Hello guys, you're gonna love this one. I'm not a mechanic but I've been working on cars for years (more than just my own). I'm not familiar with Acuras so I was hoping someone might be familiar with what kind of problem this is. I'm working on a friend's 2006 TL base I believe, A/T. It starts not always the first time but it will run good with slight stumble at idle (slight). I can rev it no problem if I give it a little throttle, no hesitation or stumbling. I can rev it if I give it almost half throttle no problem, again no hesitation or stumbling, it actually runs good. I can drive it, forward and reverse gears and hit all speeds no problem for at least 20min no stalling or problems. I can leave it idling for 45min no issues. As soon as I pump the throttle (rather quickly) it stalls most of the time. I can give it almost full throttle with no problem (as long as I push the throttle down at no more than a medium pace). If I push the throttle down around halfway or more and I flick it down quickly like I'm trying to take off quick (while driving or not, while in gear or not, while engine warm or not) it stalls immediately. It can be at low RPM or middle RPM or high RPM when I do it, will still stall the same. When it stalls the ECM locks up and stops responding and communicating. I know this because unless I recycle the power with the key it won't start/run the fuel pump/communicate with a scanner. There are usually no DTCs triggered (but sometimes I get P0685 Internal circuit power lost). Also while the ECM is locked I can communicate with other modules on the CAN BUS, so it's not a BUS problem. When it stalls it's like someone just removed power from the engine, no spit or sputter, it just turns down to a stop like the key was turned off, dash lights stay on but usually all the errors are triggered. Even the tachometer needle gets frozen where it was until the engine spins to a perfect stop, then the tach needle drops to zero. Once I recycle key sometimes it starts right away but sometimes I have to recycle key a couple more times and try again each time. When it starts it runs and idles smooth like nothing happened.

When it dies I noticed that the power and grounds to the ECM are okay, no bad ground connections and no flickering or unstable power. The battery turns over the engine with ease so the battery is not weak (but I noticed after about a few days to a week without running it the battery is completely dead, but with a quick jump it starts no problem). After ECM lockup the PGM1 relay is still on and main power remains at ECM pins (IGP I believe). VCC power to sensors drops from 4.8V to 1.5V and doesn't return to 4.8V until key power is recycled. The fuel pump relay is off when it's stalled and the power relay to the throttle body control module dies as soon as the engine loses power. The signal to the throttle body control module gets lost as soon as the engine loses power, one wire goes to battery voltage while the other goes to 0V (normally both wires show around 10V DC to ground because it's a communication line with a pulsing signal.

Parts that have been changed by owner:
Crank position sensor
EGR Valve
APP sensor

I have personally cleaned and checked the throttle body (and when I say I cleaned and check it I mean I disassembled the whole thing, pulled the electric motor out and disassembled that, cleaned the brushes on the motor and checked resistance to all commutator sections, made sure no shorts and all resistances were even to windings, no burnt windings, put everything back together, greased the gears, still same problem, might even happen easier now). I also cleaned the throttle plate mechanism but it was moving smooth anyway. I've never seen a Trottle Position error or other throttle body error except once but I think I caused it when I unplugged it one time.

I did also try unplugging the throttle body and starting the car. The car stated and ran weird but idled no problem. With throttle press it did rev the engine (sort of) but no stalling no matter what I did (quick throttle slow throttle full throttle).

I changed the ECM with a used one (two actually), they both show the same problem (not sure if the computers are good or not but they run the car, harder to start than original ECM though).
I also have a good scanner so a ran a throttle body actuator test, it fails every time, complaining that DTCs were triggered but none are saved. During test solenoid checks okay, the throttle plate opens to 2 degrees then closes, no error, the throttle opens to 20deg then closes, no error, the throttle opens to 79deg then the test stops and complains of DTCs (note: during throttle actuation test the throttle plate moves very quickly).

I'm at a loss guys, I'm leaning toward the throttle body control module being bad and glitching the ECM causing it to freeze, but I don't want this guy to throw any more parts at this car until we know what's wrong. I've searched the forums, no one has ever complained of the throttle body control module going bad let alone changing one. Also no one has ever complained about stalling due to quick throttle demand. I'm not sure what to do/try next. Any insight would be greatly appreciated.

