Idle Insanity!

[SnowMongoose]

Mkay, long story short, my idle is all sorts of fucked up.
<running generally rough, but yeah>

for the past long time, its been idling really rough, at somewhere around 1500 RPMs
<cant tell you for certain, since my tach hasnt worked at all since I did the GTE swap>

anyway, we were fucking around with it last night, and realized that the ISC was loose...
so we tighten it up a bit, and voila, the idle smooths out.
<still high, but pretty damn smooth>
said smooth idle only lasted a couple minutes, then back to rough, the engine even almost died a couple times.
fire her up a couple hours later, same deal, starts out smooth, then after 20 seconds or so, gets rough....

pretty much narrowed it down to TPS, ISC, Vacuum, or fouled plugs...

so yeah, my questions would be... ideas?
also, the TSRM says that after you shut down the engine, the ISC should make a ticking noise... but mine doesnt seem to...
how loud is that noise supposed to be? is it possible that my terrible ears just missed it?

phew.

Cliffs: Car idles high, starts smooth, then quickly gets really rough. ISC is/was loose.

thanks in advance.

 

[Supra Blues]

TPS clicking is def. easily heard. If you don't hear clicking, take the ISC off and test per the TSRM.

Also, check that the TPS is in proper adjustment.

 

[SnowMongoose]

thanks, will try tossing on my spare ISC.

hijack my own thread!
http://www.cygnusx1.net/supra/library/TSRM/br/BR_39.html
wtf are matchmarks?
<I need to remove a rotor disk to replace a wheel stud>

 

[mkIIIman089]

They're just like little tick marks that line up with something/other tick marks.

 

[SnowMongoose]

k, that brings me to the question of, how the hell do you get the rotor disk off?
the TSRM gives me no idea...

 

[mkiiSupraMan18]

rotors as in.... brake rotors?

Just take off the caliper.... take off the caliper bracket........ pull? unless the mkIII's have the screws in them.... there MIGHT be a phillips screw holding it in. they can be a real bitch to bust loose, hope you have an imact.....

 

[SnowMongoose]

I'd hope that the rotor is held on by more than one cotter pin, but I could be wrong?
anyone?

 

[GrimJack]

Well, the lugnuts hold the whole thing together... plus the disk can't really go anywhere with the caliper bolted on, either.

 

[SnowMongoose]

so, with the caliper off, I should be able to...
yank the disk off?

 

[americanjebus]

so, with the caliper off, I should be able to...
yank the disk off?

yes, but rust will fight you, put a small block of wood on the rotor and hammer arround the rotor or take a rubber mallet and hit in arround it to break it loose. i was freaked out when i found out only thing holding it on is the lug nuts and caliper.

 

[SnowMongoose]

awesome


back towards my original question, when the TSRM says to apply battery voltage to something, is that talking like car battery voltage?
lol, sorry for so many questions guys, your help is much appreciated.

 

[SnowMongoose]

<crickets>
anyone?
I ask about the battery since I ran 9 volts through the ISC, with no effect...
dont know if that means its toast, but at the same time, dont want to risk running a 'real' battery through it and burning it out.

 

[Supra Blues]

awesome


back towards my original question, when the TSRM says to apply battery voltage to something, is that talking like car battery voltage?
lol, sorry for so many questions guys, your help is much appreciated.

12 volt battery power.

 

[SnowMongoose]

hokay...
dropped in the new ISC today, it clicks and all...
but no change in the rough idle.
as far as we can tell, no vacuum leaks...
anyone have any idea whats up?

 

[SnowMongoose]

bump!

gonna play with the TPS and Vacuum stuff, no idea what else to try...
only thing to add is that when at very low throttle <like 10% pushed> sometimes when I let off it doesnt lower the revs...
at which point I blip the throttle and it rises, then drops down and idles roughly lower, then over 10 seconds or so rises back up.

<meh got nothin.>

 

[kewlcoconut]

I was just browsing another supra forum and found this one, and came across your thread. I have the exact same problem I think. I have been trying to diagnose and fix it for a while now. My ISC is fine, clicks and everything. My TPS seems fine, I should check it more thouroghly.

If you drive your supra for lets say, 30 mins, then turn it off, then back on in about 10-15 mins, does it start up really bad? Like is the idle iratic, and the engine dies? Mine has that problem along with the bad idle.

