Alright I have been going through the parts catalog and there is a oil pump and also a metering oil pump. Recently my vehicle is putting me into Hard cel with limp mode , but after a few mins fail safe mode goes away. and everything is normal. but the cel remains even after clearing it, it comes back almost right away. I have checked all the wires following the DTC check for P1688, but have not opened the Metering Oil Pump yet. I have ordered the metering oil pump and wiring harness from ecu to pump etc and pump to ecu. Do i need to order the oil pump too?? and why do this car need two oil pumps?

 

One pump is to lubricate the rotating parts of the engine. The second is to pump oil into the combustion chamber to lubricate the rotor seals.

 

The RX-8 has a regular oil pump for lubrication, like all other cars.

The other pump is to send a tiny flow of engine oil into the rotor housing to lubricate the apex seals. The pump stroke and flow is controlled by the computer, more when driving hard and using lots of throttle, that's why our cars "use" oil and must be topped up.

The pump is not really a DIY job, even if it is working properly a poor adjustment will still result in a check engine light.

Without a dealer in-country, I think I would be selling my RX-8.

S

 

ordered the metering oil pump,and wiring harness ; u think problem won't be solved even after that?

 

The service manual doesn't have any special procedure for installing the metering pump other than just bolting it on, connecting the wiring harness, re-connecting the oil pipe, clearing the trouble code, starting the engine and checking for leaks.

For code 1688 it shows the following possible problems:

• Metering oil pump malfunction
• Metering oil pump switch malfunction
• Connector or terminal malfunction
• Open circuit in wiring harness between main relay terminal C and metering oil pump terminal C
• Short to GND in wiring harness between main relay terminal C and metering oil pump terminal C
• Open circuit in wiring harness between main relay terminal C and metering oil pump terminal D
• Short to GND in wiring harness between main relay terminal C and metering oil pump terminal D
• Open circuit in wiring harness between metering oil pump terminal A and PCM terminal 2V
• Short to GND in wiring harness between metering oil pump terminal A and PCM terminal 2V
• Open circuit in wiring harness between metering oil pump terminal E and PCM terminal 2W
• Short to GND in wiring harness between metering oil pump terminal E and PCM terminal 2W
• Open circuit in wiring harness between metering oil pump terminal B and PCM terminal 2Y
• Short to GND in wiring harness between metering oil pump terminal B and PCM terminal 2Y
• Open circuit in wiring harness between metering oil pump terminal F and PCM terminal 2AB
• Short to GND in wiring harness between metering oil pump terminal F and PCM terminal 2AB
• Short to GND in wiring harness between metering oil pump switch terminal A and PCM terminal 2N
• PCM malfunction

 

wire connections are all ok, but still woul change them. metering pump will be replaced, will be left with the pcm. the only problem when ever I order a part it takes 10 days to get to bangladesh from japan. one thing though is the metering oil pump switch inside the metering oil pump?

 

It's not clear, but based on the diagnostic procedure, it looks like it's inside the unit. There's no separate part for it listed so it must be inside.

 

I think its time you mod the metering oil pump to get 2 stroke from a separate reservoir.

 

is this a common problem in rx8's at this kind of milege? 19000

 

First occurrence I'd heard of, seriously you should consider the MOP mod for both engine longetivity and better revving.

 

there was also someone else who had the same problem had his mop changed 2x and pcm 1x but later found that the wires were to blame. however i am pretty sure that my mop is out. About the mod, i don know how a normal engine works let alone a rotary, wouldn wanna deal with that knowing the nearest mazda dealer is about 2 countries away from me in singapore. I am ordered the mop and wiring harness on tuesday and should be here by next saturday. Will post detailed pics of whats gonna happen. I am still shocked that the mop can just give up like that in 18000miles and i service EVERY 1500 miles (YES..engine oil and oil filter). Maybe I also need to change the PCM since I dont have any flash updated on it and only way to do it is by getting a new one. Well wish me luck folks. some OT, I just couldn help and ordered an IS350 , decided to put the 8 to rest and use the Lexus more and keep the 8 along with the evo ix as a weekend car. But don get me wrong, I will probably order another 8 early next year. Gotta have the Galaxy Grey.

 

Problem Solved. Instsalled new MOP. Its running well . Lets drive a few hundread miles...hope its fixed for good.

 

Congrats...hope this fixes it for good You sure get your share of problems...and without a dealer it must really be a pisser

 

yes true, but my boys here are very skilled, they can take apart the whole car and build it in 24hours. So as long as i can point out --'change this' it takes no time. the mop + eps wire change took 3 hours and here is the best part $45 for the whole job. wonders of living in the third world.....

 

I have the same problem. ... P1688 since yesterday and comes back even after clerance...occasionally the car starts and runs ok but generally goes in limp mode.
What is the part number for the MOP and the wiring harness. I have two other problems also wiring related.... the steering is playing up and the Bose amp stiopped working three days ago... should I check the connectors...

seriously the electrics are giving more trouble than the Lucas on my 1969 mini cooper and Italian 1969 Alfa and 1973 Fiat 124 sport coupe

In Pakistan... no dealers... I and my mechanics are it

 

I got P1688 and more spesific information is ”Dispensing oil pump stepper motor control circuit 4”.

I changed the oil pump but I guess there is something eron with the electricity before oil pump and stepper motor.


Have any idea what should I do?


Check for the wires and if there is not electricity in one (number 4) of them?

 

Juspe

Not sure if you got rid of the p1688 code or not, and the limpy CEL that comes for free with it?

If you have not had any luck after checking electrical plugs and general wiring condition for obvious issues, then try adjusting the switch.

I had same issues recently and this has worked for me so far, for how long we will see! Its free and easy to do when someone tells you or shows you.

Just loosen the two 8mm? nuts on the OMP and move the switch a little, retighten nuts then see if the OMP is happy. You might or might not have to clear CEL afterwards. I read in another thread to double check your CEL status afterwards by disconecting neg terminal on batt, then reattach before scanning for codes again.

This def worked for me anyway. Good luck