Update: '07 With The Rough Idle

[Green GX]

My '07 has had a rough idle since it was 3 months old. After many trips to two local dealers their conclusions were: (Dealer A) Unless the computer spits out an error code, there's no problem; we can't troubleshoot any further. (Dealer B) "We've had a couple of other cars in here that do it, so its normal," or, "yeah, we know it does it but we're not sure why."

I figured if the local dealers aren't going to take the initiative to find this problem I'd try and force the issue. So, back in early July I asked one of the dealers if Honda has a diagnostic data logger to capture problems on the car. The answer is yes they do. I told the dealer I wanted them to get one because I want to find out why this thing has a roughness when idling.

After five weeks of waiting and many repeat phone calls, always to a different person, the dealer got a data logger. They installed it. (plugged it in) And, I drove around a few days pushing the green button when the idle got rough. I took the car back to the dealer yesterday where they downloaded the data and sent the data to American Honda.

While waiting at the dealer, I wondered why it was taking so long just to unplug the logger and send the data to Honda. It turns out Honda saw that the voltages were either too high or too low at the Mass Airflow Sensor. (already a known issue on this car) So, they recommended the tech check the valve clearances. (2nd time in ~7000 miles) I had to leave the car overnight because the dealer had pulled the cylinder head and was marinating the top of the pistons to remove excess carbon. Hmmmm, wonder where that came from?

Bill

[freedml]

Re: Update: '07 With The Rough Idle

sorry they aren't taking better care of you!

[Green GX]

Re: Update: '07 With The Rough Idle

They changed one spark plug, too.

After they test drove the car their conclusion was that they didn't notice the symptoms I complained about. Ironically, I noticed it on my way home a couple of blocks from the dealership. (and this morning)

My car has a roughness at low idle that the dealer can't find and solve. I'm driving another one here at work that came off the assembly line 17 cars later and it's idle is smooth; just what you'd expect from a Honda.

Bill

[John Mitton]

Re: Update: '07 With The Rough Idle

Does the rough idle only occur after you have been driving a bit and then stop (at a light for example)? All vehicles run a catalyst efficiency test which runs the engine rich then lean to see if the cat is working properly. This test generally is programmed to run every so often after the car has warmed up and then comes to a stop/idle. Could be this test is not executing properly.

[larrycng]

Re: Update: '07 With The Rough Idle

The mass air flow (MAF) need to be checked and maybe a known good MAF installed for comparison. The MAF is one of the big factors in fuel injection pulse width (delivery), but it should be trimmed by the O2 sensor. Check fuel trim during the rough idle period and see if it changes significantly. Also if fuel delivery changes significantly, there should be corresponding changes in MAF, O2, RPM, manifold vac (if equipped). If not, there is a problem in a sensor.

Eventhough NG is a low carbon fuel, rich mixtures will leave carbon. If the miliage is bad, there is a possible source of carbon. The other source would be engine oil (valve guides/seals, or piston rings). How's engine oil consumption compared to the "average GX"?

As for the CAT monitor, good possibility, however that is usually a once per trip monitor. Most of the time that is usually run at highway speed so it not so noticeable (not familiar specifically with Honda drive cycle requirements). The CAT monitor would only explain one rough idel sequence per drive cycle (Key on, start warm up, etc., to key off), what about the rest of the rough idle occurances during the drive cycle. Did the CAT monitor go to completion (readiness status will tell the tale) and you will not have a completed drive cycle if all of the readiness are not set to complete. If there is an oil problem, the CAT and the O2 can be damaged

The data logger is a great idea if the techs can run comparisons between sensors. I like to graph the readings, close the door, get a cup of coffee and donut (beer and sandwitch -- what ever) and compare the sensors. If there is a problem it will show up. If not, then, and I hate to say it, start substituting know good parts (that assumes that the electrical connections have been checked and qualified)

Just a few thoughts

Larrycng

[Wellarmed]

Re: Update: '07 With The Rough Idle

Larry gave you some very good suggestions of items to look at. When you say that the tech pulled the head to marinate the piston tops (on a CNG motor?) in order to remove the carbon buildup? This is very uncommon. I would have reviewed the mechanical condition of the engine before disasembly, and that includes a compression AND leakdown test after adjusting the valve lash. Did you say the valves were out of lash at 7K miles? That is also highly unusual at such a low interval. What type of oil consumption is this engine experiencing? What is the cat efficiency when looked at with an infrared thermometer? Not just your scan tool! Even if you were in open loop mode, I highly doubt that you would be experiencing that level of carbon buildup in a CNG engine. In a gasoline motor maybe, but CNG? Have you run a synthetic motor oil before proper break in has occured? Is the carbon buildup even on all four cylinders? Have you checked the KV requirement of the ignition system and inspected/replaced the spark plugs? What about the spark plug boot condition. What is the Ohm value of the spark plugs? are they within 1 Ohm difference? If EVERYTHING with the engine condition looks to be within spec, then what is the condition of the fuel system? What are the high and low pressures? Are there any other consumers of fuel at your location exhibiting your sysmtoms? Has your range significantly decreased since purchase? Have fuel filters become plugged? I have seen failures related to the electronic portions of vehicle systems but they are generally far and few between. Most problems that arise are still mechanically related thankfully. I always eliminate mechanical malfunction first before I begin examination of electronic systems, but that is just my personal pet peve. I unfortunately have learned mostly from my own mistakes and not from others mishaps. Please keep us informed, as i am curious what your outcome will be.

