Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

Stalling, Low Oil Pressure, Irradic Idle

35K views 32 replies 15 participants last post by  gmcjimmy4x4 
#1 ·
Hello. I've been roaming this site for a few weeks trying to solve my trucks' problem to no avail, and the dealer has not figured it out yet either. I have an '02 Envoy SLT I6(69k miles), and starting about a month ago, the truck started stalling at lights, and when idling.

The RPM's would jump up and down from about 200-1200, then the computer says low oil pressure, and shuts the truck off. I am able to restart immediately. I have been to the dealer 5 times in the past two weeks, and I am still having the problem. Here is a list of things I have done, most from reccommendations I've seen on this site.

-Cleaned Throttle Body
-Changed Fuel Filter
-Ran a bottle of Techron

This is what the dealer has done
-New Fuel Pump
-New camshaft sensor connector
-New camshaft sensor after car threw a SES light on the last trip on this past Friday

The truck cut off on me again today, and I am lost...can't get back to the dealer until the day after Christmas. As much as I love this truck, I may be trading it in for a Ridgeline if I cannot get this problem fixed. I have had no other issues with this turck for the 2 years I have owned it. The dealer has been totally working with me up until now, refunding me the $800+ for the fuel pump, and putting in a new camshaft sensor free of charge due to my frustration.

Any ideas...?
 
See less See more
#6 ·
similar problem

I was having a problem similar to your and I replaced the oil pressure switch and haven't had the problem since. The switch is located on the passenger side of the engine above the oil filter. I have an 04 trailblazer it wasn't to bad to change and I bought the part at advance auto parts.
 
#10 ·
Stalling while in Park at traffic lights

Hello,

We've had this same issue suddenly start happening the past two months or so. Twice while my wife was driving it, and once while I was driving, three days ago.

My experience with older cars is that this would happen when you were stopped at a light, while the vehicle was in Drive..........but this problem with our 2004 Envoy happens while it's in park. The message console quickly read "Low Oil Pressure" after the engine kicked off.......but only displayed that message for a BRIEF second. If I hadn't been looking at it, I would have missed the message.

The Envoy did start right back up though. Is replacing the oil pressure switch, which is mentioned above, the best solution?
 
#11 ·
I am having the exact problem with my vehicle. Low Oil Pressure and all. Seems to be a universal problem. I am extremely disappointed by this. It almost feels as if there is less power too. Anyone else feel the same way who is having the same problem?
 
#15 · (Edited)
I actually just changed mine yesterday after getting the "low oil pressure" message a couple times. There are a few model numbers that show up as correct, but you need the ACDelco D1843A (which replaced the older D1838A) - Amazon has it for $25 shipped. It fits a special 1 1/16" socket since the edges are sort of rounded - get the short one I linked to, not the deep-socket one as it won't fit between the sensor and frame rail.

It's really a quick 5-10min job. The sensor is right above the oil filter and has a green 2-wire plug coming out (ignore the red arrow, the pic is from another thread). It's not hard to reach once you figure out where to stick your arm ;) Also, a bit of oil will come out with the sensor, but not much (maybe 1/2 oz). I did it when the engine was hot so if you do the same watch where you stick your face when removing it.

 
#16 ·
i thought it was a switch, not a sender... that the needle on the gauge is a representation of oil pressure based loosely on engine RPM and coolant temperature...

switch meaning closed or open much like motorcycle oil pressure switches (no read out, just a light)

sender meaning variable voltage depending on pressure.
 
#17 · (Edited)
Like you said, ours is just a 12 PSI switch (which is what the link points to) - it's the PCM that keeps the gauge around 40 PSI and makes the needle arbitrarily move with RPMs. It's really just a dummy gauge.
 
#19 ·
it's not a dummy gauge, it's a feel good gauge.

so my question is, since the engine RPM is low, the oil pressure would be low, therefore the light would illuminate if under 14 PSI... why would changing a pressure switch solve the problem?
 
#24 ·
Hi guys,
We had ours lose power, glide to a stop and when we tried to re-start it would stall out with the "low oil pressure" display come on. Much like everyone else describes here. Had to have it towed home. Called a friend who owns his own shop...."probably the oil pressure sensor". Replaced it. The car refuses to start. Not even catch.

I have a 2004, Trailblazer ext w/ V8 (5.3L). The sensor was located on the top of the engine block toward the rear of the engine (nearest the firewall). To access it I had to disconnect both fuel lines (quick disconnect) and a PVC line.

Do I need to do something else to purge or bleed the lines of air? the only bleeder valve I could find was near the fuel filter near the gas tank. Clear the ECU? any extra help thanks, otherwise it's a trip to the shop.
 
