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Old 07-04-2005, 07:44 PM   #1
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Hunting Idle!!!!

I hope someone out in forum land can help me!! I have a 2000 Boxster which I have been having problems with the idle stabilizing. I have taken the car to Pioneer centres in San Diego twice where they have not been able to fix a thing. Black Forest also located in SD thought the car may have vacum leaks which it did not they also recomended that I replace the MAF which I did, still no luck. I have spent nearly $800 and have not had any luck fixing the problem. I do have an EVOMS high flow intake which I do not believe is the issue but I can not be sure. Can anyone help??

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Old 07-05-2005, 06:52 AM   #2
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How unstable are we talking?

I have fixed this issue in the past (believe it or not) with a can of Chevron FI cleaner with Techron.

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Old 07-05-2005, 11:20 AM   #3
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It's cheap, low labor diagnostics! "It might be.... We'll replace that part and if that's not it, we'll go to the next part?". I don't blame him for guessing because most people would choke if he said "I'll figure out exactly what it is before I replace anything. It could be one of 8 different things so it will take me about 4-8 hours to figure it out and you will have to pay me for those hours."

If a mechanic ever replaces parts when diagnosing your problems make sure he gives you the part that was taken out just in case he's wrong. Most parts are pretty darn expensive (especially a MAF) and you have a replacement for later when something really happens or you can sell it on eBay.

When you say you're having trouble with the idle stabilizing, are you talking about a steady up and down movement in RPMs or an erratic movement? What is the range in RPM that it fluctuates between? With your first description, and not looking at anything, I'd say vacuum or sensor too.

Next, how much do you want to get into it? You can do most diagnostics yourself, but it can take a good bit of time and you need a few tools. The tools are 1/3 of what you've spent so far so it's worth it if you are interested in learning the inner workings of your Boxster.

Start cheap like Brucelee suggests with the Techron FI cleaner then go from there.
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Old 07-05-2005, 02:17 PM   #4
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Quote:
Originally Posted by Brucelee
How unstable are we talking?

I have fixed this issue in the past (believe it or not) with a can of Chevron FI cleaner with Techron.

Bruce can I pick a can of the Chevrom with Techron stuff at any automotive store??
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Old 07-05-2005, 02:34 PM   #5
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Quote:
Originally Posted by deliriousga
It's cheap, low labor diagnostics! "It might be.... We'll replace that part and if that's not it, we'll go to the next part?". I don't blame him for guessing because most people would choke if he said "I'll figure out exactly what it is before I replace anything. It could be one of 8 different things so it will take me about 4-8 hours to figure it out and you will have to pay me for those hours."

If a mechanic ever replaces parts when diagnosing your problems make sure he gives you the part that was taken out just in case he's wrong. Most parts are pretty darn expensive (especially a MAF) and you have a replacement for later when something really happens or you can sell it on eBay.

When you say you're having trouble with the idle stabilizing, are you talking about a steady up and down movement in RPMs or an erratic movement? What is the range in RPM that it fluctuates between? With your first description, and not looking at anything, I'd say vacuum or sensor too.

Next, how much do you want to get into it? You can do most diagnostics yourself, but it can take a good bit of time and you need a few tools. The tools are 1/3 of what you've spent so far so it's worth it if you are interested in learning the inner workings of your Boxster.

Start cheap like Brucelee suggests with the Techron FI cleaner then go from there.
I will start with the Techron additive and then go to the next step.

The idle fluctuates between 500-900 rpm. It never really goes any lower or higher then that.

At this point I really just want the car FIXED!! I am really tired of not having the car work at its best caliber. I know that when I write to the forum I am always able to get the right answers.
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Old 07-05-2005, 06:13 PM   #6
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You should be able to find the FI cleaner at most auto stores. I buy it by the carton at Costco, as I have a fleet to maintain.
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Old 07-05-2005, 07:59 PM   #7
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Hopefully the Techron takes care of it. If the first tank doesn't do it, use it fill-up. Depending on how dirty the injectors are, it can take a bit to clean them up.

If it's not normal after two tanks then hope for the "check engine" light with a sensor code that lets you know what's going on.

Good luck!
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Old 07-05-2005, 11:13 PM   #8
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We had an egas and non egas car with this problem at a work on cars day. We cleaned the carbon out of the throttle body. I have not talked to the owners since then to see if that fixed the problem.
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Old 07-06-2005, 05:31 AM   #9
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BTW-regular use of Chevron gas will keep the FI clean. Here in Kalifornia, we have crap gas. This is the only brand I use now.

