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Rough Idle Diagnosis

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Frank Mills

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Discussion starter · #1 ·
2005 Ody, EX
Saturday night, 7/7, everything was running fine, and then I came to a stop light (had been driving for Uber for appx 4 hrs), and the van started idling rough. The shakes would go away when I'd accelerate, but nearing every stop, the shakes would come back and continue until I'd take off again. I nursed it home and started working through diagnosing the next day.
  • Ignition Coils
    • Cranked van and unplugged all 6 ignition coils one at a time
      • unplugging 4, 5, & 6 (coils closest to grille) caused idle issue to worsen, indicating that those coils are allegedly ok
      • unplugging 1, 2, & 3 (coils furthest from grille) gave zero reaction, indicating that those coils are allegedly bad
        • purchased new coils, but then decided I should test the spark plugs before installing new coils
          • Should have tested spark plugs first :rollingeyes:
  • Spark Plugs
    • tested 1, 2, 3, 4, & 5 and saw blue/purple spark, allegedly indicating that they were good
    • tested 6, which tested fine with blue/purple spark, but the coil and the plug had oil all over them
      • Bike to the store to pick up valve cover gasket, grommet, & spark plug seal set
  • Bike to Store
    • Nice weather, nice tunes. Mediocre speed
  • Valve Cover/Plug Seal
    • Removed everything to get to front valve cover, since the only oily tube was in the front - all others were dry
      • replaced valve cover gasket, all 3 spark plug seals, and valve cover bolt grommets
      • Cleaned up oil out of 6th cylinder
    • Buttoned up the valve cover & intake manifold according to torque specs and patterns, plugged in all sensors and re-connected hoses (Or so I thought)
    • Installed new ignition coil in the formerly oily 6th cylinder (boot cracked on old one when I was trying remove the oil from it)
    • Checked oil level (all good!)
  • Cranked car
    • No rough idle!
    • Removed plugs from all 6 coils, one at a time and each caused the rough idle until re-plugged, and normal idle returned!
    • Went to test drive the car, initially putting in reverse to back out of driveway
      • VSA and ! came on and I was met with a distinct "thud" sound/feeling. When trying to drive, vehicle wouldn't accelerate above 10 or 15 mph
      • TPS Sensor wasn't plugged in! and the vacuum hose that connects to the top of the air intake hose was also disconnected
        • plugged in TSP Sensor and aforementioned vacuum hose
    • cranked car
      • VSA and ! were gone!
      • acceleration returned, but...
      • bad idle also returned
  • Back to Ignition coils
    • made sure all spark plugs were tight, as I'm now hearing a puttering noise from the right side of the engine (!!! WHY !!!?)
    • individually unplugged 4, 5, & 6 - all caused further idle issues, once again, allegedly indicating that they are working
    • individually unplugged 1, 2, & 3 - all caused zero change in the rough idle, once again, allegedly indicating they are not working
      • replaced coil 1 with a new coil - no change
      • swapped coil 5 (which was allegedly working) with coil 3 to see if I'd get a different result, i.e. if the coil now in the 5 spot would cause no change in the idle, and the coil in the 3 spot would cause a change - hoping this would indicate that the actual coils are bad, or not
        • Same result as all prior tests - coils over 4, 5, & 6 positions changed the idle (even with the swapped coil in the 5 spot that previously showed zero change), & coils over 1, 2, & 3 showed no change to the idle, even with the new coil, and the swapped coil from 5 that had previously changed the idle, now sitting in the 3 spot
  • I'm stuck, so I'm making this post
    • any help/ideas?
    • I can nurse the car to Advance Auto and have the check engine code(s) read after work, but I'm also a bit concerned about the puttering noise that wasn't there prior to changing the gaskets
 
#4 ·
Set the crank pulley to top dead center mark and then there are two access holes in the upper timing covers where you can view the cam timing marks.
 