I had my intake manifold cleaned out/checked all of my hoses/replaced the knock sensor/checked the ISC/checked the TPS. and I still can't find the problem. I am in the same boat as you.

Someone on another forum posted that it could be a hole in the cat converter, but I highly doubt that would cause the engine to die.

Can someone help us? haha

 

[SnowMongoose]

lol, I seriously doubt it has anything to do with a cat, since Im running an open 3 inch DP right now.

The engine doesnt die, though it does have a hard time firing up sometimes
<even beyond the cold/wet and no Cold start injector>

and here I thought I was alone.

 

[kewlcoconut]

yea i thought i was alone on this problem as well haha. I have 2 problems with my supra right now that need to be resolved. tomorrow i am going to check out everything i can think of for this problem. and i probably need to get my steering rack fixed...or the gear housing. ugh...this car can be a pain to fix, but i still love it. haha.

i will let you know if i find anything that has to do with the iratic idle that we both get.

 

[GrimJack]

Here's the info from Reg on rough / erratic idle:

Section 1 ~7M-GE & GTE Engines 1.0: Idling problems

On a warm day, when restarting the engine, as when leaving a gas station or coffee shop after a short visit, the 7M-GE and 7M-GTE engines may exhibit weak idling, hard starting and putting around at 500 rpm for a short period. If this happens only very occasionally it is perfectly normal and is caused by a condition called HEAT SOAK, which happens, after shutting off the engine. After shutdown the water pump and fan are no longer cooling the engine so the heat from inside the engine comes out into to engine bay cooking everything in its way, EFI sensors say "Wako sure is hot in here," gasoline in the fuel rail on the intake manifold is boiled {not to mention a host of other thermodynamic conditions that occur after shutdown}. All Engineering levels are taxed.

To combat this inherit EFI {Electronic Fuel Injection} problem a number factory installed electronic and mechanical engine control systems are used, but under certain conditions they fail to correct the problem completely. For the most part EFI is a wonderful system allowing great fuel economy and silky smooth drive ability so a small bug like HEAT SOAK is still a more livable end than going back to carbs. If this rough idling symptom is happening more often than seems normal there may be a problem with one or more of the following: Cold start injector time switch, Bad Fuel, Throttle position sensor, Plugged or restricted fuel filter or gas cap, Idle speed solenoid air valve (ISC Valve), Fuel pressure, 2 speed fuel pump system, Head Gasket, Air intake leaks, Engine mechanical, Fuel pressure up VSV {vacuum switching valve}.

Other points to remember about the idle speed control valve (ISC valve) are: After shutting of the engine you should here a faint clicking sound for a short time after the engine is killed, this is normal operation.

Unplug the wire at the ISC valve after the valve makes its normal clicking noise after engine is shut off, will cause the engine to run in high idle when the engine is restarted. This is a good sign that the ISC valve is working correctly.

When E1 & T1 in the check connector (Diag Block) are shorted, this will cause the valve to go to a standard closed position. This is the first step in setting the curb idle and ignition timing.

Failure of the ISC valve is not a common problem, what should be checked is the seat section of the valve that sits in the intake manifold. When the ISC valve is removed, this seat will remain in the hole in the intake manifold. This seat valve will get sticky and not work smoothly due to excess carbon and deposits in the intake manifold.

The Bardal Super Tune kit comes with a can of gunk for the fuel tank and a can of gunk to be slowly sucked into the intake manifold while the engine is running at high idle. This gunk stuff works great. Also included in the Bardal super tune kit is a can of gunk that is sprayed into the intake plumbing, and throttle body. Spray this gunk into the airline going into the idle speed control valve. Presto changeo the valve will most often work fine again. Wins also makes a good fuel injection cleaning kit that works wonders as well. The Wynns kit does not have the can of gunk spray, but it does a great job on the injectors and intake manifold.

When the VSV for fuel pressure up is working correctly it allows the fuel pressure regulator to receive atmospheric air pressure to its vacuum port when the engine is hot. To test this VSV you can unplug the vacuum line from the fuel pressure regulator and start the car to see if the vehicle starts normally. If it does the fuel pressure up VSV is the problem.