I replaced my TPS and calibrated by following this guide : http://honda-tech.com/tech-misc-15/diy-calibrating-voltage-tps-2947986/
I could not achieve 0.5v at closed throttle so i adjusted the idle screw to bring up to spec. now my idle is high at 1500rpm. I also readjusted the throttle cable. Do you think i have it too tight? how else can i achieve spec at 0.5v closed throttle without adjusting the idle screw?
Thanks
The way that guy does it in the how-to you linked is completely wrong. You should never adjust the throttle stop screw to attempt to get the tps voltage in spec. Any change in calibration should be done by loosening the two little bolts holding the tps to the throttle body and pivoting the sensor. You should also be attempting to set the idle spec (throttle plate closed) first and checking the WOT position just as a check to verify you have full range of reading on the sensor.
By adjusting the throttle plate stop screw you’re actually changing where the the throttle plate will stop when the throttle is released and in this case probably causing your high idle (throttle plate not fully closing/vacuum leak). I would suggest trying to get the screw back to it’s original setting, set the idle using the FSM, and start over on the TPS calibration. Were you trying to get the tps in spec with the throttle cable installed or with it removed?
At first I had set the TPS by closed throttle to 0.5v but every time I WOT I would only get 4.04. So I looked up if I missed something and found the thread mentioning to set at WOT first to 4.5 then use idle stop screw to adjust closed throttle.
I will have to put everything back to original setting and start over. Luckily I remember what my closed voltage is at when I setup open throttle to 4.5.
After much research I see that it’s not important to get open throttle in spec as I should be calibrating for closed throttle to 0.5.
I had the throttle cable attached when calibrating. Sorry what is FSM?
FSM is the Factory Servive Manual. You can download them online for free or purchase hard copys from helmsinc. Extremely valuable tool if you’re working on your own car. I would consider it the best tool to have if performing almost any job on your car. Get a copy!
I would suggest getting the throttle plate screw back to its original location before doing anything else. Usually they have a yellow paint mark from the factory to help line it up correctly. They are set at the factory and should never be moved.
I would say the WOT voltage isn’t as important as the idle voltage but you should be seeing something close to the expected voltage at WOT or you’ll probably run lean at WOT as the ECU bases its fuel delivery partially on information it gathers from the TPS. At WOT it will ignore the O2 and dump more fuel. I would say the spec at idle is more important though because you will probably be spending more time at idle than WOT. If the TPS is out of spec it can actually cause high idle, bogging, and all kinds of other driveabilty issues.
When I calibrate a TPS I disconnect the throttle cable so the TPS actually recognizes that the throttle is in a closed position and then reinstall the throttle cable and follow the base idle procedure from the service manual. It can be touchy, don’t get discouraged!
oh yea i have a service manual.
i regret messing with that screw. :bang:
so i brought the screw back in place. recalibrated the TPS to 0.48v and WOT was actually to 4.5v. replaced throttle body gasket while at it. now idle is hovering around 1000rpm to 900rpm. after headlight and AC on, it drops to about 800rpm but doesnt stay steady. it bounces from 800-900rpm and randomly it would dip below 700rpm and bounces back to 900rpm. I give it a quick rev to 2k rpm and it would drop idle down to 600rpm and almost stalling out. I do this a couple times and it would drop like its about to stall out.
I covered the throttle body with my hand and it stalls right away so i dont think i have a vacuum leak. I gave up on finding out what the culprit was so i started driving home. when letting off throttle to a coast in neutral, rpm is at 1100rpm to 1000rpm. when it comes to a stop, it would drop to 900rpm. again, it would bounce 800-900rpm.
what could this issue be? it wasnt like this before messing with the TPS. i only took out the throttle body to replace the TPS. I didnt mess with FITV or IACV.
I read a couple forums and says to clean the FITV if having rough idle. If i didnt have rough idle to begin with before calibrating TPS, can the FITV be an issue? what else can i check?
That idle issue resembles my own before calibrating my tps. Mine was only .03 volts out of spec and it would do similar idle hang-ups and high idle at times (almost always). I think it is due to the ecu trying to compensate using the iacv and it can never get the spec it’s looking for. Might be worth trying to calibrate it again, I know it’s a pita but once I got exactly .50 I eliminated my idle issue completely.
It’s also a possibility that the idle plate screw isn’t exactly where it was before and is allowing a tiny bit of air through the throttle plate while the ecu thinks it’s fully closed. You pretty confident it’s exactly where it was before?
i cant say it is 100% back into stock position on the throttle stop screw, but i used the tps reading as a guide. i remember before messing with the screw, i set my WOT at 4.5v, closed throttle would show 0.37v. thats when i messed with the screw per the HT instructions to raise the screw to show 0.5v. so i backed it down to 0.37v, but i kept doubting myself if that is correct. I looked online and there are infos here and there saying to back out the screw all the way, then screw in to touch, once touched, turn in a little more until you hear a little ‘pop’. the little pop is suppose to signify that the butterfly is unstuck.
my current TPS reading is 0.494v and WOT is 4.55v. i didnt think the hundredth value would make a difference, but i will try to calibrate it again to get it to exact 0.500v.
on another note, when i turn on headlights/AC, i remember seeing the idle use to raise, but now it drops. the IACV suppose to help raise the idle when there is load right? air could’ve been in the system from removing the coolant lines under the throttle body. does this sound like a symptom of air in cooling system causing the IACV to not work properly?
