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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 01-06-2010, 02:08 PM
garyiso garyiso is offline
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2002 Chevy TrailBlazer LT EXT
Black 4.2L I6 4X4
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Location: Mt carroll,il
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low oil pressure

Check gauges light comes on, low oil pressure stop engine warning oil pressure gauge drops to zero. Only occurs after engine is warm, only at idle and is sporadic. Took to garage said everything checked ok no codes reported. Oil level ok doesn't make any noise car running ok. What to do next or ignore it Gary
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  #2  
Old 01-06-2010, 03:19 PM
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the roadie the roadie is offline
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Is your idle RPM stable at a rock solid 600, or is it jumping up and down like 400-800 RPM every 4-5 seconds if the AC is on?

If so, and you have over 30K miles, spend $4 and 30 minutes and clean your throttle body. A miracle cure to GM's misdesign that denied us a proper PCV valve. The back of the throttle body beyond the butterfly valve looks like the shower drain of a pig farm ranch in East Roosterpoot, OK.

http://forums.trailvoy.com/articles....ticle&artid=91
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  #3  
Old 01-07-2010, 01:53 PM
garyiso garyiso is offline
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2002 Chevy TrailBlazer LT EXT
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I do not have the ac on. I'm talking about the oil pressure gauge going to zero not rpm. Why would throttle body have anything to do with oil pressure? It does go back to normal when you are going more than 10 mph. Gary
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  #4  
Old 01-07-2010, 05:30 PM
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wardak33 wardak33 is offline
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2002 Olds Bravada
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There's a reason why he first thought of a dirty throttle body.

You get that message when your engine stalls, no matter what the actual cause is. I've cut the power to my fuel pump and still get the message. Throttle body because that's the number one cause of engine RPM's bouncing everywhere and stalling on these trucks. It only happens when you have the AC or even the front defroster running. This usually happens when the battery is disconnected and the PCM loses its memory on how things actually are.

Clean it and give it a try. It happens to almost everyone on this site.

Give us more info on your truck like miles, past maintenance and any recent work to make sure..
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2002 Oldsmobile Bravada: 4.2L I6 w/ G80 Locker, AWD, TBSS springs, HD bilsteins, 6000k HIDs, Mobil1, Iridium Plugs
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  #5  
Old 01-07-2010, 07:56 PM
garyiso garyiso is offline
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2002 Chevy TrailBlazer LT EXT
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Thanks for info. I just bought this last month with 92,000. Seems to be in very nice shape and like driving it but it is a gas hog. I think I'm the reason gas prices are going up. Gary
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  #6  
Old 02-11-2010, 08:08 AM
garyiso garyiso is offline
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2002 Chevy TrailBlazer LT EXT
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Join Date: Dec 2009
Location: Mt carroll,il
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low oil pressure

Had oil changed and throttle body cleaned but when warm and coming to a stop check gauges light comes on low oil pressure, stop engine warning. What next?
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  #7  
Old 02-11-2010, 10:31 AM
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christo829 christo829 is offline
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Could be a bad oil pressure sensor, which is really only a switch that trips
at around 12 psi.

Any chance you can put a T adapter in, and put an analog gauge inline?
You still need the regular sensor in place to placate the PCM. What
you're seeing on the gauge is just a lie generated by the PCM to make
the driver feel better.

Another member mentioned a similar issue, and it turned out to
be a loose or missing vacuum cap on a port, but I can't remember
which one. When the vehicle came to a stop or even slowed down,
vacuum fell off and the truck assumed it was getting shut down,
which triggered the low pressure alert among other things.

If I can find that specific thread before someone else finds it, I'll repost.

Good Luck!

Chris
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  #8  
Old 02-11-2010, 09:25 PM
WOOLUF1952 WOOLUF1952 is offline
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Quote:
Originally Posted by garyiso View Post
Had oil changed and throttle body cleaned but when warm and coming to a stop check gauges light comes on low oil pressure, stop engine warning. What next?

Just for s**ts and giggles: Was the t-body removed for cleaning? Or just the face sprayed clean?
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  #9  
Old 02-12-2010, 12:53 PM
garyiso garyiso is offline
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2002 Chevy TrailBlazer LT EXT
Black 4.2L I6 4X4
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Location: Mt carroll,il
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low oil pressure

Went to dealer and asked them and they said they cleaned it attached so I guess that means they just sprayed it. Gary
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  #10  
Old 02-12-2010, 01:08 PM
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the roadie the roadie is offline
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That's not an effective cleaning. Even if it isn't the cure for your issue, it's still a good thing to do. Link in post #2. Make sure to disconnect the battery to force a PCM relearn.
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