Honda Prelude Forum - PreludeDriver.com

I am puzzled. I managed to replace the timing belt and made sure every hose, connector and wire were back in it's original position. After every was put back together i:

1. reconnected the battery terminals
2. started up the car...Sounds Great! No weird, strange or knocking sounds. Engine Cold start idle around 1300 RPM
3. I went to get my cell phone and wallet because I was going to take it for a Test Drive
4. approximately 3 minutes later RPM now approximately 7500 RPM, when I went to put it into "D" (Drive): Engines sputters and dies.
5. Start car up and will only stay running if I give it Throttle/Gas. Engine Dies at Low RPM (7500)
6. Let Engine cool. after a few hours I start it up and it does the same thing.

conclusion: When the engine is warm and I give it throttle/Gas it will Die. If I don't touch the gas pedal..it will idle forever..just if I give it gas the engine will rev up and die after it idles down to 7500.

what I done:
1. Listen for vacuum leaks=None
2. No Check Engine light Flashing or ON
3. Shorted out the Blue Service Check Connector (SCC)hoping it would kick out an CEL Code=None
Note: When I got the car...engine idled a little rough, but it never sounded like it was sputtering or gonna die...I thought it needed a tune-up and I was going to do it after the timing belt replacement. I am 3 owner..No known history on the car.
4. Looked at the timing and it looks to be within the Plus/minus 2 degrees of 15.

Service manual says to check/replace the EACV. Expensive part for me to buy and have it not be the problem.

Any suggestion, ideas or advice will be welcome. Thanks Guys!

The symptoms do sound like a bad EACV, but I don't think you need to replace it just yet.

The EACV valve and the IAC valve work together to control the idle based on engine temperature. They require coolant flow to function. As a first step, I suggest that you make sure your engine coolant is bled correctly before you do anything else. It's possible that a bubble is just stuck in the system and is not allowing the idle systems to work well.

Thanks Speedo, I will look into the Coolant Theory.

Newbie Question needs clarification: you wrote "The EACV valve and the IAC valve work together to control the idle based on engine temperature....." Is the EACV valve and the IAC Valve the same Physical Unit (bolts to the intake manifold, 2 wire connector with 2 (incoming/outgoing) coolant lines)?

Note: I will also try to remove and clean this unit too

OK..This is what I done since Spiffyguido suggested the "bubble in the coolant system" theory.

1. went to the local auto supply. bought Throttle Body & Air-Intake Cleaner
2. removed the IAC Valve (2 X 12mm bolts)
3. removed the 2 hose clamps (coolant)...but could not get the hoses off...looked inside the vale anyway.
4. looked in the 2 opening
a. 1 opening had a screen...did not look dirty. Sprayed it anyway
b. other opening..I could see inside...sprayed it anyway
c. used compressed air and allow to dry for a few minutes

5. I was expected to see coolant run out...I DID NOT SEE 1 DROP! No coolant! 1 of the 12mm bolts looked like it had dried coolant on it (white dry power).

Does this support Spiffyguido's "bubble in the coolant system" theory? If so, I need to research how to "Bleed the Coolant System".

6. everything put back together

7. Car restarted from Cold...will not Idle without giving it gas. Yup...I am making my problem worse!

8. Reset ECU...
9. Shorted Service Check Connector... No CEL Codes displayed.

Thank goodness this is not a Daily Driver Car. ...Not making any Forward Progress.... But, I am learning a lot!

7. Engine will start and idle if I give it gas/throttle.

Thanks again!

The EACV and IAC (Fast Idle Valve) are not the same unit. On your car, the IAC valve (Fast Idle valve) is mounted horizontally on the underside of the throttle body. It has two coolant hoses running out of the bottom of it. The EACV is horizontally mounted to the front of the intake plenum and has two coolant hoses as well. See the picture on page 9-2 of the 1992 service manual (see our manuals section).

Bleeding the engine coolant is very easy to do and is covered on page 10-5.

thanks for the clarification and reference Picture in the Service Manual. I cleaned the EACV earlier. Should coolant have been leaking or present when I unbolted it???? None was present...perhaps blocked hose(s).

Attempted to Bleed the Coolant System...Was hard to do because the car will not Idle....But It IDLED once and I was able see a steady stream of coolant coming out of the bleeder port before the engine died. Closed Bleed Port..engine will not IDLE without me giving it some gas.

I will look at the FAST IDLE Valve next.

Question: Should I see coolant coming out when I remove either the EACV or FAST Idle Valve is removed?

Yeah, you should see some coolant in those lines.

Go ahead and follow the steps for idle adjustment as well. Your idle may just need a nudge in the right direction.