[dfiore]

I believe I have narrowed down my power loss problem to the air intake. If I put my hand over the intake, the idle doesn't change. It has to be either the throttle position sensor or the IAC sensor. I keep forgetting what thatstands for. Anyway, they are both reveted onto the left of the throttle body where the air intake comes down and in, just behind the radiator. Unfortunately, they are riveted, like I said and the throttlebody would cost me $160 at a parts yard or $650 new. I have 2 questions. One, Is it worth my time to remove the entire throttlebody and attempt to clean the 2 sensors or should I just get a replacement? $$$ :?: Second, how difficult, on a scale of 1 to 10, is it to replace the throttlebody :?: If it isn't tough and it's worth cleaning, I'll try it soon. I'll just need to order a new gasket before I do. Thanks all!

 

[Jackmpg]

Power Loss

Hi dfiore,
When you put your hand over the throttle opening did you do it at the elbow that connects to the throttle body or remove the elbow and stop the air directly at the throttle body? If you did then the test was done correctly. Honda states that any adjustments done to the throttle body except for the idle adjustment (under rubber plug) require replacement of the throttle body. We're not supposed to touch it. Replacement is not too bad, 2 nuts, 2 bolts, 2 connectors, 2 water lines and throttle cable.
You could have a vacuum leak somewhere else, the large vacuum line that goes to the brake booster or loose bolts/nuts that hold it down, for instance. Just snug them, tightening would probly warp the body.
You may be on to something, but on our car there's other places to check for leaks too, such as our plastic intake manifold. Sounds like a good time to carefully go thru the intake/vacuum system completely. Jack

 

[Willie Williford]

If you completely block off the opening from the air cleaner hose to the throttle body the engine should "die".

Hook up a vacuum gauge somewhere in the vacuum line assy. You should be able to see the vacuum erractic behavior on the gauge indicating an air leak somewhere.

Did you ever do a "compression check" like we suggested before? It should read 128psi (when new) With your number of miles, who knows.

Mine read 125psi at 118,250 miles.

 

[Insightful Trekker]

The IAC (ICAV, Idle Air Control Valve) can usually be successfully cleaned. The TPS (Throttle Position Sensor) cannot :!:

A "dirty" IACV may allow too high an idle but its usually opposite, frequent stalling. Throttle body replacement is based on skill level and AFAI remember your EGR attempt gave you trouble. Either due to salt corrosion, improper tools or lack of experience (no insult intended :!: ). A throttle body is a few "points" more difficult than an EGR because of the hoses and need for a proper fit on replacement else you will create a new problem. Nothing that you can't easily see or would be a Doh! after the fact but I hope you get my point...

With some thoughtful care and proper tools its not advanced in the sense that any precision measurements or alignments are needed. But if you round off one of those bolts/nuts you've more than doubled the "work".

What is _critical_ is that the throttle cables be properly installed and inspected for damage before reinstallation. Some types of goof's could cause the throttle to hang *wide open* without warning :!: :!: :!:


HTH!

 

[Insightful Trekker]

125 psi sounds a bit low to me Willie given the Insights 10.4:1 compression ratio.

Ultimate pressure can be calculated after defining air temperature (IAT) and atmospheric pressure (BARO). WIth "normal" new leakage's allowing for a 10% loss, up to 20% is considered "serviceable". But even if its maxed, without other symptoms its just a general indicator of overall internal engine wear.

But there can be major differences in the accuracy of gauges. Remember its not only the specific pressure but the differences in pressures between cylinders. And if your trying to evaluate "top" or "bottom" engine wear a "wet" test also needs to be compared.

This is where a percent leak down test shines vs. a simple compression test. And Dan has been advised months ago in an earlier post of its benefits.

Further vacuum leak diagnosis is definitely indicated before "worrying" about internal engine wear.

HTH!

 

[Jackmpg]

Throttle Body

Willie, John
Yeah, your both right. I'm pretty sure the mechanic did a compressoin test when Dan had the car at Honda. Leak down test, probly not. I did fail to mention about points like the gasket and o-ring for the throttle body. Not much to do but plenty to mess up if ones not careful. Checking with a good vacuum guage is a good idea. If I remember correctly, we used to spray an arisol to assist in finding vacuum leaks. Do you think that might work and if so what type of arisol? Jack

 

[Willie Williford]

John:
The service manual states 128psi as "new"
The test was also done with the IMA disabled which would yield less than 400rpm. cranking speed. per the service manual.
Elevation may have something to do with my test as the "INSIGHT GARAGE" is at 2,450 ft.elevation.
Jack;
I normally use the "spray carb cleaner" or WD40 for locating vacuum leaks.

 

[Insightful Trekker]

Yup Willie your correct :!: pg 2-2, "Engine Assembly" section. But its a _minumum_, not new. With 28 psi differential being the acceptable maximum.

HTH!

 

[dfiore]

Leak down test

I don't think anyone's ever mentioned that to me before. I did take the large intake hose off the throttle body and stuck my finger in the small hole on the side. No effect. When I rev the engine by the throttle cable, there is a little hissing from the butterfly, which I think is normal, but there seems to be no added suction at all. I really wish I knew as much about this as I do about computers! :lol: I can check the vaccuum to the brakes tomorro morning, but my braking seems fine, and common sense would tell me I'd notice something. Jack, if you know how to test this stuff, maybe I could drive to Venice some Saturday. Mileage has dipped to the 40s now and it 's not seeming so unique. Tomorro, I check all the bolts and screws I can. The only thing I found today was the sensor that goes into the side of the large air intake hose was very dirty and I cleaned that. - Dan. PS A compressiontest was done.

 

[Willie Williford]

What was the compression reading? (in psi) at cranking speed, no IMA.

 

[dfiore]

compression

The dealer didn't give me raw numbers, but they did say that although 1 of them was slighty lower, they were all within tolerance.

Dan

 

[Johnmarkzimm]

The IAC (ICAV, Idle Air Control Valve) can usually be successfully cleaned.

Does anyone know of any instructions or video of how to clean the IAC (Idle Air Control)?