So my 2002 Envoy has no mods and the Oil Pressure Gauge is bouncing all over place when I'm idle or stopped. Here's what I know and have done. The RPM's in idle hold at 600. No visible oil leaks or pooling in engine compartment. Cap is tight. Engine isn't making any unusual sounds. Cleaned the throttle body. New Oil Pressure Sending Switch. My next step is to replace oil pump with repair kit from rock auto??? Or, does anyone have suggestions or dealt with something similar??? Any help or insight is greatly appreciated
Low Oil Pressure Stop Engine
- Thread starter macinnis17
- Start date
RayGumm
Member
- Apr 16, 2014
- 630
My guess would be that the new oil pressure sending switch is faulty.
Our oil pressure gauges are essentially fake. If the sending switch registers a psi of I think 15 or more, then it sends the needle to around 40. The needle under normal operation will fluctuate, but that is literally just the PCM moving it around to trick you-it is not a real indication of oil pressure. Just a computerized guess depending on throttle position.
If the new switch you installed is faulty, that could cause the needle to jump around.
Our oil pressure gauges are essentially fake. If the sending switch registers a psi of I think 15 or more, then it sends the needle to around 40. The needle under normal operation will fluctuate, but that is literally just the PCM moving it around to trick you-it is not a real indication of oil pressure. Just a computerized guess depending on throttle position.
If the new switch you installed is faulty, that could cause the needle to jump around.
I guess I'll try another switch first. It is strange that when the car is initially started cold, the pressure is fine and operates normally with a little fluctuation depending on engine rpms. Pressure reads 40 psi or a little more. But, after the engine warms is when the gauge goes haywire and drops all the way to zero when stopping or at idle. Just frustrating watching the dash having a disco party.
AtlWrk
Member
- Dec 6, 2011
- 674
I assume from your title that you're also getting a "Stop Engine" warning on your DIC? This would rule out a stepper motor issue.
If the behavior is the same before and after the new switch was installed I wouldn't think the switch would be the culprit (though it could be). You could also have a wiring issue.
Does this behavior only happen at idle? Does it only happen after the engine has warmed up? In other words, if a little extra pressure (cold oil, higher revs) eliminates the warnings then you may have a genuine low pressure problem. What kind of maintenance has the truck seen? When is the last time the filter was replaced?
My next move would be to get a mechanical oil pressure gauge hooked up and see what kind of oil pressure you actually have at idle. If you're right at the threshold of the switch you'll see the gauge bouncing back and forth.
EDIT: Answered some of the questions before I posted my reply. You really need to hook up a gauge and see what's going on.
If the behavior is the same before and after the new switch was installed I wouldn't think the switch would be the culprit (though it could be). You could also have a wiring issue.
Does this behavior only happen at idle? Does it only happen after the engine has warmed up? In other words, if a little extra pressure (cold oil, higher revs) eliminates the warnings then you may have a genuine low pressure problem. What kind of maintenance has the truck seen? When is the last time the filter was replaced?
My next move would be to get a mechanical oil pressure gauge hooked up and see what kind of oil pressure you actually have at idle. If you're right at the threshold of the switch you'll see the gauge bouncing back and forth.
EDIT: Answered some of the questions before I posted my reply. You really need to hook up a gauge and see what's going on.
GM, Delco. Havent had any problems to date with filters. Of course, can't rule it out. Truck always gets those.
You never know. I try to stay all OEM if possible, if not I'll splurge for the good shit on parts. I'd rather try replacing a filter before getting into some of the more time consuming work. But, whatever it takes to keep the truck on the road. Just checked oil level and it is good and full.
Hatchet
Member
- Nov 21, 2011
- 2,405
Did the truck do this prior to last oil change? I would drain some of the oil an check for metal flakes.
I know i'm going straight to worst case scenario, but here is what mine was doing. Id get that warning low oil pressure and all the jazz for a few months. Happened randomly but only when engine was warmed up. Last year got rod knock, when we opened the oil pan. The oil pick up screen was filled with metal specs clogging it and preventing correct amount of oil to get sucked up. Not saying this is your issue, but a few bucks in oil is cheap insurance.
I know i'm going straight to worst case scenario, but here is what mine was doing. Id get that warning low oil pressure and all the jazz for a few months. Happened randomly but only when engine was warmed up. Last year got rod knock, when we opened the oil pan. The oil pick up screen was filled with metal specs clogging it and preventing correct amount of oil to get sucked up. Not saying this is your issue, but a few bucks in oil is cheap insurance.
