plugs and the idle would have improved briefly after changing the plugs.

I believe the EGR valve should only have voltage when it is being commanded to open and the voltage will depend on how far the ECM wants it open.

And no it isn't normal for these engines to shake like a mad dog.

After looking back over this thread, I just realized we didn't have you try cleaning the IAC valve. That would be another easy thing you could try.

Key on engine off pump running 65psi
Key on engine running 57 psi
Key on engine off pump off 65psi for 2 sec and then drops to55psi

blazer94 · #29 05-08-2005, 09:34 PM

Quote:

Originally Posted by blazee

What was your fuel pressure for each of the following situations:

1)KEY ON, ENGINE OFF, PUMP RUNNING.

2)KEY ON, ENGINE OFF, PUMP OFF. (DOES IT REMAIN CONSTANT?)

3)KEY ON, ENGINE RUNNING.

He was probably asking about the coolant due to the notorious leaking Chevy intake gasket. Let's hope that isn't the problem. If it were leaking you should have seen deposits on the plugs and the idle would have improved briefly after changing the plugs.

I believe the EGR valve should only have voltage when it is being commanded to open and the voltage will depend on how far the ECM wants it open.

And no it isn't normal for these engines to shake like a mad dog.

After looking back over this thread, I just realized we didn't have you try cleaning the IAC valve. That would be another easy thing you could try.

Yes, blazee is correct, that was what I was asking about. And yes, you might have seen a brief improvement after putting in fresh plugs. plug # 6 and # 3 usually show first signs. Also, I wonder, did you try cleaning the MAF? Other common causes of missing at idle are all the things mentioned so far, plus faulty coil, bad spark plug wires ( I know you replaced them) vacumn leak, incorrect timing, faulty TPS (Throttle position Sensor) and fuel line / filter problem. Just out of curiousity, how was your oil when you changed it? does it smell of gas or coolant? blazee has you on the right track, tho, of using a system of elimination to check for cause / solution.

freddie cosme · #30 05-08-2005, 11:56 PM

Quote:

Originally Posted by freddie cosme

Key on engine off pump running 65psi
Key on engine running 57 psi
Key on engine off pump off 65psi for 2 sec and then drops to55psi

Im starting to wonder....My coolant resorvior is brown and my radiator is getting there. I think I will top them off and monitor them.

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