ISM Pipe of Agony - way loose

[Beachdrifter]

Hi all,

So while I have been trying to find out why my car was starting and immediately shutting off, after checking all other possible culprits, I began to see the Idle Speed Motor.

Upon closer inspection, I noticed the tube that comes from underneath to the bottom of the mixture unit was very loose. This tube I have found out is also called the 'pipe of agony'. I could easily move the tube
right to left in about 1.5 inches each way with no resistance. At one point I ventured to try to pull it out of the hole, but I stopped because it seemed like nothing was gonna stop it!

Something tells me this doesn't seem right. I believe this should be firmly held in place by a sort of oring and copper ring? If this is so loose will it cause a sort of vacuum leak that would prevent a car from idling or even trying to rev at stand still ?

I think this is my issue, any thoughts?

Thanks,

[WelmoedJ]

Hi all,

So while I have been trying to find out why my car was starting and immediately shutting off, after checking all other possible culprits, I began to see the Idle Speed Motor.

Upon closer inspection, I noticed the tube that comes from underneath to the bottom of the mixture unit was very loose. This tube I have found out is also called the 'pipe of agony'. I could easily move the tube
right to left in about 1.5 inches each way with no resistance. At one point I ventured to try to pull it out of the hole, but I stopped because it seemed like nothing was gonna stop it!

Something tells me this doesn't seem right. I believe this should be firmly held in place by a sort of oring and copper ring? If this is so loose will it cause a sort of vacuum leak that would prevent a car from idling or even trying to rev at stand still ?

I think this is my issue, any thoughts?

Thanks,

The most known reason why it's called the Pipe of Agony is because it's giving most owners a hard time to get it in place correctly.
However once familiar with the pipe's behavior and knowing the tricks, one can intsall the Pipe within a couple of minutes.

The pipe itself has no stop.
The Pipe has a seal (O-ring) confined in a brass cup.
Installing the O-ring with no cup makes need of creating a replacement *)
Installing the Pipe goes smoother when using some grease on the last 1 inch of the pipe.
Using a flashlight while holding down the air plate will show the opening (left forward side) the Piper has to go into.
A good hand/eye co-ordination is very helpful in getting the pipe in while looking at the hole from inside the mixture unit.
The Pipe itself needs the rubber hose to the ISM **) and has to be clamped at both ends of the hose.

*) Replacement brass cup: I used a copper washer of sufficient size (fit) and hammered it a bit bigger, then pushed it into place.
*) Usually the brass cup is still there, but you need to take the mixture unit out to enable an easy replacement of the O-ring.
*) Use grease on the O-ring for easy passage of the Pipe.

**) Mind that the ISM (Idle Speed Motor) also could contribute to killing an idling, just started engine.
**) Check the valve for correct functioning and also check the switch and wiring to the ISM

[Bitsyncmaster]

The pipe will feel loose if the O-ring and pipe are greased. The flash light trick in the dark should verify if you have any leaks.

It's only a pipe of agony if that brass ring falls out. Then you really have to remove the unit to get the o-ring and brass ring locked back in.

[Citizen]

This pipe of agony I have heard about of course, but have almost no knowledge of. I always want to learn more about my car too, so does anyone have any pictures (if that's even possible considering its location), or a reference diagram, part no., etc.)?

Thomas

...

[DeLorean03]

This pipe of agony I have heard about of course, but have almost no knowledge of. I always want to learn more about my car too, so does anyone have any pictures (if that's even possible considering its location), or a reference diagram, part no., etc.)?

Thomas

...

It's connected to the ISM by means of a small rubber hose. It is featured on this page - #21:

http://store.delorean.com/c-338-2-5-0-motorecumicroswitch.aspx

[DeLorean03]

**) Mind that the ISM (Idle Speed Motor) also could contribute to killing an idling, just started engine.
**) Check the valve for correct functioning and also check the switch and wiring to the ISM

It might help him if the details to determine if the ISM was bad or not were given. He seems to suspect this is the problem, but we don't know if he knows how to diagnose it or not.

Randy, to make sure the pipe is installed fully, push down on the air sensor plate and look at about the 10 o'clock position. You should see the end of the pipe protruding into the mixture unit. The end of the pipe is NOT your typical cylinder shape. The end is cut in such a way that it resembles more of a spear tip (not sharp) than a flat cylinder end. You can see it here in this picture a bit on the right end:

24051

There was a time I tried to take a good photo of the pipe properly installed inside the mixture unit, but my camera proved to be inferior.

Too bad my old engine was sold, or I'd tell you just take the ISM off and try it =/ ....

