RPM @ idle, Fluctuates between 950 to 2000 Options

[Bigblock]

Started up fine, then started to fluctuate between 950-2000 in neutral. Drives fine, until idleing @ stops, then goes nuts!!

It revs up & down in like 2 second intervals.

Things I will check tomorrow--

Dizzy, plugs & wires. Thinking about spraying the throttle body with carb cleaner. Check vacuum lines.

Any help, tips or tricks GREATLY APPRECIATED!!

Thanks!!!!

[stephen_lee]

big vac leak will make it do that.

[Bigblock]

stephen_lee --

Thank You!!

[stephen_lee]

You find the cause?

[Bigblock]

stephen_lee--

I will post-up what I find out. I have most of the afternoon off so I will have time to go at it.

[Bigblock]

Found it!!!
Busted PCV!!!

The nipple of the valve is in the hose, the valve itself is broke flush with the valve cover!!
How do I get it out??

[Bigblock]

Got it! A lil friendly persuasion with pliers!!

Tach seems to be off a bit?? Sounds normal but shows idle @ 1200 compared to 950??
Other than that, runs // drives normal.

( edit )
Tach is responding slow.
When I slow down, the needle takes about a second to show drop in RPM??

This post has been edited by Bigblock: Oct 26, 2011 - 12:07 PM

[SwissFerdi]

Maybe reset your ECU?

[Bigblock]

How do I reset ECU?
Disconnect the battery for a few minutes?

[Keiri]

Pull the ECU fuse for a minute then plug it back in. Turn car on and let it run until warmed up (or around 5 minutes). Shut off.

That should be all there is to it..but the experts will post if I've led you wrong.

[Bigblock]

Found 2 vac hoses needing replaced--
Just behind the EGR modulator going to something bolted to the firewall. There is an electric plug
connected to it.

Anyone know what diameter these hoses are? They are in very bad condition & I don't want to remove them until I
get the proper size.

Thanks for all the help!!!

[stephen_lee]

i would replace all the hoses if a few are in bad condition, as they all have been exposed to similar conditions. take a piece into the parts store & ask for that same size

[Bigblock]

Going to do it in the morning. Drive it there so they can see them.
All vac hose will be replaced.

[Bigblock]

Replaced all vac lines.
Start up idle is 1800, warmed up idle is 1400.

Pulled the fuses for ECU & put them back in 15 mins later.
Pulled the 1 in the engine bay & the 1 in the car.
Tach still has slow response when slowing down // gear changing.

What next??

I can't thank you guys enough for the help!!

[xrav22]

Replaced all vac lines.
Start up idle is 1800, warmed up idle is 1400.

Pulled the fuses for ECU & put them back in 15 mins later.
Pulled the 1 in the engine bay & the 1 in the car.
Tach still has slow response when slowing down // gear changing.

What next??

I can't thank you guys enough for the help!!

Make sure your throttle cable isn't dragging. Grab the actual cable by the engine connection and push it backward as if you were giving it gas. Mine was binding a little as my cable is rotting through the plastic. Otherwise like they say vacume lines and check sensors so they are not disconnected or broken plastic.

[Bigblock]

Throttle cable is good.

There is an audible " ssss " noise on the back side of the motor! : (

Any tip on what it may be or what to check?

When I push in the clutch pedal after driving 60 mph, rpm drops to 1000
then goes back up to 1400??

[stephen_lee]

vac lines that run on the rear of the 7A are:

ac idle up (to the solenoid that has 2 vac lines and a 2 wire connector)
and power steering idle up, also 2 lines, runs under the manifold, a little larger than normal vac lines.

[Bigblock]

Thanks for the info stephen_lee!!

I'm going to go to my friends shop tomorrow morning & put on a lift to check
things all around!!

Here's hoping I find & fix the issue!!!

[Bigblock]

K, so I found out--
Disabling ( pinch closed ) the A/C idle up lines, either 1 of them
idle drops & hissing stops!!

I don't have the A/C hooked up, so --
Can I cap off the sources & be ok til I can get an idle up valve OR
is it a needed part?

( edit )
Capped off all the idle up fittings.
Much better!-- Idle right at 1000!!

Thanks Stephen_lee!!!
First Celica domination in Texas, then the Nation, then The World!!!
LOL!!!


This post has been edited by Bigblock: Nov 1, 2011 - 5:50 PM

[stephen_lee]

that valve is a "normally closed" type valve. its stuck open obv lol. you can try to save it by spraying throttle body cleaner into it.

as far as i know, AC is the only thing the ecu uses it for.