Idle bouncing warm & cold

[warsloop]

youtube.com/watch?v=TKuesPzp1Fs&feature=youtu.be

Hello everyone, I've a really nasty problem on my MR2 REV1 3SGE Since I remounted the throttle body and changed my radiator, i've got a bouncing idle. By my own research it can be the coolant not fully bleeded. I've also heard about the ISCV ?
Today I've tested the connector and it send 13-14V to the ISC valve.
Someone told me that air in the Throttle body coolant hose will "neutralize" the iscv??

BUT before i removed the coolant and the rocker cover, the idle was great. higher when cold and proportionaly decrease when warm. I've shot a video just above, if anyone can give me an advise on where to work on ? also i've see this post : mr2oc.com/60-normally-aspirated/190252-another-high-idle-thread-answers-not-questions.html but I dont know if the bouncing thing is related to this..
Also last thing to note is when I disconnected this pipe ( red elipse ) I feel a suction and when I place my hand to block it, the idle came back to normal ! In fact I feel it maybe a little high ( but i'm not really sure), but it dont bouncing anymore !!
drive.google.com/open?id=16ZVNBi-h3pBGWvVcvYX8cVKPN_1gV1AX

It's like whatever the engine is cold or warm nothing change, idle bounce and stay really high...

I've shoot another video when it's warmed up

youtu.be/89I7qtxlp1

any help will be greatly appreciated ! Thanks !

[oVerboost]

If you've removed and played with any throttle settings including removing the throttle body, I think there are some videos on YouTube or maybe someone with more info can add a link I can't find much - but there is something you need to do when playing around with the throttle body sometimes.

Did you connect everything back up the way it was? I know that's a daft question but compare your engine to online pictures of the vacuum pipes etc.

[warsloop]

Thanks for the answer.
Yes everything was checked..
If you mention the Throttle position sensor, it working great, no ecu diagnostic code 51 or whatever everything is fine..
The only thing I suspect is the idle switching control valve..
Whenever cold or warm engine, if I remove the 3 pin connector, nothing happened.. Same high and bouncing idle!
Someone told me like I said that the iscv can be "neutralized" If there is air in the coolant passage of the hose bottom of the Throttle body..
The air bleeding is a real pain, maybe because it's the first time I do it but it's a real pain..
All I just want to know is : can a bad bleeding of the coolant can do this kind of thing I have filmed in my video? Can a "simple" presence of air bubble anywhere can makes my idle high and bounce??

As I said, the tachometer is offsetet by like 800 rpm, so it bounce for real between 1700 and 1900

[Pauln]

I've had irregular idle issues in the past on my rev 2 turbo, but I must admit I've not seen my engine hunting quite so regularly as that.

I wouldn't have thought air in the coolant hose to the throttle body is causing this. Some folks have joined both hoses together to bypass the throttle body all together to avoid increasing the air intake temperature. I believe the throttle body is only connected to the cooling system to help in really cold climates.

I guess air in the coolant could cause a problem with the ECU temperature sensor not always being in the coolant. But I would have thought that would produce a more random hunt.

It is however worth checking that the coolant overflow tank is full as I've heard that can sometimes introduce air into the system if it's not.

Going back to the ISVC, the usual issue with this is that it gets gummed up and sticks. The fact that you can measure the voltage going to it doesn't prove it's actually opening and closing correctly, it just confirms that the circuit controlling it is operational.

But the bottom line is that if it wasn't doing this before it sounds like something hasn't been reconnected correctly or has gone out of adjustment, or been damaged.

Did you clean the throttle body while it was off including the small airway that bypass the butterfly, and was the butterfly closing fully without sticking or without leaving a gap around it?. Did you fit a new throttle body gasket?

The only other thing that I can think of that might impact on the idle speed is the idle up circuit. this increases the idle speed when the electrical load at idle increases, switching on aircon, heated rear windscreen etc. It might be worth checking the small bore rubber pipe between the two is connected correctly.

Paul

[warsloop]

Thanks Paul for the reply!

