3.2 Idle Speed Adjustment ????

[cary]

Had a problem with the car dying after "cold" start. Giving it a little rev up. It would die after returning to idle.

Time for Idle Speed Adjustment

Jumpered the test plug. Measured the idle at 750 rpm. Not Good. So I adjusted it to 900 rpm. But I noticed that it seems to idle smoother with the Idle Speed Controller "jumpered" off. ?????

Pulled the jumper. Idle returned to about 840 rpm. Not high enough. So I jumpered it again. Adjusted it to 990 rpm, hoping it would return to 900rpm. Pulled the jumper. It settled in at about 850 rpm. That didn't work. So I returned it to 900 with the jumper in.

Being that it idles better with the ISC jumpered out and I can't get it to 900rpm. Is it time for a new Idle Speed Controller ?
Are there any definitive tests ?

TIA

Opps... Forgot to say, raising the idle cured the problem. But I like the smoother idle with the ISC jumpered out.


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Cary Kutter
77 Euro Carrera w/3.2
PCA Region - Big Sky

[This message has been edited by cary (edited 08-01-2001).]

[nhromyak]

I have noticed this smoother idle too, however, I found mine idles smoothly with the O2 sensor disconnected. I believe this puts the DME in an "open loop" state.

Anyways, I found that setting the speed at 850 with the ISV jumpered works fine for me. When the engine is at running temp or colder it actually idles at 750. However, when it gets warm - or hot, it idles at 850.
This seems good enough for me.
Good luck.

BTW: My '85 specifies the idle should be at 850 +/- 50 rpm.


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Nick Hromyak
'85 Carrera 7 & 9 Fuchs
Havin' Fun in Sacramento

[cary]

My Haynes showed 880 +/- 20. So I went to the high side, to cure my problem.

Thanks for the help.

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Cary Kutter
77 Euro Carrera w/3.2
PCA Region - Big Sky

[jlex]

Hey guys, I'd like to adjust my idle as well... it's running about 450 rpm on my '85 3.2. I remember having to jumper my idle speed controller on the Volvo, so I know what you're talking about, but I don't know where the connector is on the 3.2 or the idle speed adjustment screw (or knob) is. I find it really funny that they don't bother to address that in the Bentley book.
Please point me in the right directions, guys. Thanks
jlex.

[cary]

Mine is a 3.2 conversion so mine isn't 100% correct.

But the test plug should look like a relay socket right next the coil. There are only 3 connectors in the plug. Two at the top and one at the bottom. Don't remember the correct alpha characters. ( Hopefully, Mr. Walker will jump in ).
But it's the bottom one and the top right that you jumper. ( upside down triangle points )

The adjuster is a 7mm brass cap right above the Idle Speed Controller ( to find this, turn on your key, engine not running. Walk back to engine. You should hear it buzzing. slight vibration to the touch ). Right above that in circular casting is the idle speed adjuster. Clockwise slowed it down. Counter-clockwise raised it.

To me it looks like a cap. That should come off. But turning it raised my idle so I didn't go adventuring...........

As for idle. You have to be reading that off the dash tach. I'm sure its higher than that. I'm measuring mine with a digital auto meter. Mine read 500, and it was really 750. Mine now reads between 8-9 on the dash tach.

Good Luck





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Cary Kutter
77 Euro Carrera w/3.2
PCA Region - Big Sky

[jlex]

Thanx, Cary... you're right. I am reading it off the dash tac. I've got a Fluke automotive multimeter that I'll break out when it comes to the final rpm adjustment.
Will print out your comments & see if I can locate all I'm looking for. Still puzzles me why they wouldn't put something as obvious as idle speed adjustment in the Bentley book. I know the DME unit is supposed to set it automatically, but that isn't always the case
regards,
jlex.

[john walker's workshop]

pop the top off one of those round black relays and use it for the jumper. push the contact down with your finger to make it work. simple and fits the plug too. the idea is that the idle should stay the same with the jumper on or off. adjust it accordingly until it doesn't change.

[cary]

John, how do you know when the Idle Speed Controller has gone tits up?

There is a significant difference between jumper on and jumper off. About a drop of 150 rpm's when I pull the jumper off.

What other adjustments can you make to get the 2 idles to come together ?

Why would it be smoother with the jumper in ?

TIA


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Cary Kutter
77 Euro Carrera w/3.2
PCA Region - Big Sky

[john walker's workshop]

you have to adjust the idle speed screw on the throttle housing to even the speeds. do it hot, and go in or out to achieve the proper speed. use a 7mm deep socket.

[Ned, NYNA11]

Thanks, John.
Guys, this good stuff is covered nicely in Bently. I have been dinking with mine for a while.
Square one is to be sure that the idle speed controller is switched on when the car is at idle. To check it, push the throttle linkage a tad beyond the butterfly closed position and you should hear the switch operate. It is in front and below the throttle and looks like a small black box. The actuation is via the linkage acting on a little knob on the switch box.
The assembly is mounted with 2 impossible to git at phillips screws and these must be loosened to move the switch. Replace them with a couple of 7 mm hex heads before even trying to adjust the switch as a little 7mm wrench is easier to use than a stubby screwdriver back there.
My idle (87) has been cycling a little, too rough at the lower end of the range, so I disconnected the oxygen sensor and the idle went to 1100 and steady.
Have adjusted the speed as John suggested and also have ordered a new sensor.
There will be more updates as I approach smoothness.
Ned Monaghan

[KTL]

This is one of the simplest and clearest topics I found on the idle speed adjustment.

Just something to add here............

If you didn't know that a black relay worked for jumpering the socket in the rear engine bay fuse panel, the two pins you want to jumper (referred to as "B" and "C" in the Porsche spec. book and repair manuals) are at 1 o'clock and 6 o'clock on the socket.

One thing to keep in mind too. Your instrument panel tach might not be super accurate. So you may not end up with the 800 rpm (84-86 cars) or 880 rpm (87-89 cars) that you are looking for. As long as the idle stays the same whether you're jumpered or not, I guess you're okay?

A good test for your tach accuracy would be to hook up an inductive tach and see how the two compare.

And as long as you're bothering to fix your idle problem, it's probably a good idea to clean the ISV (Idle Stablization Valve) since it has a lot to do with the idle quality. It's the Bosch cylinder with the two hoses coming out of it. Right in front of the throttle body staring you in the face when you're looking at the idle screw. Remove and clean it with some electric parts cleaner (just like brake cleaner except for electrical things) and let dry.

ISV: