I think my oil pressure sender needs a good cleaning. It will read normal sometimes and other times it will flutter around and then it will just read zero other times. I'm assuming it actually has normal pressure and either the gauge or sender isn't working properly because it hasn't taken the plunge yet and it has been sitting at zero whilst driving for a while. I am curious ,though, as to if no oil pressure will trigger the check engine light.

The other day I was driving home from school and it was doing the normal BS (reading very low or no pressure) and the CEL lit up. I stopped to check if it was actually low on oil or if there were any issues and everything seemed fine. So i was gonna flash the code out but when I turned the key back on the light was off. It hasn't come back on since. Any thoughts on that?

On a completely unrelated note: The other day I changed plugs and wires and holy hell was it a pita! Im used to the FC where the coils are on the fender not under the throttle body!

 

A bad sender doesn't generate a CEL. It's never happened to me, but the oil level sensor will trip a buzzer.
I suspect the two are unrelated.
The sender has just a single spade connection near where you were routing wires to the coils. It's also near that oil filter pedestal, which can contribute to a bad connection. Before replacing the sender try removing the connection/and or cleaning both ends.

Yeah, they aren't in a "fun place" There are a few suppliers of brackets to relocate the coils.

 

Yeah when I was doing the plugs and wires a cleaned the connection. I think I will just try removing it and giving it a good, thorough cleaning. It has almost 103K miles on it after all.

 

The ECU will store the code, all you need is a paper clip to pull them and see what else is happening. http://www.banzai-racing.com/FD_S5_error_codes.htm

 

I wasn't aware that it stored codes after the light was off. Thanks.

Also, I took the oil pressure sender out last night and cleaned it up and when I took it for a drive it seemed to be working much better.

 

The oil pressure senders are notoriously unreliable
I just ordered a new one from Ray for $94.76

 

Today was the second time I replaced an oil pressure sender. When the engine was fully warmed, and running slow or at idle, it would show zero pressure, along with occasional wild swings of the needle. Replaced for a ridiculous sum of money, though last time I replaced it myself. Pretty easy, actually. Since this is a design problem, has mazda ever put out a notice, or redesigned the sender? Any good fixes?

 

Maybe Ray @ Malloy would know if there was ever a re-design.

Strange...bad senders aren't universal. AFAIK, my sender is the original one...never been changed. At least not in all the years I've owned it. I don't even remember cleaning it when I had it off for a rebuild 3 or 4 yrs ago. I think I just re-installed. I have the occasional loss of indicated pressure at idle when the engine is fully warmed up. But when I clean the connection it's fine again.

 

As far as I know Mazda never updated that sender. They just got rid of it later, the '99-02 FD's have no oil pressure gauge, they have a boost gauge. Which is far more useful.

Yes, oil pressure senders are $80-90 and that sucks, but a new one will do the trick and last a good long time before it goes out. You can probably buy 2 sensors for the cost of a good oil pressure gauge. Also, I like to have everything in my car working, the gauge sitting at zero or whatever is bobo.

Also, really, oil pressure is not really that important on a rotary. I've yet to see someone who destroyed an engine that could have prevented it if they were looking at their oil pressure gauge. The only time you really need to watch oil pressure is after a rebuild to make sure you didn't goof up the front cover O-ring or something like that. The oil level sensor is VERY important and a great system, though.

Funny thing is FC oil pressure senders NEVER fail. The FD senders read a higher pressure and I guess that redesign made for lack of reliability.

Dale