WCT13

iTrader: (1)

So their is 2 things that may be wrong with my 94 z28.

The cars oil pressure reads 60-70...at 1k rpms...it reads 60-70 at 6k rpms?

It does have a HV pump...and when you SLAM the breaks the OP drops to 0-10 sometimes.

And the next problem is, we put a 3500 stall in the car and got a new pcm cause the other one was faulty. The cars speedo reads 75mph in second gear at 6500 rpms...it used to read 60 at 6500...it shifts at the same points as it used to though, goes into OD at 45 mph like usual...
cruising in D at 3k rpms it is at 80mph...is the speedo hallucinating? or is it reading the speed right? Cause if it is I didn't know a stall could do that!

CALL911

iTrader: (17)

The oil pressure; make sure you have enough oil in the car (sorry, but had to cover the obvious). Low or near no oil pressure when slamming on the brakes is nothing out of the ordinary. I've got very large aftermarket brakes on my Z, and when I brake at high speeds my oil pressure has dropped so low I get a "check guages" light. That being sail, you should see an increase in oil pressure with an increase in RPM. Not many things this could be past the pump, the wiring to the gauge, and signal.

The speedo being off is likely because the PCM you got was for either a 6-speed car or a car with different gears than you have. A simple handheld tuner should be able to set this right for you.

bufmatmuslepants

iTrader: (3)

Slamming on the brakes and the oil pressure goes to zero is the oil rushing to the front of the pan and getting shallow at the rear where the pickup is, I bet your pickup tube fell off. Happened to me, pulled the pan, tube just lying there.

WCT13

iTrader: (1)

Its welded on so its good.

And the pcm was setup for the stock gears and a a4 but it came out of a roadmaster?

mab6680

iTrader: (1)

ive had my welded pickup tube fall off before if you bang on the pan you will here it moving around in there. the second time i found a clamp type thing on jegs (555-23620) that bolts to the pump housing and clamps on the pickup tube. haven't had it fall off again after that.

LT1_383_Stroker

I think your pressure being at 60-70psi from 1k to 6k means that the pump is moving so much oil that the relief spring is always releasing. That is probably normal.

Another factor is the high volume pump. They move more oil; I've heard that they can evacuate the pan faster than it can drain back in some cases. I too have a HV pump but haven't had any issues with pressure loss. I never brake the car hard though, either. My pump probably doesn't move as much oil as yours, though. My pressure at idle and hot does come down to 40-50. It fluctuates with the 'lump' in the cam.

If you are confident that the pickup is on securely (thump the pan for rattle and fish around with a coat hanger) maybe it's time for one of those pressurized tanks.

Good luck!

WCT13

iTrader: (1)

ok, ill check that this saturday, but if the tube fell off, wouldn't something not work right?


Since you have a HV pump, what kinda motor mods are you using? And have you had any problems with the cam eating the drive gear?

I have a 355 lt1 with a hot cam, exhaust, CAI, working on headers and just got to get a day off to install the 1.6 RRs.

Also, I noticed today before the belt broke on my car, that the Oil Pressure was at 55 and didn't fluctuate. I am thinking of running a thinner oil in their to see if that can lighten the load on the car.