I hate to make a thread about this but I have no choice.

Lots of Searching has goten me a few ideas but no avail.

The idle keeps bouncing ITS NOT A VACUUM LEAK I've checked every hose and like on the motor. I've spray'd water over everything while its running, no change in the way it runs.

I checked the plugs to see if the porcelain around any of the plugs were cracked, they weren't (read that in a thread).

I have NO idea why its doing it. The only thing I changed was the midpipe to a stock main cat.

I thought the cat might have goten clogged, so I unbolted it, it just kept doing the same thing as before.

When I turn the fans or lights on the revs will jump up and the bouncing will increase (you can hear that in the vid) When I turn the fans off it goes back to its normal bouncing...

When I first got the car it ran drove just fine. I let it sit for a few months and it started doing that

It doesn't bounce when im driving but i can feel like the gas is going on and off.

I've replaced the pump and map sensor.

I'm out of idea's.

Heres the vid.

http://www.putfile.com/media.php?n=badidle1

 

Can't see crap from the video.

When you turn on appliances such as fans or a/c or whatever, it increases the load hence the increased oscillation. Normally, it would cause a bump up in rpms, but theres something funny in your case, therefore it increases the oscillation.

What are your mods?
How much is the RPMS oscillating by?
Did you check your TPS?
Does it get better after the car is warmed up (idle doesn't oscillate as much)?
Are you running the airpump and are you on the stock ecu?

 

Only mod is a down pipe.

I haven't checked the TPS because I don’t think it could just change from fine to horrible just like that.

it doesn’t matter if its warmed up or stone cold it still does the exact same thing.

Air pump is on, and it is the stock ecu..

there’s a vid where you can see the rev's jumping

http://www.putfile.com/media.php?n=bad261

 

start unhooking all the idle control stuff

 

So, the only things you touched were the d/p and the cat. The only things in that area that might be related is the o2 sensor, the airpump hose to cat, and maybe the ground. By the popping noises, it seems to be running unusually rich.

Dont really know what else to say.

 

Hell I didnt even touch the down pipe.

The only other thing that I screw'd with was the stock fuse box, I swaped it from my old white FD, both were in just fine and dandy working order (except the main fuse, i replaced it though)

 

you should get a test light and test both sides of the fuse's while shaking the wires to see if one is loose

 

I have seen a bad earth cause a shitty idle and poor power on an old piston engine. Not sure in this case..just throwing an uneducated suggestion up..

 

Shoot me down / flame me if you will! I may not have many posts to my name but I've been around for approx a year and seen how a lot of you guys dont welcome 'newbies'.

I've recently had the exact same problem. Unburnt petrol ( or gas as you call it ) was igniting in the exhaust because it was running rich on warm up, VERY rough idle and when at road speed it was like the throttle was being lifted even though my foot was steady.

I was checking all the obvious things like you did, the only thing made the car idle normally again was when I checked my coolant level and found it needed approx 1 litre of coolant (strange for me as I check it weekly), topped it up and I dont get the problem anymore! I dont understand why this made a difference! but it worked for me. Give it a try.

 

This probably has something to do with your thermowax sensor on the throttle body. When the car is cold, it keeps the double butterfly valves fairly closed so you don't boost until the car is warmed up. If you were low on coolant and it didn't get circulated through the TB lines, the wax would never expand to open the valves. This could (and apparently did!) cause what you described since the ECU is now expecting a certain amount of air flow at that temperature and has a hard time correcting for what it doesn't expect.

Good newbie

 

The idle control system only has a few inputs, but it can be tricky at times. Possible culprits -

- O2 sensor. The ECU relies on it for feedback at idle to tune the idle mixture. If it's bad, or the wire has a hole rubbed in it and is shorting to ground, you'll have weirdness. Also, there should be a ground strap that goes from the frame of the car to the main cat to cat-back flange - this helps the O2 sensor's signal quite a bit.

- ISC. The idle speed control does frequently gum up with oil and crud, and if it's stuck you'll get a surging idle. Pull it off, clean it with carb cleaner, lubricate with WD40, and then get two clip-on jumper wires. Hook the two wires up to the two electrical connections on the ISC, hook one wire to the positive terminal of the battery and then tap the other lead to the negative terminal of the battery. This will work the solenoid back and forth, getting the lubricant in there and helping to break it free if it's slightly stuck.

- TPS. Go ahead and check it - it's not directly related to your problem, but it's worth checking.

Good luck!
Dale

 

It's your Idle Speed Control. Disconnect it and see what happens.

What should happen is a wild hunting. Your car sounds exactly like is should sound if the ISC was disconnected.

Follow Dale Clarks instructions to automotive bliss.

 

My vote goes to the TPS.

 

I had a problem with the air pump harness/connector when my idle kept jumping just like yours, same as the video, once I fixed it, the idle was good as new, check it out it may be your answer...

I doubt TPS will give you trouble unless the bolts were loosened and TPS mooved or is gone bad on it's own.

 

Thats guys, after work im gonna try everything out

God I hope something works...

 

i bet your air intake temperature sensor is fried...my car didnt sound like yours does but it deffinately made my idle go crazy....try unpluggin it to see if it makes a difference while the car is running...good luck

 

I had a similar surge problem with mine after removing the aws connection from the intake elbow. perhaps the mods youve done have affected your system similarly to how mine was affected.

what i wound up doing was tweaking the idle air setting on the bottom back of the throttle body and the throttle body butterfly set screw on the front top and the stop for the throttle lever to anti stall dash pot. there are posts that discuss the various settings i just mentioned including tps.

a suggestion, if you do mess with those adjustments, make notes on which direction you turn these screws (cw / ccw ) and how many turns (1/4, 1/2, 1 turn) etc. do one adjustment at a time in small increments and note any changes. you can also take a bic white out correction pen to mark threads for additional pre adjustment referencing.

it took a few days of minor adjustments and driving to calibrate and monitor the effects of my changes, but it is now a lot smoother and the surging only happens occasionally and in short duration.

good luck

chuck

 

Well guys i think i found the problem...

And HOLY ****....

i think the leak was sooooo big it didnt matter how much water got in there....

 

holly sheezzzzzzzzzz First time for that one. Damn your intake looks pretty raunchy...

 

JB-Weld anyone?!

-Alex

 

how hard did you torque the intake manifold?

 

how did you do that?

 

Its setting right now

Beats the **** outta me how i tq'd it down too tight...

cough stupid moron friends cough....


Ill post pics after the JB has set, i already got a guy thats gonna sell me a new one w00t.

 

That's PRICELESS!

-Alex

 

do i need to check my mid pipe and make sure it isnt cracked too??? cause you torqued on them pretty good.....