Extended Rough Idle and Stalling diagnose on '04

[dan596]

Hello All,

I've been trying to resolve a rough idle, poor gas mileage, misfire code problem for a while now. These forums have been invaluable and have resulted in my investigating many things. I wanted to summarize where I am at and what I thinking for next steps to see if anyone has any suggestions.

I working with an '04 MDX Touring with 150k miles on it. For the past 5-10k the idle has been getting rough. My wife puts about 300-400 miles a week on this vehicle and the symptoms are most notable during cold starts but after warming up the idle can still be rough. The fuel mileage has dipped some as well. The vehicle continues to throw P0300 thru P0306 codes with the CEL and VTM-4 lights coming on. Here is a brief history:

1. When this first happened I tried some fuel injector cleaner/system cleaner. It ran a little better for a while but problem returned soon.
   
2. Because of I was thinking this was related to poor fuel delivery and breathing, and my experience with VWs and carbon build up , I did a Sea Foam treatment of the intake. I have to assume it was pretty clean because it did not produce the volumes of black smoke expected. Again, car ran better for a while then problem returned.
   
   It is at this point I should note, I do these services on the weekend and it runs fine for me all weekend. Then my wife takes the MDX away for the week for business and the problem re-occurs. Needless to say this results in the typical her thinking I'm an incompetent home mechanic, and me thinking she is jinxed.
   
3. Read forums for more info and service manuals and decided to
   - replace the PCV valve,
   - clean the PCV lines (they were in good shape),
   - replace the EGR valve.
   Again I cleared the codes and the car appeared to be running fine. And again she took it away and problem returned.
   
4. Having believed we had the plugs changed when it was in for 110k service/replacement of the water pump and timing belt I had dismissed ignition trouble. I was wrong. The plugs hadn't been changed. Seeing as we got the MDX with 70k miles there is a good chance they were the original plugs now at 150k miles. So I got some NGK iridium plugs and got to work. The original plugs on the surface looked to be in good shape, but I replaced them anyway. The interesting exception here I found on cylinder 2 and 4 (the two middle cylinders) that both plugs were loose resulting in blow by. The ignitions coils for both of these were caked and cooked with oil as well. I found it interesting that had I not pulled the coils, I would have never known this....An unfortunate consequence of the coil over design I wouldn't experience on an old distributor design. Not having replacement coils handy I tested the old ones, they worked so I reused them with the new plugs. Seriously at this point I figured I had really found the problem, because with the new plugs in the idle really smoothed out. Of course, knowing it would be a good thing to replace those cooked coils soon.
   
5. The MDX ran great for over a week, but then my wife reported the CEL came on again (no VTM-4 light this time). I pulled the codes and only got misfire for 4 cylinders. Yes, two of them were the fouled ones....but this was a change from getting the P0300 code and misfires for all cylinders. Not having time to fix it, I cleared the codes and sent her on her way for the week. Bad mistake..read on.
   
6. This week I got the call that things had escalated to where it is now stalling while driving. It still starts/idles rough on cold mornings. I'm faced with driving to her location, trading cars, and hoping I can get back with MDX. Last night, I started more Forum search and came up with the following next areas to dig into:

• Water in Fuel (Wife swears she is only putting in high octane, but water could still be there)
• The earlier mentioned coils pack, but I find it hard correlate this to the stalling
• Valve clearance adjustment. To my knowledge this was never done.
• O2 Sensors - Was thinking these could be bad, or I fouled them with the Sea Foam treatment
• Low Fuel pressure or clogged Fuel filter - but usually this become apparent under heavy throttle/demand.
• Deterioration in the ignition wiring, but I would think there is a separate code for this.
• Clogged EGR ports - most post say this is no longer a problem on '04 but still a possibility

I'm leaning towards the Valve timing as it seems this has produced good results for several people....not to mentioned it was a required 105k service item the dealer overlooked. I have the service manual, tools and home-mechanic experience to want to do it myself. I'm looking for input as to if it is worth saving the $500-1000k estimated service cost or are the pitfalls and first time - experience with this particular service task too risky.

Any feedback, input is very much appreciated.

Btw....here are links to some of the other threads I gathered info from. I thought about just continuing one of them, but felt it might be better to collect all the references together in this one thread.

car stalling

http://www.mdxers.org/forums/73-2001...warmed-up.html

http://www.mdxers.org/forums/73-2001...ne-stalls.html

How does the oil get in here ?

Check Engine+MisfireCode == Change Spark Plugs?

[carguy07]

I would get the valves adjusted (and pay to have them done). I just priced out my 105k service today at a local Honda dealer and they quoted $200 - $250. They did try to talk me out of having it done if they were not noisy, but for a couple hundred dollars I'm just going to have them adjusted and not think about it for another 100k miles.

[CODOG2]

I thought a mechanic could measure the reading across the MAP sensor and determine if a valve adjustment is necessary - or something like that

[artbuc]

Originally Posted by carguy07

I would get the valves adjusted (and pay to have them done). I just priced out my 105k service today at a local Honda dealer and they quoted $200 - $250. They did try to talk me out of having it done if they were not noisy, but for a couple hundred dollars I'm just going to have them adjusted and not think about it for another 100k miles.