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#8 ·
Before you go cleaning the throttle body, know that you will need a bidirectional, enhanced data scan tool to reset the PCM and do the idle relearn. If you don't have that then you will likely add some other idle problems. It will idle high and not come down. It will drive down the road at 45 mph with your foot off the gas. There is no way to fix this without a high end scan tool.

If you can increase throttle just slightly and it runs smooth then a dirty throttle body could be the issue. The throttle body, however, would affect all the cylinders equally and that's not the symptom we have here. I'm not ruling it out but I'd probably check timing first before I clean the throttle body.
 
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#9 ·
Sudden change can not be throttle body. Just my thoughts. Also like John Clark suggested, you might need a scan tool. I did it without it. Didn't removed the throttle body, but cleaned it from the air filter side with some one inside pressing on the gas pedal. Then removed the battery cable and reconnected and it worked fine. Wish it was like my 02 Passat where it would relearn if left the key on (not engine) for more than 30 seconds or something.

Any chance that the fuel injectors are not giving enough fuel on this side of the engine? Just thinking about it.

Jumped timing belt, can it happen? I mean with the design like that. Weak tensioner can cause this? I dont know too much about it. So far only did one TB job and that was not even in Odyssey.

Try to pull the codes first and see what it is showing and please update once you fixed it.

Good luck...
 
#10 ·
Yes, a timing belt problem can happen. I've seen these very symptoms from a timing belt that was off a couple of teeth. More than likely the codes are just going to be misfire codes.

As for injectors, this could easily be gleaned from looking at fuel trims on a live data scan tool.
 
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Discussion starter · #11 ·
John Clark said:
Yes, a timing belt problem can happen. I've seen these very symptoms from a timing belt that was off a couple of teeth. More than likely the codes are just going to be misfire codes.

As for injectors, this could easily be gleaned from looking at fuel trims on a live data scan tool.
Click to expand...
Thanks, John
Will I have to remove the PS Pump/Serp belt to get the crank pulley to TDC and check the timing marks, or can that be done with less dismantling?

If the timing is off a little, does that mean I need to replace the timing belt, or can the timing just be reset, or is it really about the same amount of work? I do most of the work myself, but for bigger things I'll take it to my mechanic - they've quoted me in between $700-800 to replace the timing belt (and water pump, for whatever reason). I know that price is better than the belt breaking and screwing my valves/cylinders, but also, that price is annoying when I'm supposed to be saving for vacation!
 
#12 ·
I don't think you'll need to do any disassembly but at worst, remove the upper timing covers. Just line up the crank pulley as shown in this pic:

https://ww2-secure.justanswer.com/uploads/HO/HondaJosh/2014-01-17_205012_tbelt.png

Then, on the upper timing covers there are rubber access plugs that you can remove and see the cam pulley timing marks. Line up as in the pic above and then check the front timing mark. You should see a "1" lined up with the marks as in the pic below:

http://repairguide.autozone.com/zne...air_guide_content/en_us/images/0996b43f/80/20/17/aa/medium/0996b43f802017aa.gif

If you see a different number then you just be 360 degrees off on the crank. Rotate the crank around 360 degrees and line it up again and see if the #1 is lined up under the front cover.

Then check the rear cover and look for the marks to line up as in the pic below:

https://www.2carpros.com/images/question_images/3686/original.jpg

(I would embed these pics in the post but that feature doesn't seem to be working anymore.)
 
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Discussion starter · #13 ·
Rough idle is gone. I found one last hose that was disconnected!
Image


As we tested all 6 ignition coils by unplugging them one at a time, each caused the engine to run crummy, as before I changed out the vc gasket/plug seals, and engine ran fine when I plugged each coil back in. The puttering sound is also gone!

It doesn't crank right away every time, but I had the battery tested a couple of weeks ago and it's about time for a new one (tested on the lower end of OK, plus it's about 4 years old).

I found an old service record that had the prior owner's phone # so I gave him a call (we had met about 3 years ago, randomly at a restaurant when he recognized their old van). He said something went wrong with their tranny at appx 102k and they replaced the tranny along with the timing belt, and other stuff (full 60k service?) somewhere around 102-104k.

