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Discussion Starter #1
On the drive in today I scanned the computer about every 20 miles, and when I parked. No codes. On the drive home, no codes until just after the long descent down the grapevine. As soon as I put the throttle back in, the misfire codes showed up. The CEL light never came on though. It really acts like the plugs are getting fouled during long periods with the throttle closed (long coast down hill). This happens in airplanes all the time. Could this be causing the misfire? There must be some other component that is failing, allowing the plugs to foul due to an over-rich mixture, but it is going into lean burn (150 mpg indicated)

If I pull each plug out one at a time and check the condition, this may provide some insight. (ha ha) Any ideas?

I have contacted 3 different Honda service departments, none of which have returned my calls. Amazing.
 

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Discussion Starter #2
OK, I thought I was crazy, but I did notice that the misfire code happened just after hitting a nasty spot in the road. I found the following information which proved to be interesting:

"The monitoring of a misfire is based on the principle
that as each cylinder contributes power, it directly
affects the crankshaft rotational velocity. When a
misfire occurs, the crankshaft speed is slowed
during that misfire. The computer monitors the
rotational velocity utilizing a crankshaft and camshaft
sensor. While the system design allows a
margin of error by requiring certain parameters to
be met before misfire codes will be stored, it still has
its share of false alarms or false detection. For
example: Rough roads can cause a torque to be
applied to the drive wheels and drivetrain. The
torque load can be interpreted by the computer as
a misfire condition, resulting in misfire codes being
stored in memory."

I have noticed that the codes do trigger on really bad roads (Like the 405). It's happened more than once. So, bumps could possibly cause false misfire codes. I would imagine that the herky-jerky thing could do it to, but I have yet to see it happen, and I've been watching.

If this car was just a toy, this would be fun. But I count on this thing to get me to work and back. I need it to be reliable. I gotta get this figured out!
 

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Skypig said:
On the drive home, no codes until just after the long descent down the grapevine. As soon as I put the throttle back in, the misfire codes showed up. The CEL light never came on though. It really acts like the plugs are getting fouled during long periods with the throttle closed (long coast down hill). This happens in airplanes all the time. Could this be causing the misfire? There must be some other component that is failing, allowing the plugs to foul due to an over-rich mixture, but it is going into lean burn (150 mpg indicated)
This is not lean burn, but no burn. I don't see how the plugs would get fouled in this situation.

Just how long is this hill? Curious. Are you in fuel-cut mode for minutes at a time? Maybe you can try giving it a little gas briefly intermittently to see if it still happens...
 

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I have done that one. It's fun, although it was so windy for me heading back down that the car actually did slow down as it went down the hill, so I didn't have fuel-cutoff the entire way down.

No codes for me, by the way.
 

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As others have hinted at on decel you are in fuel cutoff mode. The injectors are turned off. The exact parameters aren't published (AFAIK) however the general parameters are near 0% throttle opening and above x RPM (AFAIK it used to be 1100).

I doubt that a spark plug inspection will reveal anything. Is the code cylinder specific?

But without the MIL (I am reading between the lines here) it was a pending code. If so then only the barest definition of a misfire condition was met. A severe enough lurch of the entire car, in theory, could set a pending misfire code.

HTH and keep us posted.

p.s. As far as the lack of a return call how can they "fix" the car via the phone? Maybe slightly better than in a NG. But you _really_ have to bring it in. :) All that could be accomplished is jawboning.
 

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Discussion Starter #7
Cool web site, SeanW. Thanks.

On a good day I can nearly coast from Tejon Pass (4195 ft) to the base of the Grapevine (700 ft), about 13 miles. After passing the summit, I slowly accelerate to 85, roll the throttle off and let the IMA charge until it hits 65, then repeat the process. This completely charges the IMA battery by the time I get to Tejon Ranch (6 miles) where the steepest grade starts. At that point, it stays at 65 to 70, throttle off, for another 7 miles.

The codes are very consistent: General misfire, all cylinders and each separate cylinder, all at the same time. (P0300, P0301, P0302, P0303.) It has never shown just one cylinder. It seems really unlikely to me that ALL three coils and plugs are malfunctioning at the exact same time, each time. I think it's a sensor or computer problem!
 

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I've been across the "grapevine" both north and south bound 6 different times in the pass three years. It is a blast. It really takes a token on "large vehicles" (look for a bonnet up) and everytime I pass one on the "up climb" I blow my horn.

