another question. Any harm in turning the motor over provided i'm careful and watch the gauges for trouble?

 

do it just long enough to see if oil pressure builds. BTW, the pump is on the front of the engine, behind the timing cover. also, the car isn't going to shut itself off due to a loss in oil pressure, so its safe to say that the oil pump, even if it is bad, is causing the motor to die.

 

are you a 100% sure the engine didn't die before the oil pressure started dropping? the engine won't drop to 0 RPM immediately when it dies in gear. the only difference will be the sound of the exhaust and lack of response from throttle input.

 

I manually killed the engine when i saw the pressure drop. And the trouble started after my mods, but I drove it immediately after the mods without trouble. Then I drove it to work (about 30 min averaging 40mph, but through traffic lights, so it is start and stop a little bit). But the trouble didn't start until I had made it all the way back home. So, approx, 50 miles or so after the mods?

 

Really sounds mod related to me. Check your work area. My guess is your egr mod isnt sealing properly. Maybe it took 50 miles to expose it.

 

Does the EGR downpipe into the manifold usually have one or two bolts on it? Mine only has one, looks strange to me, especially when the goal is a seal

 

If I remember right it's just 1 bolt. I think what Slowpoke was trying to say is that even if the oil pump is bad it will not cause any hesitation or make the motor want to die.

 

There is only one bolt for the EGR, that is correct.

 

One bolt, but very easy to over-torque it. I believe the correct setting is like 5 in/lbs. However, when I overstripped mine it caused a vacuum leak. Which meant a very high 'hanging' idle; not a dying car.

My $.02 is it's not the oil pressure or pump either. I've had that happen as well ( lost a motor at 35K miles which GM refused to do anything about ). When that happened, the car still ran , just loud as ****.

I'd look towards verifying the fuel pressure is right with an external gauge.

Although it happened at the time of mods, it may be something entirely different.

 

I don't think it's the oil pump. Sounds like you need to drive it some more to figure it out.
You were very good to shut off the car when you saw the oil pressure go down.
However, if the pressure comes up, I'd assume the temporary low gauge reading was because the engine was stalling.
You could have just had some water or air in your line or the EGR leak sounds probable.
The EGR only has one bolt.
Oxygen sensor is another good possibility or maybe even crank sensor.
I would just drive it some more and see what it does. It sounds like whatever it is, it is intermittent so even if you stall, you'll be able to fire it back up in a few minutes and get back home and on LS1tech!

 

Ok, tonight i checked battery output, 12.4 v. Eliminated as far as I'm concerned. Checked all electrical connections and sensor connections I could. All are snug. Retightened bolts, the only ones I could tighten were the three holding the throttle body on. About a half to 3/4 turn each.
Another question, I had also re-oiled my filter, maybe over-oiled it a little as there were beads of oil still on the filter when i checked it.

The final step I took tonight was pulling the pcm ign fuse and cranking it. I cranked it pretty solid for 10-20 seconds, oil pressure remained at 0 the whole time. As soon as I take the key out it goes up to 20 but its always at 20 when its been sitting for a while. Should the pressure have built while cranking, or was i supposed to wait a couple seconds for it to build or something?

 

Pulling the PCM fuse probably killed your gauges...

Over oiling the filter sometimes gets crud all over you MAF sensor wire - might be a good place to look (very easy). Could quite possibly be your problem right there.

I agree that it could be crank sensor or cam sensor starting to fail or loose connection, but that would also cause a hard starting situation. The crank sensor is hard to get to (behind starter) and the cam sensor is way in the back of your manifold, also hard to get to.

Your EGR is used to cool combustion chamber temperatures at cruising speed. If your problem occured at a stop or shortly after - you could rule that out, besides, if there were a leak, you would see a high idle.

I'm definately leaning to the dirty MAF wire. I don't want anything to happen to your car, but it sounds like driving it again might help you diagnose the problem. Sometimes it is hard to build pressure just turning the car over. It actually causes more damage then starting it for the 3-5 seconds it takes to build pressure in my oppinion. Even though there are no codes, you PCM might have some stored missfire data that will help if you have an ignition problem.

Let us know what you've checked and if you've tried to drive it.

 

PCM IGN fuse ...I'm wondering if that fuse disabled the oil press gauge?
Perhaps trying it with spark plug wires disconnented?
I'm sure someone else will chime in as to whether that should have worked or not.

 

after my MAF sensor went it would stumble. the only way to get the car moving was to unplug the MAF. doing this would cause the car to run on previously stored fuel tables. give it a shot.

 

I turned it over this morning before I left for work and ran it a couple of mins, oil pressure normal, all my gauges reading ideal conditions and a nice smooth idle. Is it possible that it was heat related?

 

Ok, I have a couple ideas to run by you guys:
1. My oil dip stick looks like this

~~----add one quart|XXXXXXX|-----------O
^
My Oil level is here.
I think its a little high, don't know how that affects things. But I was thinking that high oil pressure along with unusually high heat (oil expansion) could have caused too high of oil pressure leading to pump failure/self-protecting shutoff.

2. My throttle body bypass could have leaked coolant onto a pulley which inturn caused the belt that powers the oil pump to slip, causing the drop in oil pressure and periodic power loss despite throttle.

I ran my car tonight for five or ten minutes and revved it. I have video/audio of the gauges, and I would really appreciate it if some of you seasoned veterans could take a look for me and tell me what you think! I did upload them to my webspace but it doesn't seem to be working. I can email it to you if you send me your addy. Otherwise I'll describe:

Idle oil pressure is at 60psi, idle is at750-800rpm
Rev to 3500-4000 puts oil pressure nearly to 80psi.

Again, I'm very grateful for all of your help as nobody I know personally has any car sense. So I'm on my own to teach myself!

 

It may be the oil pump, mine gave out 8 mths ago with no warning and with 42,000 miles, the messed up part is that it went out as soon as I turned the car on. It cost me about five hundred for everything, that including the oil pump and the labor cost.

 

Your oil pump is not belt driven so you can rule the leaking coolant out. It's at the front of the crankshaft and spins as the crank is spinning (underneath the timing cover).

 

Did you check the MAF element to see if it was oily?
This sounds electrical/sensor related.
I would do an oil change and put in the proper amount too.
If it were my car, I would fix the oil situation, drive with the radio off and assume all is well until I had another incident.
Good luck!

 

yeah, oil change is this weekend, but as far as checking the maf i looked at it, it looks normal and i can't think of any way to safely clean it.... Those wires are damn fragile. Anyway, i bought autotap so hopefully i'll be able to start chasing it.... is oil pressure that high normal though? damn near 80, just under.