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Discussion Starter #1
By way of background. This is an '05 LX that I purchased in August. It had 93,500 on the clock. It currently has 95,200. It runs well but gas mileage is not good (15 city 19 hwy). Also, I can feel a slight miss in the engine at idle but usually pretty slight. I am progressively trying what I can to improve mpg.

My first step was to replace the plugs. I installed NGK IZFR5K Laser Iridium plugs as called for. Pretty much nothing changed. The miss is slightly less noticeable, maybe, but still there.

Tonight I ran 1/2 can of Seafoam through the brake booster line. I followed the instructions on Seafoam's web site, which were:
1. Warm the engine fully
2. Raise the rpms to 2000
3. Slowly poor 1/3 to 1/2 can into the vacuum line (I used 1/2 can)
4. Turn off the engine and let it sit for more than 10 minutes (I let it sit for about 25).
5. Start the vehicle and run it hard for 2 to 5 miles (I did a number of 20mph to 50mph pushes with the pedal floored. I did that for about 15 minutes around my neighborhood because I live more than five miles from the expressway.)

After the second 20 to 50 push I noticed that the Check Engine light was on. I honestly don't know whether it was on when I first restarted the van or if it came on later. It definitely was not on anytime before the Seafoam. How do I determine what the problem is?
 

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Get an OBD II code reader and scan the code. My money is on an O2 sensor code - the seafoam probably cleaned some stuff out of the engine which then gunked up the primary O2 sensor. A drive on the highway in 3rd gear for several miles may burn the gunk off and clear things up.

As for the miss, it could be from a defective coilpack, a clogged fuel injector, or a bent, burnt, or sticky valve. I'd start by doing a compression test and go from there. Also could be an EGR problem (if it is missing at idle).

Do you still have the old plugs? "Reading" the plugs can help you figure out what is going on, such as a lean mixture or detonation.
 

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Discussion Starter #3
Update

I had the code read and it is P0301 (cylinder 1 misfiring). I asked and they said that was the only code stored. The van seems to run quite well. I have very good acceleration. Performance seems to be a bit better after the Seafoam but it was never bad. I was working on improving mpg. There seems to still be a very slight misfire but I am not even quite sure of that because it is so slight. It is (and has always been) only noticeable at idle.

I am going to clean the O2 sensor and possibly do the EGR cleaning.

A couple of questions.
1. Does the CEL just go off on it's own once a problem is taken care of?
2. If the system throws a code does the CEL always come on to let you know there is a code?

Thank you kindly for your help.
 

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Discussion Starter #5
Update

I went back to the place that read the code for me (Pep Boys here in Maryland). I wanted the code deleted so I could start fresh. My intention is to swap the #1 coil with the #3 coil.

Also, I asked the guy to clear the code. I kept seeing it after a few seconds. I asked if he was sure he was clearing the code. He said he was and that the system kept rethrowing the code.

I want to make the CEL go off and make sure the code is gone so I know that if the CEL comes back on and/or I get a code it is new and not from before so I am going to disconnect the battery for a while. I saw a post on the forum here that said that resets the CEL and removes any stored codes.

So I have three questions in relation to my problem
1. I am presuming that if the coil is the problem and I swapped it from #1 cylinder to #3 cylinder I should now get a P0303 code instead of P0301. Is that correct?

2. Could the guy who checked the code be right that the code he cleared would reappear within like 5 seconds?

3. How long do I need to leave the battery disconnected to get rid of the CEL and stored codes?

Thanks for the help.
 

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Discussion Starter #6
Get an OBD II code reader and scan the code. My money is on an O2 sensor code - the seafoam probably cleaned some stuff out of the engine which then gunked up the primary O2 sensor. A drive on the highway in 3rd gear for several miles may burn the gunk off and clear things up.

As for the miss, it could be from a defective coilpack, a clogged fuel injector, or a bent, burnt, or sticky valve. I'd start by doing a compression test and go from there. Also could be an EGR problem (if it is missing at idle).

Do you still have the old plugs? "Reading" the plugs can help you figure out what is going on, such as a lean mixture or detonation.
HI redmondjp

Thanks for the suggestions.

I have read some info here and am still not sure, are O2 sensors cleanable?

Also, I have read info here on EGR issues (plogged port, defective EGR valves, etc.) but can't find info specifically relating any of these to an '05 LX. Do the EGR issues mentioned apply to an '05?

Also, I do have a compression guage (with hoses and adapters). Is there anything special I should know before doing a compression check on this vehicle. I am planning to simply remove all plugs and check cylinders one at a time. When I crank the engine with all of the coils disconnected and the plugs removed will that cause any issues with the computer modules or anything?

Thank you and whomever else may reply.
 

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Discussion Starter #7
CEL Issue Corrected But Misfire Still There

I wanted to determine if the coil was bad so I swapped the coil with a different cylinder to see if the code would go to P0303. I didn't know how else to turn the CEL off so I disconnected the battery for a few hours. When I reconnected the battery and started the van the CEL was gone and hasn't come back in about 100 miles. However, the slight misfire is still there.

