I just finished tearing the engine down to the block and had about 100 miles with a truly smooth and beautiful running engine. Yesterday however there was a slight change and I need to figure out why this has happened.

I have been closely watching my oil pressure just because and also I changed the oil pump and screen. (btw- I have a bosch gauge in place of the oil pressure sender because the gauge in the dash is shot.)

When I first got it together the oil pressure would vary pretty widely, not sporadically, it would rest at 20PSI when parked or idleing to 65-75 when driving around. Now the pressure on a normal drive will max out around 65 and the van doesn't seem to have the power it did a few days ago. When you hit the gas it bogs down a little, it's almost "squishy" and makes kinds of a groaning when you give it gas.

It's not a huge difference and most people probably wouldn't notice.

And the last night a few times it was feeling like the engine was building up pressure when I was at a red light with my foot on the brake. The oil pressure was staying at 60ish and idled rough. Like it wanted to go and was getting impatient.

I just hope I didn't spring a new vacuum leak after all this. I cant find any but I haven't gone nuts yet.

getting no check light

Hope this makes sense -
here's recent work done that might relate.-
Every sensor on the throttle-body is brand new / new cat and muff / new O2 sensors / new oil and filter / all new gaskets and seals from the heads on up / new thick aluminum plenum plate / new dist / fairly new plugs and wires /

not loosing or burning oil best I can tell

 

So you just tore down the engine instead of diagnosing the problem? What if it was a $10 sensor causing the problem?

 

Haha- no. This is a new probelem since doing many much needed repairs.

 

Oil temperature has a huge effect on Oil psi at any given rpm.

My maximum oil pressure is ~68 psi cold, and when hot it is about 62PSI but at 2200 rpm using M1 0w-30 oil. Hot at idle speed ( ~525 rpm) it is 16 PSI.

The thicker the oil grade, the lower the rpm maximum oil pressure is reached before the bypass is activated.

Your rough running likely has absolutely nothing to do with your oil pressure, and if you are reading 60PSI when the oil is hot at idle speed, either you are running 80w140 gear oil, or your aftermarket gauge lies like a politician looking for some pork.

 

i paid closer attention today and the PSI stays up regardless or idleing or driving when the van is cooler. When it's up to operating temp the gauge read 25psi at park and 65psi while driving normally (30-60mph).. i dont have a tachometer to know my RPMs. so it sounds like you are dead on about the temp affecting the pressure....

im running full synth 10w-30.

What I still dont understand is why for the first 75 miles or so since putting the van back together did the oil gauge typically read 75psi and run way better. it just feels a little ball-less now...

Also checked my gas mileage after 100 miles. 11.9mpgs.. not good... I used to get 14.5 city mileage and I always considered that bad- Ive done EVERYTHING I can think of to get that back to 15-16.5 like it used to be.

although the distributor cap doesn't change the timing it can be turned slightly left and right, the extreme of both will stall it. Is there a way having this not perfectly set could screw things up? I feel like I read somewhere twisting this is what sets the fuel injector timing... maybe im in left field... just and idea.

 

Oil psi and rpm are fairly directly related, until the bypass valve kicks in.

More oil PSi is not better, oil psi is a as long as it is above the minimum all is well. The hotter the oil the thinner it is, so the more rpms are required to push it to the higher levels.

If it was oil PSi keeping the bearings from metal on metal contact then we should all run as thick an oil as possible, but the psi is related to the oil flow through the engine. the Oil film strength itself it what keeps metal on metal contact from occurring. the oil is pumped through bearings to keep oil in them, and to remove heat generated at the friction points.

If you twisted the distributor from where it was originally, you have screwed up your fuel injector timing, and this of course will negatively affect both power and economy.

I do not know the procedure for getting it right on a MPFI engine.

Alloro does.

Your Oil PSi is fine, it is your fuel injector timing which is all out of whack now. When oil PSi is insufficient, it sounds like the engine is angry with itself and trying to kick its own a$s, and succeeding.

 

i think you're right- ill do some digging on how to properly set these.

 

It can't be calibrated at home. You have to bring it back to the dealer to sync the fuel injector timing.