I have a rumbly...

[82ColEd]

Ok, it's time for me to get my head squared onto the idle on my car.. :ugh

Symptoms:
Cold start, choke is on, runs at 1000rpm, like someone nailed it to the number..

When the choke goes out, it drops down to around 350-400, almost killing the engine, if i am not watching it (taking it out of gear, or giving it a little gas), it kills the engine. Even driving it, it drops like a rock, but as i am under acc. it comes right back..

After that, it idles at around 750-800, hopping around a bit on the tach, where before the move, it was idling at 550 like a rock..

Also, when it does idle, the car shakes left to right. Looks impressive but gets a little tiring for the fillings after a while.. :eyerole

Now, me not being overly technical, i havent checked on anything yet, warmer weather just started, so i might get a chance now.. Looking for some pointers. Last time i had a side to side shaker, one of the plugs had fouled, repeatedly on Number4, but thats been fixed (by throwing big stuff at it, like cables, dist etc) for years..

The ECM/CCC doesnt throw any codes, all seems to behaving normally and i fixed a small vaccuum (sp?) leak on the AC selector (the knob broke off on the selector, inside, so the selector came off, thus hissing, Glued the knob back into place, no more snakes in the Air. )..

So: Any easy to look for items? Other then the procedure for the qjet setup, any easy tweaks to get the idle back to normal ?

Any and all help welcome.. ;help


Tia!


-Stefan

 

[KANE]

Ok, it's time for me to get my head squared onto the idle on my car.. :ugh

Symptoms:
Cold start, choke is on, runs at 1000rpm, like someone nailed it to the number..

When the choke goes out, it drops down to around 350-400, almost killing the engine, if i am not watching it (taking it out of gear, or giving it a little gas), it kills the engine. Even driving it, it drops like a rock, but as i am under acc. it comes right back..

After that, it idles at around 750-800, hopping around a bit on the tach, where before the move, it was idling at 550 like a rock..

Also, when it does idle, the car shakes left to right. Looks impressive but gets a little tiring for the fillings after a while.. :eyerole

Now, me not being overly technical, i havent checked on anything yet, warmer weather just started, so i might get a chance now.. Looking for some pointers. Last time i had a side to side shaker, one of the plugs had fouled, repeatedly on Number4, but thats been fixed (by throwing big stuff at it, like cables, dist etc) for years..

The ECM/CCC doesnt throw any codes, all seems to behaving normally and i fixed a small vaccuum (sp?) leak on the AC selector (the knob broke off on the selector, inside, so the selector came off, thus hissing, Glued the knob back into place, no more snakes in the Air. )..

So: Any easy to look for items? Other then the procedure for the qjet setup, any easy tweaks to get the idle back to normal ?

Any and all help welcome.. ;help


Tia!


-Stefan

Sounds like your IAC motor has a dirty passage and your TBs are out of sync with regard to idle air.

Just my $.02-

When the choke engages, your engine cleans it self up. So, that means when it runs rich and allows in more air it is okay. When the choke is not engaged, it stumbles yet throws no codes. That tells me your issue is outside the purview of your computer's monitoring. The IAC can only fail or work in the eyes of the ECM. It can't detect dirt. It also can't detect the two TBs being out of sync.

To be safe- clean out the IAC system. Then, flow test the injectors (to make sure they are even). After that, set reset the TBs so that they work in tandem evenly.

See if that clear sit up...

 

[gmjunkie]

I'm CornFuzed???? Is this a cross fire or a Q jet???upthumbs

 

[82ColEd]

I'm CornFuzed???? Is this a cross fire or a Q jet???upthumbs

Sorry, Jesse, apparently me comfuzed too:

Of course it's a X-Fire.. :duh

(Me going into a corner now to hide )

This is what i rememvered LINK, but for whatever reason it stuck as QJet in my head. :duh

 

[82ColEd]

Sounds like your IAC motor has a dirty passage and your TBs are out of sync with regard to idle air.

Just my $.02-

When the choke engages, your engine cleans it self up. So, that means when it runs rich and allows in more air it is okay. When the choke is not engaged, it stumbles yet throws no codes. That tells me your issue is outside the purview of your computer's monitoring. The IAC can only fail or work in the eyes of the ECM. It can't detect dirt. It also can't detect the two TBs being out of sync.

To be safe- clean out the IAC system. Then, flow test the injectors (to make sure they are even). After that, set reset the TBs so that they work in tandem evenly.

See if that clear sit up...

Good one, Johnny..

While i never even heard of the IAC motor (Ya never stop learning on these cars), i shall find and clean it and see if that does it.

How does one flow test the injectors (without too many tools at hand, or what do i need toolwise)?

