what causes engine idle to surge up and down? - Honda-Tech - Honda Forum Discussion


what causes engine idle to surge up and down?

Reply
 
 
 
Thread Tools Search this Thread
Old 03-29-2003, 12:19 PM   #1
Honda-Tech Member
Thread Starter
iTrader: (1)
 
PatrickGSR94's Avatar
 
Join Date: Jan 2002
Location: Nowhere and Everywhere
Posts: 29,225
Default what causes engine idle to surge up and down?

On a D16Y8, what causes engine idle to surge up and down continually? I checked my repair manuals in the troubleshooting section, but it only talked about engine idling too high or too low, or a rough idle. Can anyone help??
PatrickGSR94 is offline   Reply With Quote
Old 03-29-2003, 12:33 PM   #2
Honda-Tech Member
 
Lord Helmet's Avatar
 
Join Date: Jun 2002
Location: Where the Hell is 29 Palms
Posts: 5,526
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

a few things like air in the cooling system, possible head gasket going bad, ...etc.
Lord Helmet is offline   Reply With Quote
Old 03-29-2003, 01:22 PM   #3
Solbros Owns Me
 
Evs-One's Avatar
 
Join Date: Jun 2002
Location: Vancouver, WA, USA
Posts: 14,462
Default Re: what causes engine idle to surge up and down? (Jim Morrison)

some of the time it's the IAC valve, but if it was, then the check engine light would flash.

Otherwise, it's most likely a vac leak. What you can do is spray carb cleaner around mating surfaces, such as throttle body, intake manifold to head, map sensor, etc. If the car bogs down when you spray in a certain location, then you found the troubled area.
Evs-One is offline   Reply With Quote
Old 03-29-2003, 01:29 PM   #4
Honda-Tech Member
 
Join Date: Apr 2002
Location: SoCal
Posts: 2,731
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

Locate the fast idle valve..inspect it, verify that`s not the problem before you start throwing $$$ at the engine.
NiiS is offline   Reply With Quote
Old 03-29-2003, 02:24 PM   #5
Honda-Tech Member
Thread Starter
iTrader: (1)
 
PatrickGSR94's Avatar
 
Join Date: Jan 2002
Location: Nowhere and Everywhere
Posts: 29,225
Default Re: what causes engine idle to surge up and down? (sinister)

Well this is an engine that was just dropped in the car. The head gasket is brand new, and there are no CEL's.

As for the fast idle thermo valve, on 92-95 Civics and 94-95 Integras, it's a little black thing with 2 vac. lines, a harness connection, and a rubber cap on top, right? On the Y8 it's different, and mounted to the fuel rail I believe. Since this engine is using an OBD1 D15 harness, we had to use the fast idle thermo valve from the D15, which is slightly broken. Could this be it?
PatrickGSR94 is offline   Reply With Quote
Old 03-29-2003, 02:33 PM   #6
Honda-Tech Member
iTrader: (3)
 
Aquafina's Avatar
 
Join Date: Jan 2003
Location: Johnson City TN
Posts: 11,391
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

Air filter needs to be replaced. There are a few things it could be though.
Aquafina is offline   Reply With Quote
Old 03-29-2003, 02:36 PM   #7
Honda-Tech Member
Thread Starter
iTrader: (1)
 
PatrickGSR94's Avatar
 
Join Date: Jan 2002
Location: Nowhere and Everywhere
Posts: 29,225
Default Re: what causes engine idle to surge up and down? (SuperStreetRX7)

it's not running any intake or filter at this point, at least not when we were testing it last weekend, just open throttle body.


[Modified by PatrickGSR94, 5:36 PM 3/29/2003]
PatrickGSR94 is offline   Reply With Quote
Old 03-29-2003, 03:03 PM   #8
Honda-Tech Member
 
Join Date: Apr 2002
Location: SoCal
Posts: 2,731
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

Quote:

Since this engine is using an OBD1 D15 harness, we had to use the fast idle thermo valve from the D15, which is slightly broken. Could this be it?
That`s where I`d start
NiiS is offline   Reply With Quote
Old 03-29-2003, 05:43 PM   #9
Honda-Tech Member
Thread Starter
iTrader: (1)
 
PatrickGSR94's Avatar
 
Join Date: Jan 2002
Location: Nowhere and Everywhere
Posts: 29,225
Default Re: what causes engine idle to surge up and down? (sinister)

hold up a sec, is the fast idle thermo valve underneath the throttle body, or is it on top of the intake manifold? If it's on the bottom of the TB w/ coolant hoses going to it, then that part isn't broken. However the Y8 TB doesn't even have a separate piece on the bottom like the D15 TB does. However the idle still surges no matter which TB is on there (D16Y8 or D15B7 TB).
PatrickGSR94 is offline   Reply With Quote
Old 03-29-2003, 05:54 PM   #10
 
Join Date: May 2002
Location: RP, CA, USA
Posts: 53
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

Was the car hot? Because if you are getting surging RPM's, its usually the Air Flow Sensors. Plus, if you were running open throttle body, its sucking in extremely hot air. When the sensor heats up, it doesnt read accurately, and your car will go into kind of a safety mode that just revs the car when its about to die, and then lets off when it thinks it can idle, so it will drop to like 400, then up to 1200rpms. There will be no CEL because the sensor still works, but it cannot read accurately due to extreme temperature.

That has happened to my DOHC mitsu before. The underhood temps get really hot with intake, and it would mess up the air flow sensor. Also, on 6gen accords some people have had the same problems, and they were fixed by reducing temps to intakes. Just a thought
Shaggs2Dope is offline   Reply With Quote
Old 03-29-2003, 08:48 PM   #11
Honda-Tech Member
Thread Starter
iTrader: (1)
 
PatrickGSR94's Avatar
 
Join Date: Jan 2002
Location: Nowhere and Everywhere
Posts: 29,225
Default Re: what causes engine idle to surge up and down? (Shaggs2Dope)

what about the air temp sensor? The D15B7 sensor sits in the intake manifold, and the Y8 one sits inside the intake pipe, and since we are using the D15 engine harness and temp sensor, it's just hanging out in the engine bay right now. What have other people done with that? People that have put a Y8 manifold into a 92-95 Civic, what did you do?
PatrickGSR94 is offline   Reply With Quote
Old 03-30-2003, 11:11 AM   #12
Honda-Tech Member
 
bretx0r's Avatar
 
Join Date: Mar 2002
Location: Northern CA
Posts: 6,606
Default Re: what causes engine idle to surge up and down? (PatrickGSR94)

vacuum leak
bretx0r is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Surging idle, wandering temp gauge needle, related??? therest Honda Accord (1990 - 2002) 9 03-15-2016 05:26 AM
Idle Surge jmeyer99 Honda Civic / Del Sol (1992 - 2000) 1 03-22-2007 05:34 AM
Engine starting to surge BoostedH23Accord Hybrid / Engine Swaps 3 08-31-2004 10:08 AM
Surging idle fix for chipped P28 running an OBD2 LS with Uberdata Mighty Hybrid / Engine Swaps 10 08-17-2004 05:29 AM
Horrible Idle Surge!? CharmCity Honda Civic / Del Sol (1992 - 2000) 10 11-02-2003 03:53 PM


Tags
car, cars, civic, crx, engine, engines, honda, hot, idle, idling, motor, odyssey, rpm, surge, surges

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -8. The time now is 02:03 PM.


 
  • Ask a Question
    Get answers from community experts
What's your question?
Send