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Old May 31st, 2015, 09:52 PM   #1
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Massive loss of engine power

I'm going to try to make this as short and sweet as possible, but there's a bit of background info that could be important as it's possible it's all related to this new issue.

I have a major problem with my 2003 Accord V6 6MT. The Friday of memorial day weekend I left for Philly to visit friends. Just after getting on 95, I was getting on the throttle pretty hard trying to make good time. Out of nowhere the engine just choked. It didn't stall, but I had no power at highway speeds. I couldn't make it up hills. The harder I hit the accelerator, the more it choked. I had to very very gradually get up to speed. The engine/exhaust also immediately changed sound. It sounds like it's drowning. I can't get it past ~3k RPM on the highway. It's slightly better in the lower gears, but it's still really bad. On a scale of 0-10, with 0 being the engine won't run at all and 10 being a power beast, it's maybe a 2 right now. It idles slightly rough, but not too bad. It doesn't stall ever. It just can't handle any load.

The one thing I gotta say about the idle though is that I still can hear a slight choking. If I rev it out of gear, you can definitely hear the choking. It's not nearly as bad as when the engine is loaded though. And one thing I discovered today is that the revs are limited to 4.5k unloaded. Normally, they're limited at 5.5k unloaded.

The background info is that I've had a lot of problems with this car over the last 6-9 months - A LOT! I've owned it for 8 years, and now it's dying it seems. The latest unresolved issue prior to this was intermittent clutch pedal problems. Sometimes it sticks, sometimes it's soft, sometimes it's hard, sometimes it works completely normal. I haven't gotten the chance to diagnose that issue short of looking at the pedal itself and checking the clutch master cylinder for leaks. My thread on here related to that problem left me thinking that I need a new clutch pressure plate. The more I think about it though, the more I don't think thats the case. The clutch doesn't slip. I think the "slipping" I felt before is just jerking related to this new issue. I put it in 3rd and 4th and released the clutch while holding the brake. It stalled immediately. When I gun it while driving, I hear the engine rev without gaining any significant speed, however the rpms stay constant. So that would indicate it's not slipping right? From what I understand, a slipping clutch would be evident by a jump in rpm but not increase in speed.

If we go back a couple months, I got stranded when the car stalled on me and wouldn't start. It was a nightmare that ended up being due to 2 bad ignition coils. Right before it stalled, the car acted and sounded EXACTLY like it does right now. But after replacing all ignition coils and plugs, I had no problems at all until last week.

Here's what I've done to the car drive train over the last 6 months...

New parts: (6) NGK iridium plugs, (6) aftermarket ignition coils, OEM air intake tube, OEM PCV valve

Maintenance: cleaned throttle body, cleaned MAP, cleaned electrical connectors for sensors in throttle body and ignition coils, ran through a bottle of Lucas fuel injector cleaner, flushed coolant

Honestly, I'm probably forgetting a bunch of other stuff.

Here's what I've done to try and diagnose this new problem...

My OBDII scanner initially read two codes, P0175 and a catalyst efficiency code (P0420 perhaps). I cleared the codes before driving down to Richmond on memorial day, and the efficiency code still has not come back on. The bank 2 running rich code comes back after only a short drive though. I've never seen any misfire codes, or any other codes at all for that matter.

It runs just as crappy when it's cold as it does when it's hot. And my scanner is showing the upstream oxygen sensors fluctuating between about 0.2V and 0.7V. So that means it's unlikely to be an oxygen sensor, right?

Based on it apparently only being a bank 2 problem (per P0175), I tried pulling the bank 2 oxygen sensor to see if it was a clogged cat. It still ran equally as crappy and the wonderful new exhaust hole blew a huge chunk of my hood liner off :-/ So it doesn't seem to be a clogged cat.

I already had one DOA ignition coil, so I tried swapping out the bank 2 coils one by one. But there was no difference in performance.

I checked the air filter and box, both are clean.

My long term fuel trims were running about -17 for bank 2 and -10 for bank 1 initially. After tinkering today, they were at about +2 and +3, but the performance was still the same.

At idle, my scanner reads ~20in/Hg vacuum, 14.7:1 AFR, warm intake temps around 130F, coolant around 190F. That all sounds about normal, right? Then again, it doesn't idle too bad anyway.

Last fill up was WaWa 87, but there's been no change with other gas. My gas mileage during my Richmond trip was horrendous. I went through nearly 7/8 tank between Philly and Fredericksburg, VA.

Oil level is normal. Tires aren't really low. Coolant is still green and at a normal level. From what I've read, it doesn't sound like it would be an EGR or TPS issue.