 

[wishuwerehere82]

The coolant temperature sensor (CTS) tells the ECM what temperature your coolant is. It then regulates the mixture and idle speed accordingly.
It may be getting out a range. and telling the ECM to idle higher than normal for the temperature range the engine is actually in.
That and a sticking IAC motor would be my first suspects.
The 2 IAC's are on the front of each throttle body and screw into the TB base. Easy to clean with a little carb cleaner spray and wipe-off. The motors inside the IAC's are servo motors that are prone to sticking when they wear.
One test is to unsrew them, plug the connector back in, and watch them when you turn the key on. They should extend and retract the worm shaft as the ignition key is turned on. If they just twitch, they are worn out.
Make sure you screw the shaft back in to the retracted position before re-installing them.

 

[gmjunkie]

I'm CornFuzed???? Is this a cross fire or a Q jet???upthumbs

I just thought I had been drinking to much Corn from a Jar!!

Sorry, Jesse, apparently me comfuzed too:

Of course it's a X-Fire.. :duh

(Me going into a corner now to hide )

This is what i rememvered LINK, but for whatever reason it stuck as QJet in my head. :duh

No need for that!! We just had a little Mis- Configuration!!! I was just going

The coolant temperature sensor (CTS) tells the ECM what temperature your coolant is. It then regulates the mixture and idle speed accordingly.
It may be getting out a range. and telling the ECM to idle higher than normal for the temperature range the engine is actually in.
That and a sticking IAC motor would be my first suspects.
The 2 IAC's are on the front of each throttle body and screw into the TB base. Easy to clean with a little carb cleaner spray and wipe-off. The motors inside the IAC's are servo motors that are prone to sticking when they wear.
One test is to unsrew them, plug the connector back in, and watch them when you turn the key on. They should extend and retract the worm shaft as the ignition key is turned on. If they just twitch, they are worn out.
Make sure you screw the shaft back in to the retracted position before re-installing them.

Alllll Righty Then!! I was just getting ready to shoot Pete a Link and he appears!!! He must be Psychic!!:L:L I have to admit I'm not much of a Cross Fire guy,so I'll just sit back, listen and learn too!! I know about enough to Burn it to the ground Screw'n Up!!

 

[82ColEd]

CTS shall be checked too.. Thanks Pete !!

And i re-read the Rochester Setup with the pics and i found the locale of the IAC(s) (I forgot all about the thing, me getting old.. )

(Btw, just cracking myself up: We sound like NASA with all the Acronyms, IAC cleaning, CTS telling the ECM.. :L)

 

[Evolution1980]

(Btw, just cracking myself up: We sound like NASA with all the Acronyms, IAC cleaning, CTS telling the ECM.. :L)

As long as your car doesn't burn up on re-entry!

 

[82ColEd]

As long as your car doesn't burn up on re-entry!

Now Now.. Baaad Andre.. :L

Bought the Liquids (Carb Cleaner, for the tank (Moly) and the Spray for the Injector), but hadnt had a chance last night. The engine was too warm, and the kid had a bit of a tizzy, 'cuz i had to work from home. :eyerole

Hopefully soon, i can clean the IAC's.. Doesnt look too complicated..

 

[wishuwerehere82]

Now Now.. Baaad Andre.. :L

Bought the Liquids (Carb Cleaner, for the tank (Moly) and the Spray for the Injector), but hadnt had a chance last night. The engine was too warm, and the kid had a bit of a tizzy, 'cuz i had to work from home. :eyerole

Hopefully soon, i can clean the IAC's.. Doesnt look too complicated..

It's easy to clean them. Just hold them with the motor up so the spray doesn't go up the shaft and get inside the motor housing. Also spray the TB inside where you unscrewed the IAC from. You will see it spraying through to the inside of the TB. Then just soak up the liquid with a cloth from inside the TB port. It probably will have a bit of carbon or varnish in it.
Spray off the throttle shafts and linkages while you're in there just to make sure they aren't sticking too.

 

[82ColEd]

Allrighty: Had a bit of time today (before it hailed.. Yoikes), the garage has a good light and i can just about lean over the engine..

Some pics, just for S&G's:

Drivers side IAC Motor before cleaning:

After:

(Yes, all the gunk is from the spring/plunger thing, wow)

Passenger side IAC Motor:

After:

And the Rochesters without the Drivers side IAC motor:

What i found was (And it ain't over yet :eyerole):
The IAC's weren't in there all that tight. I was able to unscrew them with my bare fingers. I tighten them up a bit.
Lots of gunk on the plunger.
Biggest thing i saw (or lack thereof):
NO gaskets on either of them.. Aeh, problem, i'd say. I imagine that causing air leaks. Now, i cant tell whether they came off on the last trip to the Dealer (Did they undo the IAC's to get to the engine cover gaskets?) or way before (Dont think so), but now i need to find IAC Motor gaskets. I shall try and have my brother in law send them over. :ugh

Also, when i sprayed the passage of the IAC, it sprayed out ok, but it didn't look like it cleaned a heck of a lot out of it, although there was lots of gunk on the rag.

