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Discussion Starter · #1 ·
My 2000 Insight has been idling high for the past couple weeks (2500-3500 RPM). However, the idle always returns to normal when the transmission is in neutral and immediately when the speed drops to < 3 MPH. I have only owned this car for < 6 mo and I purchased it with a MIMA :):) which I'm still learning how to use effectively, but I would like to ask the experts of this forum their opinion.

I have checked that the MAP sensor has +5VDC and is grounded properly, but I haven't yet checked the sensor signal itself. Also, I will take the IAC valve a part this weekend to clean it, and check for vacuum leaks. Aside from this, I'm not certain what to try next?

Currently I have code P1128 set (MAP sensor signal)

Any advice would be greatly appreciated.
 

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2001 5S "Turbo"
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Do you mean as in............while de-accelerating from X speed to 3 mph with foot off gas pedal, or sitting there in gear.

PLEASE include your location in your profile.

THank You
Willie
 

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Discussion Starter · #3 ·
Willie,

Thanks for your reply. I left out a few key points.

The car behaves normally when in gear. The high RPM's only occur when the vehicle is > 3MPH AND the car is in Neutral (i.e. between shifts, coasting, etc).

I'm concerned that I may damage the clutch by engaging gears when the RPM is too high. The car is a 2000 Insight, with 170,000 miles. I have also replaced all 3 ground straps.

Thanks in advance,

H.D.
 

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HD
I would check the vacuum lines, especially at the throttle body and MAP sensor.
You might see them "splitting" on the ends.
Maybe even pull them off and clip off about 3/4-1" from the ends.

HTH
Willie
 

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I agree with Willie that you may have a vacuum leak. You can check for it by spraying engine starting fluid around the vacuum lines and or intake manifold and then look for a change in engine idle. If a leak is present, the starting fluid will cause a definite change when it gets sucked in to the engine

It would also be advisable to spray starting fluid around the brake master cylinder, where it bolts up to the power booster. There is a rubber gasket in there that helps seal it. A leaking brake master cylinder can let brake fluid deteriorate the seal causing a vacuum leak. This usually manifests itself with an immediate loss of power brake boost at AutoStop. It did in my case. HTH.
 

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Discussion Starter · #6 ·
Thanks for the suggestions everyone! I sprayed a liberal amount of starting fluid all around the hoses, and brake master cylinder with no success in finding the leak. The engine shoots to 4000 RPM with the clutch in and the vehicle is moving > 3 MPH. As soon as I hit 3 MPH, the idle returns to normal. Could this be an actual problem with the IAC valve? I haven't removed it yet.

I also checked all of the hoses and there doesn't appear to be any leaks.

I may put this up for sale if I can't find the leak soon, as I need it for primary vehicle transportation. It's equipped with a MIMA as well. I've spent several hours at this point.
 

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Maybe your ECU is going into some kind of loop?

I'd love to see a video of this. I assume autostop also doesn't work when braking down from say... 20 mph?
 

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Discussion Starter · #8 ·
I will try to post a video of the exact symptoms.

After this problem started occurring, I disabled the MIMA and IMA, so autostop will not function with my current setup. I have a separate issue with the IMA light coming on in extreme inside temps (90 deg F+).

I've read on other sites that may other vehicles can exhibit my same symptoms, and it's often due to the IAC valve or MAP sensor. I will try to remove the valve this weekend, but the location is less than optimal to get to.
 

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Wow that is weird and consistant. It actually spools up as you approach 3mph then drops immediately after.

I mean, speed shouldn't have any effect on the idle calculations, so... ???

All I can say is if it says the MAP is bad, try changing that and see what happens?

Sam
 

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Check and charge your 12V battery for a starter.
It looks light you have a problem with your IMA battery.
It also looks like one of your turn signal bulbs is out.

Need more history on the vehicle, mods, etc.

Willie
 

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ECU Reset / Idle recalibrate

A) Try disconnecting the 12V battery, reconnect after a few minutes wait and then drive the car.

The purpose of this is to make the ECU run an idle relearn / recalibration procedure.

B) Have you checked the throttle cable for free movement? Could it be frayed internally and snagging in the cable sheath?
 

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Discussion Starter · #13 ·
It turned out to be a faulty capacitor on the throttle smoothing circuit. I just bypassed the circuit and my Honda is idling normal again! I purchased this car 6 mo ago from a "hyper-miler" who added this circuit to help with lean burn. I got the added benefit of a MIMA system which I'm still learning about.

Thanks again,
HD






Sent from AutoGuide.com Free App
 

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It turned out to be a faulty capacitor on the throttle smoothing circuit. I just bypassed the circuit and my Honda is idling normal again! I purchased this car 6 mo ago from a "hyper-miler" who added this circuit to help with lean burn. I got the added benefit of a MIMA system which I'm still learning about.

Thanks again,
HD
I have an accord that has the same issue you have described. It's been driving me nuts! Could you explain more about bypassing the throttle smoothing circuit? Is that on the ECU or something mechanical? How did you figure out that was it? Glad you were able to fix it.

Cheers!
 
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