Did your throttle plate set screw have a spot of yellow paint on it from the factory? If it did I would use that to line it up in its original location. If not, unfortunately I don’t know a better way than the way you already did it. I don’t know how good of an idea I think that popping the plate idea is though. Seems like it could potentially damage it.
.494 is pretty darn close to .50. I’m not sure if .006 volts has much if any effect on the tps. I don’t know how sensitive the tps is to thousands of a volt.
With the car warmed up if you cover the two ports leading to the fitv and iacv does the idle drop at all? If it does, to what rpm? Does it stall?
Bubbles in the coolant system can cause idle issues too. If you have any doubt if it’s completely bled, can’t hurt to bleed it again.
I know how frustrating these idle issues can be. I’ve had a couple different cars with the surging/high idle and they can be a PITA to figure out. Just gotta be methodical and patient. Very patient… lol
Maybe someone can use a feeler gauge to see what’s the gap size from butterfly to throttle body. Someone’s gotta mess with this screw before! How would a technician bring back to spec? This is so frustrating! Haha
I am completely stumped. I took off the throttle body again to check on the screw to see if I can see any paint left, but its all gone. While I was at it, I took off the FITV and cleaned it. Recalibrated the TPS and got it spot on 0.500v and WOT at 4.64v. Put everything back and started the car cold. idle seems steady at 900rpm but then it should be much higher because of cold start. It doesn’t surge/bog. I let it warm up and idle still at 900rpm. Tapped the throttle a little to see if rpm will drop and it did go down to 600rpm. Then it goes back to the bogging up and down idle from 800-900rpm. I have no idea what to check now.
isn’t there an ecu reset that needs to be performed?
So before you had a consistent high idle that would begin surging when the engine warmed up. And now you have a low idle on startup and still surging when warm?
When you cleaned the fitv did you tighten down the white internall ring? If you did, it’s possible you overtightened it and it’s not allowing air to pass through the valve and raise engine rpm. I’m just spitballing ideas here. I think you should try running the engine with the intake off and check for vacuum at both ports in the throttle body while the engine is idling and surging and see if you can determine what you have going on with the air bypassing the throttle plate.
i did that the first time and idle will still bounce after warmed up.
[QUOTE=rollinmyda;2330959]So before you had a consistent high idle that would begin surging when the engine warmed up. And now you have a low idle on startup and still surging when warm?
When you cleaned the fitv did you tighten down the white internall ring? If you did, it’s possible you overtightened it and it’s not allowing air to pass through the valve and raise engine rpm. I’m just spitballing ideas here. I think you should try running the engine with the intake off and check for vacuum at both ports in the throttle body while the engine is idling and surging and see if you can determine what you have going on with the air bypassing the throttle plate.[/QUOTE]
yea, low idle at startup now.
when i cleaned the FITV, i tightened down the white ring, but backed it out maybe 1 turns. so its not tightened all the way down. ive been troubleshooting with intake off. i was able to stall out the engine by putting my hand over the throttle body which essentially be the same as covering the 2 holes?
im at SEMA for the rest of the week so i wont be able to get back to the car. trying to gather and research more ideas on how to smooth out idle.
[QUOTE=polobreaka;2330960]ive been troubleshooting with intake off. i was able to stall out the engine by putting my hand over the throttle body which essentially be the same as covering the 2 holes?
[/QUOTE]
Not necessarily. If you block the whole throttle body opening you are blocking all 3 sources of air entering the intake manifold. Covering the throttle body opening, the IACV port, and the FITV port together should cause the engine to stall. By performing that test you’re eliminating the chance that you have a vacuum leak elsewhere before the cylinder head. By plugging one or both of the bypass ports you can see how the engine responds to the missing vacuum boost to eliminate that the throttle plate is misadjusted which is a possibility in this case since the throttle plate stop screw has been moved.
It’s also beneficial because you can see which component (iacv or fitv) is causing the vacuum leak that’s causing the surging condition. I would guess that it’s the ECU activating the IACV but speculating is pretty pointless.
I have a similar situation where I can easily stall my car by blocking the TB, but even with the fast idle valve blocked off on the side of the manifold, I still feel vacuum at the lower port inside the TB.
Short version: I have a mystery leak inside the TB or TB gasket I can’t seem to fix.
I’m thinking about just getting a new manifold and TB anyway, which is the main reason I have not found the energy to fix it.
So covering the IACV hole, then engine stalls. If covering the FITV hole, I feel vacuum but doesn’t stall. This is performed with engine warmed up.
The rpm drops significantly when you cover the IACV port or the engine shuts off completely?
engine shuts off completely when covering the IACV hole.
i thought after warmed up, the FITV shouldnt have a strong vacuum? if any, it should be very minimal to none right? i also readjusted the FITV by backing out the white cap even more. cold ilde is at 1400rpm, then slowly drops down as it warms up.
Yeah I don’t think the engine should die completely with the IACV port covered. It’s been a while since I’ve done that test but I believe the idle should just drop to the base idle rpm with that port plugged. Maybe the throttle plate is still misadjusted. I never had an idle issue on any of my da/dbs, only on my accord and civic which are obd2 so I can’t really comment on the FITV vacuum. If your throttle plate is completely shut the FITVs bypassed air may be the only thing keeping the engine running.
just read that if engine stall when IACV port is blocked then IACV is working.
I still need to bleed the cooling system to see if it will help with idle.