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I'm trying to diagnosis a power loss issue at low RPM (under 3,000) and am wondering if the intake air bypass solenoid could be faulty. My 2011 TL SH-AWD is more sluggish than normal at lower RPM, then really takes off at around 3,000 RPM+. Sometimes it is more subtle than others, but when its really running sluggish it's like someone flips a switch at 3k and it takes off. Anyone else have this issue? What things should I check that would cause sluggishness/hesitation at lower RPM? Would it hurt anything if I were to temporarily wire the solenoid to a constant 12V to see if it makes any difference?
If so, you might just try applying a 12V source to it to see if it turns the plate. You'd probably want to remove the IM cover (cover with the Acura logo) to see if it's working. Maybe the plate is jammed somehow.
Thing is, from what I understand, the valve is closed at lower RPM's then opens at higher RPM's. So if you're getting crappy low end performance, maybe that means it's stuck open? Dunno. I'd take the cover off the IM to see what's going on.
Another idea I read, if the voltage application doesn't work, is to remove the actuator (leave it plugged in) then have someone rev the engine up past about 4000 RPM's to see if it turns. That worked for someone on the 2G TL. Not sure if it's the same on a 4G, or if it would even turn at all when there's no load applied. You could also disassemble it to see if any teeth are broken or shake it to see if there's rattling. On the 2G, the teeth were made out of plastic and ended up stripping on a few cars.
Good idea. Not sure that would work, but I can try. Worst case, I'd just pull it off and jumper a couple wires to the battery (or any battery for that matter). I'll also check for any abnormalities in the movement of the butterfly valves. Speaking of butterfly valves, I can't seem to find a picture of them. Also, are the intake runners a different part?
The plate/valve is #2 in the diagram. The actuator and plate are now attached to the IM cover since the 4G TL. So if you remove the IM cover, you'll also be removing the actuator and plate once you disconnect the electrical connection. They used to be part of the intake manifold itself. I can't find a pic of the 4G but here's the old 3G assembly with the IM manifold:
Actuator circled in blue, butterfly valve/plate in red.
But like I said, this isn't exactly how the 4G looks anymore. The IM doesn't have that assembly:
Instead, it's on the IM cover. Couldn't find the underside but you can see the actuator attached to the plate now, not the intake manifold. The valve/plate is on the underside. I'm not sure why they changed the design.
The intake runners are the tubes running to the cylinders after you take the IM off:
Removed:
Of course, you don't need to even take off the intake manifold to diagnose/replace the actuator but FYI anyways
I'm trying to diagnosis a power loss issue at low RPM (under 3,000) and am wondering if the intake air bypass solenoid could be faulty. My 2011 TL SH-AWD is more sluggish than normal at lower RPM, then really takes off at around 3,000 RPM+. Sometimes it is more subtle than others, but when its really running sluggish it's like someone flips a switch at 3k and it takes off. Anyone else have this issue? What things should I check that would cause sluggishness/hesitation at lower RPM? Would it hurt anything if I were to temporarily wire the solenoid to a constant 12V to see if it makes any difference?
You can get a copy of HDS (honda diagnostic system) off ebay and use the actuator test to see if it's functioning, and as well as data log function so you can take snapshots of what the car is doing.
Acura has those valves there so under 3K rpm less air makes it in thus giving us better MPG while cruising!
I'd be interested to see what the snapshots show, esp for the torque convert engagement vs engine RPM. Sometimes a failing torque converter make the car feel down on power. I had it happen twice in my 760 and got new trans with new torque converter and it solved it. Unless I was at 2800 RPM or above the car felt like a 4cyl.
. Would the torque converter engagement data be shown using this tool, or do I need the Honda tool? I'm not exactly sure how to interpret all the data, but it is my understanding that I should start by looking at the short term fuel trim and long term fuel trim (STFT and LTFT). One thin I found odd is that the EGR error often goes to 98% and stays there. Would a sticking or faulty EGR valve cause low RPM sluggishness?
Last edited by mossman77; May 28, 2019 at 04:24 PM.
I monitored the short term and long term fuel trim yesterday evening, and the LTFT was mostly negative 2 or 3%, which if I understand correctly indicates a rich condition (not enough air). I also monitored the EGR error and it mostly sat at 99.2%, but would sometimes read 0%. It would change to various percentages in between as soon as I pressed the accelerator, so it appears to be working, but apparently it is sticking fully open a lot if in fact the error is actually 99.2% as the meter displays. Except an EGR valve that is sticking open would cause a lean condition wouldn't it?
Last edited by mossman77; May 29, 2019 at 01:17 PM.
