Matt Mergenthal

Okay so last year I bought a set of the NGK Iridiums and installed them. I did gap them to spec of the CL. I see on here a lot of people say do not gap them because they come pregapped. When I checked the gap, they were not to spec of the CL. I have been a random misfiring problem a lot lately followed with horrible gas mileage. Im thinking the gap might be the problem. What is the reason everyone says not to gap them? How do they come "pregapped" when they are not gapped to spec of the vehicle. Help Pleaseeeee!

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iTrader: (2)

Gapping plugs is what they did in the old days.

I have installed plugs twice and they were just the normal ngk iridiums and I did not touch the gap.

When did the problem start. What is right after u gaped the plugs?

If there is no correlation then I would be inclined to say it's not the plugs. Do u have any DTCs ?

Matt Mergenthal

I've been having the problem for a while now so I'm not really sure when it started. The gap IS there for a reason though and it still doens't make sense to me to not gap them to what the manual says. I have a bunch of DTC's for misfires. They come and go as they please. one day its cylinder 1 then 4 then 3 then 6 then 2 then 5. Then random/ multiple misfire....

Karanx7

iTrader: (2)

When you buy the correct plugs for our cars, they are already gapped to the correct spec. If they were off, someone dropped them.

Matt Mergenthal

That doesn't make sense though because when I looked in the manual, and grabbed the gap tools and measured the gap it was off by a lot...

TheWeez

Werd. And you're not suppose to adjust the gap on iridium plugs. They should be correctly set when you buy them. As Karanx7 said, if they're out of spec, something happened to them.

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iTrader: (2)

put in a new set of unmolested spark plugs and see what happens.

with any luck that will fix the car and u will know not to gap ur plugs anymore lol.

did u put the correct plugs in the car?? cause cl and cls are different

fuzzy02CLS

iTrader: (2)

Or the wrong ones were in the box, or you got the wrong specs for your car.
The correct plugs come pre gapped.

Matt Mergenthal

Ok so I have an update. I put in all new spark plugs which was a waste because they were exactly the same plug and the old ones were only a few months old lol. Still having the misfire. I did do some research on iridium plugs though and found out why they are not gapped to spec for the CL. The gap is smaller because the iridium plugs have a much more precise and explosive spark than a normal plug. So they came gapped to like .28 or something like that but in reality the spark generated is fine for the CL. It also stated that If you gap them bigger, You will have a bigger spark burning more gas and essentially more hp and torque. Don't know how I feel about that though. lol I'm leaning towards the coils now. I had one coil die about a year ago and only replaced that one. I think I'm going to replace all 6. I did start it and unplug them one at a time before the new plugs and coils 1 and 2 barely made a difference when unplugged....

On a side note,
just ordered some Tein Coilovers!!!!!!!!

justnspace

iTrader: (1)

just replace coil 1 and 2.

no need for all 6, per your test.

Matt Mergenthal

So all 6 spark plugs and all 6 coils were replaced. Spark plug gap was not touched and it still says misfire in cylinder 2.... I'm guessing it's gotta be the fuel injector? I don't know where to go from here.

Accord316

My 03 CLS too have the same problem showing the check engine code mis-firing all cylinders...this happened after I installed new plugs as well. What's funny is sometimes my check engine light will turn on/off automatically from time to time


1 year later my mechanic installed new plugs and still shows mis-firing so he suggested I try some fuel injector cleaner for a while if that will work. He also said it was not bad coils causing the problem.


I've read in the MDX forums somewhere that valve adjusting maybe needed to fix the problem

Matt Mergenthal

Yea I saw that same thread. My next step is to try checking the fuel injector.. Does anybody know of a DIY or know how to do it?

noonewins

I'd start with running some injector cleaner through the system. There are some great cleaners on the market that can help. I see where u replaced all the coils, maybe as a final check, swap coils from one cylinder to another and also use dielectric grease on wire contacts to coils and the contact from coil to spark plug.

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iTrader: (2)

I have used Z max and honestly it worked like a MOFO... have not had to do it on this car thankfully (knock on wood). but i am going to be doing it this spring along with new plugs and air filter to get my MPG back up... its been 2 years since i touched the plugs or air injen cai filter.

this winter has been a gas consuming nightmare... averaging about 400kms or so before having the fuel light come on. tho its city driving and every morning i let the car heat up for 5-10 mins..but still.

thats a lot of fuel at 1.45 per liter.

man i cannot wait to get my brand new summer rubber on my car. back on rails baby...can't wait.

Accord316

Well, so far I added some ethanol cleaner in a full tank of gas and my engine light is turned off...

Let's see if this helped alleviate the misfiring all cylinder problem.

Couple years ago I filled up with 85 ethanol gas by accident and it's possible the excessive ethanol causes the misfiring...I've read and heard that ethanol is bad for the engine and that it's a good idea from time to time to use an ethanol cleaner

Matt Mergenthal

Okay so back to misfire problems. I changed out all 6 plugs, all 6 coils, fuel injectors 1, 2, 3 and did seafoam and intake and egr clean. still misfiring. Took it to a local acura/ honda shop and they did a bunch of tests. Fuel injectors, coils, and plugs all good. Put new egr valve in and that was fine. Did a compression test. Highest was cylinder 6 at 180 psi and lowest was cylinder 5 at 120 psi. He said he is leaning towards a burnt or bent valve... The only "hope" he gave me was that, he said he had codes for misfires on cylinder 6 which should not be misfiring at all and its possible it might just be the ECU. HELPPPPPPPPPP. He recommends i try a new ecu and if thats not it, do a 3.5 or 3.7 swap...

gnuts

iTrader: (1)

have the valves been adjusted? Does the car run rough?

Matt Mergenthal

Sorry. The valve adjustment was the first thing he did.

Matt Mergenthal

Car only runs rough at idle but over 1500 rpms it's good as new. Problem I'm having is I'm averaging 13 mpg...

Accord316

how many miles on car....when did rough idling start

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iTrader: (2)

when the valves were adjusted did that change the cars symptoms... valve clearance issues can cause all sorts of weird shit happening.

if u are getting 13mpg it sounds like ur car is stuck in open loop mode and never actually is burning the fuel correctly.

have u checked the IACV for the rough idle? cause that is what controls idle and it is really finicky.

have u checked the o2 sensors ? sometimes they can go sorta bad, and give bad readings without the car actually recognizing its the o2 sensors fault... then the car shits out codes to blame other components when in fact the o2 sensor(s) are the root cause.


ecu I would likely try if nothing else works it could very well be a lemon ECU.. tho it is super super rare, you cannot base the diagnoses off of odds the good new is u can find them for 100 so thats not too bad.

Matt Mergenthal

I haven't checked either. When I check them, what am I looking for? I'll go browse through the service manual..

Matt Yosh

Sounds similar to problem I was having with my CL. Turned out to be burnt exhaust valves and bad piston rings in my motor. Try doing a wet and dry compression test. It is quick, easy, and doesn't cost much if you don't already have the necessary tools.

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iTrader: (2)

i have never even seen these cars burn a drop of oil. I cannot imagine what someone must have put that motor through to fail internally.

maybe it overheated badly or something.

these j32a motors super reliable usually. maybe i just dont beat the piss outta my car anymore...

Matt Mergenthal

Downshifting into an over-rev could do it

YeuEmMaiMai

the plugs are already correctly gaped when purchased. gapping the plugs will result in damage to the electrode in the center of the plug.

I did my plugs at 90K miles with iridium's and they are still good @136K. I did not gap them, just installed them straight up and no engine codes since...