3.2 idle speed/mixture adjustment?

hcoles · 08-02-2005, 10:32 AM

I did a search and didn't find much so if the thread I need is out there please indicate so I don't waste peoples time....

I just did a top end on my 3.2. I want to get the idle and mixture properly set because right now the idle is a bit rougher than I expect. The only change is from a stock cam to Camgrinder 964.

As far as I can find out there are several adjustments:
1 - side of throttle body - throttle plate stop has a locking nut
2 - front of throttle body - has a plastic cap over the hex adjustment
3 - under the mass flow sensor body - 3mm Allen to adjust CO or I guess the idle mixture

I've tried adjusting to get the idle speed up to 880 indicated on the tack, not sure if that's accurate. Can't quite get it up there...the #2 adjustment seems like almost all the way out and starts hissing a lot. I feel like if I move it out any more the adjustment plug will fall out.

Tried adjusting the mixture 3mm Allen with O2 unplugged. Screwed it all the way in and couldn't seem to detect much idle quality difference or speed difference. I screwed it back to where it was or I think where it was.

Also, I feel like the idle control module (rotational valve) should be "centered" somehow so it doesn't run out of "travel" as it tries to adjust for AC coming on and moving slowly without adding throttle.

The idle is not that bad right now. The idle does seem to be smoother when the AC comes on. The idle speed response to AC or slowly moving the car does seem to be slower than before.

Any ideas or instructions?

I think my next move is to really check what the warm idle speed is using an optical tack we have here at work...I guess I'll first try painting a white mark in the AC pulley groove.

Thanks,

-Henry

MBEngineering · 08-02-2005, 02:52 PM

Hi you will have to take of the relay cover on the left side of the engine bay, behind it you will find a socket which looks like a round relay holder , a tool plugs in with a small switch on it (porsche part) to switch off the idle valve, so you can addjust the idle, in your manual you should have instructions to jump this without the tool, set the idle & Co then remove the jump wire, will check in the morning in the manual which to jump.

regards mike

hcoles · 08-02-2005, 03:06 PM

Mike,
I know about this plug on the left side. I've seen this and done it. I think the contacts are B and C....it's on the 911chips.com website. Lower contact and upper right contact at about the 1:30PM position as you face the plug. It could be I need to try again but it seemed like I almost had the screw all the way out and still didn't get to 880. This makes me think I should maybe crack the throttle stop open just a bit. If your instructions/etc. show a different two contacts to short or ? please let me know. Thanks much.
-Henry

MBEngineering · 08-04-2005, 01:16 PM

Hi sorry have not checked yet, also check for air leak's in the breathing system and the oil filler cap is on tight and sealed.

regards mike

hcoles · 08-04-2005, 05:57 PM

I went by my mechanics place today and he said it idles good and is better than most he sees. I would have him fix it but I told him it's embarrassing if I can't fix it myself, he understands me by now. It has a 964 cam so that adds to the roughness. After running it a bit more it really is not that bad. I think I'm being a bit paranoid about it. It is still surgy at low speeds however. The plan is to have the CO reset and then see about getting the idle back up to 880...it now indicates 800. The mechanic thinks something is amiss because the idle adjustment screw is very far screwed out. I guess I'll keep messing around with it. I haven't seen any intake leaks but didn't look too hard yet.

Thanks,
-Henry

MBEngineering · 08-05-2005, 02:16 PM

Hi have found the test manual for the 3.2 engine , the pin holes are B & C for the jump wire, idle at 800 +- 20 rpm, i have the test plan book wkd 490 920 if you cannot get hold of this book over there , send add and i will run a copy off for you

hcoles · 08-06-2005, 05:53 AM

MB,
Thanks for the confirmation of the pins and offer to send pages. Please don't go to that trouble at this point, unless you can get access to a scanner/fax. I'll try a few things again and see if I can get the idle up to 880.

Is the wkd 490 920 a Porsche publication or ?

Thanks again,
-Henry

MBEngineering · 08-06-2005, 02:08 PM

Hi yes that part No is a porsche part No, the idle should be 800 rpm NOT 880rpm, as porsche say 800+/- 20 rpm
regards mike

hcoles · 08-08-2005, 05:06 AM

Hi Mike,
89's or at least US versions of 89 3.2 had the idle spec. changed from 800 to 880. I pretty sure of that. This agrees with my mechanic and the Bentley book (if I remember correctly).
Thanks,
-h

Jeff Alton · 08-08-2005, 08:21 AM

I have 964 cams in my 3.2m, I set the idle at 950. It is rock steady and smooth.

Jeff

hcoles · 08-09-2005, 03:23 AM

Jeff, Thanks....I'm still working on getting the idle up to at least 880.
-h

kepperly · kepperly's Garage

Make your self a tool out of an old relay by takeing the plastic top
off and plugging it into the socket. to go from closed loop to open loop just push thr contacts into the closed position and try to match the idle speed between open and closed.

Keith Epperly 87 slant nose turbo look carrera cabriolet

hcoles · 08-09-2005, 08:06 PM

OK, will try that....I guess what you are saying is you can short and unshort B and C while adjusting the idle up or down to where you want... correct? Or is it short and unshort and make my way to 880rpm? The idle speed is set when the short and unshort speed doesn't change....as you said. Can't hurt at this point. Should the CO be set before doing all of this or maybe doesn't matter...can easily be done after CO set.
Thanks,
-Henry

s5uewf · s5uewf's Garage

Did you ever solve this issue Henry? I ask because I am seeing the same symptoms.

I can short out the pins on the left fenderwell and then back out
the 8mm air bypass until it is almost all the way out before the idle comes up to 800 or so.

Did you end up doing anything differently to solve your issue?
Has anyone else done anything different than adjusting the air
bypass screw?

The fact I need to back out the bypass screw so far tells me the idle is set rich right now, and a lot of air is needed to balance the mixture. Is this a correct assessment?

hcoles · 05-13-2006, 12:36 PM

I didn't fix it yet...the idle is sort of choppy but runs ok. I would stll like to see if it runs smoother at 880.
Sorry for late reply..this computer was on the fritz and I didn't check email until now.
-h

s5uewf · s5uewf's Garage

I fixed mine by screwing the air bypass back in to where it was, then turning the CO mixture 3mm allen counter clockwise to lean the mixture until I got a nice steady idle with the bypass jumper in place on the left rear fenderwell. I got bypass idle to match the idle when the jumper is removed.

I plan to check the stoich with a voltmeter when I get a chance over the next few weekends.

Hope this helps.