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sprinkles08, ASE Certified Technician
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Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Acura RSX Type-S: Have a question regarding my 2003 RSX Type

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Have a question regarding my 2003 RSX Type S with a very high idle. Somewhere around 3500-4000 almost right after start up. I saw you answered a smiliar issue and wondered if you could help me out?

Hello and welcome to JustAnswer!


For the idle to be that high it is very likely a vacuum leak.


Hopefully you made sure that the IAC moved freely when it was apart for cleaning. A bad IAC could cause this, but that's pretty high for the IAC to be causing it.


It could be a very high signal voltage from the throttle position sensor, but again it's pretty high for that. Unplugging the TPS would bring the idle down if it was causing it.


You don't mention how you checked for vacuum leaks but I'm assuming you at least did a visual inspection and found nothing.


What I would recommend is covering the throttle body opening with a piece of cardboard and see if the engine dies. If it stays running then it's receiving air from somewhere else between the throttle body and cylinder head, if it stays running then you know for sure there is a leak.


Obviously hoses that are off or damaged, the throttle body or intake gasket could cause this. On the bottom of the intake in front there is a plate bolted on that runs almost the span of the intake and this is sealed with a gasket. This gasket may be where your leak is and it may be something that was overlooked when checking for leaks.

Customer: replied 3 years ago.

I checked the IAC it wouldn't move freely at all. I managed to get the end off and begin turning it. At first it would barely move at all, after lubing and cleaning it today it started moving pretty freely. I re-installed and got a much lower idle. However it still sometimes creeps up to about 3000 RPM. Also when accelerating, the car stops accelerating at around 4500-5000 RPM like a rev limiter. Would these two issues be related?


I checked for vacuum leaks by spraying carb cleaner in the engine by over certain hoses where and where the intake is and the throttle did not return to normal so I assumed that to be my leak. Also as the car has some aftermarket mods, I took it to a tuning shop. They found a small vacuum leak and repaired it and they could not find anything else. I will check with the cardboard trick and see what happens.

With it running that fast you won't likely notice much of a difference when running carb cleaner over small or moderately sized leaks. It sounds like the IAC may need to be replaced but let's try the cardboard first to ensure there aren't any leaks going undetected.
Customer: replied 3 years ago.

Okay, I will throw the TB on tomorrow and test with cardboard to see. IF not can I replace the IAC without changing the TB or will I need a new TB?

You can replace the IAC by itself if necessary.
Customer: replied 3 years ago.

Good news. I'll be in touch tomorrow to let you know how my TB test goes.

Sounds great!
sprinkles08 and 11 other Car Specialists are ready to help you
Customer: replied 3 years ago.

Just wanted to ask you also if the acceleration cut out at 4500-5000 RPM would be cause by the sensor issue or if it is unrelated?

Is that while driving or in park/neutral? There will be a lower rev limiter if you are in park or neutral.
Customer: replied 3 years ago.

No while idling in neutral I can rev it all the way to redline. While driving it cuts out while accelerating under load.

Are any codes setting?

Customer: replied 3 years ago.

It has a rear O2 sensor code which I have ordered. Prior to taking the throttlebody off the first time it did not do this. After reinstalling the TB it started.

Customer: replied 3 years ago.

I have an O2 sensor code which and I have ordered the sensor. Prior to taking the throttle body off the first time it did not have this issue. It only started after reinstalling the throttlebody the first time.

I'd go ahead and get the idle issue repaired first then and see if that takes care of everything. If not then we'll have to dig deeper on the acceleration problem. If you do have a large vacuum leak then it may be seeing that and inducing a lower rev limiter for safety/self preservation.

Customer: replied 3 years ago.

Okay, I'll do that cardboard test today when I get the chance and see if that makes any difference and let you know. If not I'll wait until I have the new sensor installed next week and get back to you.

Sounds great!

Customer: replied 3 years ago.
Alright, just did the cardboard test and the car does die when I cover the throttlebody with cardboard, so no vacuum leaks..
Did you unplug the throttle position sensor with it running to see if idle came down? If it doesn't then I'd go ahead with replacing the IAC that we know has issues.

Customer: replied 3 years ago.
The idle does come down but now it's surging between 1100 and 2000 rpm.
It came down with the TPS unplugged? If the throttle blade is closing all the way and idle comes down with the TPS unplugged then we have a TPS problem.
Customer: replied 3 years ago.
Throttle is closed, idle is down, when I plug the tps back in the idle goes up again. I can't see the butterfly valve in the TB move at all, it is constantly closed.
We definitely have a bad TPS then.

Customer: replied 3 years ago.
Okay so I should order one of those as well?
Yes, if the idle comes down when unplugging the TPS we definitely need to replace it.
Customer: replied 3 years ago.
Can it be replaced without replacing the TB? It looks almost riveted into the TB.
Actually no, I just double checked and the TPS is serviced as an assembly with the throttle body.