Surprised you aren't adjusting the valves yourself? You obviously have the know-how. Reminds me of my 74 TR6. Bought that baby brand new. Had to adjust valves every 5k.

[carguy07]

Originally Posted by artbuc

Surprised you aren't adjusting the valves yourself? You obviously have the know-how. Reminds me of my 74 TR6. Bought that baby brand new. Had to adjust valves every 5k.

I probably could do it, but I just had knee surgery 3 or 4 weeks ago and I'm still a little hobbled. But honestly for a couple hundred dollars I would rather pay for someone's experience rather risk making a making a mistake. I just don't like messing with the valves on modern engines (or V6 timing belts for that matter).

[artbuc]

Originally Posted by carguy07

I probably could do it, but I just had knee surgery 3 or 4 weeks ago and I'm still a little hobbled. But honestly for a couple hundred dollars I would rather pay for someone's experience rather risk making a making a mistake. I just don't like messing with the valves on modern engines (or V6 timing belts for that matter).

Understand. I did TB and struts all around two or three years ago on my Avalon and RX300. By the time our MDX needs struts and TB, I will be too old (I think) to take on those jobs, especially with what I read about the Honda crank pulley bolt. My problem is lack of trust in the stealerships. Hopefully I can find an honest, competent indie. Thanks for all of your help-I enjoy your posts. Hope you have a quick recovery.

[tlynch]

clean your EGR ports, all the way down, not just the upper portion.

[dmdavies]

I'm a bit confused. Are you talking about valve timing? or valve clearance? While granted the valve clearance can have a minute affect on valve timing, the valve timing is generally affected by the timing belt and cam & crank alignment. Interesting comments though! I have an 03 that has suffered from a rough idle now for about the last 20K miles. I have been unable to find the cause. I tried much of what you described. Because it was due for a timing belt anyway I put it off until that point. I did the full 105K mile service (and water pump) and also changed the plugs and adjusted the valves, new tensioner belts, hoses, etc. etc. It was fairly straight forward other than trying to bust that crank pulley nut loose! I was sure that in all that it would solve the rough idle problem...it didn't! Still has a rough idle...though I haven't seen any other symptoms....except, I have had a few P2279 codes (Intake Air System Leaks) that have come in then quickly reset. So, I too am searching for an answer. But, I doubt a valve adjustment will have an affect. But, keep us posted! Thanks.

[dan596]

Hello Folks,
The story continues. To answer the last question, I was speaking of the valve clearance adjustment. Instead of my driving to my wife's location, her father took it to the local Honda dealership that they have gone to for years (Her must have bought/leased over 50 hondas from this place over the years). Same P0300 thru P0306 codes present. In the end for $400, they did:

1. Found Spark plugs loose and tightened.
2. Found values very tight and adjusted.
3. Checked coils
4. Performed ECM update.
5. Performed Fuel System Service.

Recommendation : Fuel Injector gunked. If problem persists they made need to be replaced.

The MDX ran smooth for a few days. When my wife returned I swapped with her. It was sooo hard to let my S6 go, but I didn't want another mid-week call. Sure enough, a few days later, the CEL and VTM lights came on and same codes presented. Under power, the engine runs smooth, but idles rough.

Tonight, I decided to verify some of the work the shop claimed and sure enough there was evidence of pulling the intake, the valve covers, and even some of the coils had been swapped around. I did, however, find plug #5 swimming in oil. Remember previously I had found #2 and #5 oil soaked. This time #2 looked good, but #5 was literally drowned in it. So what does this mean?
A. Is it really possible for that much oil to push past the plug? I don't think so, plus I would think it was draw back in.
B. I have a head gasket leak around that plug port. Oh wonderful.

Anyone have an opinion if this oil bath is enough to foul the coil/plug connection and cause the misfire problems? Does it make sense that the problem with this one plug could cause the misfire codes for all plugs? I'm about to do some more Forum/online research, but just wanted to update.

[nicegy31]

Did you try and do a compression test. If you do this you could see if you have oil leaking in to your cylinder and this could cause the oil problem to foul the plugs. I can see that code saying the all the plugs are fouled. I have the original manual if you like I can make copies and e mail some pages to you. I hope your able to figure this out.

[carfan87]

When my dads F150 spark plug hole filled with oil it would start to mis but it most prominent at a higher speed.

As a side note when our 2004 MDX was still under warranty our CEL and VTM lights went on and it did not run well and for some reason the AWD did not work right (it failed during a snow storm of course). We brought it in to Acura and they replaced one of the 02 sensors and then it worked great. I still don't understand why the AWD did not work...

[Trigger_thyme]

I have to chime in guys. The oil in the plug tube is not in any way from the combustion chamber. The oil is from the tube seal in the valve cover. It only makes sense that issue would arise after the valve adj. I have done a ton of V/A's on this style engine and know how easy it is to cut the fragile seal while pushing it into the cover.