I shall also test the IAC's tomorrow, completely spaced when i had them out. Question though: How to you 'screw the shaft back in' ? Dont want to wreck them, replacements are a 2 weeks away kinda thing here in Euro Land.. (Order in US, shipping, possibly customs having a tizzy :eyerole One of the things i miss, ie. go to the next Autozone pickup parts).

Also: Idle wise, it didn't seem to make much difference, IAC's being cleaned, but without the gaskets i don't expect it to. Also, hadn't had a chance to add the injector cleaner to the tank, wanted to do that today, but the hail (small but..) kicked in before i got out to fill up the tank. hnoes

 

[wishuwerehere82]

How to screw the shafts back in?

The easy way:
Plug the motor back into the connector with it out of the TB. Turn on the key, and wait for it to retract into the housing. Turn off key.
But from what I see in the pictures, both of them look like they are already in.
When you test them out, if they don't do anything, then that's your answer.

The Borg-Warner part # is 21741 Idle Air Control Valve. Comes with new gaskets.

Did you look inside the TB hole for the gaskets? They are clear nylon, might be there but invisible unless you look close.

 

[wishuwerehere82]

One other thing that just occurred to me that would affect your idle speed after it is warmed up is the EGR valve.
The only time the EGR valve is supposed to be open in under acceleration.
If it is sticking open and not closing when you go back to idle, it will cause all kinds of shaking, stumbling, and stalling.
The control valve is behind the pass. side TB on a bracket, and the vaccuum hose to it come off the base of the TB - to the valve- and another goes to the EGR valve can. Check it by pushing up from underneath the EGR. The diaphragm is spring loaded and will push up and spring back when released. If it feels creaky, instead of smooth in actuation it might be sticking.

 

[82ColEd]

Ok, checked the car today and (no surprise), you guys are right on the money..

- IAC Motor(s): No movement when the key is turned. So i have to replace those (At $79.99 per in the resto places online, ouch :ugh). Unless you think the electrical to them could have taken a dive?

- EGR Valve: It does move up and goes back down; initially i thought it was dead too, but that was me, pushing on it one sided. So i took it off and with both hands holding it, pushed up and it comes back down ok. The more i did it, the better the movement was, but i could hear and feel the air being pushed out the stem. It's old, but it seems ok.

- CTS: After i located it, i wiggled the cables and parts of the cabling on the tip came off. The cables are oxidized on the tip, and the yellowish cap seems broken in half, as i can see the black gasket. Or is that just the connector that i can take out and replace/fix?

Some pics, best i could down in there. Hard to see in the pics, but i might need a new one as well (and fix the cable connectors)..

Now onto the joy of either finding a GM/Chevy Parts place here locally or ordering in the US and paying S&H and Customs. :ugh


I should be ok to drive in the meantime, right? Other then weird idle and the shakes, nothing will break? hnoes

Thanks for the help, nothing beats the , once i have the parts, I'll update the thread with the result.

 

[wishuwerehere82]

All that looks very familiar.
The collar on the CTS is supposed to mate with the plug to hold the connector on. Mine was broken too.
As long as you can get the wires back on to the sensor in the meantime,( either re-crimping the contacts, or soldering the wires directly to it, ) it should work until you get a replacement.
Most new CTS's have a better(re-designed) connector on them. Make sure to get the proper mating connector for your wire harness too.

For the IAC's, well they will do mostly nothing as is, but probably won't hurt anything to just put them back in until you get new ones. Yeah, they aren't cheap are they?
One other test you could do is to check them one at a time while the engine is running.
Then they should be extending and retracting to adjust the idle speed dynamically while in operation.
But you still need new gaskets for them.

 

[Evolution1980]

...or you could always just grab an intake manifold and carb from a 1980 and call it a day!

:L

 

[wishuwerehere82]

Hey !
Show some respect here.
We're going to get NASA certified before we're done here you know.:L

 

[82ColEd]

...or you could always just grab an intake manifold and carb from a 1980 and call it a day!

:L

:L
Sorry, cant do that. Dont wanna go back in time.

Hey !
Show some respect here.
We're going to get NASA certified before we're done here you know.:L

 

[82ColEd]

Allrighty:

Placed the order with Rockauto.com just now.. ~$200 plus $58 shipping.. :ugh

Ah well, that includes 2x IAC valves, AC Delco, the EGR Valve, AC Delco, the CTS and it's pigtails from AIRTEX.. Rockauto seemed to be the only place to A) ship international and B) have all the parts i need online.

So, now, the waiting begins..