unstable idle

quarkhimself · Post by **quarkhimself** » Thu May 29, 2014 2:00 pm

is this a test for the fitv or the iacv ? my fitv is located on the lower side of the throttle body and my iacv is located on the front side of the intake manifold.

Post by **Merlin** » Thu May 29, 2014 2:01 pm

It is s test of your IACV.

quarkhimself · Post by **quarkhimself** » Thu May 29, 2014 6:57 pm

ok so i did exactly like in the video, and the engine tries to stall like you said. i can hear a pop sound when i remove my finger.the idle only starts to go up an down after i touch the throttle, could it be related to the TPS ?

Post by **SPYDOR** » Thu May 29, 2014 7:11 pm

As I understand it you can simply disconnect the TPS connector and see if you still have the problem as that quickly tells you if it is causing the issue.

Cutz · Post by **Cutz** » Thu May 29, 2014 7:30 pm

quarkhimself wrote:i got the iacv out and cleaned it, it was quite dirty and now is really clean.i also had another look at the fitv, that plastic thing was tightened all the way, so i turned it 3/4 of a turn loose.i also removed the radio fuse for about 5 minutes.put everything back together and the temperature gauge reaches the half point without any troubles, but as soon as i touch the throttle it starts to go up and down again. this time it seems i made some kind of small progress because it only happens when hot after i touch the throttle and it seems like it goes from around 700-1200 instead of 700-1500.could this be related to the TPS ? is there anything i can do to test or fix the TPS ?

before you proceed any further check your Throttle Position Sensor...

get out your multimeter (i'm assuming you have one).

measure the voltage between D11 (red/black) & D22 (green/white) on your ECU -- they are both on same multiplug going to the ECU.

With the ignition on and foot off the throttle you should read 0.5v on the multimeter. with your foot flat to the floor it shoud read 4.5v.

as you slowly touch the throttle the reading will go up SMOOTHLY from 0.5v to 4.5v accross the throttle range.

if the reading jumps at all or your start or ending voltages are different you may very well have problems.

if the TPS is out of range i.e. it reads 0.3v to 4.3v then you will need to loosen it from the throttle body and rotate it slowly until it reads right....only problem is you need to take the voltage readings AT THE ECU, otherwise your reading might be slightly off and defeats the whole object of trying to sort it.

hope that helps

Post by **SPYDOR** » Thu May 29, 2014 9:17 pm

Cutz wrote:only problem is you need to take the voltage readings AT THE ECU, otherwise your reading might be slightly off and defeats the whole object of trying to sort it.

What do you mean by 'AT THE ECU' exactly? I tested mine recently by following a guide which showed them fitting a wire/paperclip into the positive middle wire on the TPS connector and grounding the other wire elsewhere.

FYI My readings were 0.029v closed and 0.273v WOT which is nowhere near what is it supposed to be.

I also tested the map sensor just to make sure they had not been swapped somehow. Before you ask, I know how to use my multimeter correctly...

No idea why the readings are so strange on mine but not worried as it works great and the readings show correctly on my Apexi AFC.

Cutz · Post by **Cutz** » Thu May 29, 2014 10:10 pm

SPYDOR wrote:
Cutz wrote:only problem is you need to take the voltage readings AT THE ECU, otherwise your reading might be slightly off and defeats the whole object of trying to sort it.
What do you mean by 'AT THE ECU' exactly? I tested mine recently by following a guide which showed them fitting a wire/paperclip into the positive middle wire on the TPS connector and grounding the other wire elsewhere.

FYI My readings were 0.029v closed and 0.273v WOT which is nowhere near what is it supposed to be. I also tested the map sensor just to make sure they had not been swapped somehow. Before you ask, I know how to use my multimeter correctly...

No idea why the readings are so strange on mine but not worried as it works great and the readings show correctly on my Apexi AFC.

the reason why you test it at the ECU is that you need to find out exactly what voltage the ECU is seeing.

if you test for voltage at the sensor, then you are not taking into consideration the internal wire resistance from ECU to sensor. i.e. if you test at sensor and set it to 0.5v by the time it gets to the ECU it could only be 0.4v or lower...you need a reference point to set the sensor from.

I've got a H22A swap in my EK civic which involved extending the engine wiring harness by at least 30cm...so i knew there wasa possiblity some sensors wouldn't be reading quite true, generally its not a problem but with the TPS it is.

e.g. the ECU sees 0.50v as the TPS being @ 0%, so if the ECU sees 0.43v instead of 0.50v it will assumes the TPS is approx -4% (negative figure), this can play havoc with your ECU because the sensor is outside it's predefined limits.

make sense?

Cutz · Post by **Cutz** » Thu May 29, 2014 10:11 pm

I've got an Apexi Power FC aswell myself.

Post by **SPYDOR** » Thu May 29, 2014 10:15 pm

Ahh, I see what you mean now, clears that up nicely, cheers. I was reading at the sensor when I did mine, no idea why my readings were so strange though! Hopefully quarkhimself will have better results!

quarkhimself · Post by **quarkhimself** » Sat May 31, 2014 12:22 am

i don't have a multimeter, never used one.i'll get the exhaust leak and the cam belt done soon, if that doesn't fix the problem i may try to replace the whole throttle body, looks easier to do instead of just replacing the TPS.