 

A couple of things...

When you clean the throttle body, you have to be very careful around the butterfly shaft because of the moly coating.
When you reinstall it, there's a learning procedure:
Procedure
1. Make sure all electrical items (AlC, audio, rear
window defogger, lights, etc.) are off.
2. Reset the ECM/PCM with the HDS.
3. Turn the ignition switch ON (II), and wait 2 seconds.
4. Start the engine. Hold the engine speed at
3,000 rpm without load (in Park or neutral) until the
radiator fan comes on, or until the engine coolant
temperature reaches 194 "F (90 "C).
5. Let the engine idle for about 5 minutes with the
throttle fully closed.
NOTE: If the radiator fan comes on, do not include
its running time in the 5 minutes.

If the battery dies more than a few times it could cause problems. Try replacing it with a known good one.

Good luck!

 

So you really think that's what is causing the ECM to lock up? I'll do that procedure, I actually just came across that somewhere else last night as I was doing research. The throttle re-learn procedure the scanner tried to get me to do included flooring the throttle until fuel cut-off occurs, this is an older car so I'm not trying to cause any issues by over revving it.

I'll give that a try and report back. I'm still leaning toward it being a bad Throttle Body Control Module. I'm going to try pulling the Fuse for that module (Fuse 1 under dash) and see if any of the starting issues or stalling issues go away. I know I won't have throttle response but at least if it clears up the issues with the ECM I'll know kind of where to go next. Thank you for your advice.

 

Also the battery, I was starting to think k that myself. He said he just changed it a month or two ago, but like I said it has gone dead a couple of times. I might pull it and bring it somewhere to have it checked just in case. Thank you again.

P.S - How do you edit your past responses/posts. Can you do that? I wanted to go back and edit my last response and I can't find an option for that.

 

Naw, you can only edit your posts for like 5 minutes, then it's history.

Is the HFL (BT) still connected? That's the usual battery drain.
EDIT: These cars are VERY sensitive to voltage and current...

 

Since the crank position sensor was changed, the Helms service manual has the crank pattern clear / crank pattern learn procedure below.
Have you tried that process with your scan tool?

 

I did try the throttle relearn procedure and it didn't seem to make a difference. I put the original ECM back in the car since the car seems to start easier with that one.

I pulled the battery and am going to have it tested tomorrow at a parts store just to make sure it's not an underlying possible cause. I have seen weak batteries cause issues with random computers in vehicles even when they start the car okay, and from what I read and keep hearing this car is extra sensative.

I didn't do a crank pattern relearn, I will next time I'm at the car. The issue was there before the crankshaft position sensor was replaced (the owner was shotgunning a bit, he was checking forums and trying to change anything that sounded like it could cause a problem with the car stalling). But I'll still perform the procedure just to make sure that's not causing an issue, I'm used to Subarus so I wasn't aware of that kind of thing with other cars.

I'll also check and unplug the Hands Free Link module if it's still plugged in. If he wants it plugged back in I'll do that once the car is running but for now I want the battery to stop dying since he's not driving it. No need to cause more problems.

I did perform the test I mentioned earlier. I unplugged the throttle body and then the fuse for the Throttle Body Control Module. Unplugging the throttle body didn't make a difference with starting but it does eliminate the problem of stalling with quick throttle demand. Pulling the fuse doesn't do much different EXCEPT, the ECM gets very unhappy without that communication link to the TB Control Module. Sometimes the vehicle is harder to start without that module powered up, so that communication link definitely effects the ECM heavily. Once I plugged the #1 fuse back in and the throttle body it's back to the original problem.

I'm still leaning on the idea that it's the TB Control Module (or something related). Since that communication link is so important, it seems it can cause the ECM to lock up if it glitches or shuts down unexpectedly. Plus we know that if the internal VCCs on the ECM get messed with, or if main power source gets drawn down for a second (like from a glitchy sensor or module) it can cause the P0685 DTC and shut down the ECM. I'm just waiting for someone who might know a little more about this or these cars to chime in before I settle on that diagnosis. Plus like I said, I'm not really familiar with these cars (it seems like Honda likes to do things differently). I'm going to try doing all the relearn procedures and have the battery checked to make sure it's not something straightforward. This guy has already spent so much money on parts and other people working on it, I don't want to cost him any more unless I'm pretty sure that's what the problem is.

