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1998 Honda Prelude
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Discussion Starter · #1 ·
Quickly paraphrasing the problem because I've posted about this before...

My oil pressure drops to nearly 0 psi once it reaches a temperature right below 190°F. Idling for about 15 mins and then depressing the accelerator and then releasing it usually does the trick. BRAND NEW SYMPTOM the car likes to kill the engine while driving it without a loss of electrical power. It cranks right back up as I coast.

I've...
  • Replaced my Rod Bearings
  • " " Main Bearings
  • " " Thrust washers
    • All the above with King XP brand.
  • Victor Reinz gasketing kit
  • New Oil control Orifice o-rings
    • Exempt for one that's on the bottom however that one was in perfect condition.
  • Valve Clearance Adjustment
  • Installed a new (to me) Certified Reconditioned Cylinder Head.
Anomalies my OBD can tell me
  • My throttle position sensor reads -0.6°
  • My LTFT and STFT drifts from 1.0 and it eventually reads 0.97 and STFT reads 0.96 when the oil pressure begins acting crazy.
Maybbeeeee I'm getting some gas in the oil as I Try to go richer since the tp sensor telling it to?
 

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JDM 4th Gen Prelude 2.2 Vtec Turbo
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How are you measuring the oil pressure?

How healthy is the charging system and battery?

Given zero oil pressure would kill the engine really quickly, it reads as though that's maybe not the problem, but merely a symptom?
 

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1999 Prelude. F20B/K20A hybrid rebuild
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Also curious how and which port you’re getting your oil pressure reading from. If you REALLY had Zero-10psi oil pressure your engine would’ve locked up and been unrepairable a long time ago.
And no, those codes and throttle position stuff has no relation. If it was running that rich and that diluted it would barely be running at all, also would damage your crank and bearings too
 

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Do you still have balance shafts? I ask because if they were deleted, it's possible the plug near the oil pressure sensor was installed too far and blocking the sensor.

Have you removed the oil pressure sensor and checked for any blockage?

All the grounds in good shape? This is sounding electrical related despite you don't lose power within the car.
 

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1998 Honda Prelude
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Discussion Starter · #5 ·
How are you measuring the oil pressure?

How healthy is the charging system and battery?

Given zero oil pressure would kill the engine really quickly, it reads as though that's maybe not the problem, but merely a symptom?
I'm measuring oil pressure with a mechanical gauge.

My alternator and battery are both also brand new. Battery hangs out at 14 Volts regardless of headlight/wipers/etc usage.

Also curious how and which port you’re getting your oil pressure reading from. If you REALLY had Zero-10psi oil pressure your engine would’ve locked up and been unrepairable a long time ago.
And no, those codes and throttle position stuff has no relation. If it was running that rich and that diluted it would barely be running at all, also would damage your crank and bearings too
Mechanical gauge and from the pressure sensor port. When my pressure light begins to flash my engine starts to shake and I turn the car off.

And I'm probably crazy but I thought throttle position and fuel trim were, in part, related. I don't have any codes.

Do you still have balance shafts? I ask because if they were deleted, it's possible the plug near the oil pressure sensor was installed too far and blocking the sensor.

Have you removed the oil pressure sensor and checked for any blockage?

All the grounds in good shape? This is sounding electrical related despite you don't lose power within the car.
I do still have the balance shafts, only the belt was removed, I don't have the ports blocked with that kit or anything.

My grounds are good, as well. I've multimeter-ed and backprobe'd and power probe'd the heck outta the car.
 

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My '97 did the "quit for no reason and restart" thing. Problem was in the ignition switch. I'm told that was not uncommon.
tommyt
 

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1998 Honda Prelude
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83 Posts
Discussion Starter · #8 ·
@Wing8806 this may be a dumb question but is there anything which is not mechanical but instead computer controlled that handles the oil pressure? Perhaps not directly but indirectly?
 

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1998 Honda Prelude
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Discussion Starter · #9 ·
Update: I wanted to look and see if I miffed up a valve clearance adj. or other cylinder head internal. When I took the spark wires out I saw a crazy amount of oil in the third cylinder. I don't even know how the car even started let alone ran for 20+ mins at a time.

Now, I know what y'all are thinking. But I had this problem BEFORE I blew my head gasket and to my recollection, did not have oil in my spark cylinders.... But perhaps I fixed the OG issue and now THIS is my issue. It's late but I'll update tomorrow.
 

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JDM 4th Gen Prelude 2.2 Vtec Turbo
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The oil comes direct from the pump where you are reading it from. Nothing mechanical or electronic sits in between.
 

