Babalouie's 911 - start on p7

[Babalouie]

Maxx Alpha-N is a plug in unit that keeps the rest of the motronic mapping, but bins the afm. I was seriously considering one for the 164. The E30 M3 guys use them a bit.

Ah, I see. Yeah there is something off the shelf for 964 like that, but it's pricey

[Gammaboy]

Last time I looked the kit was $700 for the Maxx, but Aussie dollar is better these days.

[Jason Broadhurst]

When you played around with the idle, it looks like the "base idle" is set a touch low.

Idle air consists of;
Fast idle screw
Vacuum ports and various hoses
Open loop idle valve values
Closed loop idle valve values

Most ECU's open loop idle control until the rpm is stable and then switch to closed loop and PID adjust to the set point. This means you need to have either the open loop values spot on.

If you end up with more air than expected (a vacuum hose off or fast idle screw too far out) and more air getting in; the idle is high or hunts on and off at the overrun cut off value.

If there is less air than expected (fast idle too far in or a expected vacuum bleed blocked) you end up with your symptoms. The idle comes down after over run can some times stall. What happens is the idle valve is open a set amount (lets say 50%), the fast idle is too far in and the rpm stays low until the closed loop control starts to open up the idle valve another few % to get it up to speed.

You usually set this up by putting it in diagnostic mode and setting the fast idle screw to a value on a placard. The diagnostic mode usually closes the idle solenoid to 0% and all other solenoids like AC idle up. You then set the idle to say 750 rpm. Now 750rpm is the minimum the motor will idle, then the open loop value of 50% open holds the idle at 1000rpm and then closed loop idle control brings it DOWN to base idle value/coolant temp.

Worth a check anyway.

[Babalouie]

Hmm...that makes perfect sense. I guess having the idle speed too low is better than too fast (in which case we might be chasing air leaks etc). I'll have a play with it

[Jason Broadhurst]

Is there a setting in the scanner for base idle?

The other option is to start the car with the idle control solenoid unplugged and aim for about 850rpm.

[Babalouie]

I don't think my freeware scanner is that sophisticated. I'll have a look in the workshop manual to see if there may be a workaround

[31GUN]

This is like yours yeah? Nah :D

[Babalouie]

It looks like an 89-91 model with the earlier mirrors. Mine's a 93 with the aero mirrors :D Oh and mine also has a leeetle more ground clearance

[31GUN]

Loving the wheel set though.

[irsa76]

Rotiforms iirc.

[thedude]

Needs more HRE 935 Vintage Series wheels. Project Nasty style...

[Agent86]

Damnit Bab, Now you've rekindled my childhood desire for a porka...

I need to try to find the book i had on F. Porsche as a kid.

[Babalouie]

Time for new shoes!


The old tyres were Advan Neova AD08, which had seen 19,000kms and two trackdays. Here's the front.


...and the back. They've worn reasonably evenly, given that I've got 1.5 degrees of camber


I'd say I've been quite happy with them and they're certainly quite track friendly in that the outer shoulders don't get chewed up at all during a trackday. Wet grip was okay when they were new, but dramatically fell off once the tyre had aged a bit and was in the second half of its life.

So I'm going to be a Yokohama customer again, but this time, I'm getting the new AD08R: http://global.yokohamatire.net/produ...ova_ad08r.html


They look kinda the same as the old ones, but the new "R" compound is meant to be quite a bit faster around a circuit. But on the other hand, the word from some of the guys who've bought the new Rs are that they seem to last just as long as the old ones did.

I guess we'll find out! Just the same, I think I better get some laptimes in the bank while the rubber is still nice and fresh. Subjectively, they feel like a gummier compound than the old AD08, in that I'm now noticing that it's almost impossible to power oversteer in some corners where the old tyres did allow some slip.

[31GUN]

I found something for you buddy. Get on it!

http://www.gumtree.com.au/s-ad/penri...els/1017487932

[clutch-monkey]

15"s might not clear his brakes? not 964 offset anyway i'd say

i will say i'm a little tempted..