Pinging and Low Power

[odiesox]

Hello, I am a new member who is actually a 20 year mechanic. I have a 94 Explorer sport 2wd with the 5 speed. I am new to Ford's DIS, and think I have an issue with the timing. The engine has 175,000 miles on it, but still runs great, with one exception. It pings under accelleration, but only in the middle of the RPM range(2000-3500 RPM). It also seems to be a little low on power, and does heat up a bit on long climbs. I am at about 1,000 ft of altitude, in a hot area, but outside temp doesn't make that much of a difference, it did the same thing when it was below 50 degrees last winter. It still gets around 20 MPG. I am getting ready for a 900+ mile trip pulling a 4X8 trailer lightly loaded, and don't want to grenade the engine. To help, the plugs were done within 5,000 miles, regular oil changes, and use Northern California mid-grade gas (which helps a little), no smoke, oilpressure is middle and above on the factory guages, temp is usually lower part of normal range, but will rise to mid/high normal range climbing for a while (more than a mile)
What can I do??
Darin
odiesox@earthlink.net

 

[mrboyle]

The first thing I'd check is for a vacuum leak. The most common location is in the intake tube between the MAF and the throttle body. The convoluted (sp?) boots in the bends of the tube will slpit and allow unmetered air into the intake and will lead to pinging.

 

[BrooklynBay]

Some engines are equipped with a knock sensor. It has either a single wire, or a double wire (depending upon the internal gound of the sensor), and is located on the lower side of the engine (depending upon the engine, and manufacturer). If you remove it, you will have a little coolant drip out. There is one way to test this part. If you have a digital multimeter, set it in a low voltage A/C range. Ground one lead of your tool, and connect the other lead to your knock sensor. Tap your engine block lightly with a small hammer near the sensor. You should get a small reading everytime you tap your engine block. If you have a setting with a data hold that automatically stores your highest reading, then see if your output is higher when you tap a little harder. If you have a dead sensor (open), or a shorted sensor, you might have found your problem (or at least one of your problems). If you are curious about what that sensor is, it is called a piezoelectric transducer. When a crystal vibrates, or is squeezed, it will produce an A/C voltage proportional to the amount of stress placed upon it. Did you ever hear about something called a crystal earpiece? Radio Shack radio kits came with them when I was a kid. This is an earpiece, not an entire headphone set. When you apply voltage to a crystal, it will resonate (vibrate). This is the opposite of what the knock sensor is doing. Crystals are also used as time bases on computers, and CB radios. They are designed to resonate at specific frequencies. That knock sensor is designed to resonate at a specific frequency (the knock of an engine). It is a low frequency, so the tap of a hammer will work well when testing it.

 

[BrooklynBay]

Here is a chart that shows the output of a knock sensor:

 

[BrooklynBay]

Here's an internal schematic diagram of a knock sensor:

The picture on the right is a typical Ford knock sensor.

 

[BrooklynBay]

 

[odiesox]

Well, the ping is gone. I should have been more thorough with my site search before posting. Removed the MAF sensor, sprayed it down with Berrymans carb cleaner, small amount of brushing with an old soft toothbrush, Disconnected the battery for 30 minutes, no more pinging, more power than since I first bought it, better gas mileage too. Later, I will change plugs for platinum autolites (.054 gap), and replace both upper and lower intake gaskets. May upgrade the MAF body, and intake system at the same time. anyone have any suggestions about this??
thanks, Darin

 

[fcfd988]

When you say "pinging" what exactly do you mean?

I have a 94 EB, 70k miles with the 4.0 V6 and I have some spark knocking I cant seem to get rid of. I have changed the plugs and wires, but it made no difference.

I also have the check engine light coming on and off every time I drive it. It will come on when you let off the accellerator and go off when you get on it. My criuse has been intermittant since I bought it back in Feb, but ever since the check engine light started coming on around 2000 miles ago, it hasent worked since.

Any Ideas??

Could all of this be related to the MAFS problem on these models??

Thanks in advance.

Wes

 

[BrooklynBay]

Find out what code you have. That will tell you what has to be repaired.

 

[fcfd988]

How do I find out the code? Is there a way to do it without a code reader??

Wes

 

[BrooklynBay]

You could have AutoZone check them for free, or you could do it yourself. Check the instructions in this link: http://www.thorssell.net/hbook/eectest.html

 

[UNTAMND]

Pinging, or Spark-Knock can be caused by many things. Sensors can go bad, or get dirty, poor gas can be the cause, as well as high heat(engine or outside temp) and engine load. If you experiance ping or spark-knock, I would first make sure I dont have a bad batch of gas, and put in a container of drygas or injector cleaner. If the problem persists, then I would start looking at sensors, mostly the maf. It is a common problem in my experiance that people often do not oil their K&N filter correctly, meaning they oil it and then toss it in and drive the vehicle; This is not correct, you are supposed to let the oil "dry" and then shake off excess oil. If you run it immediatly, then the oil gets into the aid and gets on the heated element of the maf, and causes it to give incorrect readings. After cleaning the maf, I would look at the intake air temp and the outside air temp. These sensors are easy to clean. O2 sensors when they go bad usually go to a default in the ecu and it normally runs rich, but it can be lean and cause problems also. If you are running high water temps and heavy loads, it is easier for ping or spark-knock to occur, so you shoudl go to the next higher octane to help prevent this.

These are some good ideas to check into, I hope it helped and wasnt too late.

 

[ma96782]

I am getting ready for a 900+ mile trip pulling a 4X8 trailer lightly loaded, and don't want to grenade the engine.

When towing......w/ a 1st Gen Explorer.......it's the transmission that causes the majority of problems. Keep your trans. cool...........and even then, it may not be enough, to prevent a mishap.

It's been said that U-Haul, won't rent a small tralier to a 1st Gen. Explorer owner.

Aloha, Mark