#28 ·
Another question about the oil preassure? The book says minimum is 12psi at 1200 rpm, my light only comes on when the rpm go below about 900rpm (or 12 psi). If the switch is supposed to alarm at 12 psi, wouldnt it call out the alarm at idle all the time? At 1200rpm im getting 26 psi. What should idle be? Mine seems to read about 600 at idle.
 
#29 · (Edited)
First post here:

I own a 2004 Trialblazer LS with an I-6 / 4.2L engine. Lately, the dashboard oil pressure gauge will just drop to zero at times, but no other warning lights will come on. The engine does not make any unusual noise even when I'm driving at highway speed with the oil indicator needle pointed at zero. I installed a new oil pressure switch ($45.00 bucks) and even went as far as changing the Bosch oil filer to a Delco, still the same problem. Normally, the oil pressure needle will run between 40 to 60 psi most of the time, then just drop to zero again. When the engine is turned off for ten minutes and restarted, the oil pressure will be back to normal. Naturally, this freaks me out every time it happens!
Yesterday, I decided to make an adaptor from the old oil pressure switch. I cut the plastic off the old switch with a hacksaw ... then drilled and tapped it for 1/4x28 threads per inch. I have a Fuel Injector Tester kit with a hose and gauge that screws into the oil pressure adaptor I made from the old switch. With this setup, I was able to remove the new oil pressure switch from above the filter and screw in the adaptor, hose and gauge.

Here are the readings I got from my engine which has 118,000 miles.
700 RPM (idle) - 19 PSI
1200 RPM - 38 PSI
2000 RPM - 52 PSI
2500 RPM - 66 PSI
Since the GM factory specs only call for 12 PSI at 1200 RPM, I am very pleased with the results from using the manual gauge which shows actual oil pressure at the filter. I took some pictures of the gauge at different RPM, and also of the test setup I used, I will attempt to post them. Hope this info is helpful to those that are experiencing similar problems with this issue.
 

Attachments

#30 ·
Ive been tring to fix the same problem. Made the same adapter and still it was a problem even though I had sufficient oil preassure. I think it might be more of an electrical problem or an idle issue. Yesturday mine was back to normal untill I had a little stumble in the idle and the rpms dipped a little and then revved up. When this happened the light popped on and then right back off. But now its not on all the time when its warmed up like before. Things I tried were cleaning throttle body, reset ecm after cleqning, oil preassure sensor(which had oil leak7ng through the sensor into the connector), and also had the same problem with the camshaft position actuator valve with oilmseeping into the connector. Something I did changed the problem slightly for the good. Before it was doing all the time at idle.
 
#31 · (Edited)
It definitely is an electrical issue, either in the wiring, circuit board or the stepper motor. Here is the weird thing that happened during my test. I disconnected the electrical connector from the new oil pressure switch, so that I could remove the switch/sensor, and screw in the adaptor. After my manual connections were complete, I started the vehicle, so I could walk around the truck to check the reading on the manual gauge. Low and behold, the dashboard oil pressure gauge which always dropped to zero when the engine is off, was currently reading 40 PSI. This is with the oil pressure switch completely removed from the engine and the wires disconnected. The dashboard gauge should have remained at zero!
But, I am not concerned about the oil gauge readings at this point, because I am now confident that my engine is receiving the proper lubrication from the oil pump.
My fuel gauge and alternator gauge are not working properly either. The fuel gauge is my next project, as I am currently working off resetting the trip odometer at each fill up.
 
#32 ·
Hi,
I am having the same issue with my 2002 trailblazer, cleaned the throttle body and it worked for 1 day. Then i am back to where i began.

Could it be something with the idling engine (or what it is called) or something with the pedal giving the throttle body its position?
Just speculating, but have anyone tried this?
 
#33 ·
I was having the same problem and a few things I did but dont know which actually fixed it are
1. Check the oil preasure sensor. Didnt fix myproblem but it was leaking oil through the internals of the sensor into the electrical plug.
2.. also check the sensor above thepower steering pump. Oil was also leaking through the sensor into the electrical connector. (My problem has gone away since I cleanef all the oil out of the plug).
3. I also did the throttly body cleaning and disconnected the battery to let the computer reset to the newclean conditions. (There are other threads that explain this in more detail on this forum.
4. I checked the oil preasure with a manual guage and found it to be within parameters. The only problem I had with that is your supposed to get minimum of 12 psi at 1200 rpms, which I had. But when you idle back to normal idle speed it drops below the 12psi. Not sure why it wouldnt tell you that you have low preasure all the time atvidle?

Anyways, those are the things I trued. Something I did seemed to fix it. I thing it was all the oil in the elactrical connectors causing some kind of short circuit or false reading.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top