Mystery Wire! Mystery Oil Pressure!

[Sonicfrog]

OK. I got the new(er) engine started in Murphy, the 87 turbo wagon, It starts and runs fine. But I do have a problem.... a mystery wire. It is a 16 gauge black wire that runs right along where the engine harness by the battery. It has a small disconnect. It is long and I suspect it may be a ground on the engine for the oil pressure sensor....

 

Oh, that is the other odd thing. The pressure gauge worked fine when I had the old engine in. Now, when you turn the key to start, the needle goes to max pressure. When you start the car, the needle will quickly go to the low end and bottom out.

 

I'll take pics of the wire tomorrow.

[TheLoyale]

Sounds like a wire for the Oil Gauge is grounding out on something somewhere. Or something is putting a major draw on the electrical system when you turn to "Start" I had this same thing with my Tac gauge, something was putting a huge draw on the system (Starter selinoid was crapping out) so everytime you were to Crank the vehicle the Tac would jump way past redline and then back to 0 RPM untill the engine started.

 

-Tom

[MilesFox]

the engine you used has a different sending unit. the sender on your new motor is for a dummy lite. its small and round. and analog sender would be larger in diameter.

 

if using an analog sender in a car with a dummy lite, the oil light will come on when you HAVE pressure, and go away during low pressure

[Sonicfrog]

Miles, I was driving home from a job, and that very thought occurred to me.... what if I installed the wrong sensor? It dawned on me that the variable resistor sensor would be the bigger of the two.... Duh!

 

I did indeed install the on / off one, thinking that was the variable one.

 

A few years ago, I chucked the crappy digi-dash for the analogue. I never bothered to pull the old pressure sensor, so I had both installed. Sad thing is, the engine install was delayed because the 1/4 port for the smaller sensor was plugged, and I couldn't get the damned plug out. So I had to modify an adapter to make it fit. Now my beautiful modification has turned out to be all for naught. Will install the correct sensor once the engine cools a bit.

 

About the mystery black wire.... It is disconnected and I'm not noticing anything amiss on the electrical side of things. I'm thinking it may go to the suspension air pump, which is no longer in use since I converted that to the good ol' RX strut and spring assembly. Until I can figure out what it might go to, I'm going to leave it off the grid.

Edited March 4, 2010 by Sonicfrog

[TheLoyale]

Oh, I didn't even think about the other sensor type. Yes that would be an issue

 

So why did you remove the air suspension? Seals getting old?

[Sonicfrog]

For a year or so, the front driverside would deflate overnight, and I'd wake up to find the car listing on one side, as if it were drunk. After a minute, it would normalize and all would be well. But one day, the system completely failed. As money was an issue, and the repairs on the pneumatic system can be costly, I took the advice of many on the list, and replaced the air suspension with a standard one. I really liked the way the air suspension handled, but I love the standard one too.

 

I installed the correct oil sensor, and all is well.

[TheLoyale]

Glad the oil sensor issue is fixed.

 

I would have changed to standard struts/coilovers aswell, much more simple in my book.