ENGINE MISFIRE AND SHAKING

When the check engine light comes on it will usually disable the traction control which is also tied into the ABS as a safety feature resulting in their lights to come on. The shudder may be caused by a cylinder misfire which in turn should cause the check engine light to flash when the misfire occurs and will keep the check engine light on. Have the computer scanned for codes to see if a misfire is present and correct from there. It may be as simple as a spark plug/ignition coil failure. When the problem is corrected and the codes cleared, the lights will go out

If the engine light flashes while driving you could damage the catalyst if it's running poorly.

check the codes first as can be an number of things.

I would try the simplest solution first, while at idle pull spark plug wire off each one at a time. When you pull a wire and the motor slows or dies, that wire and plug are good. If you pull one off and nothing in the way the motor runs changes, the plug or wire is defective.

For engine misfiring problem check the help links mentioned below. Click the link below to go through the troubleshooting procedure :---- OBD-II Trouble Code P0300? http://schematicsdiagram.blogspot.com/2011/12/obd-ii-trouble-code-p0300.html
-------- Engine misses and truck jumps? Hard to down shift? Issue with high gear only? http://technoanswers.blogspot.in/2012/02/engine-miss-and-truck-jumps-hard-to.html

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Bad miss at idle?

http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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Engine Misfire codes for car?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html
Engine Misfire codes?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

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Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

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Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

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This will help.

Thanks.

Misfire could be a number of things:
a) spark plugs - change them if used over 15K miles - inspect/regap.
b) spark plug wires - change them if over 15K miles - inspect
c) ECM (electronic control module) - test with HEI (high energy ignition) tester.

The shaking tells me that the engine is running on less than its normal compliment of cylinders - the shaking is produced by the imbalance caused in the engine by one (or more) cylinder(s)
not firing at all.

The "Check Engine" light probably is coming on due the the misfire condition. Go to Pep Boys or
Advance Auto Pats, where they'll tell you (free) your codes causing the "Check Engine' light to be
lit - the code coming from your truck's computer will probably be one or more of:
P0300 - Random/Multiple Cylinder misfire detected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected
P0303 - Cylinder 3 misfire detected
P0304 - Cylinder 4 misfire detected
P0305 - Cylinder 5 misfire detected
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected
P0308 - Cylinder 8 misfire detected
P0313 - Misfire detected with low fuel

A flashing cel indicates misfiring. A common problem is a bad ignition coil. The easiest route for diagnosis is the check the trouble codes(autozone and some other parts stores will scan for free, or an OBDII code reader is not too expensive to buy). The code should tell you which cylinder is misfiring(PO301 means cyl #1, 302 cyl #2, etc). Once you know which it is, swap the ignition coils around. If you have a #1 misfire, swap coils 1 and 4, clear the codes, then check it again. If the misfire moves, you know you've got a bad coil. If the misfire is air or fuel related, as with an intake leak, other codes should come up as well as the misfire.

I found this; if it helps.
The injectors need to be cleaned, if an engine is experiencing any of the classic symptoms of dirty injectors, such as lean misfire, rough idle, hesitation and stumbling on light acceleration, a loss of power, and higher hydrocarbon (HC) and carbon monoxide (CO) emissions.
Lean misfire may also trigger a misfire code and turn on the Check Engine light on 1996 and newer vehicles with OBD II systems. The code often will be a P0300 random misfire code, or you may find one or more misfire codes for individual cylinders, depending on which injectors are most affected.

the web page was:
http://www.aa1car.com/library/2003/ic30336.htm

Hope this helps

I had the shaking problem too, had the #5 coil replaced and the shaking instantly stopped.