Customer: replied 3 years ago.
So I need to buy a new TB then.... That's unfortunate.
Yes, it is but the price I'm showing isn't very expensive at all.

Customer: replied 3 years ago.
It looks like I can get one off of eBay guaranteed with warranty for 6 months. That night be the best option.
That may be the cheapest way to go and I'd definitely recommend something with a warranty.
Customer: replied 3 years ago.

Alright so... I got a new throttlebody and installed it. The car wont even start now. Do you have any idea why? It came off of a wrecked RSX-S which would have had to be running as it was in an accident and was totaled. The car now just cranks but wont run. If I put the old one on with the bad sensors it runs as we discussed before but has that power cutout at 4-5 thousand RPM. I assume there's no way the throttlebody is somehow programed to the car.

With the new throttle body in place will it start if you open the throttle?
Customer: replied 3 years ago.
It runs extremely rough and almost stalling. Pretty well just puttering if I hold it open all the way. I can smell gas fumes quite a bit as well if I keep it open.
Do you have a voltmeter?

Customer: replied 3 years ago.
I think I do somewhere... Are u thinking of testing the sensors? Does it sound like this new throttlebody is defective? I also used gasket maker to out the new one on as I didn't have a gasket.. Would that effect it?
Did you use RTV silicone or something like that? That shouldn't be an issue as long as passages didn't get plugged.
Customer: replied 3 years ago.
I was pretty careful not to cover anything. I used a gasket maker from an auto parts place that I have used before. Any ideas??
If you can dig out the voltmeter I'd like to check the voltage on the center throttle position sensor wire with the key on, both on the replacement throttle body and the old one. I'm thinking you may have a bad TPS in this throttle body.
Customer: replied 3 years ago.
Okay. I'm not sure how to check the voltage. Can you reply explaining to me how and I will do it tonight when I get back?


Ground the black lead of your voltmeter and set the meter to the 20v DC scale.


Turn the key on.


Insert a straightened paperclip into the back side of the connector on the center wire of the TPS, push it in until it makes contact with the terminal.


Touch the red meter lead to the paperclip and read the voltage.


Let's do this for both throttle bodies, you don't have to completely install the old one, just plug it in.



Customer: replied 3 years ago.
Why would the other throttle body still allow it to run if the tps on that one is not working either?
I'm wanting to compare the reading on the replacement throttle body to the old one to see if the voltage is much higher on the replacement, in which case it will think the throttle is open further than it is.

Customer: replied 3 years ago.
I'm a bit confused as to where the paper up goes.. Can't seem to get a good reading
If you can't get a good connection with the paperclip then you can pierce the wire if you want, just make sure the hole gets sealed when we're done.
Customer: replied 3 years ago.
Okay so we have done that. We got no voltage on the middle but we did get 5 on the left side. When we touched the middle with the pin and the red one and grounded the black there was 0 voltage. Only got five with the left side wire. Not sure what to make of it. Same result in both throttle bodies.
With the throttle body unplugged is the wire shorted to ground? You would set the meter to the 200 ohm scale and touch the red lead to it just the same

Customer: replied 3 years ago.
Alright so I've connected the clip back into the back of the plugin from the car, disconnected from the TB set to 200ohm and get no reading. As soon as I set it to OHM a 1 appears before connecting it. After connecting it and grounding the black while apyong the red lead to the pin the 1 remains.. No change.
With the TPS unplugged and key on, what voltage do you see if you put each meter lead on the outside wires in the connector?
Customer: replied 3 years ago.
Not sure if I'm doing it right but I can't seem to get a reading.

You'd set the meter to 20v DC, unplug the sensor and turn the key on. Place each meter lead on one outside wire in the connector and read the voltage shown on the meter.



Customer: replied 3 years ago.
It reads 4.97 volts.

That's what we wanted to see.


Is the center wire shorted to ground?

Customer: replied 3 years ago.
Do you mean the actual wire itself? It's hard to tell because it immediately goes into the wire covers it's the other two..

Does it show resistance to ground using your voltmeter? It should show an open circuit.



Customer: replied 3 years ago.
With the center wire hooked to connected to red lead and the black lead grounded I don't see anything chane. It just says 1 on the screen all the time whether it's connected or not while on OHM's. Dont get any reading on 20V at all. Is that what we're looking for?
Yes, that's what we're looking for. We've verified that the sensor ground and reference voltage are ok and we've just verified that the signal wire isn't shorted to ground. You didn't see any voltage on it when backprobing and that tells us the TPS isn't working and creating a signal.

Customer: replied 3 years ago.
So the TPS on the new throttle body isn't working either? Wow this is annoying. Fortunately it had a guarantee though. So whats the next step? Go find another throttlebody? It's weird that two throttle bodies te car wouldn't run or even start, and the original it runs but doesn't run properly..
It does look that way. If it was working then you should have seen voltage on the center wire in the TPS connector with it plugged in. It sounds like it's time to find another throttle body.