I just don't get what could be the problem. It sounds like it's suffocating or drowning or something. The harder I get on it, the more it bogs down. The only other possible source of the problem I can think of is with fuel pressure. But I don't have the tools or expertise to check that kind of thing. I just want to rule everything else out before I resort to taking it into a shop and wasting even more money.

Sorry, there was nothing short about this post at all lol

Last edited by Fat Ryan; May 31st, 2015 at 10:06 PM..
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Old June 2nd, 2015, 11:17 AM   #2
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Anyone?
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Old June 2nd, 2015, 01:45 PM   #3
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^ No new codes? This is crazy, I am at a loss. Can you post a vid of the car idling and while driving? It's hard to diagnose an engine without seeing or hearing it, especially with everything you have already tried.

I may go out on a limb and say on of the new coil packs went bad.
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Old June 2nd, 2015, 03:02 PM   #4
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There are three cats. Undoing one oxygen sensor won't clear the exhaust pathway of all three. How many miles does the car have?
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Old June 2nd, 2015, 03:24 PM   #5
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^ No new codes? This is crazy, I am at a loss. Can you post a vid of the car idling and while driving? It's hard to diagnose an engine without seeing or hearing it, especially with everything you have already tried.

I may go out on a limb and say on of the new coil packs went bad.
I have a couple different video runs I recorded with live OBD-II data (using my Blutooth scanner and the Torque app). Ill post them when I get home from work. But just a warning, the audio is super magnified and distorted, so its not really useful in terms of listening to the engine. Unfortunately, that's just how my phone is :-\

If it helps, I could record the actual engine bay at idle, but I still don't think the audio would be very useful.

And no, no new codes. I only get P0175. It seems as though the bank 2 coil packs are fine, since I already tried swapping them all. I figured there was no sense in pulling Bank 1 packs since my DTC is a bank 2 code.
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Old June 2nd, 2015, 03:26 PM   #6
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There are three cats. Undoing one oxygen sensor won't clear the exhaust pathway of all three. How many miles does the car have?
Yeah, I was assuming it would only be necessary to pull the bank 2 O2 sensor, since my DTC is for bank 2. Even if all cats were clogged, wouldn't pulling at least 1 sensor show some amount of improved performance?

Car has 173k.
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Old June 2nd, 2015, 04:04 PM   #7
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didn't you have the same problem a few months ago? Maybe its time to say F it and swap a motor in?
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Old June 2nd, 2015, 05:25 PM   #8
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didn't you have the same problem a few months ago? Maybe its time to say F it and swap a motor in?
It may be related, but it's not the same exact issue. A couple months back, I was getting misfire codes, 1-6 and random. The engine was misfiring and stalling. So I ordered 6 new coil packs and 6 new plugs. After installing everything, I still had a rough idle and misfires. After days of troubleshooting, I figured out one of the new coil packs was a dud. After replacing it, all was good.

The one similarity, as I mentioned in the OP... When I got stranded that couple months back, my car sounded very odd and had significant power loss seconds before it stalled and wouldn't restart. I remember it vividly, it was identical to the way my car acts and sounds right now. Except now I'm not stalling out (yet, at least). So that really makes me think it's all related. But I can't figure out what the issue is.

Unfortunately, my finances won't allow for me to swap a motor. If it comes to that, I'm just going to have to be car-less until I can save enough money for the swap or figure out a fix on my own.
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Old June 2nd, 2015, 05:44 PM   #9
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Pull all your plugs, take pics and post it on here. Also, try swapping out the front bank coil packs, even if you dont think that's the issue. It's possible that a cat is clogged and is triggering another. I've seen odder situations.

Any odd smells? Lots of fuel, anything burning, etc? You change the timing belt, valve adjustment? Change o2 sensor? You MAP could be going out

PS - If you cant go past 3k rpm, the ECU is throwing you in limp mod for some reason. Maybe the ECU is taking a crap
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Old June 2nd, 2015, 05:55 PM   #10
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Some of these dont apply to us.


In other cases, there may be performance problems, such as a lack of power on acceleration and some "coughing" or misfiring. The vehicle may have trouble idling, especially when warm or when sitting at a stoplight.