I get in the fast lane, use the IMA untill about 1/2 gone, downshift to third and GO. Lose some mileage, but you will make it up on the "way down."

We have the Mountain Springs Grade in the San Diego area on Interstate 8, between Ocitillo (sp) and Jacumba that is similar.

A 6% grade, a definate challenge.
 

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Agreed. The ignition system would be the last item on the list. Save your effort for a better match of the symptoms. Although you did buy it used didn't you? Check to see if the correct spark plugs are installed. And remember the Insight's plugs are _indexed_, it takes a specific plug in each hole. The ground tang's shadow must be in the generally correct location. This is unusual for a non racing application. And is a reflection of how much engineering tweaking that went into the Insights design goal of high MPG.

More than is needed to know about spark plugs:

http://www.centuryperformance.com/spark.asp

There are 4 differently indexed spark plugs. The index mark is a letter A thru D and is found at the top metal "bullet" where the cylinders coil connector makes electrical contact. The corresponding index mark is stamped on the cylinder head and will be visible with the coils removed. For each cylinder simply match the stamped mark on the head with the spark plugs mark. Incorrectly indexing plugs or installation of a different style of plug will more than likely effect the lean burn mode. Limiting maximum MPG. Will someone eventually find some other setup that works? More than likely. Will it exceed the stock setups performance? (MPG) Not likely.


If this situation is reproducible, e.g. it happens repeatedly (but not necessarily always or exclusively) on this long downhill then I would wonder about a leaking injector that is failing to close, allowing enough fuel to load up the intake and sputter when throttle is reapplied.

EDIT: Never mind this idea. The engine continues to turn in this situation and the intake would continuously purge.

Note to self: Do not attempt NG diagnosis on first cup of coffee.


I'd recommend to note the general situation that the code(s) recur. If a pattern emerges it will be an aid in diagnosis and repair.
 

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Discussion Starter #10
Insightful Trekker said:
Agreed. The ignition system would be the last item on the list. Save your effort for a better match of the symptoms. Although you did buy it used didn't you?
Bought it brand new in Oklahoma City while there for training in September of 2002. My wife flew out to drive my Dodge Ram (V-10) back to Bakersfield. I drove the Insight. We had to stop 4 times to fill up the truck at $40.00 a pop, and about twice for the Insight. I do love this car!

The CEL light and misfire codes started last month after the 45,000 mile service at "that" honda dealership about which I will no longer complain. They, of course, deny all responsibility. They did the following: General inspection, tire rotation, oil change and change the cabin air filter. There are a bunch of connectors and wires near that filter. Do you think they could have damaged something there thats causing electrical problems. I'm reaching here.
 

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I'm working on a theory also., and reaching!

Need one question answered.

Does it happen when there is one person or two people in the car?
 

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Willie Williford said:
I'm working on a theory also., and reaching!

Need one question answered.

Does it happen when there is one person or two people in the car?
I am officially curious to hear this one.... :wink:
 

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Discussion Starter #14
Just one. I'm pretty much the only person who has ever driven the car and I never have a passenger. This car is strictly for the commute.

I am really interested in your theory!
 

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One of the first things a competent mechanic will do in an "intermittent" problem is check all connections (wire/hoses etc.) related to that item that either controls the fuel sytem or ignition electrical component.

Ford also recommends a "wiggle test" on some of there electrical problems that are apparently "intermittent".

Being as how there are no CEL lights it is something the new "technicans" as they are called now (instead of mechanics) can't understand.

There comments are "when the cel light comes on I'll change the part".

Another "hint" to the problem is that "it mostly happens on a rough road or when going over bumps".

I inquired as to the number of people in the car because years ago I had problems with a Ford Mustang that would almost die while brakeing to a stop. It only did it wnen a passenger was in the front seat. The problem was finally traced to the fact that the passenger was "pushing on the brakes" while the driver was comeing to a stop. The passenger was pinching a connection to ECU that was mounted on the passenger fire wall.

Ford must of know about the problem because the next years model ECU was mounted farther up on the firewall and the wireing routed under the dash. (Passengers should not be co pilots.)

The ECU on the Insight has a protective cover over it, but most of the wireing going to the (6 I think) connectors are exposed, wrapped and just laying under the carpeting. ...........Just a long shot, but because he is driveing solo, it throws that theory out the window.

Is there somene in his area that could maybe meet with him and do a "drive evaluation"?
 

