My car will not run above 1000RPM. I checked the sensors on my FC commander and the Oil Pressure sensor is highlighted with a reading of 0.00V. I checked the Oil Pressure sensor on the left side of the engine just below the filter and the one wire is attached to the pressure sensor. There is a broken wire above it, but I can't see where it was connected and have no Idea what it does. Is there a wiring diagram available for the sensor system? What is required besides that single wire connected to the oil pressure sensor for it to work?

 

The pressure sender is indeed a single wire.

The connection has a reputation for going bad even though the oil pump is fine.

You can find a wiring diagram and factory service manuals in the sticky thread at the top of this forum.

David

 

join the club haha. Sender itself also goes bad too.

 

I cleaned and reconnected the single wire going to the oil pressure sensor and reconnected the broken wire near it to what looks like aground on the engine block just behind the trailig sparkplug connection for the rear rotor. Still reads 0.00Volts on the FC commander!
How does the sensor work? Is it supposed to go to ground if the pressureis good? I imiagine it's resistance varies to represent a prssure. So if I jumper it to ground with a resistor in series I should be able to get a votage reading. If this works then the problem iswith the sender. If not, thethe problem is in my wiring harness or ECU?

 

Oil pressure sender lead is on the alternator/battery/starter harness. The lead on the engine harness goes to the small coolant sensor right next to it. Make sure you didn't mix them up.

 

Ahh so that little guy next to the oil pressure sensor with the broken wire isn't a ground but a coolant sensor. That may have solved my loss of water temp indication on the dash problem.
I jumpered the lead from my oil pressure sender to ground and the voltage reading on my power FC did not change. Nor did it change when I jumperd it to the posiive terminal.

So I want to confirm I'm looking in the right area. The indication onmy FC commanded is a highlghted 0.00V for "VMOP" on my sensor/sw check. The manual says this coorelates to Metering Oil Pump Position Sensor.

Is it normal to read 0.00V with the engine not running? Where is this sensor located? What is it supposed to tell me?

 

I don't know the voltage values off the top of my head, but I'm sure they're in the factory service manual. You can download that from the link stickied at the top of the 3rd gen forum.

Dave

 

First off, the PowerFC (or the stock ECU for that matter) doesn't get an input from the oil pressure sensor. That just goes straight to the gauge, that's it. What does the line on the PFC say that's giving you the error? It might be related to the metering oil pump or something.

You can leave the oil pressure sensor and water temp sensor for the dash unplugged all day and the car will run fine. Now, if the engine has problems and you don't know about it the car will stop running fine, but the ECU doesn't care about those inputs.

Dale

 

^ really, the water temp sensor input doesn't go to the stock ecu or pfc? so then how does the ecu know how to respond if the car overheats?

 

Thanks for the imput. Since the oil pressure sensor just inputs into the instrument cluster and not the ECU then I will focus on the metering oil pump position output. How does the metering oil pump work. Does it run when the key is in the on position or must the engine already be running? The PFC just shows the output voltage from the Metering Oil Pump position sensor to be 0.00 and highlighted. The Highlighted part indicates an error and my engine doesn't run above 1000RPM.

 

The FD has, more or less, 3 coolant sensors. One is for the dash gauge, one is for the ECU, and one is the thermoswitch for the fans.

In theory, it could be done with one switch, but the redundancy is a good idea.

Dale

 

OK, just looked in the PowerFC manual. Is the line in the sensor check screen that shows 0v the "VMOP" line? Might even want to post a pic up of your sensor check screen. If so, that's the oil metering pump. I didn't think the PFC would do a limp mode with it bad, but regardless the OMP is something VERY important to your engine's well being, if it's saying nothing you need to fix that before going further.

Dale

 

I looked into the oil metering pump being the source of my problems and discoveed that I do not have one. There seem to be blanks intalled where th manual says the pump should be. The previous owner emphasized how it was important that I premix my fuel. This may have been why.

 

sorry to kinda thread jack but, can you just get an after market oil pressure gauge and just was out the stock sender unit without modifying anything?

 

I know it's an old thread, but for anyone's future reference, I can confirm that the PFC will NOT put you into limp with a bad OMP.
If I understand your question correctly, the answer is no. You'll need the sensor for that particular aftermarket gauge. Most that I've seen have used an aftermarket adaptor on the oil filter pedestal inorder to install that sensor.

 

i could not find the values for the sendor yet but here is the impedience the gauge should read i would assume the sender matches?

Continue checks for at least two minutes each to correctly judge condition. Allowable indication error is twice the width of the needle. Oil pressure becomes low when engine is cold because eccentric shaft bypass valve operates.

1. Disconnect electrical connector from gauge sender unit and connect red lead of checker 49 0839 285 to connector and black lead to body ground.
2. Turn ignition switch to On position and proceed as follows:

1. Set checker to 80 ohms. Gauge should indicate 110 psi.
2. Set checker to 110 ohms. Gauge should indicate 60 psi.
3. Set checker to 200 ohms. Gauge should indicate 30 psi.
4. Set checker to infinite ohms. Gauge should indicate 0 psi.

3. If gauge indicates correctly, replace gauge sender unit.
4. If gauge does not indicate correctly, repair wiring harness or replace oil pressure gauge.

 

and also i have never had my oil pressure gauge reading correctly, i have never been able to find the oil pressure sender lead mabye Rotary Experiment Seven's post will help me find it, or mabye mine was ripped off?

 

im not understand if you understand me or if i understand you.. so let me rephrase it lol...

Say i bought a stri gauge or defi gauge and it comes with an oil sensor. can i just remove the stock one and use that location to put the stri/defi gauge in its place?
-benny

 

A couple of things that may help you:

The VMOP as shown on the commander is the metering oil pump position feed back voltage to the ECM. If no MOP exists this will indicate 0.0V. The PFC has no limp home mode so should not be a reason for the limit to 1000 RPM.

There are two coolant temperature senders, one temperature switch, and one coolant level indicator. One temperature sender is located on same side of the spark plugs on the rear plate known as the meter sensor. This one is next to the oil pressure sendor and has a single wire. This sendor is for the temperature gauge (meter) and nothing else. The second sendor is located behind and below the coolant fill housing this one has two wires. This sensor is specific to the ECM and is used for fuel calculations. The temperature switch is used for cooling fan operation and the level indicator only operates the low coolant light on the dash and the buzzer. None of these instruments will be a reason the engine is limiting RPM.

If you did, in fact, ground either the oil pressure meter sender (single wire) and/or the coolant meter sender (single wire) you will peg the gauges and damage them. They are designed for a ground bias of 0 to 5 volts and by grounding you applied a full 12 volt of ground bias. To test for damage quickly touch the wires to ground while monitoring the gauges; if the gauges peg you should be OK. Hopefully no damage has been done to your gauge cluster.

If you do install an aftermarket oil and temperature gauge you can remove the meter sensors and install the the new gauge sensors but your factory gauges will be disabled. It is agreed the factory temperature gauge is of no value and reliable temperature must be read from another source. I have found my factory oil pressure gauge is accurate and has very good response time so no need (in my case) for an aftermarket unit.