First some background:

I have a 2008 Fit Sport A/T with 77,800 miles on it. Three weeks ago, I had the valves adjusted to clear a "misfire on cylinder 3" code that I was getting. They checked the coil packs and spark plugs first, and both were ok...at least on cylinder 3.

Now the issue:

During some of my daily commute, I am able to use cruise control, which I set at 70 MPH. While driving home one day earlier this week (with the cruise control on), I felt a little jerk or bump while going up a slight incline. I hadn't felt this before, so I stashed it away in my mental notes. I noticed it happening a few more times during the week, and one time it occurred while accelerating without the cruise control on.

While coming home from dinner tonight, I was going up a long incline section of highway (cruise control set at 70 MPH), and it jerked/bumped a few times...more than it had any time previously. I looked down at the tachometer, and I didn't see any movement in the needle. It happened one more time on the highway before I got home, and again, I saw no fluctuation in the RPM's on the tach.

After I got off the highway and onto surface streets, I put the transmission in "S" mode and accelerated to redline in 1st and 2nd gears from a couple of traffic lights, and the engine pulls smoothly to redline with no hesitating nor any jerking or bumping sensation.

It only seems to occur when on the highway and going up inclines. I don't feel it when I'm driving on surface streets or accelerating to get up to highway speed.

I've read about the issues with coil packs and needing valve adjustments to cure misfires, but I'm not getting a CEL. I suppose it could be a coil pack issue since the dealer probably only checked cylinder 3, since that was the one that was getting the code. I've also read about issues with the EGR valve causing similar problems.

Or...could it be something with the transmission? I did 3 drain and fills over 3 sequential oil changes last year, so the fluid is pretty fresh. I did notice that after this valve adjustment service, it seems like the transmission is shifting slightly differently than it used to when first starting from a full stop. If I recall correctly, I think it feels like it's going into 2nd kind of early, but don't quote me on that. It just feels different than it used to.

On the plus side, my fuel economy has improved since the valve adjustment (they also replaced the air filter).

Any insight as to what might be going on with this jerking/bumping would be most appreciated.

 

I have yet to understand the physics, let alone a real life experience, behind a valve adjustment curing the cause of a misfire code. Improperly adjusted valves which create an unideal valve overlap condition, will reduce the power the engine can produce and reduce your mpg but it won't cure a misfire problem. Dealers like to call this out first because it's pure labor money for them and it allows them to tell you they've at least ruled it out as a cause. I've had many Honda cars, and on some the valve tappet clearance was +.005" off for years (because it wasn't adjusted for 10 years) and I never had a code.

I had the exact same problem, even with cyl #3, though my hesitations became more pronounced over time to the point where I just replaced the engine with a salvaged engine, which solved the problem. However, my problems also included various other codes (P0403, P0203, P0303, P0055, C1555), which were checked and found to be false negatives. The dealer basically threw their hands up and offered a trade in value (which was basically only 2k below Kelly blue book for dealer trade in).

All told I have a theory that these engines are prone to carbon build up issues that affect the valves. I think carbon could get stuck in the valve seats, not allowing them to close all the way, etc... When I did a leak down test I got better numbers after tapping on the valve tappets with a rubber mallet, possibly dislodging some carbon deposits. Another issue I think is quality coil packs. Get Honda OEM. The Beck Arnly and others actually have a different internal spring design, which may be an issue. I had problems with new replacement Beck Arnley coil packs after 100 miles on them.

 

Thanks for the info, CTCT.

In regards to a valve adjustment curing a misfire code, all I can say is that I read several instances of it in this forum. I had also read about the coil packs being the cause of misfires, which is why I asked the service department to check that first. The first time I had it in there, they checked the coil pack in cylinder 3, said it and the spark plug were fine and cleared the code. The CEL was back on less than a week later. When I took it back in, and they called me stating that it needed a valve adjustment, based on what I had read on this forum, I wasn't surprised.

Since the valve adjustment, the CEL has not come back on, and there's no more vibration at idle after a cold start. I am also, as previously stated, seeing an improvement in my fuel economy.

But now I seem to be having this occasional jerking/bumping sensation at highway speeds. Could this be due to coil packs? From what I've read, it's possible. It's also possible that it could be the EGR valve. I am guessing that it could also be the transmission or the cruise control, although I've felt the jerk/bump when the cruise control was not being used.

While running errands today, I put the transmission in "S" mode and used the paddle shifters, going up near the redline where possible, to maybe "blow out" some of the carbon build-up as I had read in other threads. I will see how it behaves tomorrow during the work commute.

I am about 700 miles out from my next oil change, so my current plan is to just watch what the car does and try to make note of the circumstances and variables when or if the jerking/bumping occurs again.

Of course, if anyone else has had a similar experience after a valve adjustment, or had a similar experience and is wasn't something engine-related, your insight and information would be great.

Thanks!

 

The jerking/stuttering at highway speeds is usually attributed to bad coil packs, based on members' testimonies over the years.

The rough idle or stalling shortly after a cold start is usually attributed to valves out of spec.

That's what I think. It's hard to diagnose your problem without seeing it firsthand, but this is how things seem to work out most of the time.