So, while it may not be the cause of my idle troubles, I'll be forking out the stupid $$ to get a new timing belt this week. Better to pay $700-800 now as opposed to wrecking the valves/cylinders later.

Thanks for all the responses and assistance!
 
#14 ·
What do you mean by "it doesn't crank right away every time?" A low battery should still crank it every time, albeit a little slow.

How many miles are on it now? If they did the timing belt at 102K it shouldn't need to be done until 210K or another 7 years.

As for the rough idle, what are you thinking caused it to begin with?
 
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Discussion starter · #15 ·
John Clark said:
What do you mean by "it doesn't crank right away every time?" A low battery should still crank it every time, albeit a little slow.

How many miles are on it now? If they did the timing belt at 102K it shouldn't need to be done until 210K or another 7 years.

As for the rough idle, what are you thinking caused it to begin with?
Click to expand...
re: Crank - it's had a slow crank for the last two months. It happens at random, and is never the same each time. Sometimes it fires up like normal, another time it will take an extra second, and another time it could take three seconds to fire. I had the starter, alt, and battery tested 2 weeks ago and the starter and alt came back just fine, but the battery wasn't putting out enough cranks. I went back this evening and same result - starter/alt were good and battery was throwing 528, when it's rated at 700, so not dead, but not great.

Van is at a little over 221k and the belt would have been done around 2013. Going to go ahead and change it so it doesn't give any fits on an approaching vacation.

I'm thinking the rough idle had to do with the oil in the spark plug tube for the 6th cylinder. I don't know why everything else was reacting the way it was when testing the coils, but it ran really well for me tonight.
 
#16 ·
I'm not so sure. Oil in that plug hole might cause a single cylinder misfire which would be easy to pick out when you did your cylinder drop testing. Usually, the leaking oil in there doesn't cause an issue other than being a bit messy. Did you check any valve clearances when you had the valve covers off? If your engine hasn't had a valve adjustment done it definitely needs it and could cause random multiple cylinder misfires. I'm skeptical, yet hopeful, that your problem is gone for good.

Good luck with it and keep us updated.
 
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Discussion starter · #18 ·
thscott said:
I thought you attributed the rough idle to a disconnected hose?
Click to expand...
I did attribute the rough idle experienced to a disconnected hose, but that was after I had changed the spark plug seals, valve cover gasket, and two ignition coils. The closest thing I could determine for the initial rough idle was either one of the ignition coils and/or the oil in the tube. Wouldn't make total sense, though, as the spark plug tube with the oil in it caused a worse idle when I unplugged that coil (allegedly signaling that it was ok). I still replaced that coil since the boot was soft (and ended up cracking while trying to clean the oil).

For all I know, a hose could have come loose and that's what caused everything, but I'd doubt it as the clamp was still on.

I'll know more once we get this timing belt changed out. I don't want to pay for it, but it's time anyway.

John Clark said:
Did you check any valve clearances when you had the valve covers off? If your engine hasn't had a valve adjustment done it definitely needs it and could cause random multiple cylinder misfires.
Click to expand...
I've never had the valves adjusted and didn't know that was a thing until I started working on this repair. Ignorance is one thing, failure to act once not ignorant is another. I guess I'll look in to the valve adjustment as well.
 
Discussion starter · #19 ·
Got the van back from the shop from getting the timing belt changed. Ended up being about $100-150 less than anticipated, so that helped. They checked my motor mounts as well, and noticed the front motor mount needs replacing. I've noticed the vibration and the "bump" when accelerating for a bit, but just discovered that the motor mounts are a common cause for such, about 2 weeks ago. I'll be handling that replacement.

Re: rough idle and such - no further issues. We'll see how that holds up. The van feels great outside of that motor mount.
 
#20 ·
Unfortunately, that motor mount is a very expensive replacement. Don't even bother with an aftermarket mount or you'll be doing the job again in less than a year. Use only the OEM mounts, as expensive as they are. It hurts but they are the only reliable repair.
 
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