MI6

Hello,

This is my first post in the MDX forums since selling my 2008 Type-S. It's nice to have an SUV and I love this thing. It's a 2007 with the Tech Package.

One issue began last Friday after I attempted to clean the throttle body. I removed it, cleaned it very well with a toothbrush and throttle body cleaner (essentially CRC brake-clean), put a new gasket on, torqued the 2 bolts and two nuts. Since then the idle has been very erratic.

I can attribute this to a few things: one, the TPS (throttle position sensor) is dead. Maybe the cleaner ruined it? I forgot to take it out of the TB housing when I cleaned it. Second, the idle air control valve is gunked up. Then again, do I even have one of these because of drive-by-wire? If so, where the heck is it? I can't see it anywhere!

Any help is truly appreciated. I once had a Jeep wrangler with these exact symptoms and it ended up being a TPS. In addition, I've read quite a few people who have experienced this with their Acura's but I have yet to find a post that has come to a definitive conclusion as to what actually solved their problem.

Thanks in advance.

db22

So before you "fixed" it it was working fine?
"If it ain't broke then .............."

hondaacurapro

There is no IAC. The idle is controlled by the throttle motor. There is really no reason to clean this throttle body. The MDX does not have a problem with carbon build up.

MI6

Thank you, your reply was certainly more helpful than the previous one

But yes, I found out the hard way with this. At 108k I have no qualms with replacing parts that have often failed me in the past. In this particular case I didn't realize it didn't have an IAC until too late. Regardless, I installed a new throttle body (which includes the TPS sensor and throttle motor) for ~$160 new with shipping. I also installed a new VSV valve.

The idle, once warm, idles at 700RPM. However, if going down the road and I switch it to neutral it stays at a constant 1300RPMs. The MDX is bucking and jerking around 30MPH. Torque converter has been ruled out by the dealership earlier, though this Friday they will be taking another look at it. They believe the 3rd and 4th gear transmission sensors may be bad, along with possibly some solenoids. They are not convinced it is an all-out transmission failure (which was/is common among many MDX's, which is a rhetorical statement in nature for sure).

Regardless, I've also done a 3X transmission flush, changed the rear diff fluid, and changed the gearbox/transfer case fluid. Nothing has helped. The idle still stays at 1300RPM during cruising which makes me wonder if it is "pulling" the vehicle along. In fact, it does sometimes. I have to be on the brakes or it will keep on going. Very strange. I've given it my all for now as I have other priorities. I'll let the dealership drain my wallet for now I guess. It's been a long and consistent problem, existing well before I cleaned the original TB.

Thanks and best regards.

Bitter Melon

I'm gonna take a shot in the dark and say its your exhaust valves that are too tight.

When was your valves adjusted and were they adjusted correctly?

MI6

Thank you for the heads up. I still haven't fixed the problem yet so this heads me in a new direction. I never thought of valves. I wasn't sure if they were hydraulic lifters or whatever and maybe the valves auto-adjust. Then again I'm treading into territory I know nothing about. My MDX just turned 109,000 miles and I have the complete history on it and the valves have not ever been checked out as far as I know.

Things I have done so far to no avail:

* New throttle body (comes with throttle position sensor and drive by wire sensor)
* New PCV valve
* New PSV (purge control solenoid valve)
* New OEM Iridium plugs
* Fuel injector cleaner x 2
* Transmission fluid change (3x fluid change w/OEM fluid)
* Gearbox fluid change
* Rear differential fluid change
* Two new ignition coils (the other four look ok but I can't tell if they are 100%; the ones I replaced were in horrible shape, orange almost with a burned smell/look to them)

I can't think of anything else off the top of my head. Other than replacing the four remaining ignition coils I'm just starting to wonder if the transmission is going bad. The jerkiness...I just don't have this with other cars, I don't get it. It's not a big jerk between 3-4 (sometimes 5th) gear but it's enough that you certainly wouldn't expect it on a vehicle of this price range. However, the MDX's history of transmission failure worries me.

I hope I've provided enough information to keep this thread going and someone help me out. I'll look into the valves for sure. I've been dealing with this problem for months now and it isn't going away.

Thanks in advance!

rpwjames

I am have same problem with my 07 mdx. Did you ever get a fix cause dealer can not fix.

csmeance

at 109K you should have done the following:

1. Timing Belt Replacement
2. Valve Adjustment
3. Water Pump Replacement
4. Coolant Flush
5. Spark Plugs
6. New Serpentine Belt
7. Oil Change

and a couple other things that escape me right now.

So right now there are a few things that need to be addressed like the stuff above. Beyond that, you also mentioned you replaced the TB. I'm not sure if the ECU needs to be recalibrated but it might not hurt to do the idle relearn procedure so the car relearns the idle.

Basically disconnect the battery for about 20 minutes and let the car drain of power. Hook it back up and put the car in accessory mode and turn off EVERYTHING like A/C, lights, radio, etc). Turn it off and turn the car ON to where it's running. Let it idle for 15 minutes (Or longer, the fans for the thermostat need to cycle at least twice). This will help the ECU relearn the throttle position for the proper idle.

As well you might need to get the new software update done that applies to some 2007+ MDX's. Check the MDX garage's TSB section for it! Replacing the 3rd and 4th gear sensors shouldn't hurt but make sure you get the right ones and they are installed properly.

amoffet

I just finished adjusting the valves on my 2004 MDX. The idle was very rough, and moreover, I had 30X codes and a check engine light on. All but three of my valves were tight. I have a few more miles than you do.

However, I did not exhibit any of the other problems with idle speed or anything like that, nor have I heard of such things. It seems doubtful. Keep us posted if you find anything.