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Car idles at 3000+ RPMs in park, even after new IAC


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kiwasabi
User

Jan 11, 2014, 5:02 PM

Post #1 of 43 (2519 views)
Car idles at 3000+ RPMs in park, even after new IAC Sign In

2001 Mitsubishi Eclipse GS 4 Cylinder 2.4L
160k miles

Hey all,

New to this forum, hoping someone can help. Been having an issue with my 2001 Eclipse GS idling too high. In park it wants to idle at 3000+ RPMs, never settling below that. When I put it into drive it goes down to 1500, and that's the lowest it wants to go. I tried putting in a brand in IAC valve and sure enough, that fixed it...for about 10 minutes. It was idling at about 700-800 like it should. Then it was idling in drive at 1200, then at 1500 again.

One thing I checked was that the throttle body properly springs back into place, which it does. Although it does almost seem like the car is accelerating when it shouldn't be. I have to fight that when I'm braking and I can barely stop the car. The other day I was actually having to use the E-brake just to stop and even then it was very challenging. So obviously I can't drive the car right now. I've disconnected the battery several times to get the ECU to reset but with the same result. Why would it work the first drive after installing the new IAC and go back to the same problem thereafter? Very frustrated at the moment and hopefully someone can shed some light on this.

Adam


Discretesignals
Ultimate Carjunky / Moderator
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Jan 11, 2014, 5:28 PM

Post #2 of 43 (2515 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Are there any trouble codes stored in the engine computer? If so, write them down.

Have you checked for vacuum leaks?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


kiwasabi
User

Jan 11, 2014, 9:26 PM

Post #3 of 43 (2498 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Unfortunately there are no error codes. Haven't checked for vacuum leaks just yet, planning to tomorrow.


Hammer Time
Ultimate Carjunky / Moderator
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Jan 12, 2014, 6:03 AM

Post #4 of 43 (2491 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

You probably want to use a scan tool that has data stream and look at the values for the CTS and TPS and see if they are in normal range. The vacuum leaks are real important too.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kiwasabi
User

Jan 12, 2014, 6:17 AM

Post #5 of 43 (2488 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Thanks for the response. All the vacuum hoses look pretty new and intact but will look at them more thoroughly. A friend who specializes in Mitsubishi is coming by tomorrow so I will see if he has the scan tool you mentioned. Some users on the Club 3G also suggested checking to make sure the line to the throttle body isn't caught anywhere, although it seems that's all OK, there's plenty of slack. Someone also said the intake manifold could be cracked, will have to check that too. Hopefully it will be a cheap/easy fix but we will see.


(This post was edited by kiwasabi on Jan 12, 2014, 6:29 AM)


kiwasabi
User

Jan 12, 2014, 11:47 AM

Post #6 of 43 (2471 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

We're thinking the TPS is bad. If it were a vacuum leak there would most likely be a check engine light correct? I haven't seen one except possibly for a minute a few days ago. Here's what my mechanic friend said: "At this point I'm thinking tps is bad, the iac was working OK then after the tps was activated a few times it stuck."

So I'm thinking I'll order a new TPS and try replacing that. All the hoses looked fine and no check engine light. I can of course check with the carb cleaner though.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 12, 2014, 11:53 AM

Post #7 of 43 (2470 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

No, don't start throwing parts at it unless you are independently wealthy and don't need your money. If you want to spend some money, have someone diagnose it professionally.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kiwasabi
User

Jan 12, 2014, 12:19 PM

Post #8 of 43 (2466 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Well I don't have the scan tool you mentioned and a TPS is only $16 new on ebay. But yeah I can see where you're coming from since I just replaced the IAC and still have the same issue. I'm not a mechanic myself, I'm paying a friend to help out. But yeah at this point it's seeming like it would've been cheaper to just have it done by a professional.

link deleted ........... not allowed


(This post was edited by Hammer Time on Jan 12, 2014, 12:38 PM)


kiwasabi
User

Jan 12, 2014, 12:29 PM

Post #9 of 43 (2464 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Actually I guess my friend does have a scan tool so we can check the TPS percentages before getting the part. At this point I'm more concerned about the time lost waiting on a part arriving than on the $16 for it.