[Green GX]

Re: Update: '07 With The Rough Idle

Does the rough idle only occur after you have been driving a bit and then stop (at a light for example)? All vehicles run a catalyst efficiency test which runs the engine rich then lean to see if the cat is working properly. This test generally is programmed to run every so often after the car has warmed up and then comes to a stop/idle. Could be this test is not executing properly.

John,

Yes the rough idle only occurs after I've been driving it for a while and do stop at a light. The first stop I make in the morning is after driving the car about 10 miles. This stop is a stop sign, so I don't stop long enough for the idle to really wind down.

The second time I stop is at a stop light after 16 miles of driving. If I do have to wait for cross traffic long enough the I can feel a rough idle. When I park the car after a 21 mile drive it WILL idle rough.

With the car warmed up and under the following conditions, the A/C off, radio on, interior fan on and either one of the turn signals on I get a rough idle. If any other electrical circuit puts a load on the system, (e.g., window run up or down, interior fan turned up/on, radiator fans cycle on, the idle will dive lower, the engine shudders a bit until the computer catches it and bumps the rpms up.

Bill

[Green GX]

Re: Update: '07 With The Rough Idle

The mass air flow (MAF) need to be checked and maybe a known good MAF installed for comparison.

Honda WILL NOT do this! Their stance, "The computer isn't spitting out a code, the car is running normal, there is no problem." They will not troubleshoot by changing parts!

The MAF is one of the big factors in fuel injection pulse width (delivery), but it should be trimmed by the O2 sensor. Check fuel trim during the rough idle period and see if it changes significantly. Also if fuel delivery changes significantly, there should be corresponding changes in MAF, O2, RPM, manifold vac (if equipped). If not, there is a problem in a sensor.

Eventhough NG is a low carbon fuel, rich mixtures will leave carbon. If the miliage is bad, there is a possible source of carbon.

With my style of driving 5% stop/go and 95% highway I average 39 mpg, can't really complain about that.

The other source would be engine oil (valve guides/seals, or piston rings). How's engine oil consumption compared to the "average GX"?

Oil consumption is so low I'd say it's virtually zero in the 8000 to 9000 miles between changes. No complaints there.

As for the CAT monitor, good possibility, however that is usually a once per trip monitor. Most of the time that is usually run at highway speed so it not so noticeable (not familiar specifically with Honda drive cycle requirements). The CAT monitor would only explain one rough idel sequence per drive cycle (Key on, start warm up, etc., to key off), what about the rest of the rough idle occurances during the drive cycle. Did the CAT monitor go to completion (readiness status will tell the tale) and you will not have a completed drive cycle if all of the readiness are not set to complete. If there is an oil problem, the CAT and the O2 can be damaged

The data logger is a great idea if the techs can run comparisons between sensors. I like to graph the readings, close the door, get a cup of coffee and donut (beer and sandwitch -- what ever) and compare the sensors. If there is a problem it will show up. If not, then, and I hate to say it, start substituting know good parts (that assumes that the electrical connections have been checked and qualified)

Just a few thoughts

Larrycng

Thanks Larry, I'll print out everyone's suggestions and bring them into the dealer next time.

Bill

[Green GX]

Re: Update: '07 With The Rough Idle

Larry gave you some very good suggestions of items to look at. When you say that the tech pulled the head to marinate the piston tops (on a CNG motor?) in order to remove the carbon buildup? This is very uncommon. I believe American Honda took the shotgun approach and authorized the dealer to do this on the oft chance that it would smooth out. I would have reviewed the mechanical condition of the engine before disasembly, and that includes a compression AND leakdown test after adjusting the valve lash. Did you say the valves were out of lash at 7K miles? No, they were checked at the normal 30K mile check-up. The car had 37K miles when American Honda told the dealer to check them again due to odd mass airflow sensor voltages. (same odd readings as at the 30K mile check. That is also highly unusual at such a low interval. What type of oil consumption is this engine experiencing? Virtually zero with 8000-9000 intervals.

What is the cat efficiency when looked at with an infrared thermometer? Not just your scan tool! Even if you were in open loop mode, I highly doubt that you would be experiencing that level of carbon buildup in a CNG engine. In a gasoline motor maybe, but CNG?

Have you run a synthetic motor oil before proper break in has occured?I put synthetic in the car at the first oil change, after 8,200 miles.

