“LOW” oil “LEVEL - Chevy Impala SS Forum
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post #1 of 56 (permalink) Old 06-04-2019, 09:54 AM Thread Starter
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“LOW” oil “LEVEL

This alert came on and engine stumbled a bit going 70 mph down the interstate. I was positive the level wasn’t low and drove to the next exit to a Costco parking lot to check the dipstick just to confirm. Oil level was spot on. When the lol light came on so did the cel. When I tried to restart the engine would crank normally but no start. I decided to replace the lol sensor in the side of the oil pan and did so in the parking lot with zero results. I have done a search and read multiple posts but there doesn’t seem to be a definitive answer to this problem. I have checked the ground on the left cylinder head and I have confirmed that I have the brass terminal.

I’m thinking I need to check the fuel pressure for which I don’t have a gauge and then if all is well attemp to get a mechanical oil pressure reading while cranking? If anyone can help I need a methodical step by step process to address this issue so I can get the old girl running again.

This is a one owner car since new with 213,000 miles. Other than more oil leaks than I can count or locate it has been an excellent runner all these years. Help please!
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post #2 of 56 (permalink) Old 06-04-2019, 11:33 AM
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First we need to know year and model of the car. My comments will be for a 94.



Low oil circuit should not prevent starting and should not set a cel(MIL). There is no MIL for the LOW OIL sensor or actual low oil in the pan, only one for if the PCM has trouble with the light bulb circuit.



It would be best to read the MIL code and find out what the PCM thinks is wrong.


The PCM primes the fuel pump for a start so:
Quote:
then if all is well attemp to get a mechanical oil pressure reading while cranking?
Not sure what information you would get that would help start the engine. The 1994 diagram shows the "oil PRESSURE switch" is what keeps the fuel pump running after a start.



If you can not read the MIL go back to basics. Take a spare spark plug connect it to a cable and ground it. See if you get spark while cranking. Call the auto parts stores and get a loner fuel pressure gauge. 40psi is normal but most cars will start with 30psi. If your fuel pressure drops to zero before the engine starts report back and you can ask about fuel pump testing.

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post #3 of 56 (permalink) Old 06-04-2019, 04:23 PM Thread Starter
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95 Impala. I’ll do some checks. I don’t have a code reader and the car is now in the driveway and not going anywhere on it’s own.
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post #4 of 56 (permalink) Old 06-06-2019, 12:25 AM
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Z09's comments about the fuel pump / oil pressure starting and running are also true for the 95.



It's a mystery why our cars record a low oil condition, but not a low oil pressure condition (as a code). I can only assume it is so that the dealer (shop) can tell if you let the oil run dry. If the oil pressure drops to zero, the engine will stop running (fuel pump is shut off), but it does not set a DTC. There is no link between oil pressure and the ECM. Now that I wrote that ... I've convinced myself. They do it so they can point their finger at you if the engine locks up.


Ok. Off the soapbox.



The ECM will not stop the car for a low oil condition, it simply tells you and sets the code. Sooner or later, you'll lose oil pressure and the car will shut off (fuel pump will shut off). The thing to note in your situation is the stumbling and then not restarting. I'm with Z09 ... verify fuel and spark. Oil pressure while cranking is not necessary. If primed properly, the fuel rail will have enough fuel to run the car for 5-10 seconds regardless. Even without a drop of oil in the car.



That said ... I don't think the low oil DTC has anything to do with your running / starting condition ... unless (ha, laugh with me here) your oil pump pumps all the oil into the engine journals and it takes 20 minutes to get back to the sump and the sump runs dry and the oil pressure drops and the fuel pump kicks on and off. Yeah ... that's out there.


Good luck.
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post #5 of 56 (permalink) Old 06-06-2019, 07:32 AM Thread Starter
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Thanks for the replies. I’m really busy with work and I don’t have to have the car to get around but I will do these checks as soon as I can and get back with results. I hate it when a thread dies because the original poster doesn’t come back with results and ultimately the resolution. If anyone has any other thoughts or ideas, I’m all ears.
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post #6 of 56 (permalink) Old 06-06-2019, 11:04 AM
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In a no-run condition:

1. Always check fuel pressure first. If none, replace the relay, then the pump.

2. If fuel pressure is fine, check spark at coil.

3. if ok, check spark at spark plug.

4. If theres spark at coil but not at the plug, replace distributor as the rotor is probably broken or fell off.

5. If there's no spark at the coil, replace the coil and ignition module.

6. If #5 doesn't fix it, replace the distributor too ;^)
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post #7 of 56 (permalink) Old 06-06-2019, 02:32 PM
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I'm gonna add to this because I'm having the same problem. Unfortunately I haven't fixed it yet.

My symptoms are this. Car runs fine, stumbles or stalls for no reason, low oil level comes on, occasionally goes off and engine keeps running, but a/c stops working. Turning off the car and restarting brings back the a/c.

Now, the fuel pump circuit goes through the oil pressure sender. Oil pressure goes to zero, fuel pump cuts out. I haven't been able to prove that throws a code. I changed the sender (there's a story in stupidity) but still have the problem.

I described the problem to a club member who is a much better mechanic than I am. His first reaction was fuel pump. I trusted his opinion. $700 and new fuel pump later, still not fixed.

The one thing I do know with my car is the ground strap on the back to the motor to the firewall is broken. At this point I think this is an electrical issue. Like you, I just don't have time to work on the car. Which is killing me.

BTW I have a 95 Caprice wagon. Most of the stuff under the hood is the same.
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post #8 of 56 (permalink) Old 06-06-2019, 06:31 PM Thread Starter
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Quote:
Originally Posted by Blue Wail View Post
In a no-run condition:

1. Always check fuel pressure first. If none, replace the relay, then the pump.

2. If fuel pressure is fine, check spark at coil.

3. if ok, check spark at spark plug.

4. If theres spark at coil but not at the plug, replace distributor as the rotor is probably broken or fell off.

5. If there's no spark at the coil, replace the coil and ignition module.

6. If #5 doesn't fix it, replace the distributor too ;^)
Thank you for the order of things, maybe I can check a few off the list this weekend.
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post #9 of 56 (permalink) Old 06-11-2019, 02:20 PM
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I have a '96 with OBD-II but I think the '95 was still OBD-I isn't it?
If so, check out how to read the codes without a reader: https://www.obd-codes.com/faq/read-g...codes-free.php

Your situation certainly sounds like electrical gremlins to me. And I know a missing ground strap will cause that other fellow problems for sure. My aftermarket fuel pump included a heavy ground wire to the body to add additional ground bandwidth for the pump. I would assume a bad ground on a normal setup could throw all kinds of odd things that are actually just the pump not operating.
Can you hear the pump prime (near the trunk) when you turn the key on?

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'96 BBB, RBT, Flowmaster AT Cat-Back, Limo Tint, K&N FIPK, Black Carpet & Mats, Corvette Engine Trim, Meziere Pump, Transgo HD Shift Kit, Body Bushings, Racetronix/Walbro wiring kit
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post #10 of 56 (permalink) Old 06-11-2019, 04:16 PM
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Check your pos and neg battery connections. I had the low oil light come on and others intermittent. Turns out the car would start fine but drive the system crazy.

95 9C1 LT1 266K, 30# Flow-Matched Ford Racing, TunerCat DIY reprogram, ACD wire$ and plug$, reground crank
89 9C1 L05 230K left it running at the junk yard.
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