1993 Ford Explorer Spark plugs carbon fouling

Tiny
ALLENHUDSON91
  • MEMBER
  • 1993 FORD EXPLORER
Engine Performance problem
1993 Ford Explorer 6 cyl Two Wheel Drive Automatic

My spark plugs are carbon fouling really fast, I only have enough time to drive around the block and back. But it is only the left side of the engine that is fouling, the other side looks perfect. I have already replaced my plugs and wires. What could be causing this?
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Wednesday, August 19th, 2009 AT 9:34 AM

11 Replies

Tiny
KHLOW2008
  • EXPERT
Hi allenhudson91,

Thank you for the donation.

If the plugs are fouling due to excessive sooting, it most probably is caused by vacumn leakages.

Other possibility could be a compression problem. Get the compression tested if no vacumn leakages are found.
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Wednesday, August 19th, 2009 AT 10:06 AM
Tiny
ALLENHUDSON91
  • MEMBER
What should the normal compression be?
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Saturday, August 22nd, 2009 AT 9:49 AM
Tiny
KHLOW2008
  • EXPERT
I could not find the specific compresion presure and this is the general guidline as specified in my database.

ENGINE COMPRESSION
Check engine compression with engine at normal operating temperature, all spark plugs removed (on
dual plugs, remove exhaust side only), and throttle wide open. Ensure crankcase is full and oil is of
correct viscosity. With compression gauge installed, use remote starter to crank engine.
Crank engine at least 5 revolutions, and record highest reading. Repeat procedure for all cylinders,
using approximately same number of revolutions. Lowest compression reading should not be less
than 75 percent of highest compression reading. No cylinder compression reading should be less
than 100 psi (7 kg/cm 2 ).
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Saturday, August 22nd, 2009 AT 10:23 AM
Tiny
ALLENHUDSON91
  • MEMBER
The compression was fine, what would cause carbon fouling on the passenger side, and not the driver side?
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Sunday, November 15th, 2009 AT 3:59 PM
Tiny
KHLOW2008
  • EXPERT
If the engine is not firing correctly, it would foul up very fast.

Possible causes are :

1. Fuel pressure and injectors. Bad injectors would cause excessive fuel to be supplied. Check if there are any clogging of the fuel return between both banks which would cause a higher fuel pressure between the banks.

2. Spark plugs and related parts. Ignition coils etc.

3. Bad cylinder head gasket, this would cause low compression which you have ruled out with the test carried out.

4. Clogged exhaust system.

You would have to concentrate on the above for the bank that is giving problem.
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Monday, November 16th, 2009 AT 8:36 AM
Tiny
ALLENHUDSON91
  • MEMBER
*1. Fuel pressure and injectors. -This is the only thing left for me to check. All of the below I have already changed:

2. Spark plugs and related parts. Ignition coils etc.(I just replaced the wires, plugs, coil, etc.)
3. Bad cylinder head gasket(i just replaced the hads and gaskets)
4. Clogged exhaust system.(Catalytic etc. Is all fine, no clogs)

How can I check the pressure?
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Monday, November 16th, 2009 AT 2:49 PM
Tiny
KHLOW2008
  • EXPERT
You would need a fuel pressure gauge and appropriate attachments to install the gauge onto the Schrader valve located on the fuel rail.

Before installation, release the fuel pressure and after installation, turn the ignition on and use diagnostics equipment to command the PCM to run the fuel pump. If you do not have diagnostics equipment, try cranking the engine a few times to see if the pressure builds up.

Was the problem there before replacement of the head gaskets?
Are the valve timing correctly set?
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Tuesday, November 17th, 2009 AT 1:09 PM
Tiny
ALLENHUDSON91
  • MEMBER
Yes, I changed the head because of that problem. I was actually changing the head gasket, and I sent the head to the shop to get it magnaflux test done to it because everyone said I needed to, and they found a crack in it. So, I ended up putting a new head on there. I dont think I can adjust the timing on the explorer, can I?
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Tuesday, November 17th, 2009 AT 7:13 PM
Tiny
KHLOW2008
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The ignition timing is non adjustable for the 4.0 L engine but the timing chain installation would affect the valve timing, which is the one I am referring to.

Was anything done or did anything happened prior to the problem occurring?
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Wednesday, November 18th, 2009 AT 9:14 AM
Tiny
ALLENHUDSON91
  • MEMBER
The only thing I did was change the fuel pressure regualtor, and I changed the vacuum modulator valve on the transmission. Other than that I havnt changed anything.
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Wednesday, November 18th, 2009 AT 12:03 PM
Tiny
KHLOW2008
  • EXPERT
Sorry for confusing you.

What I meant was, when did the initial problem occurred and was any repairs carried out prior to it happening?
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Thursday, November 19th, 2009 AT 6:00 AM

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