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Old 07-06-2005, 08:22 AM   #10
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I am going to buy a bottle of the Chevron FI cleaner today. I hope that this takes care of the issue. I love the car but this erraditic idle is driving me nuts!!
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Old 07-08-2005, 06:06 PM   #11
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If in fact the spray doesn't work, heres an idea....I've had some idle headaches myself on my 98'.....Three parts took to solve the problem: 1) Idle regulator valve, 2) Fuel regulator valve and 3) Vent line.....When you remove the engine cover you will see a plastic tube (about an inch thick) that makes a U-turn from the throttle body to the oil separator unit (that's your Vent Line), attached to the end of this line and to the throttle body are the Idle regulator and right under that is the fuel regulator....replacing these parts did it for me along with the gas filter under the car. Good Luck!!
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Old 07-18-2005, 06:00 AM   #12
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how much were the parts?
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Old 07-19-2005, 01:57 PM   #13
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I had a very similar problem about 6 months ago. I to have the EVO High Flow Air Intake System and which I have been running for over a year now. Great Sound! Anyway I was getting the very same bouncing up and down idle but, no check engine lights??? Well I took some time and reopened the engine compartment to find that one of the clams that hold the tubs together had somehow come loose? I installed it myself and I made sure it was all tight but, I guess it came loose anyway. I reconnected the loose pipe where extra air was getting in and the problem went away.

Recheck all your connection up to the throttle body, sounds like a vacume leak.
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Old 07-20-2005, 09:35 AM   #14
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guys, I have done the Chevron additive and gas, put in the new MAF and tightened up my intake making sure all is snug and no leaks. The idle regulator seems fine, I believe this to be true because when I have a cold start the car does not have the "hunting idle" issue until it warms up. anymore suggestions???
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Old 07-20-2005, 12:01 PM   #15
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Quote:
Originally Posted by psuball1
guys, I have done the Chevron additive and gas, put in the new MAF and tightened up my intake making sure all is snug and no leaks. The idle regulator seems fine, I believe this to be true because when I have a cold start the car does not have the "hunting idle" issue until it warms up. anymore suggestions???
Unfortunately you're getting to a point of replacing parts if you don't have any diagnostics tools. If you really want to get into it, the AutoTap does a great job with reading the sensors while the engine is running. They have two types, one that connects to a computer through USB and the other connects to a Palm device. Great product for $180. http://www.autotap.com It's not a miricle worker though. You have to take a little time to learn how to understand the readings it gives you.

There are several things that can cause the changing idle. Most often it's a vacuum leak or bad PCV valve. Next is O2 sensor. Next is bad MAF sensor. Basically sensors that adjust the fuel/air ratio. Then there are other sensors that are much less likely to cause that problem, like the knock sensor, but it is possible. The easiest way to figure it out is to plug it in and see what is changing as it goes up and down. Otherwise you just have to start swapping parts.

O2 sensor swaps can help and I think they are pretty easy to replace on the Boxster. If you decide to replace them, start with the ones before the cats. Buy just one and pick the one to replace. Keep the old one and see if it takes care of the problem. If not, swap the one you took out with the next one. If neither fixes it, go to the O2 sensors after the cats and do the same thing. Check because I think the after sensors are different from the before. If none of that works, don't worry, O2 sensors only last about 100K miles so you have replacements for the future.

Other than that, without any kind of readings it's a guessing game.

Good luck!
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Old 07-21-2005, 10:15 AM   #16
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The O2 sensors are next on the list. If the check engine light does not come on is it still possible to have a defective O2 sensor? Is there a way to check them?
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Old 07-21-2005, 11:35 AM   #17
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Quote:
Originally Posted by psuball1
The O2 sensors are next on the list. If the check engine light does not come on is it still possible to have a defective O2 sensor? Is there a way to check them?
Yes, it is possible. The only way to check the sensor is to plug into the OBD system and read the output of the sensors. They change their voltage output to change the volume of air in the fuel/air mix. You have to see if the output voltage is going up and down along with the up and down changes in the idle. AutoTap does those readings.
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Old 09-20-2005, 05:16 PM   #18
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Hey,
I've had the same problem now for a while.

I have a 2000. boxster.

I noticed though if I turn on the A/C, the idle fluctuations are minimized...a lot.

I've only noticed it after the car warms up.

During the winter months in Atlanta, I didn't appear to have had the problem.

Also, it doesn't happen every day and I get no dash lights stating there is anything wrong.

I hope this info is useful. If it continues I guess I'll seek the dealer.

Regards,
Will
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Old 09-21-2005, 05:30 AM   #19
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Quote:
Originally Posted by willcapp
Hey,
I've had the same problem now for a while.

I have a 2000. boxster.

I noticed though if I turn on the A/C, the idle fluctuations are minimized...a lot.

I've only noticed it after the car warms up.

During the winter months in Atlanta, I didn't appear to have had the problem.

Also, it doesn't happen every day and I get no dash lights stating there is anything wrong.

I hope this info is useful. If it continues I guess I'll seek the dealer.

Regards,
Will
Where are you in Atlanta? I'd be happy to plug in my AutoTap OBDII program record all of the sensor readings to see what's up. If it's a sensor, it can create the problem but not give any lights because it's still within the limits set by the computer. AutoTap reads each sensor and reports the voltage output or resistance, depending on the sensor. Then you can compare the readings to normal and see what's up.

I'm on the north side (GA 400 corridor) in Cumming. Let me know if you want to get together and I'll try to help if I can.

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