A continuous 98% seems awfully high for the EGR. It's possible at just the right throttle and RPM but I don't think I've ever seen mine stay there for any more than a few seconds. And it's not easy to get it to stay there. It has to be at just the right throttle and RPM.
You might try disconnecting the EGR and see if that helps. The ECU will compensate although you'll get slightly lower mileage, a CEL, and theoretically a hotter burn due to no exhaust gas introduced during partial throttle. But if it's the EGR, that may help diagnose it. A lot of exhaust gas at low RPM / low throttle may cause the engine to run rough.
Yes, a negative fuel trim indicates either too much fuel or not enough air. It could be due to either but I don't think I'd sweat it much. If it's always negative then it might be worth investigating but for most cars, a range of -5 to +5 is perfectly acceptable. For older vehicles, up to -10 to 10+ is considered ok. Mine fluctuates between about -3 to +3 depending on driving conditions.
I pretty certain that the run-of-the-mill OBDII reader isn't going to provide any data on TQ engagement.
Something else you could do to diagnose the EGR is to give it full throttle at lower RPM's. Obviously it's not going to take off like a rocket since this isn't a particularly high-torque motor. But if it responds well, it could very well be the EGR, since the ECU will signal the EGR to close when at full throttle.
Something else you could do to diagnose the EGR is to give it full throttle at lower RPM's. Obviously it's not going to take off like a rocket since this isn't a particularly high-torque motor. But if it responds well, it could very well be the EGR, since the ECU will signal the EGR to close when at full throttle.
What do you mean by "if it responds well"? I can be driving in sport mode in 2nd or 3rd gear at 2,000 to 2,900 RPM, floor it, and not much happens (meaning the car hardly accelerates). I've had to abort lane passing on more than one occasion because the acceleration just plain sucked.
Any chance it's a transmission issue? I mean these vehicles and Acuras in general are known to have issues with transmissions. Isn't there a way to take the transmission out of the equation and check the health of the engine under load? For example, forcefully apply the brakes to keep the car stationery while applying throttle?
Last edited by mossman77; May 31, 2019 at 09:22 AM.
I took a look at my EGR yesterday at higher load (not max load) and lower RPM. It didn't reach much over about 40%. I suppose looking at the EGR during moderate to high load and lower RPM would be better than a subjective assessment of how the car is running. What I originally meant was to try and notice any hesitation or the engine running rough when at higher loads but lower RPM. If too much exhaust is being introduced into the engine at any given time (more than the ECU is tuned for), it's going to cause the engine to run rough.
I'm starting to think it may not be EGR related however, based on your fuel trims. I was reading about how fuel trims can be affected by a faulty EGR. If the EGR is stuck open (or open too much), the fuel trim will likely go significantly positive since too much exhaust gas will result in a lean condition. Conversely, a stuck closed EGR may result in a negative trim. So if your trims are ok, it seems the EGR may not be the problem. However, I still find it weird that you're seeing it stick at 95%. I'd still recommend you disconnect it and see what happens. At that point, the ECU will simply add fuel/air as it normally would if the EGR wasn't present, since it detects that it's not operable.
I've never had transmission problems in this car so I can't speak to that. However, it should be easy to tell if the torque converter isn't locking up, which is the only thing I can think of that would cause the problem you're describing - the TC not locking and absorbing a good deal of power at lower RPM's. If you gun it at lower RPM's and the RPM's stay relatively constant (slight spike but not much), that would pretty well indicate that the TC is locked. For mine, even if I gun it at 1500RPM in 5th or 6th gear, it sticks at that RPM and just accelerates very slowly (in manual/sport mode of course).
I'm just shooting in the dark really. I've never had that problem so I've never had to solve it
I took a look at my EGR yesterday at higher load (not max load) and lower RPM. It didn't reach much over about 40%. I suppose looking at the EGR during moderate to high load and lower RPM would be better than a subjective assessment of how the car is running. What I originally meant was to try and notice any hesitation or the engine running rough when at higher loads but lower RPM. If too much exhaust is being introduced into the engine at any given time (more than the ECU is tuned for), it's going to cause the engine to run rough.
I'm starting to think it may not be EGR related however, based on your fuel trims. I was reading about how fuel trims can be affected by a faulty EGR. If the EGR is stuck open (or open too much), the fuel trim will likely go significantly positive since too much exhaust gas will result in a lean condition. Conversely, a stuck closed EGR may result in a negative trim. So if your trims are ok, it seems the EGR may not be the problem. However, I still find it weird that you're seeing it stick at 95%. I'd still recommend you disconnect it and see what happens. At that point, the ECU will simply add fuel/air as it normally would if the EGR wasn't present, since it detects that it's not operable.
