3.2 idle

[WI wide body]

My stock 3.2 Carrera engine idles at around 800. Seems like it would be more steady a bit higher. How do I increase it without changing anything else?

Thx.

[Quicksilver]

Originally Posted by WI wide body

My stock 3.2 Carrera engine idles at around 800. Seems like it would be more steady a bit higher. How do I increase it without changing anything else?

Thx.

The idle is in the chip. The later chips increased the idle from 800 to 880 so it would be a win-win to put in the #1267355358 28 pin chip. In addition to the idle increase you should see some improved throttle response and a bit more power. If your DME isn't 28 pin it is a real easy conversion to switch it from the 24 pin chip.

[hcoles]

the idle is software controlled. I wondered re. the accuracy of the tach. When I was getting a smog check I watch the rpm at idle on their equipment, 880 dead on.

[WI wide body]

Yeah I knew it was pretty much a pre-set deal in the chip or the brain but I was just wondering if anyone figured out how to just increase the idle a little without affecting anything else.

Thx guys.

[WI wide body]

Actually, I thought I read somewhere that a 28 pin chip will not work in my 1986 Euro version Carrera. Is that true?

[hcoles]

many 3.2's don't have a rock steady idle, my car doesn't, but was helped by a deep tune up (plugs, wires, cap, rotor), I have a 964 cam, leave it alone and live with it or see if Steve Wong can suggest a chip, have someone else listen, it might be you are too sensitive, been there done that, I've noticed that during the warm up period 15seconds to 1 min. the idle is very steady and then it gets a bit bumpy

[Jonny042]

You will NOT be disappointed with a SW chip. I think it will help idle but better confirm with Steve. Even if it doesn't help the gains elsewhere will blow you away.

[ischmitz]

You can pretty much make any chip work in any 3.2 DME. The pin number (24 vs. 28) is due to the memory size of the chips. If the original DME has only 24 pins you can add the missing 4 pins and then use the later chips.

Next, there is a late ROW (357) and a late US (358) version of the Porsche software available commonly referred to as 357 or 358. Both come in the 28-pin EPROM and have the elevated idle. You can use either. The Euro version is ever so slightly more agressive to account for the better gas. And then of course there are aftermarket chips.

Poor and hunting idle can have a lot of reasons. Check your mixture and make sure there are no intake leaks. Next, make sure the idle microswitch engages and is working properly. That should give you a good set of pointer where to start looking.

Cheers,
Ingo

[hcoles]

we might want to consider if there is an idle system issue or just a bit of a rough idle, if the experts say it should be dead smooth then fine, experts here that have driven my car say it is good compared to some, so I guess I really don't know what to suggest

[WI wide body]

Ingo and hcoles,

I recently changed the plugs, rotor, cap, plug wires, etc and had a shop check the injectors and do "3 gas" or "5 gas" check (or whatever they call it) and it really runs fine. Not much of a rough idle or hunting (except the first few seconds when it starts up) and it accelerates and goes down the highway very good.

It just seems to idle too low!

Maybe it is just me being over critical. Gotta remember the engine and the rest of the electricals and gizmos have 82K on them and are 25 years old.

But thx for the input.

[WI wide body]

BTW Ingo,

How did that 3.6 get in your old 911? I had a '74 Carrera and it had a great running 2.7 in it!!

[rusnak]

There is an idle adjustment screw, but you want to adjust to spec idle speed, not higher unless you have an altered sofware/ chip, which may be the case. You might do some research into your row chip.

[kidrock]

I always believed that the '87-'89 3.2's should idle at 880 rpms, as opposed to the '84-'86's that should idle at 800 rpms.

To WI Widebody, my opinion is that you may want to adjust your idle first. If you have any idle issues after the adjustment, then post back with your results. There are several issues that affect the idle on Motronic systems, but it sounds like you may just need an adjustment.

Do you know how to jumper the B and C ports on your diagnostic plug? If so, go ahead and do that and adjust your idle (motor properly warmed!) at the adjustment screw on your throttle body.

If that seems Greek to you, let us know and we'll walk you through it.

[dshepp806]

This jumper centers the ICV (there-abouts), I'm told. And that the adjustment simply moves this center point. Is this correct? Does this have more to do with a "starting point" for the DME-controlled idle.

My 89 seems to be a bit low on RPMs at idle. My first hunch is to VERIFY "where" she's actually idling to verify the RPM gauge reading. Next would be to look at mixture? (V-leaks aside)

Definately NOT 880 RPMs....for now. Maybe 810....

