The Classic Idle Surge Question

[HBWaterfowler]

Hi all,

I know this is a very common question, but I'm waisting a lot of time searching and not finding the answers I want, so please fill me in on what my next step should be on solving this problem.

I have had bad idle problems for about a year now, and I have yet to do a vac/boost leak test. In my defence, I can hear nothing, and dont see/feel anything in the ovious areas to check. Nothing is loose or anything like that, so yeah I need to do this still.

But in the mean time, since I don't have a compressor to use for now or the kit to test with.

I have done the following:
Replaced the TB with one from the crazy throttlebodys.com guy
Replaced the ISC with a black one brand new

I was thinking of replacing the o2 sensor next.

Here is what my car is doing...

A typical day: start my car in the morning, it idles fine (1,500 high, but consistent), drive to work, stopping at various red lights where it idles between 1200-1600 but mainly right on 1500, and my car does not like hot starts to much (low idle/stall untill i drive for about 5 seconds then back to 1500).

I have my idle set kinda high to keep it from stalling, but once the symptoms go away I will lower it to 800.

SO what I'm wondering is... What are my next steps to getting rid of them problem?

I know I need to do a vac/boost leak test, and I will sooner or later. But once I do that and that is factored out, and considering the other two things I have done, what would be next? I'm thinking a a new o2 sensor.

Keep in mind too, the car is a 1992 Laser, and I have a JDM installed with 60-80k miles on it. So most of these parts would need replacing around 60k+ miles.

I'm thinking I wanna do the spark plugs/wires too.

When I'm idling it will kinda make this misfire noise like: zzz, zzzz, zzz, pahhh, zzzz, zzzz, zzzz, pahh, but very light, and u can feel it with ## hand at the exhaust too.

Another thing too, I have the vac lines on the TB capped off.

If you have any questions let me know.

I just want to get a list going of things to try.

So... like:

1) Vac/Boost test
2) ... ????
....so on

P.S.
I dont think my TPS is set up correctly/works at all. I had my roommate check it with a voltmeter and it read zero at wot or closed.

 

[Lofty]

Check for any exhaust leaks. My headers and flextube are bad and I have a feeling that this is causing my idle surge.
Someone very mechanically minded said the same thing, so I will be installing them this week.

 

[Gstclipse69]

TPS Adjustment
IC Pipe Tester
A boost leak tester in 20 bucks max and is invaluable. You will need this countless times if you keep your car for a prolonged period of time and can tell you a lot about your intake system. Definitely buy or make a tester first and get an air tank and test that sucker.
Some other things that *could* affect idle surge, as I had this problem awhile back and read everything that was available; maf, o2 sensor, fiav, exhaust leaks, throttle cable too tight, and vacuum leaks.

 

[hard2kill]

do you have a atmosphere dumped bov?

 

[HBWaterfowler]

I have my BOV going to the intake (I have a MAT not installed, for TB mount, plans for venting to atmosphere).

I just read up on the Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge) (Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

I think I do have a exhaust leak too, maybe at the o2 housing or flex downpipe area.

So, what I'm thinking so far:

1-Vac/Boost Leak Test
2-TPS Ajustment/Test
3-Throttle Cable Too Tight (it is, thats how I keep my idle high)
4-02 sensor
5-Exhaust Leaks

If that doesn't fix it then I guess FIAV block off.

Does that list look like it's in the proper order?

Oh yeah, I forgot to mention, I have the cyclone intake on right now (no EGR valve) and the butterfly valve is blocked off keeping the 8 rutters open at all times.

ALSO, ... sigh... the TB from the crazy throttlebodys.com guy is 63mm bore from sock 60mm, mounted to the stock 60mm intake.

I think I have a lot of things to test/replace. I'm planning on putting on the stock intake manifold, and have it boredto 63mm to match. I would think it wouldnt matter if its bored 3mm over, but who knows?

Just for the hell of it, I'm going to go check the spark plugs to see if they are fowled.

 

[Highbooost]

Do you have the coolant lines hooked up the t-body? Also, how is the o-ring on the biss screw?

Check all those things and get back with me.

Later Dr Turbo

 

[HBWaterfowler]

Yes I still have the coolant lines hooked up to the TB. BTW on that note, my intake mani is very hot, almost as much as the engine (temp gauge shows always low at start, but then warm at 11 o'clock).

I feel yeah on the BISS o-ring, I already swaped it. I have a referb TB that I used the new o-ring I got with the referb.

I also messed with the throttle cable slack, and I have it all good. I also ajusted the BISS much tighter, 2 1/2 turns out; about. Idles at 750 all jittery. I guess I need to get this MAFT on here and see if it helps, but with no wb o2 to ajust the MAFT settings with.