[jawn101]

I have been re-sealing mine for years with a little bit of sensor-safe RTV around the brass cup before pressing it into place. It seals up beautifully and is easy to remove when the time comes. The O-ring that I've gotten in tuneup kits has never quite fit properly.

[Beachdrifter]

It might help him if the details to determine if the ISM was bad or not were given. He seems to suspect this is the problem, but we don't know if he knows how to diagnose it or not.

Randy, to make sure the pipe is installed fully, push down on the air sensor plate and look at about the 10 o'clock position. You should see the end of the pipe protruding into the mixture unit. The end of the pipe is NOT your typical cylinder shape. The end is cut in such a way that it resembles more of a spear tip (not sharp) than a flat cylinder end. You can see it here in this picture a bit on the right end:

24051

There was a time I tried to take a good photo of the pipe properly installed inside the mixture unit, but my camera proved to be inferior.

Too bad my old engine was sold, or I'd tell you just take the ISM off and try it =/ ....

Thanks Jeremiah,

I will look through the pressure plate to see if I see the tube. Good insight!

As far as the ISM, I went ahead and took off the two rubber hoses on either end.
With a flashlight, I could see the air valve shut. When I put the key to the "on" position, I could feel it buzz, and the valve would open maybe like 1/16th in.
While still with the key on, if I were to "relax" the idle switch by pulling the throttle spool, I could see movement in the valve and it would open like 1/8th in more.
But overall , it seemed the majority of the valve was closed,

I'm wondering if this is correct movement of the valve. I've read you should be able to see straight through it when the key is "on". Is this true?

I also took it out fully and sprayed it with carb cleaner to see if it was sticking, but it didn't change anything.

Thanks guys,

[DMC5180]

http://www.youtube.com/watch?v=fUOK0ksB0Gs

Your valve should work similar to this. This Valve was a bit sticky which accounts for the somewhat jerky sweep action. The Key was cycled twice.

[Beachdrifter]

Great video thanks! Mine is no where even half open when i cycle the key. It's like almost entirely shut the whole time, just barely opens. I think I have an ISM issue?

[rdarlington]

Mine was acting up so I took it out and blasted it good with some MAF sensor cleaner and jiggled it around its axis. Basically twisting/rotating it back and forth to get the valve to open and close and move freely. No problems since.

-Bob

[Beachdrifter]

According to Hervey, he says if I have a leak in this tube where it connects to the air mixture unit, I will have an uncontrollable high idle.
Well, since my tube feels loose (can move it in and out), my assumption was that I would have an air leak, BUT I am not getting any high idle symptoms, mainly low idle and car starts and shuts off issues.


24055

I will assume I don't have an air leak, so at this point what bothers me more is that my Idle Speed Motor will not open even half way when cycling the key.

Can an almost completely shut ISM prevent the car from staying on after initially igniting and prevent the engine from reving at idle?

[Bitsyncmaster]

According to Hervey, he says if I have a leak in this tube where it connects to the air mixture unit, I will have an uncontrollable high idle.
Well, since my tube feels loose (can move it in and out), my assumption was that I would have an air leak, BUT I am not getting any high idle symptoms, mainly low idle and car starts and shuts off issues.


24055

I will assume I don't have an air leak, so at this point what bothers me more is that my Idle Speed Motor will not open even half way when cycling the key.

Can an almost completely shut ISM prevent the car from staying on after initially igniting and prevent the engine from reving at idle?

You have a rare problem of idle speed to low. I would turn the curb idle screw in until you get it to idle. Then you can post how good you hold 775 RPM cold and hot to determine if you idle system is working.

[David T]

You have a rare problem of idle speed to low. I would turn the curb idle screw in until you get it to idle. Then you can post how good you hold 775 RPM cold and hot to determine if you idle system is working.

Loose is a very subjective description. It needs to be tight enough to seal but loose enough to move around to install. One measure is, if you put it in a position, it will stay there and not flop over. If it won't stay in a position it is probably too loose.

[DMC5180]

The 600 rpm sounds like something I had happen to me once.The ISM valve end Bearing had become gummed up with carbon soot. The valve was for all intensive purposes, stuck and very stiff to move Open maybe a 1/16 th. I sprayed a little WD-40 in there and physically moved the valve open, then I would energize the ISM with key to make it close to work it. I did this 3-4 times until the valve became FREE. You could quickly flip/twist the ISM back and forth on it's axis and hear the valve click open closed (Stop to Stop). After that I reinstalled it turned the key and it fired right up @ 775 and stable.