Menu
What's new
By:
Advanced search...

How to test/clean Throttle Position Sensor and Throttle Body

-Rich-

-Rich-

Members
Messages
468
Reaction score
26
Location
Rickmansworth
Car
2.4 Tourer Auto
In my quest to find out what is wrong with the rpms dropping on my car and after alot of searching/reading I am convinced it is either the TPS or the sensor on the TB, if not the TB itself. The rpms only drop when I lift off the throttle, when I am accelerating or just keeping pressure on the pedal they don't drop and the car idles fine as well.

I have no codes or stored codes, I read them yesterday. I have an ODBII cable and use Scan XL but it only gives the throttle position reading and doesn't check the sensor itself, it wasn't available in the PID list.

This seems to be a very good guide on how to check the TPS sensor and I'm ***uming it's the same procedure for the sensor on the TB itself? Does the TB butterfly open with just the ignition on, I'm thinking it does cos the guide doesn't mention about starting the car?

I have cleaned the TB once before but while it was in situ so I am going to remove it this time to give it a thorough clean. Is there anything I shouldn't clean or areas I need to concentrate on?
 
TypeR said:
***uming you have eliminated a dirty IAC Valve?
Click to expand...
This is built into the throttle body I think so has already had a clean. Besides if this was the culprit I'm sure the rpms would be affected at idle as well?
 
Sounds silly but have you checked for slack in the accelerator cable?
 
F6HAD said:
Sounds silly but have you checked for slack in the accelerator cable?
Click to expand...
Yes I did that and took some slack out of it, which didn't make any difference apart from the car rolls forward more when in drive. I took some slack out of it, too much in fact cos the rpms started jumping from say 2k to 4k in one leap, rather than be progressive. I tightened it a fraction more, which stopped that but I've still got the dropping rpms when I lift off the throttle.

It drops to idle speed, around 650rpm and then rises again where it will stay put (with my foot off the pedal) until I press it again to open the throttle, lift off and it drops, this happens most of the time. It does it from low speed to around 50mph but seems ok after that.
 
You may need a throttle recalibration. I've done this before with my hds.. Where are you located?
 
F6HAD said:
You may need a throttle recalibration. I've done this before with my hds.. Where are you located?
Click to expand...
That's the first time I've heard this mentioned, does this recalibrate the TPS, the TB or both and what would cause it to un-calibrate?

This issue started about 3 weeks ago now out of the blue, was sweet as a nut before then and I didn't do anything before it happened. As you've mentioned HDS I take it I can't do this myself and I'm 200 miles from you :(

I'll strip everything down and clean it thoroughly this time, reset the ECU and do the idle learn procedure again but if that doesn't work I'll have to book it in somewhere. Last thing I needed TBH, got an expensive couple of months coming up as it is :(
 
Been doing some Googling and I came across this thread - http://www.pakwheels.com/forums/performance-modification-tune-up-preventive-maintenance/180157-attention-8th-generation-civic-3rd-generation-city-accord-owners-dbw-related

Now this problem started before I even touched the TB and other sensors but is there any truth in that, just cleaning the TB means you need it recalibrated?

I was actually going to remove it on Thursday and clean it inside out but I'm wondering if that's a good idea now? Could I make things worse?

After cleaning it in situ the idle was and still is fine once it had re-learned it, I only seem to have erratic rpms but then they only drop not rise as well.
 
I only know about the recalibration because I've done it on a k20 after a throttle body replacement.

I'm actually down south all week. Can't tell your location from my phone.
 
I have a couple of questions I don't think I've asked.

When I removed the TPS I noticed it is riveted to the throttle mechanism. Can this be removed to clean it internally, do they get dirty? I ***ume that as the pedal is pressed the cable pulls the mechanism, which turns something inside the sensor?

With the TB, when I cleaned it before I'm pretty sure the butterfly was not completely closing, there was a slight gap but I'm going to double check this and will try to get a photo. If air is getting in when it shouldn't be can this cause the rpms to drop?

Just to add the car has developed another symptom, the gear change has become notchy and I can feel it everytime.
 
Yep it turns the potentiometer

I don't believe you can split the rivets and take it apart. It's riveted and not bolted for a reason and probably ***embled to tight tolerance specifications..

Did you source a replacement APP sensor?

Not sure on the gap in the TPS but your error was specific to APP voltage low

Has the error returned since?
 
-Rich- said:
I have a couple of questions I don't think I've asked.

When I removed the TPS I noticed it is riveted to the throttle mechanism. Can this be removed to clean it internally, do they get dirty? I ***ume that as the pedal is pressed the cable pulls the mechanism, which turns something inside the sensor?

With the TB, when I cleaned it before I'm pretty sure the butterfly was not completely closing, there was a slight gap but I'm going to double check this and will try to get a photo. If air is getting in when it shouldn't be can this cause the rpms to drop?

Just to add the car has developed another symptom, the gear change has become notchy and I can feel it everytime.
Click to expand...
I think it should close but not 100% sure if its necessary. However I would think it should, that's when the idle valve takes over and regulates the air in take. Sometimes the flap can have carbon and dirt build up on the edges. Have a good look and see if you can clean it
 
F6HAD said:
Yep it turns the potentiometer

I don't believe you can split the rivets and take it apart. It's riveted and not bolted for a reason and probably ***embled to tight tolerance specifications..

Did you source a replacement APP sensor?

Not sure on the gap in the TPS but your error was specific to APP voltage low

Has the error returned since?
Click to expand...
No the error hasn't come back.

Hopefully found a couple of APP sensors that are a reasonable price but they all have different numbers stamped on them. I thought this was a part number but I'm thinking it's a serial number now?

TypeR said:
I think it should close but not 100% sure if its necessary. However I would think it should, that's when the idle valve takes over and regulates the air in take. Sometimes the flap can have carbon and dirt build up on the edges. Have a good look and see if you can clean it
Click to expand...
Some threads I've read for other cars say there should be a very slight gap, wide enough to get a sheet of paper in, which is about what mine is.

Fahad suggested I don't touch it again as it tested ok and cos it's electronically controlled I might mess it up forcing it open again. Unless there is a way I can get it to open without me touching it? The IACV is built into the TB but I'm not exactly sure of the location of it.
 
Just bought an APP sensor so hopefully I will have it in a few days - fingers crossed it is that!
 
Got the APP sensor yesterday, fitted it last night and so far the issue has gone :)

Sometimes when I lift off it drops slightly below where it should be, maybe 300-400rpm then rises again but our Civic does that as well so I think it's an auto thing. The rev counter is dropping progressively though, not jumping straight from 2k rpm to 650rpm!

There is one thing I've noticed over the last few weeks is that my idle speed keeps changing slightly, sometimes it's 600rpm others around 750rpm. Is this the ECU adjusting it as it learns or could the IACV need cleaning? I cleaned the TB on the Civic yesterday and noticed a small hole inside it, before the butterfly. So if this is the same on the Accord I could try cleaning this with some pipe cleaners or similar?
 
Good stuff and looks like re diagnostics was correct it was your APP all along.

The revs dropping could just be the aircon kicking in and out
 
The aircon isn't working so it's not that but I do have the radio and fans on, might be that.

It doesn't do it all the time, just occasionally it will drop to where it should be then blips slightly below before rising again. As I said the Civic does this as well so I don't think it's anything to be concerned about.

I can't even remember how it used to behave when I got the car as I never paid attention to the rev counter until I saw the noticeable drop I was getting.This issue has probably made me paranoid as well!
 
Just enjoy the car now mate
 
You must log in or register to reply here.
Top