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Important Read for people with ZDX or TL SH-AWD TB swap
Here why some people have issue with the larger TB. It has to do with how the TB is controlled. On the TL/S it is controlled by the TPS while the ZDX and TLSHAWD are controlled directly by the ECU.
long story short even with hondata it will not and cannot be fixed. Its a hardware problem not software.
Since people often swap to larger drive by wire throttle bodies, we tested Civic Si, TL Type S and ZDX throttle bodies for compatibility.
There are two types of drive by wire systems that Honda uses. One where the ECU drives the throttle body directly (Civic, TL, RDX) and where there is a separate throttle controller (S2000, TSX before 2007).
ECU driving the throttle body directly.
throttle-civicsi.png
throttle-civicsi.png (13.76 KiB) Viewed 156 times
ECU communicating with the throttle controller.
throttle-tsx.png
throttle-tsx.png (30.88 KiB) Viewed 156 times
All throttle bodies have two components - a DC motor to position the throttle plate, and a throttle position sensor to determine where the throttle plate is. The throttle position sensor has two resistive elements (A & B) for multiple redundancy. The motor is driven both open and closed by the ECU or controller, switching voltage across the motor using two sets of transistors.
Tests - Throttle Position Sensors
1. TPS A & B voltage
A. Civic Si
Closed 0.60 / 1.48 volts
Default position 0.85 / 1.67 volts
Open 4.00 / 4.20 volts
B. TL-S
Closed 0.62 / 1.50 volts
Default position 0.89 / 1.72 volts
Open 3.85 / 4.07 volts
C. ZDX
Closed 0.60 / 1.47 volts
Default position 0.90 / 1.72 volts
Open 3.97 / 4.17 volts
2. Throttle plate position
A. Civic Si
Closed 0.1%
Default position 7.8%
Open 105%
B. TL-S
Closed 0.0%
Default position 9.1%
Open 100.3%
C. ZDX
Closed 0.1%
Default position 9.5%
Open 102.6%
The TPS sensor for each throttle body works in the same way. The default position is different for the TL & ZDX throttle bodies.
Tests - Motor
1. Motor resistance
Averaged over 6 measurements, open direction and closed direction, using actual current for set voltage
A. Civic Si 2.85 ohms
B. TL-S 1.70 ohms
C. ZDX 1.35 ohms
2. Peak current @ 14V
A. Civic Si 4.9 amps
B. TL-S 8.2 amps
C. ZDX 10.4 amps
As the throttle body gets larger, the motors are higher torque / higher current. This is not proportionate to the throttle body opening area, as the ZDX throttle draws almost twice the current of the Civic throttle body.
Under real world conditions the throttle controller will vary the current to the motor in order to position the throttle plate. The current required to do this will be around the same for each throttle body (roughly 1 amp). However, the peak current is much higher on the larger throttle bodies. This is likely to be a problem if the transistors in the throttle controller shut down from over current or over temperature.
With the Civic Si / R18 ECU, the throttle controller uses a IC chip to drive the throttle body motor. The IC is rated at 5.0 amps continuous current, and has over current and over temperature shut downs. Switching to a throttle body which uses more than double the current is likely to overload the controlling IC.
Conclusion
Bigger throttle bodies draw more current, potentially overheating the controlling circuitry, causing erratic throttle operation and errors. This cannot be fixed by software.
How come the autos don't have these issues, only the manuals?
Can the electronics be swapped out 100% between the TBs?
Or maybe a dual TB setup like what gerzand did on his custom mani, where one TB is the slave, mechanically linked to the other. The DC motor seems to have enough torque to open both, or maybe gerzand upgraded the motor?
no idea. But it could be that the AT doesn't shut off its injectors like the Mt does. It is also constantly connected to the engine. Rev hang/rev up usually happens when MT change gears either to upshift or downshift. It probably cause a spike in voltage.