Common Problems That Trigger the P0172 and P0175 Code

PCM software needs to be updated
Mass Airflow Sensor (MAF)
Defective Manifold Absolute Pressure Sensor (MAP)
Engine mechanical problems
Defective Oxygen Sensor
Defective Fuel Pressure Regulator
Defective Coolant and/or Air Temperature Sensor
Thermostat is stuck open
Ignition Misfires
Defective Throttle Position Sensor
Defective or restricted fuel return line
Defective Fuel Injectors

Common Misdiagnoses

Oxygen Sensors
Fuel Pump
Fuel Injectors
Fuel Pressure Regulator
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Old June 2nd, 2015, 05:56 PM   #11
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Pull all your plugs, take pics and post it on here. Also, try swapping out the front bank coil packs, even if you dont think that's the issue. It's possible that a cat is clogged and is triggering another. I've seen odder situations.

Any odd smells? Lots of fuel, anything burning, etc?

PS - If you cant go past 3k rpm, the ECU is throwing you in limp mod for some reason. Maybe the ECU is taking a crap
Yeah, I think you're right about not ruling out bank 1. After my coil pack debacle a couple months back, I probably should never rely on DTCs to tell me anything useful lol. It's pouring rain right now, so I'll have to check the plugs another time.

I do not smell any fuel. I thought I was getting a faint burning smell periodically over the last few weeks, but it could easily just have been other cars. It was very faint, and I couldn't pinpoint a source by the type of smell.

I wouldn't say it's a hard 3k limit. It's just roughly around there. My car can't get much past that in 5th and definitely 6th. I can pass it in other gears, albeit gradually.

This video is just about uploaded, so I'll be posting a link shortly. It's kind of hard to tell, but in the video, I try stomping on the pedal in 1st on a few occasions. It's very slow to accelerate, though you can hear it trying. When doing this, it starts to buck around 4k, then it hits a rev limit shortly after.
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Old June 2nd, 2015, 06:02 PM   #12
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I had a similar problem with my 2001 CL. However, it would only act up when it was hot. The engine sounded like it was choking and would run like crap or not at all. It took me a while to figure out the issue. I changed the EGR valve and cleaned out the ports and still didn't fix it. It ended up being the fuel pump relay. The part was like 35 bucks and I think the relay was under the steering column. Of course this was a CL, so I'm not sure if this will help. Just thought I would let you know because it sounds pretty similar. If I were to guess its either your cats are plugged up or the fuel pump relay might be a possability. I hope this helps. Good luck
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Old June 2nd, 2015, 06:05 PM   #13
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Electrical wise I would say it's any of the below, but some kind of code should show, unless it's on the brink of complete failure and just hasnt triggered the code.

- MAP (Comes as one piece with TB)
- APP sensor (seen some weird crap happen when these start going)
- Plugs
- Coil packs
- 02 sensor (this shouldn't limit revs though)
- Injector (again, dont think this would limit revs.)
- ECU (If the ECU is done, maybe it's the culprit and reason it's not showing codes)

FYI, I have every part above if you want to test them. Just pay the shipping and small deposit on them and I'll let you use them to test. PM if you want. If they dont work, send them back and I'll send your deposit back
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Old June 2nd, 2015, 06:10 PM   #14
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OK, here's a video I just recorded on my way home from work. First, I drive with some sensor data displayed, then I pull codes (there currently are none cause I reset them last night and the catalyst checks haven't completed yet), then I switch to some live graphs to show sensor response with RPM.

Again, the audio is deceiving. You'll hear metal clanking throughout the video. That's empty Monster energy drink cans on my floor lol. I wish I could get a more accurate recording of the engine noise. The engine/exhaust can best be described as sounding like a cross between the deep-ish ricer rumble of a WRX and the wet fart gargling of a mustang... emphasis on the wet. Its a little louder overall than it typically is, but it sounds muffled.


https://youtu.be/NtlNS7fLETk
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Old June 2nd, 2015, 06:16 PM   #15
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Electrical wise I would say it's any of the below, but some kind of code should show, unless it's on the brink of complete failure and just hasnt triggered the code.

- MAP (Comes as one piece with TB)
- APP sensor (seen some weird crap happen when these start going)
- Plugs
- Coil packs
- 02 sensor (this shouldn't limit revs though)
- Injector (again, dont think this would limit revs.)
- ECU (If the ECU is done, maybe it's the culprit and reason it's not showing codes)

FYI, I have every part above if you want to test them. Just pay the shipping and small deposit on them and I'll let you use them to test. PM if you want. If they dont work, send them back and I'll send your deposit back
I might take you up on that. Is everything OEM? And what is APP?