 

[91_ECLIPSE_GSX]

Sorry i Know this is on here my case is slighty different.
i have a 91 gsx i got it in march. i used to have to let it warm up or it would surge untill it was at running temp, sometimes turning ac on would stop it temporarily. i removed the throttle body and cleaned it really well, i replaced the gasket. the biss is all the way down idle stays between 750 rpms to 1100 rpms changing after it idles for a second. i tried grounding the ecu and timeing thing didn't change anythig.
just recently the surge would sometimes stay or come at random. it will stop when fan turns on a/c doesnting effect it much it just drops the idle for a second. i thought maybe the tps was not adjusted right i removed the throttle body again and adjusted it and installed an egr block off. after reinstalling everthing the problem worsend the idle surge was faster and sometimes idle would go up to 3000 rpms.
i have tested tps the ohms seem to change smoothly and are close to the range the manual says. the idle switch is good, the switch by the throttle cable. the isc seems to be alright one coil is at about 100 ohms im going to replace it. disconecting it doesn't change anything, disconecting the idle switch sometimes raises the idle.
after putting the egr block off on and adjusting the tps when trying to adjust the idle something made a ticking sound i believe it was the egr valve solenoid. i just plugged the vacuum lines going to it. i am doing a vacuum leak test today or tomorrow.
Sorry its so long, any help would be great i am confused i have read alot and don't want to just start throwing money at it.


Also The Person That Owned It Before Me Put A Switch On The Maft Harness I Believe To Where The Waste Gate Solenoid Went Anyone Know What That Would Be Or Do. Ill Check The Wire Tonight To Find Out The Color.

could a maft fix my problem i've heard of people fixing it with one

 

[dyno_detour]

Many things are a factor when it comes to idle surge.


My car "during the summer" would idle around 2500 rpms after running 15 min in the heat.


My recommendation is to loosen the throttle cable.

It is easy to find. Follow the cable back from the throttle body and you will see it directly behind the intake manifold. There are two bolts, one of them may have some other wires and junk on it as well but you still need to loosen it. Just loosen it an 1/8 of an inch or less.

That fixed my idle surge problem. I would try it for sure!

Good Luck,
Ryan

 

[91_ECLIPSE_GSX]

Yeah I've adjusted it a little no difference. Thanks for your help though. i believe its possibly coolant related. it leaks a small amount of coolant don't know where hopefully not through throttle body how would i be able to tell? could i do a bypass on the fiav with out the block off to test if it fixes it or would that not work. sorry i'm a noob, just need help. i have been trying to fix this problem since i got the car. ive spent hours reading. and days working on the car

 

[TOONAH]

In addition to what the other members have posted: Are you sure it is leaking coolant? Perhaps it is consuming coolant via a mildly blown Head Gasket. Did you ever grossly overhead the engine? Could have happened on a very hot day after you turned the engine off. If the fan did not come on the heat soak can warp a head. If the HG went bad due to a warped head a cylinder(s) could be sucking in air throught the HG. Causing erratic idle. Pull all your spark plugs and see if any are steam cleaned. You do not always see steam coming from the exhaust pipe. I am always suspicious when an engine mysteriously looses fluids. I had a truck that ate transmission fluid. I found that the bloody radiator gave out inside between the coolant section and the trans section and my trans had coolant in it. Thats why I always use trans coolers now. My other thought is check the IAC and the Cam Angle Sensor.

 

[91_ECLIPSE_GSX]

i have fixed the idle surge by replacing throttle body shaft seals i also rplaced the injectors seals. the idle isn't perfect and its slightly high(1400) moves slightly. any thoughts? my tps is adjusted right the ohms aren't in the right range though. also my isc ohms are off on one coil could that cause a high idle?

 

[91_ECLIPSE_GSX]

alright i was wrong some how the throttle switch(switch by throttle cable) went crazy and my idle surge stopped. thats also why i had the high idle. i have messed with the isc i think it may be bad i have disconnected it adjusted it put it back in with out reconnecting still surges. could it still be the isc? i need help badly! could the coolant temp sensor cause the surge? the only thing that fixes it is having that throttle switch disconnected or when its wigging out.

my car has always reved up like 500-1000 rpms every time i shift before it drops to idle or i go on the gas. so even if i push the clutch in to stop it revs a little then goes to idle. any one know why?

 

[HBWaterfowler]

I'm not sure if the "throttle switch" you are talking about is that metal plate that has two bolts going into the intake manifold? But I think your problem is, it's to tight. The cable that goes from the throttle body to the plate at the intake should have some looseness to it, some "slack". That is my guess. It's pulled so tight it is making the ide stay at 1,000 rpm and when you let the clutch out thats why it goes to 1,000 then the cpu ajusts for idle and it drops down to 500. Ya think?