ecu codes

[icu2gel58]

My check engine light went on ....I purchased a Codekey that you plug into the ECU...........the codes that came up said #1 cylinder, #2 cylinder, and #3 cylinder are misfiring. and the 4th code said multiple misfires....Is this bad..?.What does this mean...the car seems to be running perfect.....no lack of power(I think...I just purchased the car)...idles fine.

please help
Mitch

[RedRacer]

If you're not feeling the engine jerking around or visibly shaking as it's running you're probably not looking at a serious problem.

Remember, the CEL is primarily related to components whose malfunction is going to impact or affect the emissions output.

There are three kinds of misfires :

Ignition Misfires --
An ignition misfire is one of the most common reasons for an engine to misfire. As the spark plugs, plug wires, distributor cap and rotor, and ignition coil wear over time, their ability to transfer the needed spark to ignite the air/fuel mixture inside the combustion chambers becomes compromised. In the early stages, the spark will only be weaker and the actual misfire will be subtle. As the ignition components continue to wear, the misfire will intensify and the combustion process can be interrupted completely. This will cause a severe jerk or shock in the operation of the engine (the engine can even backfire through the air intake system).

Any ignition misfire will cause raw, poisonous hydrocarbons to be released into the atmosphere. This is why all 1996 and later gasoline-powered vehicles have a dedicated "misfire monitoring system" built into their emission control systems. Raw hydrocarbons can also destroy a catalytic converter, so 1996 and later vehicles will flash the Check Engine Light to alert the driver of a misfire condition.

Lean Misfire --
The lean misfire is another common reason for an engine "miss"—this is due to an imbalanced air/fuel ratio (too much air). Since an engine needs a richer (more fuel) mixture for a smooth idle, this problem is more noticeable when the vehicle is idling. The lean misfire may decrease or disappear as the engine speed increases because the efficiency of the volumetric flow into the combustion chambers increases dramatically. This is one reason why a vehicle gets better mileage on the freeway than in the city. An EGR valve that is stuck open, a leaking intake manifold gasket, a defective mass air flow sensor, a weak or failing fuel pump, or a plugged fuel filter are some of the many causes for a lean misfire.

Mechanical Misfire --
Mechanical problems can also cause an engine to misfire. Common causes of a mechanical misfire are—worn piston rings, cylinder walls, or lobes on a camshaft, a leaking head gasket or intake manifold gasket, damaged or broken rocker arms, defective fuel injectors (and/or the electronics that control them), and a slipped or incorrectly-installed timing belt. Generally, this type of misfire has more of a regular thumping-type of feel to it. It is usually noticeable regardless of engine speed; in fact, it may even intensify as the engine speed increases.

So those are the three main groupings for engine misfires. I'm willing to bet that you are looking at a simple problem with a simple solution.

If I were you, I would start by replacing the spark plugs. Make SURE you use HONDA/NGK plugs. Don't use anything else in your Honda. They are what came in the car from the factory, and you need to use them as well.

If that doesn't stop the codes, then try the plug wires next.

If that doesn't help, go for the rotor and cap.

If that doesn't help, go for the coil. (top of the distributor under the rotor, cap and leak seal)

If that doesn't help, go for the injectors. You can start by cleaning them (I recommend SeaFoam) if cleaning doesn't help, then look into replacing them individually.

But I am pretty confident, especially since you say the engine is not running poorly or obviously missing or jerking, that you just have a bad plug or plugs and maybe wires.

Let us know what happens and don't hesitate to ask more questions if you need help.

[icu2gel58]

Thank you for the comprehensive response...Sounds like a complicated procedure to track down what is causing the misfire.....I am not a mechanic, and cannot do the work myself. How much do you think it should cost to change out the spark plugs as a first step.?

Thanks again
icu2gel58

[spiffyguido]

Spark plugs are pretty cheap, and you only need basic hand tools to switch them. Check out our video in the videos section on how to change spark plugs.

[RedRacer]

If you can pull a rubber spark plug wire and boot off of the spark plug tip in the head of the engine, if you can operate a socket, you can replace your plugs.

Plugs, for your car, Honda recommends platinum. They're actually kind of expensive. From Honda, you're looking at about 20 dollars US, per plug. From a dealer like NAPA or Pep Boys, about the same give or take a couple of dollars.

Your car calls for : PZFR6F-11 NGK brand (you can also use PKJ20CR-L11 DENSO brand, but NGK is a superior product IMO)

You can go to AutoZone and sign up so you can view their repair guide on spark plug replacement, BUT, even better, you can check out Spiffy's YouTube production of "How to change your spark plugs" online, as he suggested. Doesn't matter what year Prelude, the process is the same.

To answer your question though, if you take your car to a garage (DO NOT USE FIRESTONE AND GOODYEAR) and have a mechanic change your plugs, you're looking at close to 150 to 200 dollars probably. 80 for the plugs, 50 or 60 for the labor, add in shop supplies, surcharges and tax, and you're close to $150 +/- bucks.

It's well worth it to learn how to do it yourself; call a friend to come help or just be moral support.... the initial investment in a few tools and the learning process will save you a LOT of money down the road.

The link for Spiffy's how-to video is at the top of the page.
Or you can access it directly via YouTube link here:
http://www.youtube.com/watch?v=ML1IaeScmAE

And don't laugh at him because he's Canadian....

[lazy10123]

i have a problem too with my honda prelude 97 can anyone help anyhelp is good ........ok well my seems to be misfiring in cylinder 1 i changed the spark plugs and spark plugs wires and disy cap and rotor and still no fix. when car is on idle you can hear the misfire but when driving car feels just fine ....car is running rich....and when i pull spark plug wires on cylinder 234 the car does react and sounds like it wants to turn off but when i pull cylinder 1 spark plug wire car does not react at all what could it be ?????????????????????

[spiffyguido]

Sounds like there's no spark going to cylinder #1. Maybe the plug is bad, or the wire. Have you tried swapping in a known functional plug?

[lazy10123]

ya i changed the spark plugs wires and spark plugs and disy cap and rotor and injectors and still nothing

[spiffyguido]

Can you verify that a spark is getting to that plug? Are you sure that the fueling system is working on that cylinder?