Now about this rough idle issue. If the dealer did their job correctly (which sounds like the leak is a bad sign) and the engine is good the map sensor voltage should below .95V (I like .90v and lower. Mine is at .85v) at idle hot without the fans on.

Other things to check are the EGR passage holes in the plenum plate. Easy to check (and should have been looked at by the tech doing the service). Remove the upper intake plenum plate bolts, check and clean the six EGR holes in the steel gasket. I like to clean the plate and all sealing surfaces with break cleaner and a rag to ensure a good seal (I doubt that's the issue but worth a look).

I'm leaning towards heavy build up of soft carbon in this engine. I would take a look into the throttle body area and the look inside for excessive build up. If needed I would do a deep cleaning with Sea Foam ..... and I mean DEEP (PM me for details if you like).

If the map Voltage (Oh... high voltage means low vacume, and well that's bad) is out of spec there will be a rich condition and carbon build up. If the V/A didn't fix it, there may be deeper engine issues.

I'm going to read the thread again to see if I missed something.

OK, read it again, and yes oil on coil is a bad thing, especially the ones that sit in it for a extended time. That is the main killer of the these coils.

As for having issues with P0300-306, that is a system wide issue. Bad coils and loose plugs will only flag a code for the one that's bad (and I doubt they are all bad, plus you wouldn't be going very far). Honda's low Ion misfire detection system works accurately.

Think I have said enough, PM me if you need to.

-Dave

[Simi_MDX]

Can you share how one can get the map voltage reading? Is it something a person can do with a volt meter? I have this same problem with the codes p0300-306. I checked my coils and plugs, but didn't see anything out of the ordinary. What is the normal course of diagnostics outside of just changing everything and adjusting everything? I was thinking of just changing all my plugs, coils, PCV valve, EGR valve, and a valve adjustment, but I am concerned that the problem will not go away after all that. I can do all the work myself except for the valve adjustment (which my indy will charge about $200 for).

[dan596]

Thank you for the input folks.
- nicegy31 : I agree a compression test is a good idea, if not related to this issue, just as a good check in engine health. I'll plan to do this and report results.
- carfan87 : I haven't ruled out O2 sensors, but I would expect some different codes if they were faulty. I'll hold on this for now.
-Trigger.. : Thank you much for chiming in. After seeing what you said, and more reading in the service manual I agree with the oil leak diagnose. This was very helpful input. I'm debating now whether to return the car to the dealer who did the valve adjustment (300 miles away ) or just replace the gaskets myself. Obviously I can't get much further with this issue until I resolve the leak.
- I've done a Sea foam cleaning via the PCV hose, and post throttle body recirculation hose, (About 1/4 bottle each) all prior to changing plugs and discovering oil issue. Since then I pulled the top manifold cover and, aside from s few pockets carbon particles (fine salt size) collecting in the nooks and with really fresh oil, it looks fairly clean. I figured these particles to be the result of Seafoam cleaning. EGR holes into the intake (coffee stirrer size) are clean. The EFR pipe and cavity had a film but not what I would call build up. I wiped and vacuumed this entire assembly out. I will still PM you to get your 'deep clean' instructions.

Simi : As Trigger suggested I'm going to check the MAP sensor voltage. There are two procedures I can find in Service Manual. One for checking DTC P0107 and one for DTC P0108 (pages 11-102 - 11-106). The procedures are very long so I'm not going to type them in put could scan and attach if requested. In short, none of these procedures indicate getting a measurement as Trigger did. However I have deduced the following:
A) Map Sensor connector has 3 wires
(1) - VCC1 (Voltage positive side) Yellow/Red in color
(2) - sensor data line, Green/Red
(3) - SG1 (ground side) Green/Wht)
B) Procedures above both reference checking between (1) and (3) for 5V. This will determine if the MAP sensor is being powered properly.
C) You can pull the PCM connector and check between (2) and pin 6 of the PCM connector for continuity to ensure the PCM is getting MAP sensor signal.
D) With all connectors attached, If you have a diagnostic tool (HDS equivalent) you should be able to get a MAP Sensor reading with the ignition switched on. I will confirm this later today with OBDII software. I expect that this is the voltage reading Trigger refers to...likely with engine started. Short of this, you would have to work out a way to get the voltage reading between pins (2) and (3) with the connector connected to the sensor. (I"m not looking at the connector but, for example, maybe you can get a needle probe from a volt meter into the backside)

As soon as I can get to doing these things later tonight I will let you know my findings.

[dan596]

Just wanted to update that I checked the MAP sensor with my OBDII scanner. It doesn't give me the voltage reading that Trigger recommended checking for. It is instead in in.Hg. I'm getting a reading of 30.5 in.Hg with ignition on/engine off and 10-11 in.Hg at idle. I can't determine if this correlates to the suggested values by Trigger, but it is an indication that the MAP is working.

Any thoughts?


BTW...I was discussing this with my brother last night and he mentioned how he had the very same rough idle problem with his accord a few years back (similar v6 engine). He said it turned out to be water in the gas...he'd put in additive and it would run fine for a while and then turn rough again. He mentioned it took several fill ups with additives to rid the problem.