Pontiac GTO 2004-2006 - Engine Trouble

I have a 2004 GTO with a D1SC on a LQ9 block. The other day i hit it and the service vehicle soon message come on, then the check oil message. I checked the car found that it was leaking oil. Other than that nothing else was out of the ordinary. There was a decent amount of oil and it had gotten everywhere so I really couldn't pinpoint where it was coming from. I cleaned it up and it sat over night, the next morning I checked to see if it had leaked to maybe see from where, all clean. Checked the dip stick 2/3 in operating range. I drove it to work (very nicely) when I got to work (only a 15 min drive) didn't see anything leaking. I wasn't able to get under the car and remove the skid plate or anything like that just a visual scan from as far as I could get under it in a parking lot. But later on that day there was oil leaking from the skid plate. I checked the oil on the dip stick it was 2/3 full again. I drove it home let it cool and jacked it up. When I removed the skip plate I found that again oil was everywhere no way to pin point. I decide that I was going let to run in the drive way with a few revs and see if i could pinpoint where it with out moving the car after I cleaned it all up.

I dropped it down started it up and it ran for 3 or 4 secs and I heard a pop, like a misfire pop or a back fire pop and the check oil light came on. I turned it off and checked everything out. No visible damage. Then I got under it and looked nothing. no oil no damage no nothing. Checked the dip stick and everything was good there. I pulled the plugs and wires, the plugs looked bad so I replaced them and I check the resistance on the wires, all good. I also installed a brand new oil pressure gauge to monitor the oil pressure. I didn't want to start the car, so I pulled the fuel pump fuse and unplugged the coil packs thinking that I should at least see some oil pressure and nothing. I removed the oil breather and looked at the rockers (as best I could) while my wife turned it over and nothing. I didn't see any oil moving.

I had recently replaced both the main and acc belts, and I changed the oil in the car and procharger. Now they didn't have the AC delco oil filter that usually get so I got a Fram one. (no knowing all the horror stories about Fram) But when installed the oil pressure sender I changed the oil filer to a AC delco and called it good.

I did plug ever thing thing back up and try and start it and nothing it started for maybe a sec and then died. I really have no idea what to do next this is my daily driver and I am in great need of getting this fixed, any help would be greatly appreciated.

Subscribed. That's weird man I hope you get this figured out.

Really hard to narrow down exactly what it is, especially since you cant figure out where the oil is coming from.

What was the code for the CEL?
Was it the Check Oil Message or Service Engine Oil?

How did the engine sound when it was running?

Its really hard to diagnose with such little info to go on.

Check oil message can be no oil pressure.

Really hard to narrow down exactly what it is, especially since you cant figure out where the oil is coming from.

What was the code for the CEL?
Was it the Check Oil Message or Service Engine Oil?

The message said Check Oil.

How did the engine sound when it was running?

Engine was running great right up until I heard the pop.

Its really hard to diagnose with such little info to go on.

Yeah I know I have talked to everyone I know and no one has anything. I really don't want to take it someone where to have someone tell me what it is then bring it home to fix it myself but I many not have a choice.

Check oil message can be no oil pressure.

I tired to check the oil pressure with the coils unplugged and the fuel pump fuse pulled but I didn't get anything. I also tried to see if the if it was pulling oil up topside on the rockers and I didn't see any.

New development, I decided to get back to basics and find out what i was missing for the car starting. I check the ignition and found that it was working, then I wanted to know if the car was getting fuel. I sprayed fuel in the intake and it started up. Didn't run long but i started. So now I know that its not getting fuel from some where. Now I know that when i checked the FP gauge the first time it was around 60 Psi, when i checked it again it was at 40, normally if prime the pumps it goes to about 60 and drops off slowly. Now its t 40 and then drops as rapidly as it goes up. I read some where about ohming out the injectors to see what resistance they are at and it would help determine if they were bad not and all of them were reading the same about 12.4. I don't know how to check the fuel pumps cause i have 2 of them back there. I think that i should also check all the fuses as well. But any help would be great thanks.

The truck style blocks used a different hole for the dipstick tube to enter through, but still offered the same access point as the ls1 blocks, so I would check to see that you have the hole plugged properly.

The starter motor isn't going to spin the motor over fast enough that an oil pressure reading will be meaningful. Was the motor knocking or making any other sounds that may indicate a problem? The check oil message means low oil pressure which can be due to a lack of oil, a problem with the oil pump, or oil pressure being lost due to a failure somewhere in the bottom end.

I read this thread on LS1GTO.com before you deleted it. Sounds to me like there is a problem with the bottom end. In your signature there is says your car makes 677 rwhp or something like that, so I presume its procharged or something. Stock bottom end LS1? Did you notice if the dipstick was dislodged when you observed the issue with the oil? The "pop" suggest something top end as well, like maybe you had valve float and had some contact occur between a valve and piston... What is your set up? What valvesprings are you running? Have you pulled a valve cover?

When you say 2/3 oil, what do you mean? You have 4 quarts? Or your oil level is 2/3 of the way toward the top of the "operating range" on the dipstick?

The oil came from somewhere. If you had some kind of piston to valve contact, its possible damage within a cylinder is causing compression blow by that is forcing oil out of the dipstick area.

You can't get it to start again? Did you check all the connections?

If you get it started and confirm it isn't holding oil pressure, cut it off. I doubt the oil pressure sending unit went bad at the same time as all these other mechanical issues appeared. I'd say its more likely you have a mechanical problem that has resulted in low oil pressure and oil loss.

At this point, were just making up scenarios. Info I have... Motor had lots of power, was driven hard, developed significant and mysterious oil leak, driven around some more, "pop" sound when started, no oil pressure, some oil still in it, things disconnected, won't start.

The starter motor isn't going to spin the motor over fast enough that an oil pressure reading will be meaningful.It registered when we primed the new motor before the first start. Was the motor knocking or making any other sounds that may indicate a problem? No it wasnt The check oil message means low oil pressure which can be due to a lack of oil, a problem with the oil pump, or oil pressure being lost due to a failure somewhere in the bottom end.

I read this thread on LS1GTO.com before you deleted it.i respoded to that comment, just poeple there are more inclined to make fun than help over there. Sounds to me like there is a problem with the bottom end. In your signature there is says your car makes 677 rwhp or something like that, so I presume its procharged or something. Stock bottom end LS1?Only thing that is original is the crank Did you notice if the dipstick was dislodged when you observed the issue with the oil?no The "pop" suggest something top end as well, like maybe you had valve float and had some contact occur between a valve and piston... What is your set up?Cast Iron 6L
Bored .030 over
Studded upper and lower
373 ci
L92 Heads
LS3 Intake
92mm TB
LS7 cam and Lifters
Comp springs and rods
Mahle Pistons
Manley Rods
Magnum Double rolling timing chain set
Melling HO Oil Pump
APS Duel Fuel pump Assembley
All ARP bolts
Coated bearings What valvesprings are you running? Have you pulled a valve cover?No I havnt

When you say 2/3 oil, what do you mean? You have 4 quarts? Or your oil level is 2/3 of the way toward the top of the "operating range" on the dipstick?2/3 in operating range It hasnt leaked any oil while is has sat. If i give it gas while i start it for a sec or two.

this happened to my buddy. the car was fine and then one day he got on it and made alittle more boost than he wanted to and broke a ring land on the piston. the car ran but ran like it was missing really bad and it had alot of blow by that came out of the back of the valve cover where the breather hose is. i would check to see if you have oil there. his was alot of oil. and if it is then i hate to say it but you need to tear down the motor and make sure your ringlands are still good

Bump, find anything out?