Is the carbon buildup even on all four cylinders? Have you checked the KV requirement of the ignition system and inspected/replaced the spark plugs? I haven't & Honda won't!What about the spark plug boot condition. What is the Ohm value of the spark plugs? are they within 1 Ohm difference? If EVERYTHING with the engine condition looks to be within spec, then what is the condition of the fuel system? What are the high and low pressures? Are there any other consumers of fuel at your location exhibiting your sysmtoms? Good question, I'll ask.Has your range significantly decreased since purchase? No, I'm flirting with 39 mpg.Have fuel filters become plugged? No, no difference after changing.I have seen failures related to the electronic portions of vehicle systems but they are generally far and few between. Most problems that arise are still mechanically related thankfully. I always eliminate mechanical malfunction first before I begin examination of electronic systems, but that is just my personal pet peve. I unfortunately have learned mostly from my own mistakes and not from others mishaps. Please keep us informed, as i am curious what your outcome will be.

Thanks for your questions.

Bill

[Lakewood90712]

Re: Update: '07 With The Rough Idle

I also don't buy the Carbon on the pistons story. I wonder what they broke during the valve adjustment that required removing the Head . Great cover story.

My 08 started doing the "Idle Stumble" at about 8 K miles. It has never come close to stalling.

The airflow sensor is about $120 ( Internet/mailorder) it's the same part as on the gasoline Civic , so I may try a new one if it gets annoying enough.

[Green GX]

Re: Update: '07 With The Rough Idle

I've talked to the folks at the Honda Customer Care Center again. I wanted to let them know the car is still idling rough and not to close the file on this one.

Here are few of their comments and my responses.

Them: "It's normal." Me: "Honda makes cars that normally idle rough? And, If it's "normal" why did the head honcho of the mechanics in the Palmdale dealership ask Curtis if he knew of anyone else here in the chat room that had the same problem and how did they fix it?"

Them: "It's normal." Me: "I drive a GX at work and it doesn't idle rough. How do I get that abnormally smooth idle installed in mine?"

Them: "Take it back to the dealer or to another dealer to see if they've missed anything." Me: "After TEN trips to two different dealers I think it's time to look into the Lemon Law."

Me: "The Ford Focus, Chevy Cobalt & Malibu and Nissan Versa I've had as rental cars while my Civic was in the shop don't have rough idles." Them: Silence.

Bill

[Green GX]

Re: Update: '07 With The Rough Idle

I also don't buy the Carbon on the pistons story. I wonder what they broke during the valve adjustment that required removing the Head . Great cover story.

My 08 started doing the "Idle Stumble" at about 8 K miles. It has never come close to stalling.

The airflow sensor is about $120 ( Internet/mailorder), so I may try a new one if it gets annoying enough.

Under what conditions does yours do it?

Mine is:

-Engine driven and warm.
-A/C off, otherwise the engine revs higher from the compressor load and it never idles down to 600-650 rpms.
-Other assorted electrical stuff on at the same time. (fan, radio, turn signal, etc.)

I'm curious if it's the same problem.

And remember, the California Lemon Law states that you have to take the car into the dealer FOUR times for the same repair in the first 18 months, or 18,000 miles in order to be covered by the law.

Bill

[Lakewood90712]

Re: Update: '07 With The Rough Idle

Bill , check your inbox , I'm sending a P. M.

[Wellarmed]

Re: Update: '07 With The Rough Idle

Very interesting replies. I personally cannot stand the flat rate system of mechanic pay as it sounds like that is the root cause of your problem, not the car. You really do need to be at a diagnostic shop that pays their mechanics hourly and has a team atmosphere where mechanics will pool resources without having to worry about beating clock rate. If you have worked at a flat rate shop then ALL jobs that do not beat book rate are dogs and are to be avoided at all costs. Honda and other manufacturers should offer incentive pay to technicians that discover defects which lead to the creation of technical service bulletins. Have your two dealerships checked for TSBs related to your specific problem? I find it very disconcerting that factory trained mechanics cannot pinpoint the root cause of a problem that is not intermittent. Intermittent by definition in automtive terms is the inability to uniformly recreate the conditions of the driveability problem. Based on your replies it seems very clear to me that the conditions are repeatable and can be duplicated under similar driving conditions. I would personally check for vacuum leaks in the induction system as well as in the Idle Air Control system. I find it interesting that the simple operation of the turn signal circuit can initate the driveability concern. Has anyone checked the charging system output? With and without the turn signal engaged? Is there a short to ground somewhere on that circuit? Remember that fuses take time to blow depending on the severity of a short, and on a circuit such as turn signals there may not be enough on time to allow the fuse to blow. I doubt that there is a problem with the contol function of the IAC circuit because it was mentioned that the engine rpms do increase when the A/C is turned on. Check the drive belt tension with a drive belt tension gauge to determine if the drive belt for your alternator is tensioned correctly. Is it glazed, cracked, splitting, etc...? Eliminate your charging system as a posible culprit before checking the turn signal current draw. Problems like this are the only thing that make working on cars interesting after you have been doing this for a while. It is a shame that you cannot devote yourself to finding a problem like this when you are watching the clock and wondering how you are going to pay your electric bill with 20hrs billed in your 80 hr week.

[Wellarmed]

Re: Update: '07 With The Rough Idle

I forgot to throw in my two cents about the effects of synthetics during engine break in. DON'T. Ring seal may be difficult or imposible to achieve if synthetics are used before proper break in.