The performance is very good. Pickup when I step lightly on the pedal seems to be even better than it was before. That includes both starting off and when I am moving. Also, mpg seems to have improved. I want to drive a bit more highway before I fill up. Then I will know for sure.

As I said, performance is, I would say, very good. The gas pedal is very responsive. I only notice the misfire when I am idling. Also, it is typically either not noticeable or very slight when I first come to a stop and gets more noticeable after I have been idling for a few seconds but it never gets beyond a slight misfire.
 

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Discussion Starter #8
(Sorry, I didn't mean to post that last comment yet.)

I realize that a misfire, even slight, is not good. Especially for an engine with sophisticated computer controls. However, I am currently unemployed so I don't want to spend more than I have to on figuring out and fixing this problem. Any thoughts or suggestions are appreciated.
 

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If you reset the code and the problem is still there the light will come right back on. Stop reading every problem on this board as possibly your problem. A single cylinder misfire is not caused by the O2 sensor, egr, or any other problem you read on the board. Did you look at the plugs as you pulled the old ones out? If one has been misfiring for a while it will look different than the others. Swapping the coil pack was the right thing to do. Did you notice if it was seated correctly when you removed it? You should also swap/replace the plug. Just being new doesn't mean it has to be good. After resetting the computer it may take several drive cycles for it to come back. Keep in mind that sea foam will loosen all the crud that has built up in the system. Trying to clean the oxy sensors is risky and will destroy it more often than fixing it. The performance of the sensors can be checked with a good OBDII tester.
 

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Discussion Starter #10
There are actually two problems here that I am trying to address. The first one is the bad fuel mileage. That is why I was looking at the posts about EGR, O2 sensor, etc. That is also why I changed the plugs and then did the Seafoam. The CEL and code didn't happen until after I had changed the plugs and used the Seafoam.

I did look at the original plugs when I first pulled them and they all looked the same. I checked a picture diagram from NGK on what plugs should look like and mine looked like their OK ones. If there was a difference in one it is something I didn't know to loook for. Any tips on reading plugs might be helpful. I still have the originals.

The misfire was there before I changed the plugs and didn't change with the new ones so I am presuming that the plugs are not the issue. If the P030? code doesn't come back is there any other way to tell where the misfire is?
 

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So you've swapped coil packs between two cylinders - any new codes stored yet? I wouldn't do anything further until you know the answer. I'm with the above poster, my guess is a bad coil pack.

A compression check is not a bad idea. Some tips:

- Crank the engine over with a manual start switch with the ignition off, or disable the fuel injection (you don't want to be spraying fuel into the cylinders during the test, as it will wash down the oil on the cylinder walls and cause your readings to go down, screwing up the test results).

- After you take the coil packs off, blow out the spark plug tubes with compressed air before removing the plugs so you don't get any debris into the cylinders. If you have a valve cover leak and there is oil around the plug, soak it up with paper towels and clean out with a spray solvent and compressed air.

- Prop the throttle plate open with a screwdriver or other object (just be sure to remove this before starting the vehicle up later!).

Besides a back coil pack or spark plug, low compression (for whatever reason) or a clogged or malfunctioning fuel injector can also cause misfiring. If your original plugs all looked the same when they came out, I'd suspect the coil first.
 

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If the plugs all look the same, the misfire may not be ignition-related but rather mechanical, i.e. cylinder imbalance. It's time to use your compression guage and see if a cylinder is off. You may feel the misfire only at idle, but it's likely robbing efficiency all the time the engine is running.
 

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Discussion Starter #13
I have driven it about 130 miles. So far no CEL. But that has been the case from the begining. Slight misfire, no CEL. It was only after the Seafoam that I got a misfire code. I am presuming that if there is no CEL there is no P030? code. Is that correct?

I will do the compression check probably this weekend (bad weather until then). Please let me know if I am correct here, if I use a manual start switch I don't have to do anything special, right? Just remove all of the plugs, prop the throttle plate open and test each cylinder?
 

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I have driven it about 130 miles. So far no CEL. But that has been the case from the begining. Slight misfire, no CEL. It was only after the Seafoam that I got a misfire code. I am presuming that if there is no CEL there is no P030? code. Is that correct?

I will do the compression check probably this weekend (bad weather until then). Please let me know if I am correct here, if I use a manual start switch I don't have to do anything special, right? Just remove all of the plugs, prop the throttle plate open and test each cylinder?
On the code, I know that in many cases there have to be so many occurrences of the code before it sets hard (which will turn on the light), and it is considered "pending" until then. You would have to have a scantool attached in order to see if you have a pending code or not (do you know anybody that owns one that you can borrow?).

Yes, on the compression test, disconnect the start wire from the starter solenoid and attach your remote start switch there. You may want to have a battery charger (if you have one) attached to the battery while you do the test. Crank the engine over 4-7 times (do it the same number of times for each cylinder), and you can watch the gauge while cranking to see when the pressure stops increasing.
 