 

Thanks, doctordoom.

I'll have all of the coil packs checked at the next oil change (in about 2 weeks).

I'm right at the mileage where that seems to happen to many folks.

 

I just dealt with this last month. The engine felt fine, started up and ran like normal but every once in awhile it'll jerk and twitch at a stop, slow speed, or lose power but gain it back on a freeway run. I was able to redline on S just fine too. Changed out all four coil packs for OEM and it hasn't been back. And like you I also recently had my valves adjusted. The two seem to be linked for whatever reason.

 

I'm sure others here will wonder why you think adjusting valves will address electrical or fuel difficulties.
My first clue is misfiring - spark plugs first, coil packs second. Judst how did they check them? Especially under load? And naturally poor gas wityh low octane will also be a source of misfiring.

If you have more than 40,000 miles on the odometercoil packs and plkugs are the number one cause of misfiring.

And replacing a dirty air filter will certainly improve mpg. A valve adjustment can too, but not as likely.

 

Spark plugs on this car are long-life plugs, for >100k mile change intervals.

There is no replacement interval for coilpacks. Sometimes they go bad, other times they don't. Just replace as needed.

I too saw a significant increase in fuel economy after I adjusted the valves. No change each time I changed the engine air filter or spark plugs.

 

Spark plugs, like most things we engineers design, are designed for a given work life but in truth have a variance in their actual life expressed in plus or minus 3 sigma based on SAE testing and historical data. For spark plugs its typically 50,000 miles because thats all the car manufacturers have to warranty their cars, Hyundai and Kia the exceptions.
The long life you believe is actually the plus 3 sigma end of the actual test results, meaning they can be functional for up to 100,000 miles of ordinary work but that is only 3% of the total number of plugs produced. The other 97% fail to perform to standards as much as 60,000 miles before, or at 40,000 miles.
If you drive harder than ordinary its often well before 40,000 miles. Ask any tech on race cars how many miles they find spark plugs last. The answer you get will be in a few thousand miles at most.
Anyone who thinks any external wearing part of a vehicle that doesn't need inspection at least every 12,000 isn't aware of the need for maintenance that all vehicles require. Cars are not kitchen knives and forks
Out of curiosity when does the Honda Maintenance schedules call for 'replace spark plugs' ?
Coil packs, too, are 'designed' to last 50,000 miles but experience has shown the plus and minus 3 sigma to be as little as 30,000 and as much as 80,000 miles. That means 3% fail as early as 30,000 miles and 3% last as long as 80,000 miles.
And yes, setting valve clearances as well as air filter or spark plugs can affect mpg, but its not a guaranrtee. If they were OK before then changing has no effect.

 

So here's the update...

On the way into work yesterday morning, it was jerking/bumping worse than it had been previously. There must have been at least 5 episodes of a couple of jerks/bumps each during my 38-mile commute. I called the service department and told them I'd be bringing it in later. I got up there around 4:00 PM, and after a little while, the service advisor told me that the tech couldn't get it to occur, and he asked if I'd take the tech for a spin. So, I did. He had only taken it on surface streets, so we got on the highway, and as soon as we started going up a hill, it jerked/bumped twice. I turned to the tech and asked, "OK, did you feel that?" He confirmed that he did. So, back to the service department we go.

Somewhere around 6:00 PM, they told me that they'd have to let the engine cool down before they could check the valves, so they gave me a car.

I had to fly to San Antonio today for work, but I had a voicemail when I landed. I called the service advisor back, and he said that they checked the valves again, the coil packs, spark plugs, etc., and all was OK. He then told me that I had a bad tank of gas, and that they drained my tank and refilled it.

At first, I was, like, "WTF? Bad gas?" But I thought about it, and the timing seemed to make sense. I didn't notice this sensation until last week. I had filled up at the QuickTrip around the corner from my house (where I've pretty much filled up every time for at least a year) on February 5th, and it was after Tuesday that I had noticed the sensation. Then I filled up again on February 8th at the same station (even the same pump, I believe), and after that is when it became really noticeable.

So...they may be correct, which is why I quoted mahout's comment about bad gas.

I pick up my car tomorrow morning, so I suppose I will find out on the way into work. The service advisor said that there would be a charge for the labor, etc., which is fair, but he said it would be under $150.00. And I will be calling QuickTrip tomorrow to get one of their claim forms since their gasoline is supposed to be guaranteed. We shall see how that turns out.

Anyway, I do hope that the issue is cleared up now. I guess I'll be buying my gasoline somewhere else for a while.

Thanks again for all of the replies, comments and advice! Lots of information to be had in this wonderful forum!

 

we suggest you attach the statement from the dealer that they think the problem is bad gas to back your claim.
I'm not absolutely certain that its bad gas but it can be if the gas is bad enough; we have a cadre here of old techs and racers who've seen about all and there is a consensus that your bucking and hesitation is more likely misfiring due to a spark plug or coil. We would expect pinging to be a first clue thats missing in your description if the gas were bad.
Our first thought is a bad spark plug gap or electrode and next a coil. Under load they can fail but be fine in just cruising.
Anyway hope your troubles are over.
BTW if you knew much about gasoline distribution you'd be wary of convenience store gas.

