Ok, the CEL comes on even more now than before and it's still a Misfire on 3 and 6. So, I can rule out fuel because I did not label the injectors and the odds of me getting those back in the correct place would be very unlikely.
So, I'm down to an ignition or mechanical problem. I suppose next step is to go through the ignition system. From what I have read, the firing order is 123456 but that seems a little strange.
I've already got the green light to just give up on the car but I can't think of a better way to learn troubleshooting than this. While I have the upper plenum off for the 10th time I might as well do a compression test and see what I get.

I'm becoming impressed that this engine can handle 4 and a half years of random misfires and not have a cylinder blowout.

 

I picked up a 5/16 piece of fuel line so I can make up an adaptor to test the fuel pressure. After that I'm going to run a compression test on it and see if there is much different between 3&6 amd the rest of the cylinders. So depending on the results it could be that the engine is running lean from low fuel pressure and overheating the oil causing the low oil pressure. If that is the case then the temperature gauge does not reflect that the engine is running hot. It would also explain the RPM flair during cold starts.

I will proceed assuming the fuel pump/regulator is guilty until proven innocent. I do need to pull the valve covers again becuase there are some collapsed lash adjusters that will not pump up. I saved all the old ones so I can use any that are still functional.

 

Fuel pressure tested and it's 50psi cranking pressure. Exactly what the book says and drops to 47 after the pump stops then slowly creeps down a pound or two over 15 minutes after that. Not bad IMO and wouldn't justify changing a pump assembly. I was going to run a compression test on 6 since it's easy to get to but when I pulled the plug boot there was about 1/2" of oil down in the well.
#4 had a tiny bit. I ran out of time but I'll pull the plenum next and do a compression test on all cylinders as well as look at the leaking plug tube seals.
It's pretty much getting down to an oil pressure issue at this point. I read something about a vacuum referenced pressure regulator but that might be the older models? This 2000 seems to be the odd year since the Chiltons only goes to 98 but the engine seems to be the same.

Here's to pulling the oil pan and pump some day soon.

 

I'm trying to come up with a game plan as far as dropping the oil pan and pulling the oil pump to check the pressure valve. It appears there are no gaskets availible aside from the ones that come with a replacement pump. So, I'm going to assume I need to make my own unless someone with a lot of experience knows. I suppose I should try stopping in to the Dodge dealer and see if I can get any information out of them as far as my problem and the gaskets which I have not yet found to be sold separately.

So far since the fuel checks out I've decided that the low oil pressure is caused by either the pump or worn main/rod bearings. This causes the oil pressure light as well as collpased lifters/lash adjusters and those are the cause of the misfire codes. I can get the SES to flash at lower speeds if I get on it and it gets around 4000rpm.
All the other times the SES flashes is at 70mph but only when the engine reaches operating temperature. So it's either leaning out just enough at that point and causes misfires or else the noise from the lifters is being picked up by the knock sensor(s) and causing the code.

Apparently the oil pump feeds itself from the pressure relief valve according to a writup on Allpar.com http://www.allpar.com/mopar/25V6.html So, it could be very possible that the relief is stuck or the spring broke causing the low pressure.

 

I came across this thread the other night and it pretty much describes all my issues except he took care of it instead of letting it go for a few years.
https://dodgeforum.com/forum/dodge-s...e-at-idle.html

The plan is to pull the oil pump this weekend and see what I can find out. I will either find some definate problems and replace the pump or else it checks out fine and I proceed with checking the bearings. I'm leaning more towards the pump at this point though. I'm putting most of my money on a problem with the pressure relief valve being stuck or broken.

Stay tuned...

 

4 hours in today and the pan would drop if I had bought 6 point sockets instead of 12 to get the exhaust cross over off. The oil pump would be off as well if the AC bracket didn't cover the pump by 1/4". A bunch of stuff was left out of the Chiltons.
I have time because I found a separated motor mount and I need a water pump while I'm at it.

