Pinging after fuel line repair/oil pressure low too

[Yenkohead]

Hi all. Long story but I managed to drill through the middle plastic fuel line (return line?) on the driver's side where you plant your feet. I repaired it with some 5/16" rubber fuel line (cut out 1.5 inches and replaced it with about 4 inches) and it no longer leaks. However, when I took it for a short drive I noticed pinging for the first time ever. To back up a bit, I noticed when I would fire it up just to idle I could detect a slight miss. I don't see any SES and since this just happened I didn't check for any codes. Secondly, I notice that the oil pressure seems really low. At idle it is just above 0. Revving it bumps it up to maybe 10psi. I checked the oil level and it is spot on and clean. I recently replaced the opti and the engine screamed without effort until just tonight.

Any helpful thoughts?

Oh yeah, 94Z with 93LT1/94 top end and PCM - pretty well stock.

Thanks,
Greg

[Fastbird]

I'd verify oil pressure via mechanical gauge. Doesn't sound good though.

[Yenkohead]

I'd verify oil pressure via mechanical gauge. Doesn't sound good though.

Reading my mind - I never was a fan of factory gauges. I'm sure hoping it's not truly low oil pressure.

The pinging is what has me baffled though. This is the first time I've heard ANY pinging......................and I would thrash it at times before, just kept pulling. It just seemed coincidental with regard to the fuel line repair. Hmmm, I wonder if some pieces of the plastic line may have made their way to the pump..............doesn't seem likely since as soon as I hit the line with the drill bit fuel flowed upward onto the floor pan.............don't ask. :\

Greg

[Injuneer]

Make sure it wasn't the supply side fuel line. The fact that fuel flowed upward when you punctured the line would indicate it may have been under pressure. The return line has very little pressure after the regulator. The supply line should be holding close to 40psi.

All it would take is a spec of dirt in one injector, blocking fuel flow, and it could start to knock. And to be heard, it would mean you are getting more knock than the PCM can eliminate by retarding the timing to the max programmed limit. That would indicate a fairly serious problem.

[Yenkohead]

Thanks Injuneer. You're correct. Fuel did flow upward when I punctured it - I'm glad I didn't have the engine running at the time. In my case it was the middle line - does this mean anything? I guess I will take the injectors out one by one and check them. Seems too coincidental since I never had pinging (knock?) prior to that.

Thanks!
Greg

[Injuneer]

I can't remember the order of the lines in the bundle, and I can't check for you since my stock lines were replaced with a totally reconfigured system with braided SS lines.

[Yenkohead]

Ok, so here is an update. Since I suspected that I possibly introduced dirt or something clogging one or more of my injectors I took out the fuel rail and all the injectors and cleaned them with a home-made injector cleaner setup I copied after looking at some You-tube videos. After reinstalling the injectors and starting it up there was still pinging under load. I noted that the water temp gauge got into the red way too quickly, so I ended up draining the fluid from the radiator and removed the thermostat completely. Then, after doing some more reading I added water to the top of the neck of the thermostat housing (to prevent such a big air gap) and sealed it good, then topped off the radiator. After an hour or so I started it up and the temp stayed around 180 degrees and the pinging was gone. Looking back I am now thinking that I may have never really gotten that big air gap out of the engine even after numerous attempts with the set screws (whatever they're called) to purge the air and/or the thermostat was sticking or not opening (I just picked up a Hypertech 160 thermostat that is going in tomorrow night). I think maybe the engine was actually getting even hotter than the temp gauge was reading, which in turn may have been the issue with the oil pressure reading being so low. Now the oil pressure is normal and there is no more pinging.

Thanks for all the advice.

Greg

[popo8]

What are u considering low for the oil pressure

[popo8]

What octane fuel are u using.

[popo8]

Remember it will help that thermostat alot more if u tune in different fan temps as well.

[Yenkohead]

What are u considering low for the oil pressure

Well, according to the factory gauge at idle it reading just above the "zero" line. When I rev it a little it goes up to, I'm guessing, 20-25psi. I hope to splice in a mechanical gauge soon. I just changed the oil today to 10W30................seems to be a little better now but still on the low side, I think.

[Yenkohead]

What octane fuel are u using.

It's been awhile since I put in some gas since it has been sitting unable to start for so long. I think it is 89, maybe 91 octane, and I added Stabil awhile ago as well. Tested out the pinging issue I was having and it seems that that has been resolved...............left a nice set of posi marks without hesitation.

[Yenkohead]

Remember it will help that thermostat alot more if u tune in different fan temps as well.

I'll have to read up on that. On the box that the Hypertech thermostat came in there was reference to using a Hypertech Power Programmer to do some tuning but I will have to do a little research to see if I have the tools I need to do that.

Thanks for the suggestion.

Greg

[popo8]

Well lt1s are high comp... so u should be running high octane. if your runnin low grade and its sat a while...that can be ur pinging. Fuel loses one grade of octane every 30days...

You will need a programmer or tuning software to adjust the fan temp.


As for the oil pressure... u should be able to stop by most any garage and a scanner will give u a more accurate oil pressure... a mechanical guage will also help.

Fyi...Gm specs say thay 7 lbs of op is low acceptable....

[Injuneer]

How does a scanner read the oil pressure on an F-Body? I think that's a Corvette only thing.

[Yenkohead]

I'll have to read up on that. On the box that the Hypertech thermostat came in there was reference to using a Hypertech Power Programmer to do some tuning but I will have to do a little research to see if I have the tools I need to do that.

Thanks for the suggestion.

Greg

Well, as it turns out, I DID have a Hypertech Power Programmer. I went ahead and installed the Hypertech thermostat and then programmed it using their basic setting. After taking it for a "required" full throttle pass to verify that there is no pinging, I returned with a smile on my face, several long black marks and no pinging whatsoever (and this was with several month old 89 octane). I went ahead and filled up with premium (92 octane) and hope to hit the track sometime in the next few weeks.

I'll report my results on a separate thread.

Thanks for everyone's help!

Greg

[popo8]

Great news... and seriously. Be careful.with low octane... especially old fuel.