I just rebuilt the engine (approx 400 miles on it), and now the oil pressure light is dimly flickering when I am at idle, once it is warmed up. I went ahead and replaced the oil pressure switch (since it was $10 bucks) and it still does it. I replaced just about everything on the rebuild as it had 150K miles on it - oil pump, water pump, all belts, everything internal in the engine, had the head redone. I throughly cleaned the throttle body, intake, replaced the PCV and hoses, even found a leak in the charcoal canister to gas tank return vacuum line and replaced it. The PCM does not show any error codes to date, and I have a ODB-II reader to check and reset it if necessary. I have not yet changed the oil and I used 5W-30 Castrol. I also noticed that when it is warmed up, and flickering at idle, if I turn on the AC, the idle speed make a quick drop as normal, the oil light flickers brighter and longer, but the engine hesitates and lopes for a couple of cycles and then recovers, and the light returns to flickering dimly.

Somewhere I read that if the engine idle speed is too low, it can cause the oil pressure to drop below the minimum of 4PSI at idle, but I have also read that since the PCM controls the idle speed based on numerous inputs from various sensors (MAP, O2, Cold air, etc., etc.) that you cannot manually adjust it.

Does anyone have any idea what else I can try? I was going to put my oil pressure guage in place of the oil pressure switch to read the actual oil pressure, but where the sensor is located, it is damn near impossible to screw the oil pressure guage into the hole, and even then, the hose is only 3 foot long.

Is there a better place I can attach my guage? If nothing else, I want to put an oil pressure guage in the car (paired with an ammeter) somewhere on/under the dashboard, what brand do you recommend and where did you locate yours? I don't want to tear up the dashboard, bang my knees, in my face, or blocking my other dashboard items/switches.

 

what does the car idle at? It also sounds like you might have used a little too much silicone on the rebuild and it could be hindering the flow out of the oil pump. can also be a leaking o-ring on the pickup. did you use a pipe cleaner and clean all the oil passages? check oil level? clogged Pickup?

 

I don't have a tach, so I do not know the exact RPM the engine idles at, but this problem just started happening this past Fri (3/6/09) after I had already driven about 400 miles. Up until then, it did not have any problems idling with or without the AC on, and the oil light did not flicker.

I does not sound too low, nor does it lope for more then about 1-2 seconds after I turn on the AC, but then it steadys out and seems to idle fine - the light is the only indicator of an issue.

The only places I put silicon were the the points on the separation gap between the oil pump and the block where it said to put it, and I put a 1/8 bead. Oil level is exactly where it was, no leaks, no drips, no runs. The pickup and pipe was soaked and cleaned with a copper bristle brush, and new o-rings used throughout - everywhere it called for one.

After I changed the sensor, I drove it about 30 miles at various speeds changing almost constantly to get the car good and warmed up. I idled at several stop signs for almost 1 minute in some cases, AC on/AC off, and the oil light did not start flickering until I had arrived back home and let it idle for about 2 minutes checking for leaks, etc. and it started again.

I dd leave out one incident that happened after I built the motor. After I completed the work and went for my first test drives around the neighborhood, I noticed that I was pouring oil out the front of the motor on my last trip. I immediately took it back home (about 1/2 mile), and when I took it apart, I found that the front oil seal had popped out of the oil pump. Most of the oil had been pumped out during this time, but there was some still in the engine. I cleaned it all up, got a new timing belt as it was soaked, got a new seal, put it in, put in almost 4 quarts of oil to bring it back to the full mark, and have not had a problem until Friday. I really do not care if it is the oil pump, as it is under a lifetime warranty, but I do not want to take it all apart again unless that is the problem. I guess that I will just have to bite the bullet and find a way to attach the oil pressure gauge and just check it properly - cold and fully warm.

Where is the best place to connect a vacuum guage to determine if I have a vacuum leak that may be affecting my idle? Since there are no manual adjustments, that is really the only other thing to check. I would think that any leaks would result in an error code to the PCM, but I could be wrong.

BTW and as an FYI, I do seem to be one of the "lucky" ones to have a whistling PCM. When I shut it down after driving it, I could hear this god-awful whine that damn near drove me crazy until I put my ear on the PCM and heard the internal racket that sounded like an 1960's Sci Fi computer whiring and pinging. I read on this forum that it is common for Neons to do that, so I'm not concerned about that - just thought I'd mention it. The ODB-II reader/reset has no problem interacting, so I doubt the PCM is bad.