I swear there are twice as many brackets and braces as necessary on this thing.
Insert frowning fire face here.

Edit:
Pan and pump are out. I don't see a while lot wrong with the pump. It does have a small amount of scoring inside but not enough to catch a nail on. I would think it should produce enough pressure though. I guess next step is to check the bearings and see if they show any obvious signs of wear and then plastigauge them. The pump relief valve has a good amount of pressure but it's a little hard to tell. It does not move very far when pushed with a small pick. I guess this is just a mystery car that will get driven until it blows up. Can't afford to sell it at this point.

 

I'm very curious to learn what you find. I'm trying to sort out an intermittent flickering oil light on our newly-acquired '99 with the 2.5l. The service records on it are sparse at best and I'm thinking that I want to do the timing belt and water pump since I have no idea if these have ever been serviced. If I'm going to be in it that deep, dropping the pan and doing a new oil pump seems almost a "why not do it?" question. I'd just be happier if I had a garage I could park it in to work on it rather than doing it in the driveway..

Just trying to get a fairly reliable starter car for the oldest daughter that will last until she's established after college and can get a newer car that she really wants.

 

Got some cheap main bearings on order off Rockauto. Don't know much about DNJ brand but they are $14 compared to the Sealed Power for $52 at the parts store down the street.
I did have to cut off one of the exhaust studs so that will give me something to work on tonight. At least it's as easy as just drilling it out and throwing in a regular bolt.

So far the main bearings were just over the limit which is pretty tight. I am still up in the air regarding the oil pump. The spring seems a bit weak considering it has a listed relief pressure of 75psi. I have a Small Block Chevy oil pump laying around and I'm going to compare the springs. Maybe I can cut it off and use that. If that does not work I am going to add a washer behind the spring to increase the overall spring pressure. I have not yet cleaned up the pump so I might yet find a small piece of debris stuck in the relief valve seat.
I'm not sure about the whole 'sludge monster' that is so common on this site but this engine is pretty clean considering this car sees mostly short in town trips and I have been really slacking on timely oil changes for the last few years.

If things go well I hope to have things back together to the point of the timing belt this weekend. I'm not looking forward to draining the cooling system but better to at least do something right out of this whole project.

I did go through the lash adjusters and found 2 that were damaged so those got replaced with some used ones that were not trashed from before. I did notice that the torque spec on the valve covers is pretty high so I might have had those loose which explains the oil in the plug wells.

I also pulled the oil filter/pressure switch adaptor and I'll get a thread spec on that and I'm going to try and get a mechanical gauge added just to make me feel better when it's all back together.

 

Just watched a video on rolling in bearings... guess I'm qualified to do that now. Looks easy enough but I would still prefer to do it with the engine out of the car. The fact that these have a 1-piece main cap makes it all the more challenging. I guess it will be using the oil pump and the transmission to support the crankshaft but that will make it all the easier to pull the bearings out.

 

Oil pump is all cleaned up and assembled. I added a small washer under the relief valve piston just to give it a little boost. Besides that the pump rotor tip to ring clearance was spot on at .0015", the ring to body clearance was at the minimum .005" and the clearance to the cover was almost tighter than the range given. I don't remember what they are exactly but the pump was well within spec. So now it's down to the relief valve or a leak somewhere in the system. I will be replacing the main bearings. I am going to bring the pressure switch in to work and verify with a calibrated standard just so I can have exact true numbers.

This evening I will be pulling the bearings and rolling in the new ones if they show up. I only hope the clearance tightens up and checks out once the new ones are in.

Someone on an Eclipse forum was kind enough to put up a lubrication diagram. Now that I've checked out the pump and will be replacing the mains, the oil goes to the top end from there. So the only other place there could be a problem is the cam bearings or rocker arm shafts that supply the lash adjusters. I don't think there is a problem at that point but you really never know. The fact that I went to 10-40 oil and it did not make a difference has me worried though. There must be a large leak that I have not found yet and really the only thing left to do is go through the top end if the problem is still present following all this work.