Heavier oil

[Smitty1021]

Yea that's where it's at. Yea my truck idles at about 450. I'm gonna try and drill it out and bump it up to around 700-800. At least I know that will keep the pressure up while at idle. I'll try the stp additive too and see if I have any luck. Any difference with running certain filters? I was running a k&n and now I put in a puralator bc I had it sitting around.

 

[Ruger_556]

Honestly I wouldn't worry about it. If it's hot and the idle comes down sitting at a light most of these trucks will run at 20 psi anyway. 30-40 at a normal idle and 40-60 running down the road.

 

[Smitty1021]

Well what worries me is when it hits about 15 psi on my dash gauge and the check gauges light begins to flicker on. I say flicker bc once it bounces the slightest bit, it shuts off. I just look at it as there has to be a reason why the check gauges light pops on when the pressure goes that low you know? Not doubting anybody's knowledge or experience, just putting that out there. I'm going to just bump the idle speed up a little bit and I guess that's that until something major happens.

 

[Keepinitoldskool]

Your oil pressure is low because your truck is idling so low. 450rpm that's almost a stall. Fix whatever vacuum leak or fueling issue you have to get your idle within spec and I bet your oil pressure will be fine.

 

[Smitty1021]

I do have an issue with a fluctuating idle but only at startup for the first 30 seconds. I have searched all of the vacuum lines and only found one issue with the brake booster hose. Replaced the iac a few times. Anyway my idle has been around 500 for quite some time now.

 

[kennythewelder]

I agree, your idel is way to low. If you raise it to 900 in park, and 750 in gear when hot, and that gives you around 30 PSI, I wouldn't even add the STP.

Your oil pressure is low because your truck is idling so low. 450rpm that's almost a stall. Fix whatever vacuum leak or fueling issue you have to get your idle within spec and I bet your oil pressure will be fine.

 

[kennythewelder]

I thought I would post this, to explain what I think is going on with your OP. You may already know this, but the oil pump is a mechanical pump that is driven from a shaft that has a grove in it on the top and bottom. The oil pump has a tong that fits this grove and so does the distributor. The distributor has a gear that is turned by the camshaft. and the shaft that is between the distributor, and the oil pump turns with the RPM of the engine, so the faster the engine turns, the faster the shaft turns that spins the oil pump, so the more pressure it puts out. The same is true in reverse. The slower the engine turns, the slower the oil pump turns, and the less pressure it puts out. This is why there is no oil pressure until the engine is spinning. If the engine is turning at 450- 500 RPM your oil pressure will be low. Rev the engine up to 750 RPMs and see what your OP is. 25-30 PSI your normal. The oil pump does have a top out put pressure of around 60 PSI or so. Once it reaches this top pressure, it won't make more no matter how much faster the engine spins. This is a stock oil pump that I am talking about. There are performance OP that push out more volume, and others that make more pressure. Anyway, you may already know all this, so the next questions that go through my mind is, why is the truck idling slow to begin with. Is there a TBI issue?, is there a vacuum issue? ( you said you already took care of that), is it a TPS sensor issue? or any sensor or ECM issues? Have you had the codes read? Also you said that you want to do an LS1 swap next summer. If you go that route you will need to modify you ECM or replace it with an LS1 ECM. I have a friend who has put one of these 383 stroker Vortec crate engines in his truck, and it is a beast.they make a direct replacement for TBI as well. 370 HP with stock set up for $2600 is hard to beat. and with 7 year 70,000 mile warranty. A stock LS1 is only 355 HP. anyway here is the web sight just FYI. http://pmcmachine.com/index.php?main_page=index&cPath=35

 

[Smitty1021]

Thanks, yea 383 was the route I was going to take but after research and talking to a friend who has done the ls swap, I decided to go ls. Thanks for all the info. I learn as I go along and this is something I have yet to experience so I turn to everyone on here. My tbi was recently cleaned out with an industrial machine for cleaning parts like these so the tbi is fine. Fuel filter, tps, distributor, wires and plugs all have about 1000-2000 miles on them. Probably about the same for the iac. I was thinking maybe the egr? I really don't know and haven't been able to pinpoint the initial idle jump and stutter while driving for the first mile after a cold start up. My fuel pressure is a steady 12.5 as mentioned earlier about fuel issue with the idle. I have swapped out the ecm to check in the past but it made no difference. Could possibly be the chip I had burned 2 years back when I did my trans swap by TBI chips. I have checked for vacuum leaks and haven't found a single one. Anyway just giving you a rundown of the majority of replacements or things I have done to make my truck.

 

[Smitty1021]

I bumped the idle up, now I'm pulling an iac code 35. Iac has been replaced I know it's good. Checked all vacuum lines and no leaks that I can see or hear.

 

[kennythewelder]

What is your OP after turning up the idel? I payed close attention to mine this morning. After warm up, at 750 RPM 40 psi. At 2200 RPS 65 PSI and it does go up to 80 PSI at higher RPMs. When its cold, 60 PSI@ 750, 80@2000. I bought my truck in 2002,when it was 5 years old. My wife drove it as her driver till 2010. It has been my driver sense. I bought the truck from the salesmans wife, who took it in on trade on a new truck from the original owner. I found his contact info in the glove box, and called him just after I bought it. He said he changed thr oil every 3000 miles, and so do I. When I bought the truck it had just over 80000 miles on it. Sorry for the long winded post, but my point is that I am a firm beliver in regular oil changes. Lol and that reminds me, I turned 213000 miles today, so I will do an oil change this weekend. Next question, what does the EGR valve look like. It seams like I remember them being troublesome on TBI engines. Also if I remember rite, they are expensive.