Sensor And other questions...

Hip Midship · 05-28-2008, 06:02 PM

Hey guys, I have a '91 MR2 N/A. And i have a slight
problem... I have no temperature reading on the
dash... do you guys know where the sensor is? I
thought it might be the one pictured, but not sure...
If any one knows where the sensor is located and could
share the location, that'd be sweet.

And another thing... I have a high idle problem...(who
doesn't) but yeah its pretty annoying... That and my
car is running really rich. Really rich, meaning its
blowing white smoke out the pipes. It doesn't smell
like coolant. And its not blue so it cant be oil.
Another giveaway is that I'm getting pretty awesome
gas mileage (Sarcasm)... Even though I like the Idea
of a mobile Fog Machine... I'd be happier if I was
able to be seen.

The guy i bought it from said that he replaced the
Plugs, Distributor Cap and Rotor, and i just replaced
the O2 sensor and Coolant sensor.

What do you guys think? I just bought the car. I love
MR2's. My brother has one and he got me hooked. They
are amazing cars. I love everything about them. And
i'd REALLY love mine if i could get it running right.

Hopefully some one will be able to Shed some light on
it.

Thanks,

surfer8 · 05-28-2008, 08:31 PM

I have similar problems, I recently cleaned my Idle Speed Control Valve and it had a dramatic effect on the high Idle. My ISCV was stuck open. Carb cleaner worked well. It can also be adjusted to close completely by loosening two little screws on the intake side of the Throttle Body. There is a pretty good test procedure in the BGB somewhere around FI 144.

Mine still isn't right, but it's running much better now and the idle is around 700 RPM.

surfer8 · 05-28-2008, 08:37 PM

From the picture it looks like you are missing the Cold Start Injector Timer Switch. I think it's supposed to add more fuel when the engine is cold. I'm not sure what happens if you unplug it, but it probably isn't good.

I'm pretty new at this also, anything I tell you could be wrong.

RideMR2 · 05-28-2008, 10:01 PM

Welcome to the forums.

If you have really rich fuel problems, check your map sensor vacuum line, it can slip off, or have cracks in it. It is mounted at the very back of the engine bay, near the trunk, and easy to spot.

Your high idle could be any one of a number of problems, many realted to oil leaks, and the throttle body being gunked up. The Idle Speed Control Valve could also be the problem, as surfer8 mentioned.

You can also try this thread for more help.

Things to do when you first get your MR2 NA

Gairloch · 05-29-2008, 07:04 AM

If you're not getting a temperature reading and you've replaced the coolant sensors then it's time to pull out a multimeter and see if there's a short in the harness.

Regarding the idle, have you looked for vacuum leaks? Unfortunately there are tons of potential causes for high idle so you want to start with the easist to deal with and go from there with your testing.

Check the vacuum lines, the easiest way to do this is by waving an unlit propane torch slowly over the vacuum lines. If you have a leak the engine will rev when it sucks the gas in.

Also check the throttle body. Pull the intake pipe off and you will see a little hole there, the ISCV (Idle Speed Control Valve). Plug it with a finger, the engine should bog. If it doesn't then it's getting air from somewhere else. Check the butterfly valve and make sure it's closing properly. It should be touching the neck of the TB but not closing hard enough to dig in. If it's not closing then you can adjust it's position with the throttle stop screw. This is a tiny little thing that you will be able to find if you rotate the throttle a couple times and watch where it stops.

Good luck!

Hip Midship · 05-29-2008, 10:34 PM

Thanks to every one for the quick replies!

Ok, so I took off my Throttle body today and oh my gosh... It was absolutely caked with crud. I guess its Oil? Idk... whatever it is, it's nasty. So should I remove the whole intake manifold and clean it out? Or should I just clean the throttle body? I'm guessing that it might be a good time to replace the Vacuum Lines, since they are pretty dirty, too.

I just bought the car. It has almost 200,000mi. What else do you guys think i should do to get it running better?

