Codes! Codes! Codes!

I know, this is usually the first thing that should be checked, and I will do so as soon as the blizzard outside will allow me. hehe.. For now, I was just hoping to get your initial thoughts on my problem.

This just started today, I noticed that whenever I came to a stop my oil pressure gauge in my 1990 Bronco, (351W), would competely go down to the "L" in the red. I checked the oil, it was a little low so I topped it off, but the problem continued. After a while it seemed to get worse. Whenever I would slow down and stop the oil pressure gauge went all the way down, the red Engine light would come on, and the truck would start to sputter as though it wanted to stall out.

All these problems went away whenever I gave it a little gas, and there were no problems at all when I was actually driving, only when I stopped. It does it mostly when the truck is in Drive, though if I let it idle in Park for a few moments the oil gauge and RPM gauge start to go down then as well and the truck tries to stall.

While I'm sure the truck is due for a tune-up anyway, I was hoping someone may have encountered this before and could give me some thoughts on what this may be caused from.

Thanks.

 

I can't recall anyone saying anything nice about the stock oil pressure guage. Mechanical oil and water temp are the way to go. You said it...start with codes for the stock oil guage is worthless. The computer may have gone into "limp along home mode" but you don't know yet. What odometer reading, oil, filter brand and how long since last oil change? Thick, cold oil may be starving it for oil. Does the engine burn much oil? How are the plugs? Is oil in the bottom of the air filter box from blow by? You may be needing something like 5W-30 or lower oil in a blizzard. 20W-50 would not flow well. Is the temp getting to 195 degrees? Bottom line....a digital code reader is thirty something dollars if you are too impatient to paper clip it and count flashes like I am.

 

He said it

 

First off, thanks for your advice. I'll look into checking whatever I can. The odometer is at 195k miles. The oil is always SAE 10w-30 because that's what it says to use under the hood. I believe the oil filter is a Motorcraft and I had the oil changed at one of those quickie places about a month ago. The spark plugs seem fine, though they need to be changed soon anyway since it's been too long without a tune-up. Just not sure why this would affect the oil pressure.

For now though, I managed to get the codes. I checked several times, both with engine off and engine running, and these are the codes that I get. I'm not sure if any would cause my problem, as unfortunately, I'm not even sure what most of them mean.

These are the codes I was able to pull. Any more thoughts or explanations of the codes themselves would be greatly appreciated. Thanks.

21: ECT out of self test range 0.3 to 3.7 volts.

24: ACT sensor out of self test range 0.3 to 3.7 volts.

33: EGR valve opening not detected.


12: Cannot control RPM during ER Self-Test high RPM check.

41: No HEGO switching detected always lean (right side).

52: Power steering pressure switch always open or closed.

77: System failed to recognize brief WOT during Dynamic Response Test (user error).

 

I have had a simialr problem on my 93' 302 since I bought it a few years ago.It actually did this today.When running alot around town and comeing to a stop my pressure gauge goes down and starts to fluctuate and my battery gauge drops also.I take off and gauges go back to normal.On again off again problem.These do not always happen together.Have yet to figure it out?

 

Is your battery and alternator good? A bad battery can cause all sorts of problems Until one of the pros on this site (I'm not one) get around to it, you might think about this....looking at http://www.troublecodes.net/Ford/ I would start with the ECT 21 If the Engine coolant temp sensor is not working the computer cannot perform well. Also check, coolant level, wires to ECT etc. and think about replacing the ECT sensor.. If I had no better information I would throw one at it so the computer would know the engine temp to adjust for.

 

The ECT and the ACT are very important sensors in the Speed density system. The ECT tells the computer what temperature the truck is at currently. You can test the resistance of this when the truck is warmed up, if the resistance is not at the right spot for the temp you need to replace it. The ACT tells the computer what the air temperature is in the manifold. Air temperture tells the computer how dense the air is through some complex math, so that the computer will allow enough gas in to run at a lean point. Your HEGO, AKA O2 sensor, is important in telling the engine if it has the right amount of gas burning in the motor. All three of these sensors are important in getting the truck to idle and perform at the optimium. Otherwise the ECU relies solely on the MAP sensor to tell it what the load is on the engine. www.fordfuelinjection.com can help you with testing the ACT and ECT with a voltmeter that can test for the kOhm range of resistance.

As for the oil pressure, do you hear any knocking in the engine or is the oil pressure gauge reading 'OK' when you are running the engine between 1500 to 2500 rpms? It is easier to ground the oil pressure switch wire out and just put a mechanical gauge in to monitor the pressure yourself. I would say to get your engine to idle right first, but if you have more than 150,000 miles on your engine with out a rebuild, it may be a sign your bottom end has seen better days.

 

I'll get the sensors checked, and probably replaced anyway, as soon as I can. As far as the battery and alternator, I've never had any problems with either, though I have had to fix a loose cable connection occasionally. I need to replace the clamps, but just keep forgetting. heh

One thing is, a few months back I had to have the gasket replaced where the cover is over the water pump. The water pump itself is fine. However, after it was done, my engine temperature gauge hasn't worked since. I wasn't overly worried since it never shows any signs of overheating or running too hot. Clearly, it's time to take your advice and switch to the mechanical gauges either way.

As for the engine, there is no knocking/clicking/pinging noises that usually accompany oil problems. Engine sounds normal. It runs fine so long as I can give it a bit of gas. It only starts to stall and the oil pressure drops when the engine is warmed up and I'm slowing down and stopping.

Anyway, let me know if you have anymore thoughts. In the meantime I'll try to have my sensors all checked and possibly replaced, (as weather and wallet permits. hehe)

Thanks again.

C.

 

The dash sensor is separate from the ECT sensor. The dash sensor is on the driver's side of the manifold in front of the number five manifold runner. The spot goes down to a water passage from the head that is blocked off by the intake manifold. It sounds like you should correct the engine idle issues before you get too much work on the oil pressure problem.

 

Well, today I discovered that I have an oil leak somewhere on the bottom of my engine as well. As soon as weather permits, I'm going to head to the carwash to spray it clean under there so I can see exactly where the oil is coming from.

Friday the 13th indeed. Ugh.