Hammer Time
Ultimate Carjunky / Moderator
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Jan 12, 2014, 12:40 PM

Post #10 of 43 (2458 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In


Quote
At this point I'm more concerned about the time lost waiting on a part arriving than on the $16 for it.


Then, why buy it from Ebay?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kiwasabi
User

Jan 12, 2014, 12:42 PM

Post #11 of 43 (2455 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

It's $142 locally at all the major part stores, $16 online. Was just saying it'd be better to diagnose beforehand like you said so as to not waste time. A junk yard is an option but I don't want to risk getting a bad part.


Hammer Time
Ultimate Carjunky / Moderator
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Jan 12, 2014, 12:47 PM

Post #12 of 43 (2453 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

I'm seeing them in the $50 to $70 range. I would be highly suspicious of anything on Ebay with that drastic a price difference.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
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Jan 12, 2014, 12:52 PM

Post #13 of 43 (2448 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Why not just test the TPS with a volt meter and save the trouble of replacing a perfectly good TPS?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


kiwasabi
User

Jan 12, 2014, 1:11 PM

Post #14 of 43 (2445 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Could you tell me how to check it with a multimeter and what to look for? I was talking to the guy at Advanced Auto Parts and he said the CTS was causing his V8 to idle too high so could be that too as you mentioned above.


Discretesignals
Ultimate Carjunky / Moderator
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Jan 12, 2014, 1:36 PM

Post #15 of 43 (2440 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

There are three wires going to your TPS sensor. The green/yellow is 5 volt reference from the engine controller, the yellow is signal circuit going to the engine controller, and the black is reference ground.

You want to connect your volt meter's black lead to battery negative and then back probe the TPS connector on the yellow wire with the ignition on.

- With the throttle valve in the idle position, voltage should be between 0.535 and 0.735 volts.
- With the throttle valve in the full-open position, voltage should be between 4.5 and 5.5 volts.

Very slowing open the throttle while watching your volt meter the voltage should climb in a linear fashion from the idle position voltage to the full throttle voltage.


Watch this for more information:

http://www.youtube.com/watch?v=8KfKfImoIXg





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


kiwasabi
User

Jan 18, 2014, 2:15 PM

Post #16 of 43 (2395 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Well it's not the TPS. I stubbornly replaced that and no change. So now I will actually diagnose the problem properly.

I'm looking at OBD II to USB VAG COM cables. Just want to verify that this will work with my 2001 Mitsubishi Eclipse GS 4 cylinder. Sounds like it works with any car with the OBD II protocol though:

Link deleted ................... not allowed


Also was looking into scan software to use. There's Evoscan which is specifically for Mitsubishis, it costs $25. Was wondering if anything free would get the job done such as this:

Link deleted


(This post was edited by Hammer Time on Jan 18, 2014, 5:46 PM)


kiwasabi
User

Jan 19, 2014, 11:21 AM

Post #17 of 43 (2383 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Alright I've got some actual info to go off of now. Disconnected the MAF sensor, the idle in park drops from 3000-3500 to ~1700-1800, which is still a little high. My question is should the idle drop even further with a good MAF connected? Or is there still another problem?

I tried hooking up an OBD II code reader to my car but it won't connect. A mechanic was over and he had the same trouble with his. From reading other threads it sounds like that's a bad fuse?

Also noticed the front of the motor smoking a bit...so that's alarming.


(This post was edited by kiwasabi on Jan 19, 2014, 11:24 AM)


Discretesignals
Ultimate Carjunky / Moderator
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Jan 19, 2014, 12:34 PM

Post #18 of 43 (2377 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Disconnecting the MAF sensor may be causing the PCM to default to a speed density configuration or causing it to revert to backup tables stored in memory. Doesn't necessary mean the MAF is the culprit. You can test the MAF sensor output, but you need an lab scope because the MAF generates a frequency type signal.

Check for battery voltage on pin 16 of the data link connector. If that is good, ohm check pins 4 and 5 to battery ground. Should be close to 0 ohms. If that checks out, you'll need a high end scan tool that is capable of communication with other modules in the vehicle to see if they are able to communicate. If communications isn't possible with anything on the vehicle using a more expensive scanner, then there is a data bus problem that needs to be diagnosed.