I've never had transmission problems in this car so I can't speak to that. However, it should be easy to tell if the torque converter isn't locking up, which is the only thing I can think of that would cause the problem you're describing - the TC not locking and absorbing a good deal of power at lower RPM's. If you gun it at lower RPM's and the RPM's stay relatively constant (slight spike but not much), that would pretty well indicate that the TC is locked. For mine, even if I gun it at 1500RPM in 5th or 6th gear, it sticks at that RPM and just accelerates very slowly (in manual/sport mode of course).
I'm just shooting in the dark really. I've never had that problem so I've never had to solve it
Exactly what I was thinking...if the EGR was stuck open, then the fuel trim would be positive to compensate. I'll disconnect it and see what happens.
Mine is the same way. If I gun it at lower RPM while in sport mode (so it won't downshift), it hardly does anything. Sounds like this is normal, albeit irritating. Shouldn't the ECU detect the fully open throttle and unlock the TC accordingly so the car can accelerate?
Even if this behavior is "normal", I'm still confused as to why the car abruptly takes off after 3,000 RPM as if it was given a shot of nitrous. Maybe the IMRC valve is sticking. I'll be taking a closer look at this as well.
What about faulty O2 sensors? Reason I mention it is because my car has been burning oil for tens of thousands of miles, so it's conceivable that components in the exhaust stream have been affected. The voltages should be between 0V and 0.5V I believe, correct? I believe they were normal.
My scan tool has graphing capability. Should I select a few parameters, graph them, and post the results?
BTW, my gas mileage sucks...about 17MPG.
Wonder what would happen if I forced the IMRC valve open all the time
Last edited by mossman77; May 31, 2019 at 09:58 AM.
Exactly what I was thinking...if the EGR was stuck open, then the fuel trim would be positive to compensate. I'll disconnect it and see what happens.
Mine is the same way. If I gun it at lower RPM while in sport mode (so it won't downshift), it hardly does anything. Sounds like this is normal, albeit irritating. Shouldn't the ECU detect the fully open throttle and unlock the TC accordingly so the car can accelerate?
I've had mine unlock the TC but stay in the same gear when on a grade presumably due to the grade logic. But it's been far more common for it to just bog down if the RPM's are still within an acceptable range for that gear. That's pretty normal.
I've had mine unlock the TC but stay in the same gear when on a grade presumably due to the grade logic. But it's been far more common for it to just bog down if the RPM's are still within an acceptable range for that gear. That's pretty normal.
I'm wishing I would have gotten a manual TL, but those are hard to come by these days. Seems to me that when in sport/sequential/whatever mode, the car should run balls to the wall. The only difference I can decipher between S and D is the ability to manually select gears.
The S mode (when not in manual mode) has different shift points, essentially keeping the transmission in a longer in order to provide more acceleration without needing to downshift. My wife exclusively uses S when she drives the car, but isn't interested in the paddle shifters. S mode won't shift into 6th under any circumstance either. Even when cruising on the highway.
The S mode (when not in manual mode) has different shift points, essentially keeping the transmission in a longer in order to provide more acceleration without needing to downshift. My wife exclusively uses S when she drives the car, but isn't interested in the paddle shifters. S mode won't shift into 6th under any circumstance either. Even when cruising on the highway.
Sorry, I meant manual mode. Other than being able to shift manually, the engine performance doesn't seem to be any different.
And I'm with you on the manual. My 3G was a 6MT and I miss it dearly. I purchased a FWD AT (isn't even offered in manual) because I didn't want to pay the steep premium for the SH-AWD. It's at least $4000 more due to the high demand for AWD in Utah. It was also the deal I made with the wifey that we'd get an AT for the next car.
Sorry, I meant manual mode. Other than being able to shift manually, the engine performance doesn't seem to be any different.
No, it's not. The engine is the same regardless. That's typically the case with all cars that have some sort of sport mode though. It's not as if the engine puts out more power. It just changes the profile the ECU uses to tighten up the throttle response and transmission gearing. Some newer cars can also adjust the steering response or suspension but there's no car I know of where the engine is somehow enhanced when the sport mode is active.
No, it's not. The engine is the same regardless. That's typically the case with all cars that have some sort of sport mode though. It's not as if the engine puts out more power. It just changes the profile the ECU uses to tighten up the throttle response and transmission gearing. Some newer cars can also adjust the steering response or suspension but there's no car I know of where the engine is somehow enhanced when the sport mode is active.
I meant maybe opening up the IMRC valve sooner to let in more air, change fuel mapping, things like that.
Regarding the IMRC valve, does it open rather abruptly around 3k RPM or is it supposed to be gradual leading up to 3k?