I'll report back once I've done all the verifying and recalibrating. Thanks again for all your help and info guys. If anyone has any other thoughts or ideas let me know.

 

Just a quick update. I haven't had a chance to get back to that car, I was finishing up another job first for a friend of a neighbor. I did get the battery checked at a parts store, they said it tested good but the tester showed it was under charged. That was odd because I've been running the car everyday for three days and at least a total of several hours (including driving), the battery shouldn't be low. Then I remembered that once while I was driving it I saw the battery light come on. It only happened once and it was on for about three seconds and went off, and this was not when the car was stalled or stalling. I think it was at low speed going through a parking lot. I couldn't figure out why it was on and it never happened again so I forgot about it. So now I'm thinking maybe the charging system is ailing. If there's any tips or pointers you guys have on that please let me know. I think parts stores still check alternators so if I can get it out without too much trouble I'll have it checked too. If that's at the heart of the problem I'll be a little dismayed and relieved. Thanks again guys for your help.

 

If you pull the alternator it comes out easier if you remove the fan shroud.

Some auto parts store will charge the battery for free---you may find that it WON'T hold a full charge.
After they die a few times, that happens.

 

With the engine idling the voltage should steadily read 13.5V if it's running normal. If it's greater than 15.1V @ 2,000rpm that indicates its faulty as per factory manual. A cheap multimeter is a must if you're a shade tree mechanic. It'll save you alot hassle from pulling the alternator if that isnt the issue.
An alternator going bad might also light up the battery light very intermittently.
You can also isolate any battery/alternator issue by jump starting it with a 2nd car.

 

my money is on battery cable

 

The reason why I titled this response is because we found the problem but haven't quite fixed it yet.