Ironic when the infinitely slower 5AT gets a break when it comes to performance
Any comments on whether its still a worthwhile mod for the auto guys? I mean i've done my reading of I_love_car's threads and a few other pertinent ones it seems like there have been NO reported issues with the auto... at all
So I thought I'd give this a shot since I finally got around to installing my TL-SHAWD mani, ZDX TB, PnP runners and outlaw thermoblock gasket onto my 2012 Honda Accord.
Here's what I did:
- Put the motor from the 3.5L accord throttle body into the 3.7L ZDX throttle body
- Put the TPS sensor from the 3.5L accord TB onto the 3.7L ZDX TB
--- I had an erratic idle at this point as well, where RPMs would jump to 1500 when I started the car and then go down to 800 RPM where it normally idles at. If I depressed the accelerator to raise the RPMs they'd go up, then when I let off they'd drop to 1k RPMs then go back up to 1500 RPMs then go down to 800RPMs where it normally idles at, so I thought I'd try the 3.7L TPS sensor.
- Put the TPS sensor from the 3.7L TB back onto the 3.7L TB and left the motor from the 3.5L accord TB in the ZDX TB.
So for a rundown of similarities and differences..
- The motors are physically identical
- The motor resistance is quite different, as OP mentioned I got 23 ohms on my ZDX motor and 3 ohms on my accord TB motor
- The gears, both on the motors and the plastic one inside the TB are identical
- The large gear that is attached to the TB shaft is identical between them
- The pick-up sensor, attached to the center of the gear on top (you can see the two tiny spots and the black electronic bit has a round sensor that slips into the spot to pick-up the reading of the moving shaft) appears identical. The plates or magnets on the shaft are in identical spots, it's either an inductive (magnetic) proximity sensor or capacitive.
My symptoms after the swap...
- Starting car idle jumps to 1500rpm and then after a second or so drops down to 800 rpm where it normally idles at.
- Shifting between gears there is a tiny delay before RPMs drop, hardly noticable and the car drives normally.
- If while driving I have the clutch in or put the car in neutral and am braking RPMs will drop to 1k and then go back up to 1500rpm, sometimes to 1800rpm, then back down to 1k rpm and then back up to 1500rpm. It does this as long as the car is moving. Once the car comes to a stop the RPMs drop to 800rpm where the car normally idles.
Not sure if anyone else has similar indications on their MT cars. I'm going to put the accord TPS sensor back onto the ZDX TB tomorrow, disconnect the battery re-do the idle learn and then take it for another test drive to see if it still does it.
I did just put in new runners as well and did a lot of work in there, so I'll check for a vacuum leak tomorrow as well.
My problem only seems to be at idle.
I did completely disassemble the TB as well and had it powder coated.
I guess worst case I'll drive around like this for a while and take apart the 3.5L TB, get the P2R adapter, have the 3.5L TB maxbored then powder coated when I get it back, re-assemble and just run a maxbored 3.5L TB with my mani setup.
well I couldn't sleep, so I went ahead and put the 3.5L Accord TPS sensor back onto the ZDX TB and gave it another go..
Car runs perfectly fine now, no rev hang, no RPM jumping up after I let off the gas pedal
So here's what was done..
6MT, 3.5L 2012 Honda Accord
ZDX Throttle body
-- Has the drive motor from the 3.5L accord throttle body inside of it
-- Has the TPS sensor (black thing on the side) from the 3.5L accord throttle body on it
TL-SHAWD Intake Manifold gasket matched
Outlaw thermoblock spacer
Ported & Polished lower fuel runners
Car runs perfectly fine, no issues. I'll get a video of it tomorrow.
So if you have the ZDX TB + TL-SHAWD IM combo and you still have your old TB then give swapping the electric motor and TPS sensor over a try and then do the idle re-learn. Should fix your problem. It's an easy swap if you have the torx bits with the little hole in the center and a phillips screw driver to remove the motor from the TB.
You should be able to do it with the TB still in the car as well, I was able to, it would be easier if it's removed but then you'll need a new gasket and have to mess with the air intake.
