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I know this Olds isn't " an old Classic" by any means, but I just got it and can't find any diagrams by Googling. I'm hoping someone can steer me to a vacuum hose routing diagram. I have a problem with it as it won't idle, but shuts down anytime I let off the gas and put on the brakes. I've read that there is most likely a leak in the vacuum hoses somewhere, but looking at the top of that 3.1 engine and intake manifold, I can't see the forest for the trees!
Any help would be appreciated!
BTW, I do like 'Classics' I've owned several Old's over the years (boy, I wish I had some of them back now! - my old car (project atm) is a 67 Ford Falcon 4 dr 3 spd stick (was on the column until my son 'speed shifted' - now it's a 2-bar 3-speed stick on the floor) that I've had for about 20-21 years. It was a daily driver for about 8 years, gave/sold it to my son for about 5 years, then I got it back and have just recently put it back on the road. NO electronics, NO EFI, bring on the EMP attacks
This is for 92/93 3.1T... should be the same for 91
Yeah, it should be the same, I think. Thanks!
I'm an illiterate with these electronic engines, gimme an old 6 or v-8, even a straight 8 and I can usually figure out what's wrong and fix it, but the electronics throw me every time. That's why I'm using the Falcon - I know it pretty much inside and out. This Olds was given to me by a friend, so I want to get it on the road for long trips - save the oldie for around town, etc. (I know, I'm a bit of a show off!)
Any opinion as to which area I should look to for leaky vacuum lines? It looks like everything runs under the intake manifold, which means pulling that to see whatever I can see!
As I said above, "I have a problem with it as it won't idle, but shuts down anytime I let of the gas and put on the brakes. I've read that there is most likely a leak in the vacuum hoses somewhere."
TIA
Last edited by jimk; February 19th, 2016 at 01:21 AM.
Are you sure it's a vacuum leak? My first instinct would be a dirty Idle Air Control valve.
Actually Joe, I don't know what an Air control valve is .... like I said, I'm an illiterate when it comes to these electronic engines. I and a neighbor were looking at it (with the help of Cruzn's diagram) and there is some kind of a control (looks like a giant dash-pot bit has wiring running to it) on the right side of the inner fenderwell (driver's side) that had a vacuum line running to it that was really in bad shape (think turning to 'rubber sand') and in the process of trying to trace that vacuum line (it goes inside the firewall and under the dash), we unplugged the power wiring to that runs to it and that's about as far as we got that day becuz a storm moved in and it was time to close the hood . Anyways, all I've done since is to re-attach that control to the fenderwell and then started it up to move it back to get it out of the way .... and lo and behold, the car runs good, no stalling or dying at idle, etc. So, I'm assuming that that is your Idle Air Control Valve - am I maybe wrong? I have run it up the street and back (it's not licensed yet) and no problems that I can see so far. I'm just going to replace a short section of the vacuum line until I hear back from you about what this control is or might be. I haven't yet hooked up the power to that control, although I will do that just to re-affirm whether the control is/isn't the problem. THANKS!!
NOTE: As soon as I am able to get this problem taken care of, I will be asking questions about door handle mechanisms, but I will start a separate thread for that
[QUOTE=jimk;901019So, I'm assuming that that is your Idle Air Control Valve - am I maybe wrong?[/QUOTE]
That's not the IAC, but if it work for you, great.
The IAC is a motor-driven valve on the throttle body that allows a small amount of air to enter the intake at idle. Unlike carbs where the throttle blades are held open by the idle speed screw, on an EFI motor the throttle blades close completely and all idle air bypasses the throttle blades via the IAC. This allows the computer to carefully control idle speed, eliminating the need for a separate fast idle system. The IAC is usually a pintle valve controlled by a stepper motor. Carbon builds up on the pintle due to reversion in the intake, and this can prevent the pintle from metering the airflow properly.
This is a typical GM IAC. The silver cone is the pintle that seats against a seat in the throttle body.
Thanks Joe, at least we know now that it is NOT the IAC
You've given me an idea tho ..... I'll see if I can find an image of the Fuel Pressure Regulator Valve (looks like it's in the right place from the drawing of the vacuum lines you posted). If that is it, I'll let you know, and if it is, is it critical if I just leave it unhooked, or should I try to replace it? In other words, is it a part of the smog system or is it something that will affect the running/fuel-efficiency of the car?
OK, with the help of a local auto parts employee, we've decided that it is the cruise control servo. I got numbers off it and looked them up online - no soap from GM .... apparently they've stopped manufacturing them! I can find a reman for anywheres from $88 to $108 .... but .... I hooked everything back up ande started the car and it runs just fine now! Dunno what the deal is, but I'll go ahead and license it so I can take it on the road amd do some test drives.
Thanks, jimk
Thanks for all the help - I just got a package in the mail - Vol 1 and Vol ll of the 91 Olds service manual ..... $4.99 plus $4.00 shipping ...... WOOT! Now I won't have to bug you guys so much ;>)
I still have issues with the driver's door handle, so I'll be working on that soon, but I just wanted to say thanks !!
Just got everything fixt, and now I'm going to sell it ....... I got a used '96 88 for a real good deal and two cars is too much! I've got my pickup truck, my Falcon, a junker Tempo with a bum tranny, and the two Oldsmobiles. I hate to part with the 91, but the wife likes the 96 better (the 91 has much more style, but the 96 gets better gas mileage), so to keep the peace ....... (unless I find out that there are some really bad things about the 96 ;>) ) .....
jim
February 17th, 2016, 03:29 PM
Vacuum Diagram, 1991 Cutlass Supreme LS
. Anyways, all I've done since is to re-attach that control to the fenderwell and then started it up to move it back to get it out of the way .... and lo and behold, the car runs good, no stalling or dying at idle, etc. So, I'm assuming that that is your Idle Air Control Valve - am I maybe wrong? I have run it up the street and back (it's not licensed yet) and no problems that I can see so far. I'm just going to replace a short section of the vacuum line until I hear back from you about what this control is or might be. I haven't yet hooked up the power to that control, although I will do that just to re-affirm whether the control is/isn't the problem. THANKS!!
