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Old Oct 4, 2008 | 04:04 PM
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Sputtering

Ok, still haven't gotten my problem fixed.
Symptom
Start it up idles fine even when I rev it up
Put it in drive and will sputter a bit then as long as you give it gas to accelerate its nice an smooth. Same holds true when driving down the road.
So far
Cleaned MAF sensor
Changed spark plugs and gap
Ran dry gas and injector cleaner through the fuel filter
New Fuel filter
Clean throttle body.
Did check oil for antifreeze

Can this be a fuel pump problem? if so how can I verify correct operation
Can this be a catalytic convertor problem?

Yesterday for I did get the infamous code PO300-Random Misfire... but did go away once the replaced the plugs
 
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Old Oct 5, 2008 | 09:07 AM
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Been doing some searches on here and from the sounds of it,it seems that broken manifold studs are somewhat common.
I'll have to check it out... it would make sense thats the type of noise I'm hearing.
 
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Old Oct 5, 2008 | 01:24 PM
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Change the IAC. Does the idle act funny when you turn on/off the AC?
 
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Old Oct 5, 2008 | 04:03 PM
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I removed the IAC and cleaned it using carb cleaner.
Checked all the vac lines that go between the tb-intake.
I did find 6 manifold bolts that are broken so I'm going to be taking all that apart tomorrow. Drove it after cleaning the IAC and can't really tell yet if its better, I'll know better once I can get it on the highway.
When I turned on the AC, there is nothing different with the idle.
 
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Old Oct 5, 2008 | 05:00 PM
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You can only get so much gunk out with carb cleaner. To do it right you need to scrape the gunk out or replace the part. Tough to clean it good. I would honestly consider replacing the IAC.
 
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Old Oct 7, 2008 | 11:13 AM
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Bought the new IAC and put it on. No difference still does the same thing.
Start off from a stop and slowly accelerate it will mis a bit,pop. Once I get up to speed its fine.
Same thing on the highway, run about 60 and let off the gas, slowly come back up to speed here comes the mis and pop again. But if I gun it, its fine.
I've been keep my scan tool with me and even read the codes when it does this and nothing.
Can I test the coil packs with a ohm meter?
 
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Old Oct 7, 2008 | 04:13 PM
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I was able to put a pressure gauge on the fuel rail today.
At idle- 30psi
Rev at idle- 28psi

In gear
At idle- 30psi
Rev in Gear- 38psi

Are these the correct pressures for the fuel pump?
thanks
 
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Old Oct 7, 2008 | 04:28 PM
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Originally Posted by yasky69
I was able to put a pressure gauge on the fuel rail today.
At idle- 30psi
Rev at idle- 28psi

In gear
At idle- 30psi
Rev in Gear- 38psi

Are these the correct pressures for the fuel pump?
thanks
Yes, but one thing, turn the key on, but do NOT start the engine - what does it read? Should be 38-40 or so.
 
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Old Oct 7, 2008 | 04:33 PM
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Originally Posted by krewat
Yes, but one thing, turn the key on, but do NOT start the engine - what does it read? Should be 38-40 or so.
Sorry forgot to post that. It was 30 with key on but engine not running. I did just replace the filter last weekend
 
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Old Oct 7, 2008 | 05:15 PM
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Originally Posted by yasky69
Sorry forgot to post that. It was 30 with key on but engine not running. I did just replace the filter last weekend
It should be 40 - sounds like the fuel pressure regulator is stuck.

Try this - with the engine running, and the gauge connected, disconnect the vacuum line going to the fuel pressure regulator and see what the pressure is - should go to 38-40. Hence, the key-on-engine-not-running test - no vacuum, the regulator should go to 38-40.
 
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Old Oct 7, 2008 | 07:14 PM
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ok I will try it tomorrow. Exactly where is the regulator? Is it back by the IAC, I tried looking today for it but didn't see it.
 
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Old Oct 10, 2008 | 01:32 PM
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Did the test again.
Key on , engine not running psi is 35-37 psi
Engine running- 30 psi- and will climb up when pressing the gas

Seems like my fuel pump,regulator are fine?
 
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Old Oct 10, 2008 | 02:04 PM
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I wonder if you have a problem with a coil or two. Coils can do some weird things when they go bad. Even if a a coil tests good it can still be bad. Ran into something similar with a small engine coil once. You could buy a new coil or two and swap an old coil for a new one in each cylinder one by one to rule out the particular cylinder COP being bad.
 
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Old Oct 10, 2008 | 02:23 PM
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Originally Posted by yasky69
Did the test again.
Key on , engine not running psi is 35-37 psi
Engine running- 30 psi- and will climb up when pressing the gas

Seems like my fuel pump,regulator are fine?
Seems about right... time to look at other things
 
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Old Oct 15, 2008 | 12:09 PM
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Sorry - didn't catch the year model...

Do you have an EGR? Could be going south.

Other than that, I'd have to say a coil is acting up.
 
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