So I did what everyone suggested. I did do the throttle learn procedure and the crank learn procedure and they did seem to help. First when I was putting in the battery after having it tested the car didn't want to start at all. Would just crank and putt once or twice and then ECM would freeze. So I thought the only thing that changed was the battery connections and wires. So I cleaned up the terminals and double check the negative terminal and still no start. Then I checked voltage across all the grounds to the engine from the battery negative and it was 0.1V - 0.2V when starting. So I thought why not jump the ground connections to eliminate that as an issue. So I grabbed a set of jumper cables cablconnected straight from battery negative to engine block. This didn't really make a significant difference but eventually after another 5min- 10min of playing with it i was able to get it to start somewhat reliably. So i figured that was part of the problem. I dud the relearn procedures and i thought that made another small difference but still hard starting and still stalling when throttle pushed quick. Evenrually after a little idling and a few starts the problem went away. I figured it just needed to run a bit and then it settled in. I then cleared all the trouble codes in all the computers and the car got very unhappy. Wouldn't start at all for about 15min of trying. When I did get it started the stalling problem was back just as bad. I was ticked off, the car didn't make sense. I figured maybe like before it needed to run a bit and then it would clear up so I chanced driving it. I was able to drive it with soft throttle without too much trouble. I noticed that when it stalled if you pushed the brake while restarting it the car started easier, almost every time. I thought that was strange. After awhile of driving with better and better results I decided to pull the jumper cables off the ground. I had just tucked them under the hood and closed it to test the bad ground theory. I pulled them off and seemingly no change at first. I drove back to the owner's house after about 10min more of driving. When I shut it off it didn't want to restart. I also checked the alternator voltage. It was rock steady between 13.7V - 13.8V at all RPM's idle to 5,000 rpm. So I figured the alternator was fine. I decided to recheck all the power and grounds to the ECU and co.ing from fuse box under dash that was getting hot. But it was late and I was ticked and needed a break from the car. I went home. I met with the owner the next day and explained how I saw a lot of corrosion around the ground straps and terminals and told him we should try cleaning them up along with the other tests I was going to run. I was going to jump power straight to the ECM from the battery once the key is on, and probably jump ground too. Then I would see if that makes a difference. As I was explaining this he mentioned about the parts he changed and how the problem changed. I tried to correct him and say how it was always stalling but there were other problems too that he fixed but this problem was still here. He said NO, the stalling problem started after he changed the EGR Valve. I remember him saying that it would rev up and down and shift out of gear and he had to restart the car to drive it, but I thought he said it would stall too. He apparently didn't say that, the stalling problem started after he changed the EGR Valve and the other problem went away. Now after checking through schematics and learning about the ECM control in this car I knew it didn't need the EGR to run. So I told him we'd check and see if the EGR Valve was causing the problem, maybe he got a bad one. I know also how sensative this ECM is to power, and I kept getting the P0685 code. I thought maybe the EGR was grounding a power VCC out from the ECM and causing the whole problem. The car was running, I unplugged the EGR Valve and had him pump the gas a bit. It didn't stall. I had him shut it off and restart it, it started right back up. I said let's take it for a drive, he reluctantly agreed but I was a little upset at this car at this point. If this was the problem this whole time I wanted to know. Plus if it stalled like before I knew how to get it started. I drove it for about 15min and then let him drive it for another 30min. Absolutely no problems at all, no stall and no trouble starting it after that. I couldn't believe it. I had him shut it off and start it five times in a row just to make sure there weren't anymore problems lurking. It started every time and never stalled no matter how he drove. He took it to work for two days now and no issues yet. I did try to plug the old EGR back in while the new EGR is still bolted in. This way if the old EGR is sticky it won't cause the car to rev and run weird. He said it never triggered a Chevk Engine light with the old EGR. I wanted to see if the old problem came back. The Caution Triangle did come up so had him disconnect the old EGR and just leave the plug hanging. We having replaced the second EGR Valve with another new one yet but I'm pretty sure we found the problem. I'm a little upset that it was so simple. But honestly if I didn't spend the time to learn the vehicle and control system I wouldn't have known what to do to check the EGR to see if it was replaced with a bad one, nor would I have know the problem so well to know if it was really gone. Again I appreciate everyone's help and suggestions in things to try. It drove me nuts but I learned a lot about Acura/Honda engine control and electronics. If we realize anything different about the issue once we change the EGR I'll let you guys know. But at the moment I'm assuming we found the problem and that's it. Although I did uncover a fuse box that's overheating and we think that's been causing his headlights to flicker. Unless of course you guys have any insight on that, after all I'm still not exactly an Acura guy. Thanks again everyone, hope I can help someone out with a problem here in the future.

 

^
Good to hear you managed to resolve the issue.
Now I'm wondering if the EGR valve he used to replace the old OEM one was OEM or aftermarket?
If it was aftermarket, what was the brand & where was it purchased from?

 

He doesn't remember what the brand was. It was only about $30. I saw the box, it looked like it came from ebay. It was a new unused but as soon as we verified it was a bad EGR Valve he knew it was because it was a cheap part. As soon as he gets a new one and we put it in I'll report if there's any issues. A check engine light did come on he said recently with the weird setup, new EGR bolted in it old EGR electrically connected. I haven't had a chance to read the codes yet but I'm assuming something to do with EGR is there.

Another quick question for anyone who knows. When I was doing a system check and it showed all the trouble codes for all the systems, codes were showing for the Body Control Module but when I clicked into that section I couldn't find the actual codes. It would 6 doc's but I couldn't find any trouble codes listed in and of the fault code sections. They all said no trouble code for every BCM system. But if i cleared them they woukd go away. I would like to know wgat they were because a couple always come back. Its not a big issue but i was just curious. Thanks again guys.

 

The new (new new) EGR Valve is installed and the car is still running just fine. No stalling with quick throttle response and it starts just fine. I think this confirms the EGR Valve was the problem. Thanks again everyone for all your help. We're still going to change the negative battery cable and clean up the grounds since that seems to be a common issue with these cars. If anyone has any questions on anything I did or found please let me know. I'm going to stay subscribed to the thread for awhile in case anyone has a question. I wish everyone well.