Others information I can give :
I removed the front air-conditioner radiator in front of the radiator but still there is the ac compressor in the back

Today I take the courage to remove the Throttle body itself completely to check everything I done
I checked the IACV valve (I guess it is iacv or iscv??) the yellow one fr underneath the Throttle body.
I managed to remove the 2 screw and the motor was rusted and blocked.. By using wd40, and a batterie I managed to test it.
First I blow air from my mouth to the tube below, air is coming thru meaning it is open
Then I connected middle pin to 12v and tested up pin, and blow no air passing! So the Iacv seemed to be working! I managed to de block it

So I was really happy and decided to mount everything back!
I started the engine and....
NOTHING has changed :'(
Even at cold or when I warm 10 min later nothing changed the idle was high and bouncy.....

Something I saw is the temp gauge in the dashboard never really got in the middle in fact it was a bit lower...

I tryed to make it Rev harder but without success... The temp not increased I believed even decreased...

Also its worth noting that when I tested the pin the ecu sent high voltage I think : 14 to 14.v volt is it not really high??

Also a video when warmed :
youtu.be/89I7qtxlp1o

Note that again the Rev is offset by like 800 rpm in fact it bounce between 1800 and 2000

I'm totally lost right now and angry at the same time..

[Pauln]

Sorry only just got back in from Cardiff.

Yes it's really called an ISC. To check this electrically, with the plug removed, you really need to check the resistance between the middle pin on the ISC body and each of the two outer pins. This should be around 19 - 23 ohms. I wouldn't worry too much about the voltage

But having re-read your original post, I missed the photo of the pipe you removed. It's a while since I had an NA, but looking at an old photo of my NA engine bay it looks as though that is the pipe to the VSV or the idle up valve I was talking about. I suggest you first try disconnecting the plug to this to see if that sorts out your fluctuating idle speed.

If it does, that suggests something is forcing it to open and close, or the valve is faulty. But if your idle has only been fluctuating since you remove your aircon rad, it's possible that this is the issue, and there may be a sensor somewhere that is now confused resulting in the VSV opening and closing> That's just a guess as I've never tried removing AC, I like my home comforts far too much.

If however you suspect the VSV is faulty, there is one easy check you can make.

With the plug disconnected try blowing into the outboard pipe on the valve (the one directly below the electrical socket) and check that no air is coming out of the other pipe. IE the valve is fully closed when power is off. If air is still leaking out of the second pipe, the valve is probably faulty.

If it's not the aircon rad removal and the VSV is operating correctly, I'm starting to run out of ideas. But from what you've said, the VSV is definitely worth checking.

Paul

[warsloop]

Thank you,

drive.google.com/file/d/1TR16LCY5-LtWOtNTioWFdSI4bxA4JG2V/view?usp=drivesdk

Where is the vsv did you mention?
Is this the one in orange above? If not what it is?? When I disconnected it nothing changed warm or cold

In fact, I bought this mr2 at 220.000km and mechanic speaking she works normal I mean idle speed working etc.. (acis actuator won't).
I just replaced the rocker cover, dizzy cap and rotor arm.
My radiator was leaking so I removed the ac radiator and main cooling radiator, let bleed the coolant etc..

That's all I can remember of..

As I said the IAC works now I mean it open or close properly on 12v order, does the ecu never give the order to close it?? Im in serious doubt..
Also no diagnostic code at all..

Also I managed to test my acis actuator vsv and it works, continuity is there and if I blow air it blocks and let pass back and forth.. But the actuator won't work either.. Even when I remove the vacuum hose I feel practically no vacuum.. Is the vacuum really strong I don't have any gauge to mesure but can we feel it by finger?

[Pauln]

Here's a photo of my old NA engine bay with what I believe is the idle up VSV in the red circle.



When the car is idling if this valve opens it allows some air to bypass the throttle butterfly to increase the idle speed slightly. Normally this is only opened when the aircon compressor is running, or you create a high electrical load by turning on something else like the rear windscreen defogger.

In your original post you said "I disconnected this pipe ( red elipse ) I feel a suction and when I place my hand to block it, the idle came back to normal !"

The pipe you blocked is the one that feeds air into the idle up VSV. If you felt suction that suggests that the idle up VSV must have been open allowing extra air to enter the intake and increase idle speed. By blocking this with your finger, you stopped that extra air entering the intake and the idle speed dropped.

With both pipes back on the idle up VSV, if you disconnect the electrical plug powering the valve it should close and the idle speed drop. If it does then the valve is OK, and the problem is that something is telling the ECU to open that valve.

If the idle speed doesn't drop when you disconnect the electrical plug, that suggests the valve is faulty and not shutting as it should.