Best!

Doyle

[kidrock]

Doyle,

Everybody here will tell you that I'm certainly no expert. I only regurgitate that which I've read over and over and over and over. And my memory certainly ain't what it used to be. That being said....

I don't exactly remember what the jumpering technique is used for. I just remember to do it, with the motor warmed up and the O2 sensor temporarily disconnected. Probably something to do with temporarily "fooling" the DME so a baseline can be set.

I advised the original poster to do a base idle adjustment because he has stated that he has no issues other than a "low" idle. If his car is performing normally, a basic adjustment may be all he needs.

Now, in the case of a surging or rough idle, certain diagnostics need to be run. Certainly, v-leaks are a major contributor to idle issues with the motronic cars (and CIS apparently, too). Searching for v-leaks is not all that tough, with the possible exception of those damn intake manifold gaskets.

I've heard from several guys who race these things that messing with the AFM screw should be one of the last resorts. But if you're fortunate and have one of those LM3 thingys, you'd be one step ahead of the game.

But if you think you have leaks, fix them first. Then, have your mixture tested. Once you have that magik 14:3 ratio (or whatever it is), then set the base idle. I'm pretty sure that's howit goes.

Sorry for the hijack. Now, back to your regularly-scheduled programming....

[86 911 Targa]

As per the above post, check for a vaccum leak, ect... first.

While the car is idling, put your finger on the ICV, and you should feel a vibration.

Try cleaning the ICV first.

Here's the jumper location.

pm me as needed.

Good luck,

Gerry

[Lorenfb]

"I just remember to do it, with the motor warmed up and the O2 sensor temporarily disconnected. Probably something to do with temporarily "fooling" the DME so a baseline can be set."

- kidrock -

Actually, not correct.

"I only regurgitate that which I've read over and over and over and over."

- kidrock -

Few if any info found on the internet (especially some forums) is factual!
A common problem encountered over and over again which continually misleads many
not only in wasted time but money too.

"This jumper centers the ICV (there-abouts), I'm told. And that the adjustment simply moves this center point. Is this correct?"

- dshepp806 -

That's correct.

1. The O2 sensor doesn't need to be disconnected.
2. The jumper just places the vane in the idle valve at its center point,
i.e. allowing an equal movement to raise or lower the idle from the preset
desired point programmed in the DME ECM. Then the air bleed screw can
be set to this preset value resulting in the idle valve remaining at the center
point once the jumper is removed.
3. The idle adjustment can be adjusted without the jumper, but a center point
won't be set. So the idle can be increased beyond the preset DME ECM value,
but the idle value will no longer be able to compensate, e.g. the A/C compressor.

[Tippy]

Thanks Loren for your expertise!

[kidrock]

Thank you for the clarification. FWIW, I did clarify in my post that I was NOT an expert.

[screenwriter-X]

Having read every thread on here and every other internet forum when I was suffering from an less than perfect idle on my 1989 3.2, I did a comprehensive study of this phenomenon. Because it annoyed the hell out of me.

In 3/4 of the cases, analyzed objectively, a less than perfect idle in a 3.2 was the result not of vacuum leaks, or chips, or anything usually pointed to. When you have those problems, the idle is not just a little off -- it is rough. In fact, in the cases where the idle was not quite perfect and only a little off, it was related to some retard at some point messing around with the air/fuel idle mixture screw under the AFM box.

It has a factory installed plug so that is not to be messed with unless and until the O2 sensor has been replaced and as a last resort it must be adjusted. And it is to be adjusted using a CO2 sensor and/or the Bosch equipment to do so. You can do it with a voltmeter method, but it is rather blind and dumb luck is required to get it perfect.

The average monkey/retard/crook at an independent shop will drill out that factory plastic plug and start screwing around with it. Often, they don't realize that they are not "tuning" the engine in any way, as the air/fuel mixture is taken over by the DME once the idle off switch is activated. See 86 911 Targa's second pic above. So all they are doing is sabotaging the ability of the DME to give you a perfect idle, because they have set it a tad too rich or a tad too lean, and from then on your DME is taking readings and making little readjustments and you can never, ever get a perfect rock steady idle again.

Unfortunately, some home mechanics fall into the same trap. Though they obviously mean well.

If you want your 3.2 to idle perfectly, you must get this air/fuel idle mixture back to a perfect setting, or all your other efforts will be a waste of time. Period.