Oil pump or sending unit?

[Trevorbarnes]

I have a 99 ranger 4x4 3.0 the oil pressure gauge is going crazy. When I'm driving it's fine but as soon as I come to a stop it drops and goes up and down it starts idling down to 500 or so and cuts off sometimes. Oil pump or sending unit any help would be appreciated.

 

[adsm08]

Sounds like a base engine issue. At this point I would recommend doing a mechanical oil pressure test.

 

[RonD]

'99 is using an oil pressure switch.
The switch is set for 6psi of oil pressure, below 6 psi the gauge will show no pressure, above 6 psi gauge will show 1/2, maybe just below, depends on the gauge.

Bouncing gauge is probably the sender/switch going bad, or it could be the low idle.
If you do not hear valve train noise then oil pressure is fine at idle.

But 500 rpm is too low for idle, check out the IAC valve(idle air control valve), that is what sets the idle on fuel injected engines, it should be 700-750rpms warm, and 900-1,000 rpms cold.
Fix this issue first, that may fix the oil switch as far as the bouncing.

 

[Trevorbarnes]

Im going to install a set of mechanical gauges that I have in the morning and that'll tell me the exact pressure. As for the idling it won't. I've cleaned the maf and the iac and still rough idle. Only way it will idle right is if I take the egr vacuum line loose. And I installed a new egr. Still does the same thing

 

[adsm08]

If it idles better when you remove the EGR vac line then it is probably the EGR vacuum solenoid that is bad, and not the valve itself. The controller isn't sealing right.

 

[RonD]

Yes ^^^

There should be no vacuum present at idle at the EGR valve.
EGR valve only opens at higher RPMs and under load.

If there is a vacuum at idle then EGR will open and idle will be low or engine will stall.
Follow that vacuum line.

 

[cp2295]

I have a 99 ranger 4x4 3.0 the oil pressure gauge is going crazy. When I'm driving it's fine but as soon as I come to a stop it drops and goes up and down it starts idling down to 500 or so and cuts off sometimes. Oil pump or sending unit any help would be appreciated.

Yeah my gauge says I have no pressure sometimes (I just rebuilt it with new pump and cam synchro among many other things). Obviously I have pressure, a that stuff is brand new so all I can say is these pressure gauges are garbage, buy a mechanical one, I bought one a month ago just haven't gotten around to installing it.. Been getting a little too lazy recently

 

[Trevorbarnes]

yes there is vacuum present at the egr at idle.
i started following the line but there are many vacuum lines.

yes i have a set of mechanical gauges i just got busy and havent put them in the truck yet found out where im gonna mount them though.

 

[stmitch]

The fact that it doesn't idle well, and has egr issues could be a number of things in the vacuum/egr system. I'd double check all connections for vacuum lines, as well as electrical harness connections. The vacuum lines get pretty crazy running to the intake manifold and everything else. Instead of trying to trace several lines, I'd start @ the controller itself. The EGR controller is mounted to the back of the coil pack bracket. It will have a connection for the engine wiring harness, as well as vacuum lines. It's the part circled in yellow of this pic:


This is a very basic schematic of the vacuum/egr lines for 98-00 3.0

 

[Trevorbarnes]

I started looking at the lines but there is quite a few

The truck has no power at all. You can floor it and nothing. And now it's using oil pretty bad at first I thought the clutch fan cod be contributing to power loss because it's locked down and turns consistently but now I'm not sure anymore.

 

[RonD]

Unplug the vacuum line from the EGR valve and plug that vacuum line(the right size screw or bolt works fine)
Then drive the truck, power should be back and engine should idle fine.

You DO need to fix the ERG issue, so this is just for testing.

 

[Trevorbarnes]

ive had it plugged and driving it that way but it still has no power at all

 

[RonD]

I would check the sparking timing with a timing light to rule out a bad Cam Position syncronizer
Read here:
http://www.therangerstation.com/tech_library/camshaft_position_sensor.html

Then do a compression test.
Compression is directly related to power, more compression = higher power, so lower compression = less power.

With all spark plugs removed and a good battery, crank should spin fast enough to get approx. 170 psi on each cylinder, 160-180psi.

Lower compression could be a loose timing chain, this might show up on the timing light test as the Cam syncro runs off the cam.

Could be some bad valve seats, I think this was an issue on some 3.0l engines/heads.
Or bad rings, but this would only be expected on high mile engines, 250k miles, but even then it would effect the power gradually not all at once.

After doing a "dry" compression test, put a tablespoon of oil(via spark plug hole) in each cylinder and repeat the compression test, compare "wet" results with "dry" results.
Compression should increase, that doesn't mean bad rings, but it should only increase by a few pounds, if you got 140 psi dry then 160 psi wet, it would indicate failing rings.

 

[Trevorbarnes]

the truck is losing quite a bit of oil, the spark plugs were coated with it so im thinking the piston rings are shot. that would explain loss of power to. I don't have the money to mess with it so im probably just gonna scrap it.

 

[Trevorbarnes]

Got the skip fixed.. And We'll believe the maf was going bad and got the fan clutch freed up the power is back however it's smoking when you first start it up and then only when you give it a good amount of throttle.

Any thoughts on this?