The MAP sensor is not integrated into the throttle body. It can easily be removed and replaced. I know this, because I cleaned mine this winter. Also, with respect to cleaning MAP, I just watched a video by Ericthecarguy that said never to try cleaning an MAP. I've heard that it's OK to clean from other sources though. I cleaned mine just by spraying MAF cleaner into it. Could this have damaged it?
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Old June 2nd, 2015, 06:31 PM   #16
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Replace map, seafoam, check for anything that could send it into limp mode, or upgrade anything that could. Sounds a lot like a limp mode without all the lights
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Old June 2nd, 2015, 06:42 PM   #17
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Replace map, seafoam, check for anything that could send it into limp mode, or upgrade anything that could. Sounds a lot like a limp mode without all the lights
What all would send it into limp mode?
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Old June 3rd, 2015, 04:17 AM   #18
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From my experience it sounds like a clogged cat. I would drop the J pipe and pull both primary o2 sensors out of the top of the precats. Take a powerful flash light and shine it thru the o2 sensor holes and look up thru the bottom of the cats. Also of course look into the third cat.

Now be aware, when a precat catalyst deteriorates and breaks up exhaust scavenging will suck small pieces of the ceramic material back into the cylinders and destroy the pistons, walls and rings. Precat deletes should be a high priority mod not only for the performance gains but also for engine life.

Now your previous issue with the loss of the 2 coil packs can easily cause the precats to start to fail and raw fuel is pushed out of the cylinder and as it hits the catalyst it then explodes damaging the ceramic matrix.

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Old June 3rd, 2015, 07:15 AM   #19
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From my experience it sounds like a clogged cat. I would drop the J pipe and pull both primary o2 sensors out of the top of the precats. Take a powerful flash light and shine it thru the o2 sensor holes and look up thru the bottom of the cats. Also of course look into the third cat.

Now be aware, when a precat catalyst deteriorates and breaks up exhaust scavenging will suck small pieces of the ceramic material back into the cylinders and destroy the pistons, walls and rings. Precat deletes should be a high priority mod not only for the performance gains but also for engine life.

Now your previous issue with the loss of the 2 coil packs can easily cause the precats to start to fail and raw fuel is pushed out of the cylinder and as it hits the catalyst it then explodes damaging the ceramic matrix.
Is this all just a simple unbolting, or does it require cutting/welding? Ive never done any exhaust work.
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Old June 3rd, 2015, 09:05 AM   #20
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^ Unbolting, except the 3rd cat. I would take Pauls advise, he's much more knowledgeable then we are on troubleshooting these cars.
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Old June 3rd, 2015, 09:20 AM   #21
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Just swap in j32a3 with pre cats deleted...save time and hassle. Have a more efficient engine much lower miles
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Old June 3rd, 2015, 10:09 AM   #22
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^ Unbolting, except the 3rd cat. I would take Pauls advise, he's much more knowledgeable then we are on troubleshooting these cars.
edit: Nvm, saw accord325's PM.
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Old June 3rd, 2015, 10:12 AM   #23
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From my experience it sounds like a clogged cat. I would drop the J pipe and pull both primary o2 sensors out of the top of the precats. Take a powerful flash light and shine it thru the o2 sensor holes and look up thru the bottom of the cats. Also of course look into the third cat.

Now be aware, when a precat catalyst deteriorates and breaks up exhaust scavenging will suck small pieces of the ceramic material back into the cylinders and destroy the pistons, walls and rings. Precat deletes should be a high priority mod not only for the performance gains but also for engine life.

Now your previous issue with the loss of the 2 coil packs can easily cause the precats to start to fail and raw fuel is pushed out of the cylinder and as it hits the catalyst it then explodes damaging the ceramic matrix.
Forgive my ignorance, but what are precat deletes?
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Old June 3rd, 2015, 10:29 AM   #24
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7th Gen (03-07)
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Old June 3rd, 2015, 10:35 AM   #25
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$$$ Yikes!

Cant I just scrape out the ceramic with a screwdriver? lol
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Old June 3rd, 2015, 11:19 AM   #26
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Buy used ones from this guy: http://www.v6performance.net/forums/...-v6-parts.html
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Old June 4th, 2015, 04:55 AM   #27
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It is a very good first line of defense, should be done before any other steps. Can't beat a clogged cat
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Old June 4th, 2015, 07:58 AM   #28
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He's screwed if it ends up being the 3rd cat. He would need a J Pipe or cut and weld a new one on.
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Old June 4th, 2015, 12:28 PM   #29
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Test pipe?

http://www.amazon.com/Megan-Racing-R.../dp/B00CXAOS5I
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Old June 4th, 2015, 12:48 PM   #30
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LOL, look at me, cant even remember where stock cats are. Who needs Cats!? LOL Test pipe will work
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