Mechanics

WHAT WOULD CAUSE A MISFIRE IN CYLINDER 4

2001 Ford Escape • 150,000 miles

I recently changed the spark plugs gaped them to specifications, changed the spark plug wires, the cap that goes to the spark plug wires and it still getting a misfire in cylinder 4. I'm thinking that it may not be getting fuel since that is the only cylinder with the misfire and also it isn't throwing out any other DTC
s besides the P0304 code.
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Apac408
August 25, 2012.




You could check the fuel injector with a test light to see if it is firing and then pull the plug to see if it is getting wet with gas.
You can always check it for spark by pulling the plug and putting the plug into the boot and ground it out on the engine or chassis.
If all that works, you might want to test the compression on that cylinder and possibly the fuel pressure.
Autoo Zone and Advance Auto loan out tools for both tests.

Where are the fuel injectors located on this car is it underneath the air intake

Tiny
Apac408
Aug 25, 2012.
If you look in line with each spark plug going down towards to head, you will see the injector in the head.
You can find the fuel rail if you can see the fuel regulator or where the fuel ine comes in. The fuel injectors will have this rail attached to the top of them as well as a positive and negative wire going into them, look for wiring harness.
These are the 2 wires you want to test with a test light to make sure the injector is completing the circuit and firing as they have a solenoid in them that moves to let gas in the cylinder.

Ok so I did a compression check and said to say it but all cylinder came out fine except for cylinder number 4 no compression at all so what problems am I looking at for this. Head gasket piston rings?
AD

Tiny
Apac408
Aug 28, 2012.
That is correct. You might have an igniton problem, unlikely, or carbon deposits on high mileage cars can melt holes through pistons. There are other reasons for mechanical damage such as oiling failure. However most likely is the head gasket.

Okay so if I remember correctly the head that is closest to the engine would be the RH gasket and the one furthest away would be the LH gasket right

Tiny
Apac408
Aug 29, 2012.
WIFEY HAS A 2003 W/ A 3.0L

THIS WAS AN ISSUE WITH HER'S THAT I WORKED ON HITHER AND YON, FOR MONTHS

I PROMISED MYSELF, I WOULD FIGURE OUT THE CYBER CONTROLLED CRITTER WITHOUT THE HELP OF A "PAY MECHANIC". TECHNOLOGY HAS WENT OVERBOARD.I'LL KEEP MY 2 JEEPS 35 AND 66 YEARS YOUNG

Reckon my symptoms are sorta the same as yours?

I had input from here also. Ended differently

Disregard all of this, if we're not on the same country road

Thought I'd sling it out there, for observation anyway. Open for any questions with mine. Hope it's simpler than mine!

I Went thru same deal w/ '03 Ford Escape 3.0 V-6

Repetitive, fast hesitations (stumbles), lasting 1-2 seconds, varied in how far the "sets" were apart, it was more evident climbing a incline, while slowly administering gas. Random or none on level ground. Every now and again at idle, but very seldom.

---No codes/ No CEL --- (cleaned 1st, and/ or replaced the following

New Plugs. Then "genuine plugs". Bah-Hum-bug, nothing wrong with the other new ones, I just installed!

Boots and springs

air filter

MAF

EGR

A new IAC for Sheets & Giggles!. Prevent-Maint. If for nothing else

Performed Mega Vacuum leak searches several times.

Fought with wife many times over situation, 2+ months!

I really hated taking off the "Plenum" so many times to access the other 3 cylinders

Each part seem to fix it for a day or two.I did not mind replacing the suggested parts, as I am all for "PM" and she's got 100,000 miles on her rig.

The final cure was #3 misfiring (lucked into the correct cylinder) I was gonna swap a new coil pack down the line, till it stopped

#3 was the ticket!

I had tried to get the Technical school to ride me with their portable machine---things did not work out, with their schedule.

I went to a salvage yard to get a used pack ($10) to swap around to figure out which was bad, then buy a new one, if the "donor pack" solved the problem.

So happened, the salvage yard guy had a machine, he found a stored code, it said #3 had misfired. My little code scanner could not tell me that.I think his was a "Snap On"

Runs perfect now, with the New $79 Coil Pack!

IF IT HAD NOT BEEN FOR THE STORED CODE, I WAS GONNA "ONE AT A TIME" SWAP THE COIL W/ THE 1ST EZ 3 TO FIND THE MISFIRING ONE. IF IT HAPPENED TO BE ONE UNDER THE "PLASTIC PLENUM"

THE PLAN WAS TO TAKE OFF AND REPLACE THE PLENUM ONE TIME ONLY!---BUT SWAP THE "3 GOOD" FRONT COIL PACKS TO THE REAR. THEN "TEST" THE 3 EZ FRONT ONES (RELOCATED FROM REAR) ONE AT A TIME WITH THE "DONOR COIL PACK"

THE STORED CODE MADE IT EZ ON ME, LOCATING THE BAD PACK

THE MEDIC

Tiny
CJ MEDEVAC
Aug 29, 2012.
I SORTA RECKON I MISSED THAT YOU NOW MAY HAVE A COMPRESSION ISSUE. WHEN I CLICKED IN GOOGLE CHROME THE AUG 25ths POST WAS ON MY SCREEN AND I. DISREGARD MY BABBLING ABOVE

THE MEDIC

Tiny
CJ MEDEVAC
Aug 29, 2012.
Thanks for the info but like I said I did a compression test and cylinder number four had no compresssion in it at all the others were fine but back to my question the head gasket that I need to change which is the one closest to the front of the vehicle is the RH gasket right

Tiny
Apac408
Aug 29, 2012.
1 min ago

FIRT TIME LIKE TWO YEARS AGO I CHANGED ALL GASKETS TOP AND LOWERS THE PROBLEM WAS FIXED AND THAT TIME MOTOR WAS UNSTABLE
TODAY IT IS ALMOST THE SAME PROBLEM I CHANGED GASKETS AND THE PROBLEM STILL BUT AND THEN I CHANGED ALL THE SET WIRE ON COILS THE PROBLEM WAS FIXED. 6 MONTH WITHOUT PROBLEMS WORKING GOOD ( AUTOZONE LIKE 40 DLL COST SETWIRE)

Tiny
Falcone
Sep 1, 2012.

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