Make sure you get the washer under the electric motor as well, there should only be one it's some type of bent compression washer. Sometimes it comes out attached to the electric motor from the magnets in the motor and other times it may be left in the throttle body. Just make sure you don't have 2x of them in one throttle body, in case maybe one got left behind and the other came out with the motor haha..
Now if only I had powder coated my IM gloss black instead of wrinkle red...
Make sure all electrical items (a/c, audio, lights, etc) are off.
Reset the ECM/PCM (pulling the power by unplugging the battery works well).
Turn the ignition switch ON (II), and wait 2 seconds.
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).
Let the engine idle for about 5 minutes with the throttle closed. (NOTE: if the fan comes on, do not include its running time in the 5 minutes.
The only problem I can think of with some of them is that the TPS is held to the throttle body in a slightly different manner as is the case with the 3.2L TB that has some like metal clip things holding it on rather than the torx screws.
I'd just compare parts as you disassemble, make sure things are the same size.
The screw head type (Philips vs torx) shouldn't matter so long as the thread and length are the same, only that the screw head itself is small enough to fit and large enough to do its job hold the part in. Looking at the photos, I'd guess it's the same screw (thread) just with different types of heads on it.
I would match the screw with the TB that it came with and not the motor, since it's the TB that has the matting threads, just in case the threads are different between the different TBs.
In other words, whatever screws the TB comes with, keep them there, swap only the part itself (DC motor).
That's true it really doesn't explain why the autos don't have the problem.
I do kind of understand why it's having an issue though. If you look at the schematics from OP's first post on the Hondata forum the ECM is receiving the TPS voltage from the TPS sensors. In my case I thought the TPS was identical, but it wasn't the car had problems withthe ZDX TPS on the TB while using the DC motor out of the Accord TB. My guess is that the resistance of the sensors themselves used inside of the TPS must be slightly different, giving the ECM a different reading for the TPS voltage based on the position of the TB shaft. Some reason it was enough for the car to still run the throttle body, but it had issues during shifts or while braking / having the clutch in and my foot off the accelerator. I think if it was datalogged now the TPS voltages would probably be pretty similar to what they were with the original TB installed.
So basically the ECU drives the motor until the TPS is at the corresponding voltage for the position of the throttle body shaft. The ECU obviously has a way to learn it'd idle position or find the proper idle, as if done improperly (AC is running or you engage the PS pump) then RPMs dip while driving if your foot comes off the gas pedal and you're braking. I've seen that problem a few times when I had my TL.
I think it just handles the idle differently. In my manual I noticed the RPM goes up a little when it returns to it's idle position before passing the 1k RPM mark after having the gas pedal pressed. When I had problems with the ZDX TPS it was trying to do the same thing, but the bounce up was a lot bigger and if the car was still moving then it would continually bounce off of the 1k RPM mark and essentially hunt between 1k and 2k RPM until the car came to a stop. At which point it would settle down to 800 RPM, so some of the car's other sensors must be playing in as well, probably the wheel speed sensors and the VSA system.
I think the auto just controls the TB differently during shifts or while braking. No clue really why it didn't show any signs of problems though on the auto cars other than that the ECU is just programmed to handle the TB in a different manner.
Very nice. Now I can consider this mod again, once funds are available lol
to be honest I'm curious if this works for anyone else, it looks like the motor dimensions may be slightly different on the older throttle bodies and the TPS sensors mount to the throttle bodies differently on the older cars
also after about two days I had an erratic idle again and had to hook up my HIM and use some old HDS software to do an ECM reset and then re-do the idle learn procedure
my accord evidently keeps the old idle learn pattern even when the battery is disconnected, so I actually had to use the HDS in order blank out the old idle learn and do the idle learn procedure
since I did that I haven't had any issues though and it's been over a week now still running the ZDX throttle body with the electronics from the accord throttle body
05-15-2015, 02:40 PM
problem solved