 

i don't suggest doing this, but there is a manual idle adjustment screw on your throttle body. where your throttle cable connects to your throttle body, there is an idle screw that holds the butterfly open just a hair. with a flathead screwdriver you can turn that screw out (ccw) to raise the idle.

 

I think that after I check the pressure with a guage, if it is close or at the minimum limit, then I might give it a go. I did read that adjusting the screw is not a good idea and can create more problems then it solves in some cases.


Thanks, I'll report the results when I know more.

If anyone wants to chime in about my other requests about where the best place to attach a vacuum guage to check for leaks, and also what a good brand of oil pressure/ammeter guages are and where a good place to put them is, feel free.

I'm thinking that I can get a small 2" pair in an enclosure and mount them in a heads-up location right on the top of the dashboard, toward the windshield and bring the wires/hoses up from underneath somewhere.

 

oil capacity is four quarts, plus filter. You could have possibly had some metal to metal contact in the oil pump from running dry.

i always check for vacume leaks by spaying carb cleaner so couldnt help you with that.

autometer makes some nice stuff
http://www.autometer.com/

 

Well, its official, the oil pump is toast.

I finally managed to connect my oil pressure guage at the location where the oil pressure sending unit was located. I want to give a "special" thanks to the A$$holes that designed where it was located - about 2 inches above the drivetrain CV joint where you not only cannot see it, but have to be part contortionist to even get hands/tools on it!

Anyway, after much knuckle-busting, I managed to hook it up and when I first cranked the car - first time in 2 weeks BTW -the oil pressure was holding steady at 20psi! Yea! So I decided to go ahead and drive around to get it up to normal op temp and check it again...........you guessed it, the needle was sitting dead on zippo, nada, nill, nutin', the big friggin 0!
Crud! If I rev the car to around 3000 rpms, it reads about 20 ~ 22psi. If I rev it way up, I can get about 30psi. Either way, both the low end of 4psi and 25psi @ 3000 rpms is out of spec.

Time to replace the pump boys! Thank goodness it is under warranty and the only thing I am going to be out is more time, but since this is a project car, not a bad way to spend a weekend - since otherwise, I would have to mow the @#$@#$#@ lawn again.......

 

That was my thought sorry i didnt say anything sooner

 

I replaced the oil pump and even the oil pick up tube JIC I did not get the old one clean enough the last time. I put in new oil and filter. When I cleaned out the oil pan, I did find some very small metallic bits in the bottom, but that can be normal for a complete rebuild during break in so I did not think too much about that. I did not find anything else in the oil or pan that would worry me - such as blobs of gasket material, etc. You could tell the oil was ready for changing after ~ 400 miles as it was almost black and smelled slightly burnt. Again, not unusual for a car during break in after rebuild.

Immediately after putting on the pump, I cranked the engine and checked the oil pressure guage - I left it attached - and it showed holding steady at 40psi. I only ran the car for about 1 minute as it was very late.

The next day, I cranked the car and the pressure reading was steady ~ 20psi. Strange, but way better then 0. So, I drove the car around the neighborhood for about 10 minutes, stopping a few times and checking for leaks, pressure, etc. No problems. No leaks, oil level was full. The pressure at idle when it got warmed up was holding at 12psi. Again, well inside any specs. Yea! So I thought......

After driving around town this time for about 20 minutes, I got home and the pressure at idle was again 0! WTF???!!! I could rev it up to about 40psi, but WTF?! This is the 10th engine I have rebuilt and I have never seen a problem like this! Oil level is full BTW. No leaks.

What in the bloody heck could be causing this? How could it go from holding steady at 12psi after driving around my neighboorhood during the initial drive warmup, to being 0 after driving for an additional 20 minutes?
Damn! This is really, really, really, annoying! How could my car possibly eat a new oil pump in so short a time? I could understand this if I had gotten bad pressure readings all along, but they started good and just went to HIAHB in under 1 hour!

 

could it be the oil pump slipping around the crank shaft? or could it be that the pump is sucking all the oil out of the oil pan before it can get back to the bottom? check your oil passages...maybe you got something in them?

Take off the valve cover and oil pan...place something on the bottom to catch all the oil, then pour a quart of oil over the top of the head and see how long it takes for it to drain into the pan...shouldn't be more than a few seconds.