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Skypig said:
On a good day I can nearly coast from Tejon Pass (4195 ft) to the base of the Grapevine (700 ft), about 13 miles. After passing the summit, I slowly accelerate to 85, roll the throttle off and let the IMA charge until it hits 65, then repeat the process. This completely charges the IMA battery by the time I get to Tejon Ranch (6 miles) where the steepest grade starts. At that point, it stays at 65 to 70, throttle off, for another 7 miles.

<snip>
Ok I've got my second cup of coffee down.

So its during this leg of your commute that the codes are readily seen?

Again not necessarily always but more often than not?

These conditions may be one of those unusual driving situations that the engineers didn't foresee. Yes you didn't begin to see this problem until recently but we've gotta start somewhere. Stepping back and trying to look at the bigger picture sometimes helps.

Fuel cut-off mode for such a looong duration at high manifold vacuum may be the culprit. Observe the fuel trim values for a "normal" leg of your commute. Both short term and long term are nominally +-6%. On Honda a +-19% will set a fuel trim code, but if you approach this value and then "rapidly" try to use ICE power the engine may balk in that these values are used to tweak the injector on time. You may be getting a momentary lean hiccup.

HTH! :)


TO: Willie Williford

True of newer "technicians". However, in this case any wire that was going open circuit would set a code. And by golly that's what's happening, misfire codes. So you can be assured that such a wire must be related to this system. And as you are aware it can be virtually any related engine control that is not part of a sub-system which would set a more specific code.

Lets put our heads together here.

All I can think of right now is that either the CKP (crank shaft position) or TDC (top dead center) sensors may be noisy. A full blown open or short would cause a subsequent code. But a damaged wire or connection could cause just enough of a signal loss to be the culprit.

The ECU is on the right side floorboard and the only connectors are at the sensors themselves or the ECU. The ECU is under the carpet and a shield so its unlikely (read virtually impossible) for it to have been damaged when the cabin air filter was replaced. But maybe worth a look. If your gonna go this route Skypig you'll need the Honda ETM. The narrative description(s) needed to substitute for a pic is beyond me.

I'd give it some time to more clearly present itself rather than chasing the long list of our collective theoretical leads.

HTH! :)
 

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Discussion Starter #17
Update:

Well, I drove the car Friday in town, no codes. Drove it hard Saturday and Sunday, including full throttle acceleration, long decels, stop and go...no codes.

Drove the 122 mile trip to work this morning, no codes.

On the drive home, same misfire codes, all cylinders, showed up at nearly the exact point to the mile as last week. That's weird. :shock:

There is no difference in how the car was running before or after the codes set. No CEL yet.

Here is a question: Does the misfire code set after a number of them or on the first one it sees? After warm-up of course. I ask this because I wonder if it's seeing constant misfiring, but taking several hundred miles to place the codes.

Here is the plan: I will let it continue and see how long it takes for the CEL to come on. If and when it does, I'll take it in with all of the info collected so far and let Honda sort it out. I can say one thing, I'm not going to let them sell me a "tune-up". There is more here than that, I think.
 

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If you want a more complete understanding of OBDII codes check out:

http://www.obd-technologies.com/info.php

I don't believe it will be available without the MIL, but do you have freeze frame data yet? If so please post it. If not make _sure_ you get it when the light is on _before_ you clear the code(s).

And I was hoping for the fuel trim values in your (this) reply. :)

(Nominal and after an event)

:)
 

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Discussion Starter #19
CEL came on during descent into Los Angeles this morning. It set the same misfire codes, so now there are 8 total codes stored, all misfires.
The conditions were the same as before, coming in and out of fuel cut off mode at the bottom of the hill. No difference in engine sound or feel.

Honda has it now. We'll see what they come up with. One interesting note; it has never happened with a full tank of gas. Only with half a tank or less. I'm not sure if that matters, and I know the fuel cap has been tight each time. I should know something "official" by Thursday. I hope.
 

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AFAIK a repeat (duplicate) OBDII code is not stored separately. The newest supersedes the older. Unless your scan tool has the ability to save a snapshot of each duplicate event.

Without hard data I, nor anyone else can be of further assistance. The freeze frame data recorded and stored (until the PCM/ECM is reset) by every OBDII system is required.

After spending all this time in this thread its like you telling a "joke" then leaving me to figure out the punch line.

:/

It very well be my confusion on this point but I thought you had easy access to a scan tool.
 
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