Jump to content

Wrx throttle body slow to close


Justin Gorder

Recommended Posts

2006 wrx project car, the throttle body will only work on setup mode because the throttle plate is so slow to close it errors out in seconds. I think my wiring is messed up but I'm not sure how, i hooked a multimeter up to the ethrottle +/- and watched as i opened and closed the throttle. I was getting almost up to 8v when i would wap the throttle then it would level out to just under 2v at wot, when closing it seemed to go to 0v pretty quick but maybe not fast enough. I've been trying to figure this out for weeks but can't figure it out any help would be greatly appreciated.

log 1.png

pid.png

Link to comment
Share on other sites

Yeah i figured. Ive attached logs and tune. Keep in mind that there may be some weird settings in the tune, im trying to learn how to tune myself. I plan on taking it to a tuner eventually but for now im trying my best. If you see any other settings in the tune that look wildly wrong please point them out so i can work on fixing them. Edit: I have a WRX107x V10 ecu

Tune 1.pclx PC Datalog - 2022-04-24 6;05;52 pm.llgx PC Datalog - 2022-04-24 6;04;41 pm.llgx

Link to comment
Share on other sites

That is very weird, I cant come up with much logic that would explain what we are seeing here.

If you set the E-throttle relay 1 (ign 8) to "none", does the throttle blade spring return by itself to the almost closed position? - about say 6-10%?  

Can you check the voltage again at the throttle motor.  The voltage at the motor should roughly relate to displayed Ethrottle Motor DC % x battery voltage.  So if ecu is showing -90% DC to hold the throttle closed, then you should see about 90% x 12V  = 10.8V at the motor.  When its showing +90% it would be the same voltage just the +/- is reversed.  So it shouldnt be showing "0V" when closed, if it is that would maybe suggest a bad crimp or something that is limiting current.  

Link to comment
Share on other sites

So, I did some more multimeter testing and am having a hard time understanding the results, so I'll just explain what I did as thoroughly as possible. First, if I hold the throttle open and then change ign 8 to none the throttle blade closes but I wouldn't say it springs closed it closes at the same rate it did in the logs. 

With the multimeter I put the positive lead on the Ethrottle + and negative lead on Ethrottle - and got around 1V.

Positive lead on Ethrottle + and negative lead on battery ground i got around 1V

Positive lead on Ethrottle - and negative lead on battery ground around 0.8V

Car at 12v and throttle blade closed for all of these tests, I repeated the tests on the ethrottle wires in the ecu harness and got the same voltage numbers respectively.

I think the wires are fine, but could there be something limiting the voltage in the throttle body itself? or in the ecu? or the ethrottle relay?

Link to comment
Share on other sites

Yes, constantly varying from about -89 DC to -93 DC and voltage varying from .85v to 1.02v 

Some codes I’m also getting that might help narrow down the problem:

84: aux9/10 under voltage

71: aux 9/10 supply 

72: analog 5v supply

Seems like it might be having a problem getting enough power to the ecu or ethrottle relay.

Link to comment
Share on other sites

I did some more looking through the logs and found that the aux supply and 5v supply seem to be fine. But i found that aux 10 (ethrottle -) is always at 100% duty cycle and that aux 9 (ethrottle +) changes from 0%-70% following the Ethrottle Dc. So, at ethrottle dc = -28.6  Aux 10 = 100% and Aux 9 =71.4% 

To me this still doesn't seem to explain why its closing so slowly but is just another indicator that something is wrong. 

Link to comment
Share on other sites

In that case I think it would be worth getting it back to Link for an inspection.  At -90% I would expect one output to be at 12V and the other to be near 0V. 

Hard to imagine how faulty hardware could cause that but I cant come up with any other logic to explain those voltages.  

Link to comment
Share on other sites

Send an email to tech@linkecu and tell them the E-throttle hardware is suspected faulty.  You could give them a link to this thread so they have an idea of the troubleshooting you have done so far.  They will give you instructions for return.  

Link to comment
Share on other sites

  • 2 months later...

I sent the ecu in for inspection and they said that they couldn't find any fault in the e throttle hardware. But plugging it back in i have the same exact problem, throttle blade is perfectly responsive when opening but letting off the pedal it takes its sweet time to close. 

Just as a recap I've tried a new throttle body, I've also tried bypassing all factory wiring and went straight from the ecu to the throttle with no improvement. I just verified that the ecu is in fact getting 12v from the e throttle relay.

So now I'm completely lost again as it seems that ecu is getting power correctly and is just not outputting correct voltages, but the ecu has nothing wrong with it. Any ideas are useful this is making no sense to me. 

Screenshot 2022-07-31 130306.png

Link to comment
Share on other sites

I just compared it to mine.. 05 sti pedal.. and mine runs at ~4.6V when at 100% TP..  ~1.0V at Idle (7% TP)

Not sure how much that would differ between 05 and 06.. and how much of an impact it would have.. but something that caught my eye..

 

Link to comment
Share on other sites

I have a Subaru throttle body on mine, and the TP tracks AP with the tiniest of delays.

It looks like from the log that you're not actually driving the throttle home. It's almost as though you've one of the throttle's "Motor" pins connected to ground, rather than the Aux output on the ECU?

Link to comment
Share on other sites

Yeah it is very odd that it can move quickly in one direction and not in the other.  It is nothing to do with your pedal that was mentioned earlier so forget about swapping that.  

I discussed your case with Simon yesterday who is our most experienced tech, like me he couldnt think of an external issue that would cause the low voltage output you appear to have here, we feel there is still possibly an ecu issue here that we missed.  We looked over the testing that was done to your ecu when it came back and although extensive, there are possibly a couple of failure scenarios where the testing we done may not have loaded the outputs enough and could have missed the problem.   

Before asking you to send it in again, can you give us a bit more background (since you called it a project car)...

  1. Is it a matched engine/chassis/loom?  ie not a DBW engine in a non DBW chassis etc?
  2. The voltage measurements that you done earlier - I assume you done at the throttle body.  Can you repeat at the ecu end (you might have to use a pin or backprobe to reach the terminal.  
  3. Have you tried another throttle? 

 

 

Link to comment
Share on other sites

On 8/1/2022 at 3:58 AM, Confused said:

I have a Subaru throttle body on mine, and the TP tracks AP with the tiniest of delays.

It looks like from the log that you're not actually driving the throttle home. It's almost as though you've one of the throttle's "Motor" pins connected to ground, rather than the Aux output on the ECU?

This is what I had thought from the beginning and was the first thing I checked and since then I've been getting all my voltage readings from back probing the ecu. However taking a closer look at the entire wire again I found one of my connectors was a pin off, causing the clamping voltage to never reach the throttle.

I'm happy to say that the throttle now responds fine when closing, almost too fast. Thank you to everyone for the input, and sorry for not double checking the more obvious things earlier. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...