 

Hiwatt: Bad gas may certainly be a problem and I'm not knocking it, but I'm so perplexed that dealers do this kind of stuff without without any rational to back it up. How do they know it was bad gas? How do they know that is the root cause and how do they trace that to a hesitation event? To me the dealer is just taking wild guesses and charging you for their troubleshooting. Good luck, I hope the gas was the issue, but I just don't see how.

 

Thanks for the recent replies and information, mahout and CTCT.

I picked up my car this morning, and I didn't even make it to the highway before it started jerking/bumping/hesitating...even while sitting at idle at a stop light.

I turned right around and took it back. Unfortunately, the service advisor who helped me on Monday isn't there today, so I had to give it to another guy.

I've mentioned coil packs, spark plugs, EGR valve, etc. to them, and the SA who called me yesterday said that all of those items were OK. He had also mentioned a software update might cure the issue when I dropped it off on Monday. Not sure if they did that or not.

Part of me has a good mind to just tell them to change out the coil packs and spark plugs anyway, but it'd be a bummer to spend that money and the issue still not be resolved.

As for using convenience store gasoline, I used to used Amoco exclusively based on information from my old Acura SA, but now they're merged with BP. Not sure if the gasoline quality is the same. The 2nd choice, according to the same Acura SA, was QuickTrip because they supposedly guaranteed their gasoline.

But it's looking like bad gasoline wasn't the issue.

Should I just tell them to replace the coil packs and spark plugs regardless?

Thanks again for the replies and information!

 

Aha ! We gathered the troops for lunch upon learning you haven't cured the problem; besides then their lunch then is free.
If you were in our shop here's what we would do:
First, check the air filter and intake system is clear; we'd probably remove the air filter just to be sure just for the testing which might start with the Fit as is but air filter removed. Naturally, check the spark plug and coil connections, too.Then (go to the end of this post we thought of more things to check now):
1. pull all the plugs and chec k the gap at 0.040" (yes I know its 0.044") and the electrode condition.
Then retest. If problem persists continue:
2. Change all 4 plugs in proper condition. retest. If problem persists, continue.
3. Change all four coils and retest. If problem disappears, OK find the bad coil or coils.
4. If problem persists, check the intake air flow measuring sytem and the ECU. What happens at WFO throttle even on level ground?
In our shop we have those parts and if they aren't the problem we don't charge for them. They might be off my car or another just for the test.
Yeah, maybe that's a test to be done just after the air filter is removed. It pretty well points the proiblem with the ECU or the throttle position or a bad fuel pump early on. Hmmn, we didn't think originally of a fuel pump or backpressure control valve but the WFO throttle acceleration can identify that possibility. That also could identify a bad injector. Too much fuel can cause stuttering as much as too little.
If thats not successful in locating the problem, we need to think a bit.
Good luck.

 

Thanks for gathering the troops to discuss this issue! That's awesome!

So, here's the latest surprising update...

I got a call from the service department a little while ago. The SA stated that they found the problem with my car: the ignition coils. One of the first things I asked them to check. Here's the surprise, though. The SA went on to say that I had an extended warranty on them, and they were going to replace all four (4) of them. In addition, he said that the warranty had a $100.00 deductible, but they would take care of that for me. This is a surprise to me because I didn't purchase the car from them, nor did I ever have them replaced there or anywhere else, so I'm not completely sure what extended warranty he's talking about. The only thing I can think of is that when I bought the car, the sales guy pretty much insisted that I get this MPP Extended Warranty. I told him that I didn't want it, but he told me that he included it with no increased cost to me (although I'm sure I paid for it somewhere). I've not mentioned this warranty to the service department, but I wonder if it's tied to my VIN.

Either way, I'm not going to ask too many questions if they're going to replace the coil packs at no charge, pay the deductible, and provide a loaner car.

I certainly hope this fixes the issue, though. We shall see.

 

Didn't think you'd get far down the list. I would replace the spark plugs too but thats a side issue if no one checked the plugs and gaps.
Hope that solves your problem.

 

Dude I'm telling you, coilpacks.

Nobody solves this problem with spark plugs, new gas, fuel injector additives, cleaners, seafoam, whatever. Coilpacks.

 

^Well I'm not sure, but I'm pretty sure. Haha

 

Update to the update...

So, it's been about a week and a half since they replaced the coil packs, and Fitty Cent has been running smoothly. No hesitation, no jerking, etc.

As for the warranty, it turns out that the original owner of my car (I'm the second owner) bought an extended warranty through the dealer. Even though I've been bringing in my car to this service center for over a year, the VIN is still tied to his information, so even though the warranty hasn't been transferred to me (hell, I didn't even know the car had one), they replaced the coil packs under that original warranty. AND they paid the $100.00 deductable for my trouble.

So, thanks to the original owner, I saved $561.00 on the coil pack replacement.

Thanks again for all of the information, comments, suggestions, etc. I actually asked them to check the coil packs when I first brought it in, but they kept saying that they were OK. Obviously, they weren't.

 

Glad to hear things worked out