Customer: replied 3 years ago.
Alright I will find another one and let you know.
Sounds great!

Customer: replied 3 years ago.
Just though I would mention that with this throttle body hooked up that isn't running I get code P1519 which I believe is IACV. Is this correct? Could that be the issue with this new throttle body I got?
Yes, that's an IAC code. If you only see that code with this throttle body then there's a definite problem there too. The IAC can prevent it from starting with the throttle closed but you shoudl be able to start the engine by opening the throttle.

Customer: replied 3 years ago.
Yea even opening the throttle doesn't do it.. Is it worth swapping the IACV from the other one that the car runs with to see if it works? Or I guess since we are sure that the TPS doesn't work that doesn't matter...?
Yes, you can definitely try swapping the IAC if you want. It may at least start and idle that way.

Customer: replied 3 years ago.
I'll give that a try and let you know.

Customer: replied 3 years ago.
Alright so the other iacv it's pretty well rusted tight and I could not et it off to swap it out. Do you think I should order one and swap it to see if that helps? In the meantime I did out the original TB on the car and as before it starts, revs high and then revs higher as it warms up. Still seems to be in limp mode as it cuts out around 4500 rpm. Not sure if that's related or not.

It's going to have a low rev limiter in park and neutral so that's probably what you're seeing there.


We definitely have an IAC issue so it wouldn't hurt to get one coming in the mean time.



Customer: replied 3 years ago.
Okay I will order a new IACV
Customer: replied 3 years ago.
Although I am not getting a iac code you think I still need one?
Yes, if the IAC is rusted and doesn't move freely then it definitely needs to be replaced. Usually the only time a bad IAC will set a code is if it fails electrically.

Customer: replied 3 years ago.
Oh well it isn't failed on the one that's on it now. Only on the one that I got that I returned because the car wouldn't start with it on. I'm back to square one with the original and high revs with limp mode engaged for some reason.
It sounds like we're just back to needing another throttle body because of the bad TPS then, correct?

Customer: replied 3 years ago.
I think so. Ill look at ordering another.

Customer: replied 3 years ago.
So I took the car to Acura and figured it would be good just to get someone to look quickly. So they called and said they got it idling normally now. Apparently the throttle cables were adjusted way too short . They're sayin however that There is still the power cut out or limp mode... Any ideas?
Did they look into the TPS signal issue?

Customer: replied 3 years ago.
They said they didn't want to diagnose any throttle body issues because it would be a big charge. I'm ordering another TB. We'll see how that works.
Let's get the TPS signal issue figured out and go from there. I think that should take care of the rest of the issues. I don't quite understand why they wouldn't look at that part of it.

Customer: replied 3 years ago.

Yea I'm not sure... They just said in order to do that they would have to take the TB apart and that would cost hours in labor so they recommended exactly what we were doing.. finding one used to see. Also said I should find somebody with the same car and swap TB's to see if it runs better with a TB I know works..

I wouldn't have expected them to take a non serviceable component apart for testing, usually you would test the wiring in a case like this which we have already done, the distinct advantage they have is a scan tool to be able to look at the actual TPS signal voltage. Maybe they were just busy!

Customer: replied 3 years ago.

I'm not sure... That may be the case. They called and it seemed they already assumed I wouldn't want anymore work done. The car is also turbo'd and they said their guess is it's something with the hondada kpro system and turbo and not TB. Even though I told them that it had no power cut out before I took the TB off for the first time and after putting it back on it had power cut out..

The aftermarket stuff on the car may be what deterred them from wanting to dig deeper on the other issue. Let's hope the throttle body takes care of it!

Customer: replied 3 years ago.

Yep I'm hoping. I'm order one tomorrow that will be in next week and we'll see how that goes. If it doesn't solve it then I can only assume it's a tuning issue. Although I think it should solve it seeing as it was fun until I took the TB off the first time to try and solve the idling issue.

Keep your fingers crossed and let me know how it goes!

Customer: replied 3 years ago.
Alright so the idle is normal now after picking up the car from Acura. Still the power cut out at around 4500 though. Not sure what to do now. They said there are too many unknown variables to diagnose and suggest it isn't tuned properly. Also it says they checked the idle air control in the duty cycle and it appeared normal. At least be car finally idles correctly. Now just need to figure out this power cutting out issue...

Does it feel like it's hitting a rev limiter when this happens? It does happen while driving and not just at idle, correct?

What all modifications does the powertrain have?

Did this start right after any modification or work was done?

Customer: replied 3 years ago.
It started happening after I took off and re installed the TB the first time. It has a Greddy turbo and intercooler as well as a hondata kpro computer. It does feel like it's hitting a limiter when you're driving however only under load. At idle it revs all the way to redline.
With the engine off can you have a helper hold the throttle open while you check to see if the blade is opening fully?

Customer: replied 3 years ago.

Throttle is opening all the way

Do you have a way to check fuel pressure?