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1998 Honda Prelude
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Discussion Starter · #12 ·
The oil comes direct from the pump where you are reading it from. Nothing mechanical or electronic sits in between.
Could the spark plug issue be where the air is getting into the system at? Here's how it goes at least in my head. The piston is always sucking and filling the spark plug hole and that's why it cranks and drives and occasionally turns off. The sucking and filling is where the gas and air is getting into my oil causing low oil pressure. The gas evaporates by the time the engine cools.

Make any sense?
 

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JDM 4th Gen Prelude 2.2 Vtec Turbo
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Not to me.

What have you done with the OEM oil pressure sensor?

If you take the aftermarket oil pressure readings out of the equation and ignore them as erroneous, what are the issues with the engine?
 

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1998 Honda Prelude
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Discussion Starter · #14 ·
Not to me.

What have you done with the OEM oil pressure sensor?

If you take the aftermarket oil pressure readings out of the equation and ignore them as erroneous, what are the issues with the engine?
I fixed the leaking plug issue. You're right it did nothing to help.

The OEM sensor stays installed on the car. I only took the oil pressure readings from the gauge one time, then removed it and reinstalled the OEM sensor.

Besides the car randomly stalling, there are no other problems with the car besides the ones that turn up when the oil pressure light starts the rapidly blink until it just is either on or steadily blinking. The engine starts to shake excessively.

Like I said before, nothing is wrong with the car until 20+ mins of idle and then I pump the gas pedal, or after 5 mins of regular driving, and once the temp is 190+°F

And I had my multimeter data graphed, when the car dies, there is no change in battery voltage. I would expect it to change if it was charging system related, right?
 

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JDM 4th Gen Prelude 2.2 Vtec Turbo
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Could be a number of things to look at, fuel supply (clogged filter or main relay?), ignition switch, main relay or a random loose connection somewhere.
 

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1998 Honda Prelude
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Discussion Starter · #16 ·
@Vtecmec I let the car keep pressing on a little while the oil pressure light went from a flicker to solid "on". My RPMs dropped to nearly 200 before I turned off the car. Everything is 700 RPM until I reach running temp and tap and release the accelerator and then all hell breaks loose.
 

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JDM 4th Gen Prelude 2.2 Vtec Turbo
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Your oil pressure will drop towards zero as the cars revs drop and it stalls. Sounds normal.

If its that concerning, the only thing is to check the oil pickup and/or replace the oil pump, which is driven at the crank. If the car has had new bearings then these surely would have been checked anyhow?

700rpm is too low for a cold start, which suggests your car needs a service and resetting back to specs.
 

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I’m nowhere near competence in motor as you guys are but I’ve had issues with oil in couple of my plugs. Was to the point where I had to push paper towels into it with small screw driver to soak up before I even attempt to remove plugs and it was because I replaced the oem seal from the valve cover with after market one so it didn’t seal properly. Where the cable plugs onto the spark plugs itself was covered with oil but the car ran fine because oil didn’t make it into the chamber.
Your symptom sounds like you have a leak somewhere. Here’s my theory:

The higher the temp., the higher the pressure. Once it got up to where it max out n should maintain, it doesn’t (bc of leak) so the ecm shuts down engine to protect motor.
 

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Discussion Starter · #19 ·
Your oil pressure will drop towards zero as the cars revs drop and it stalls. Sounds normal.

If its that concerning, the only thing is to check the oil pickup and/or replace the oil pump, which is driven at the crank. If the car has had new bearings then these surely would have been checked anyhow?

700rpm is too low for a cold start, which suggests your car needs a service and resetting back to specs.
My fault, I should have included that I was only talking about 700rpms being a consistent variable when the car is warmed up and has only idled with nothing on.
 

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1998 Honda Prelude
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Discussion Starter · #20 ·
I’m nowhere near competence in motor as you guys are but I’ve had issues with oil in couple of my plugs. Was to the point where I had to push paper towels into it with small screw driver to soak up before I even attempt to remove plugs and it was because I replaced the oem seal from the valve cover with after market one so it didn’t seal properly. Where the cable plugs onto the spark plugs itself was covered with oil but the car ran fine because oil didn’t make it into the chamber.
Your symptom sounds like you have a leak somewhere. Here’s my theory:

The higher the temp., the higher the pressure. Once it got up to where it max out n should maintain, it doesn’t (bc of leak) so the ecm shuts down engine to protect motor.
That sounds like sound logic to me, and I would've told you I agree with your theory a few days ago.

But I managed to fix the spark plug chamber's oil leaks, and took an extra close look at the valve cover and could find no leaks there. It took, what I perceived at least, quite a bit more time for the oil pressure problem to manifest, but still did happen. I could also just have thought it was more time. I concluded the leaking spark plug cylinder was its own issue.
 
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