My guess is that when you pull the plug out the valve will close and the idle speed will drop, just as it did when you put your finger over the pipe.

If that's true, you need to work out why the ECU is telling the valve to open. My best guess is that this is to do with removing the aircon radiator.

Hope that all makes sense.

Paul

[warsloop]

Hi Paul thanks for your help!

Today I give the mr2 a drive of around 27 km
The car feels way better than before, it revs really good even if the acis is always open( my actuator won't work either...)
But I know it's cold here like 11C and I removed the back grid of the engine so the engine is opened and cooled by the wind, but my temp gauge never going to middle. It stayed below 1 unit even if I really push it hard!
Which sensor send info to gauge? The one in the radiator? Or the thermostat?
Without this nasty idle it run really fine

[Pauln]

As you originally had aircon there should be two radiator temperature sensors at the front. These just control the two radiator fans.

In the engine compartment around the thermostat area there should be two temperature sensors. The green one is for the ECU, the other one is usually gray and is for the temperature gauge.

If the weather is cold and you've removed the tray inside the na engine lid to expose the complete grid it's possible the engine may be running on the cool side. Have you felt any of the coolant pipes after a hard run, if they are cooler than usual, the sensor may actually be OK. If they are as hot as you'd expect and the needle on the temperature gauge is never getting above the first division, then it could be the sensor is faulty or you have air in the coolant system. The tail tell sign of air in the system is that when you turn the engine off after a run you can hear bubbling from the engine compartment.

However, taking the inner tray off the engine lid may not be a very clever idea on an NA in the rain as you may find water getting on the alternator which will greatly shorten it's life.

When I had an NA, like a lot of other folks over here, I actually fitted a turbo engine lid as this offers better protection for the electrics in the rain. Mind you it does rain a lot here.

The other thing early mr2's are known for is leaking capacitors in the ECU. When this happens the gunk that come out of them start eating into the circuit board tracks which can cause no end of issues. Well worth whipping the cover off the ECU at some point to check, it's pretty easy to spot any gunk coming out the bottom of the capacitors, and if you catch it early enough you can just clean it up before it does any real damage and replace the capacitors. I've had this issue twice now, on my rev 2 turbo, and these days it's very hard to find a replacement rev 2 turbo ECU.
Paul

[warsloop]

Yea yea don't worry, I just don't mpoutned back the engine grid only for testing purpose! As it was sunny outside and I wouldn't drive it for too long that's why. Of course after I will use it I will definitely mount it back!
On my car I've only 1 temp sensor in the front radiator.. It definitely control the fan! I removed it tested it before I fill the coolant, and at some point the fan begin to do their job to cool down the radiator.

I will send a picture of my engine to show you what I had.
That's very weird, seems like the ecu thinks I'm always in cold state...
Do you have a picture of where is the sensor which send temp stat to ecu?
But shouldn't have I a diagnostic error code? I checked for error and the check engine blink for ever like 3 tile per second on diagnostic mode..
If I can't get this issue I won't have the choice but go to a garage to check it even if I'm a little confused..

[Pauln]

I've looked back at all my photos of my NA and can't find one that shows the temp sensor location as it's a bit tucked away. But here's a photo of my Turbo engine showing the two sensors. Hopefully that will help you find them on your NA, which probably has them in much the same location, but I'm afraid it's some year since I had an NA and can't really remember.



If you're still having problems finding them, show me a photo of your engine around the thermostat area and I'll try and point them out.

Paul

[warsloop]

PROBLEM SOLVED!!!!

IT WAS THE THROTTLE. BODY GASKET !

mine was a ajusa xxxx one too much thin and I replaced with the original one and it worked like a charm!!!

Also fixed the actuator!! It was a vacuum pipe broken
drive.google.com/file/d/1O-tGnyIgnSz7QqhB5ivrw11ygPbbSCX2/view?usp=drivesdk

The idle never bounce again! It is high cold and slowly decrease to around 950 1000 rpm!! Im so so happy!!

Thanks all for your help and hope that will help other people!!

[Pauln]

Wow, it looks like something was hungry and has been chewing at your pipework

Any way glad it's sorted.

Paul

[warsloop]

Yes Paul thank you very much for your help and tryingness!
Appreciated it!

[Draven]

Glad you got it sorted