I believe you should consider having a drive-ability specialist that has experience with Mitsubishi systems check this out. The amount of time and money your wasting swapping parts could be saved by letting a pro diagnose it for you. When and if they determine the culprit, you can decide if you want to perform the fix on your own.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jan 19, 2014, 12:35 PM)


GC
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GC profile image

Jan 19, 2014, 12:35 PM

Post #19 of 43 (2372 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Unplugging the MAF doesnt tell you much. 1. Need to find out what is smoking. 2. Need to get communication through DLC. What did the code reader say when plugged in? Does check engine light prove out (come on for couple seconds then turn off) when you start the car? If yes, check fuse for DLC make sure its in good shape. If all looks good, you're probably gonna have to take it in for some diagnostics.


____________________________________________________
Willing to help, willing to learn... Rob


GC
User
GC profile image

Jan 19, 2014, 12:37 PM

Post #20 of 43 (2369 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

You win DS


____________________________________________________
Willing to help, willing to learn... Rob


kiwasabi
User

Jan 20, 2014, 2:05 PM

Post #21 of 43 (2356 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Discretesignals, thanks for the detailed reply. Unfortunately I have to be honest and say that stuff is really out of my realm of expertise and I think you're right that I need to have a professional look at it.

I forgot to mention that I had a spark plug melt/explode a month or 2 ago. My friend was able to get the metal out of the cylinder it seemed but maybe there was something that had already gotten pulled through the engine. I'm hoping not but am worrying that might be behind these problems.

"Unplugging the MAF doesnt tell you much. 1. Need to find out what is smoking. 2. Need to get communication through DLC. What did the code reader say when plugged in? Does check engine light prove out (come on for couple seconds then turn off) when you start the car? If yes, check fuse for DLC make sure its in good shape. If all looks good, you're probably gonna have to take it in for some diagnostics."

1. Another friend who is a former Mitsubishi mechanic was telling me that the smoke is probably just the MAF sensor and Throttlebody cleaner/sprays I used combusting. He said they tend to come out as a light gray or white smoke. So I'm hoping that's all that is. It did start after I cleaned both of those so I'm hoping that's what it is.

2. The code reader just kept saying, "Verify vehicle - ensure key is turned on". It wasn't talking to the car at all, and I ensured the connector was good and plugged in and that the car was powered on.

The Check Engine Light isn't turning off at this point. But it only started coming on when I disconnected and cleaned the MAF sensor. Before that I wasn't getting any kind of Check Engine Light when it was idling way too high which is what made me think the computer is very confused.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jan 20, 2014, 2:19 PM

Post #22 of 43 (2354 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

What! You had a plug explode leaving debris in a cylinder? How? Just one? Man before much else I'd be getting a scope to look thru plug hose to see what the heck things look like in there.

Just twice both were carbs and both people were holding choke open to "de-flood" engine and killed the whole engine with item going in, in both cases,

T



kiwasabi
User

Jan 20, 2014, 2:24 PM

Post #23 of 43 (2350 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

It was only one. They weren't the oldest plugs but they weren't super new, somewhere around a year and a half old. I parked on a hill facing up and didn't realize I was on ice. Had a hell of a time getting out of that spot, ended up putting down leaves to get traction and get out. Slipped around a bunch and the RPMs got really high. After that the cylinder wouldn't fire at all, so seems that's what did it.

My friend used a magnet to get the metal piece out, seemed he got everything...but very possible he didn't. So a scope would be a good idea.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jan 20, 2014, 2:34 PM

Post #24 of 43 (2346 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

Thread is getting long - sorry. I'd want to see inside now no matter how that happened. Many engines won't way over rev without load but who knows in the situation?

Still not funny but a hospital carpenter used a nail that got sucked/dropped in and surprisingly made it all the way. He had a medical scope. One good look and cyl. wall plus valve damaged beyond chance of fixing. Crappy old car so not the world but killed it, T


kiwasabi
User

Jan 23, 2014, 6:45 PM

Post #25 of 43 (2329 views)
Re: Car idles at 3000+ RPMs in park, even after new IAC Sign In

So my friend who was a Mitsubishi tech before going into the Army says he thinks it's a bad torque converter. Sound plausible?

Btw, just trying to narrow it down while I save up money to have it fixed. I'm going to be riding the bus for at least another couple weeks. Thanks for all the help thus far guys.






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