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You could try an injector cleaner in the gas tank for the slight missing. The misfire has to hit a threshold within a time period before it will set the CEL code. The code may have been caused be the seafoam getting in the cylander temporarily.
 

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Discussion Starter #16
The good news is I checked mpg with 178 miles since last fillup and got 19.8 mpg. That is both city and highway.

As I said, I am going to do a compression check this weekend and after I run the fuel level down I will add injector cleaner. I will post results of both here.

Thanks for the advice.
 

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Discussion Starter #17
Don't use actron compression tester!!!!!!!!!!

I will do a more complete post later but for now, take my Title advice. I went to do a compression check using this compression tester and am now in the process of removing the front head to get their piece of junk adapter out!!!!!!!!!

The adapter screws on to the hose connector and is held on by an O ring that gets pinched. It worked fine on the first cylinder but on the second one the hose unscrewed but the adapter stayed in the spark plug hole. I will explain later all that I tried to get it out. For now, suffice to say, it wouldn't come out.
 

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Discussion Starter #18
Actron Compression Tester (follow up)

So you know what I am talking about, here is the tool -
Amazon.com: Actron CP7827 Compression Tester Kit: Automotive

If you look at the adapter and the fitting it screws on to you can see that an O ring holds it in place. You can also see that an O ring on the other end seals it in the spark plug hole. In my case the O ring at the spark plug hole held tighter than the one that holds it to the fitting.

After repeated attempts I realized that the O ring on the fiiting wasn't going to hold tight enough to remove it. I remembered that the adapter has flats for a socket wrench. The spark plugs for the Odyssey take a 5/8 socket. That is too small to fit their adapter. I am guessing they designed it to use a 13/16 socket (which is the larger spark plug size) but even an 11/16 is too wide to fit in the spark plug tube. So much for that idea.

Twisting the hose is how you normally insert and remove this tool so I figured that if I could lock the adapter to the fitting I could remove it. I put medium strength threadlocker on the fitting threads and screwed it down into the adapter. I waited about a half hour and tried again. The fitting and hose were now locked to the adapter but the adapter wouldn't budge. I did, however, find out that the crimp that holds the rubber hose to the fitting doesn't hold tight enough either. The hose turns but the fitting and adapter don't.

It was getting dark so I gave up for the night. I emailed Actron'e Tech Support about the problem. The next day they had emailed back and suggeted threadlocker on the fitting. I called tham to see if they had any other ideas. The guy I talked to was surprised that the hose turned. That was all he offered. He seemed very disinterested. I pushed him for more and his only other suggestion was cut off the part of the hose that was sticking out of the tube and push a screwdriver down the hose to expand the hose and make it tighter at the crimp "or just do whatever it takes to get it out". Like as if I wasn't frustrated enough with Actron that I needed them to add insult to injury with that stupid statement.

I went to Harbor Freight and the only screwdriver I could find that was long enough was too large to fit in the hose. I honestly don't think that would have helped anyway.

I am guessing that what is making the adapter so difficult to budge is that the engine was at close to operating temp when I started and it was significantly cooler by the time I thought to try the threadlocker. I have had spark plugs in and out of that hole several times in the past few weeks dealing with the Misfire code and I inserted and removed it every time by spinning the socket extension with my fingers. I also felt no real resistance when I threaded the compression tester adapter in and since you install it by twisting the rubber hose I don't believe I could have exerted enough force to crossthreaded it. Certainly not without feeling the resistance. I have also been doing mechanical work for 40 years and I know what it feels like when something is crossthreaded.

So, as I said in my last post, I am in the process of removing the head so I can have the adapter removed. Fortunately and unfortunately I am currently unemployed. Fortunately because I have the time to do this. Unfortunately because money is tight. The only real consolation is that even though it is 10,000 miles early I can do the Timing Belt while I comfortably have the time to do it.

Forgive this for being so long, I know I tend to overexplain things. I just wanted to explain so folks know I am not just bashing the tool because I did something wrong.

The bottom line is I strongly suggest that you don't ever use this tool for an Odyssey or any other car with recessed spark plugs. In my opinion this is a poorly designed tool. To me it shows that their engineers gave little or no thought to how you would remove the adapter from an engine where the spark plugs are recessed in tubes (which is more than a few cars). That makes me wonder how well other tools of theirs are designed and thought out. I personally will think long and hard about ever using another Actron tool.
 

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That tool looks *exactly* like what HF sells. I have one but still in its shrink-wrap. The instruction it came with had me my head scratching. Twisting the hose to put the tool in and out of the cylinder head did not seem the right way and that is why I have yet to try it on my lawnmower engine. I appreciate your long writing.
 

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Tough break! It's too late now, but I suppose thread-locking something solid (like a pipe) into the adapter might have removed it. Best of luck!

The link to Amazon doesn't work, but here it is on the manufacturer's site.
Actron®
 
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