05-28-2008, 06:02 PM	#1 (permalink)
Hip Midship No Skills Join Date: Jun 2007 Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Sensor And other questions... Hey guys, I have a '91 MR2 N/A. And i have a slight problem... I have no temperature reading on the dash... do you guys know where the sensor is? I thought it might be the one pictured, but not sure... If any one knows where the sensor is located and could share the location, that'd be sweet. And another thing... I have a high idle problem...(who doesn't) but yeah its pretty annoying... That and my car is running really rich. Really rich, meaning its blowing white smoke out the pipes. It doesn't smell like coolant. And its not blue so it cant be oil. Another giveaway is that I'm getting pretty awesome gas mileage (Sarcasm)... Even though I like the Idea of a mobile Fog Machine... I'd be happier if I was able to be seen. The guy i bought it from said that he replaced the Plugs, Distributor Cap and Rotor, and i just replaced the O2 sensor and Coolant sensor. What do you guys think? I just bought the car. I love MR2's. My brother has one and he got me hooked. They are amazing cars. I love everything about them. And i'd REALLY love mine if i could get it running right. Hopefully some one will be able to Shed some light on it. Thanks,

05-28-2008, 08:37 PM	#3 (permalink)
surfer8 tenacity Join Date: Mar 2008 Location: SE Indiana Posts: 102 Thanks: 4 Thanked 3 Times in 3 Posts iTrader Rating: (2/100% )	From the picture it looks like you are missing the Cold Start Injector Timer Switch. I think it's supposed to add more fuel when the engine is cold. I'm not sure what happens if you unplug it, but it probably isn't good. I'm pretty new at this also, anything I tell you could be wrong. Last edited by surfer8; 05-28-2008 at 08:38 PM. Reason: spelling

05-29-2008, 07:04 AM	#5 (permalink)
Gairloch Dreaming of apexes Join Date: Aug 2005 Location: Minneapolis, MN Posts: 4,426 Thanks: 114 Thanked 219 Times in 192 Posts My Google Map iTrader Rating: (7/100% )	If you're not getting a temperature reading and you've replaced the coolant sensors then it's time to pull out a multimeter and see if there's a short in the harness. Regarding the idle, have you looked for vacuum leaks? Unfortunately there are tons of potential causes for high idle so you want to start with the easist to deal with and go from there with your testing. Check the vacuum lines, the easiest way to do this is by waving an unlit propane torch slowly over the vacuum lines. If you have a leak the engine will rev when it sucks the gas in. Also check the throttle body. Pull the intake pipe off and you will see a little hole there, the ISCV (Idle Speed Control Valve). Plug it with a finger, the engine should bog. If it doesn't then it's getting air from somewhere else. Check the butterfly valve and make sure it's closing properly. It should be touching the neck of the TB but not closing hard enough to dig in. If it's not closing then you can adjust it's position with the throttle stop screw. This is a tiny little thing that you will be able to find if you rotate the throttle a couple times and watch where it stops. Good luck! __________________ "Inside the car, the world beyond the driver's immediate horizon ceases to exist. Alone with the solitude of his desire, survival sense numbed by the speed, he's outrun the mediocrity of the outside world, slipped the shackles it tries to clamp on us all. He is running free, chased only by a fear of failure, for failure is to risk ejection into the real world." ~Mark Hughes

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05-28-2008, 08:31 PM	#2 (permalink)
surfer8 tenacity Join Date: Mar 2008 Location: SE Indiana Posts: 102 Thanks: 4 Thanked 3 Times in 3 Posts iTrader Rating: (2/100% )	I have similar problems, I recently cleaned my Idle Speed Control Valve and it had a dramatic effect on the high Idle. My ISCV was stuck open. Carb cleaner worked well. It can also be adjusted to close completely by loosening two little screws on the intake side of the Throttle Body. There is a pretty good test procedure in the BGB somewhere around FI 144. Mine still isn't right, but it's running much better now and the idle is around 700 RPM.

05-28-2008, 10:01 PM	#4 (permalink)
RideMR2 No Skills Join Date: Sep 2006 Posts: 31 Thanks: 1 Thanked 2 Times in 2 Posts iTrader Rating: (1/100% )	Welcome to the forums. If you have really rich fuel problems, check your map sensor vacuum line, it can slip off, or have cracks in it. It is mounted at the very back of the engine bay, near the trunk, and easy to spot. Your high idle could be any one of a number of problems, many realted to oil leaks, and the throttle body being gunked up. The Idle Speed Control Valve could also be the problem, as surfer8 mentioned. You can also try this thread for more help. Things to do when you first get your MR2 NA

05-29-2008, 10:34 PM	#6 (permalink)
Hip Midship No Skills Join Date: Jun 2007 Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Thanks to every one for the quick replies! Ok, so I took off my Throttle body today and oh my gosh... It was absolutely caked with crud. I guess its Oil? Idk... whatever it is, it's nasty. So should I remove the whole intake manifold and clean it out? Or should I just clean the throttle body? I'm guessing that it might be a good time to replace the Vacuum Lines, since they are pretty dirty, too. I just bought the car. It has almost 200,000mi. What else do you guys think i should do to get it running better?