Hard Start / Rough Idle in Cold Weather - Acura MDX Forum : Acura MDX SUV Forums
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post #1 of 4 (permalink) Old 11-05-2012, 05:32 PM Thread Starter
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Hard Start / Rough Idle in Cold Weather

Thanks in advance. I searched around on this topic and found several different posts (valve adjustment, EGR valve, PCV valve, throttle body cleaning, etc).

This morning was a colder one than awhile in the Northeast. A 2005 MDX with 112,000 miles would not start for my wife.

I came out and gave it a few turns and it finally started but was stumbling and sounded awful. I only let it run for about 20 seconds and shut it down.

It was after that I came inside and did a quick google and saw many "cold" related problems. For the hell of it before calling a tow truck I went back out and gave it another go. It started right up, stumbled a TINY bit for about 5 seconds, then a few little stumbles over the next 20 seconds then the car ran fine. Drove it all day on and off it's been perfect (no lights).

So my question is, is there any official troubleshooting process to follow to attempt to pinpoint the problem? I'd prefer not to blindly start replacing sensors and doing cleanings. Is there any way to "test" an EGR valve? or PVC valve? MAP sensor, etc?

All help appreciated.


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post #2 of 4 (permalink) Old 11-28-2012, 01:57 PM
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I've got similar problems and am also looking for a place to start. I've got an '03 w' 130k miles. The MDX starts fine but runs rough when cold (not really cold, here in CA only about 40-50 degrees...really just first start of the day). When I put it in gear, it dies. It does this several times, then after a few minutes, seems to be fine for the rest of the day. Occasionally it sets codes: P0175, system too rich, and P0301-6, cyl 1-6 misfire, and P0300, random multiple misfires. But these are transient codes tat clear right away. As soon as it's warmed up the car runs great and is averaging 21 mpg so I know things are generally good. Although I haven't cleaned out the air plenum or adjusted the valves, I find it difficult to believe these could cause the symptoms. I did replace the timing belt and water pump, plugs, wires, etc. at 115k miles but actually was having this problem prior to that maintenance. I was hoping I'd find something during that process that might solve this problem....Nope! Same problem now for about the last 25k miles. I did talk to the local Honda dealer who said unless there is a permanent code set, they won't even look at it. So, like Justin above, I'm looking for someone who might have had a similar problem and found an easy solution. I'd be most grateful for suggestions. Thanks.
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post #3 of 4 (permalink) Old 01-21-2013, 11:01 AM
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Hard Start / Rough Idle in Cold Weather

Live in CA and had the same problem...pulled the hood off (plastic piece). Removed the air cleaner and hose. Inspected the throttle body...what a mess. Disconnected the electrical connection and cleaned the throttle body with "Throttle Body Cleaner" (DO NOT USE CARBURETOR CLEANER) with a rag and my old toothbrush. A general note is that I did not spray any cleaner directly into the channel. Apparently there is a sensor somewhere behind the throttle body that gets destroyed...did not see anything but didn't take the chance. After that no more cold start problem. I don't claim this is the fix for everything, just a suggestion to check. By the way took to Hohen in Carlsbad to identify the problem...what a $%^%$$#@ waste of time. Hope this helps everyone...
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post #4 of 4 (permalink) Old 01-23-2013, 01:27 AM
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Hey, thanks for the tip. I was headed in that direction, thought it might be a gunked up throttle body, but didn't want to go through the effort unless someone had had good results. Unfortunately the car is 300 miles away right now in San Luis Obispo and I am in San Diego and having a hard time picturing, in my mind, the engine, and what you did. Did you perform all this in the car? Did you remove the intake manifold and clean it? If not, how did you manage to keep the gunk from going through the engine? Did you just clean the upstream side of the butterfly valve?...or could you get some of the downstream side with the throttle open? I don't recall...is the throttle body integral to the intake manifold or can it be removed and cleaned separately? As a SoCal guy you can relate to this....last summer going between San Diego and San Luis Obispo my tranny blew up in Oceanside. I had it towed to Hoen in Carlsbad...I was stuck...300 miles from home. I ended up paying them $4600 for a rebuilt tranny....Ouch!

Dan M Davies
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