Paulie964

Aight, I really need some help from you guys ... Time to get some collective forum brain power going here.

So after 4 months of bad luck with mechanics and this rebuild, I finally get my car back ... but its not running right.

Here is what was done.
- Engine rebuilt
- Autothority MAF
- LWF
- Cam regrind
- Primary/Secondary bypass pipes
- 911Chips custom tuned chip (tuned for all upgrades)

Now the problem ..

The car won't idle. It fires right up, but every time I come to a stop, I have to feather the gas back to idle ... otherwise it dies. And then its still 50/50. (my starter is getting one hell of a workout) According to my mechanic, the car is running too rich at idle and the idle needs to be brought up a little. According to the dyno shop, the car is running too rich at idle, and too lean at WOT. According to 911chips, the potentiometer on the MAF wire harness is not adjusted properly. (to me, it looks unadjustable ... but I may be wrong) (pic included)

Any advice you guys can throw at me, would be GREATLY appreciated ...

mr pg

I see you went for the LWF. Could it be the well documented stalling problem often assocated with this? This was originally fitted to the RS, which also had a different ECU. Try a search.
I read recently that the idle can't be adjusted, but maybe someone else can confirm this?

Paulie964

the car actually came with a LWF (nice little surprise bonus). I didn't really experience much stalling before the rest all this was done. I won't deny that its not contributing to the problem, but I'm pretty sure its beyond that.

And yes, you are right. The idle is adjusted electronically. When off the gas, the throttle "mechanism" sits on a switch. There is also a WOT switch.

garrett376

My opinion: LWF + reground cam + mimimal exhaust backpressure = stalling issues

I'd imagine you would need to have someone reprogram your engine electronics to try keep it idling. Was your custom tuned chip custom tuned to your actual car on a dyno? Or just theoretically tuned to your mods?

Dwane

Try cleaning Idle Stability Valve.

J richard

+1 I would contact steve wong and see if he can help you out. This is basically the same setup I have on my street car it's a PITA with the ac on, with ac and lights forget it...you can change your driving style, basically as you pull up to a stop leave it in gear until the rpms. Drop to idle speed 900 or so then pit the clutch in, driving like this the stalling is minimized....

What kind of cam grind do you have? Typically a hotter grind will require a faster idle and can only be done electronically...

Paulie964

Tuned theoretically to the mods I provided to Steve Wong...



My mechanic tried replacing the the entire idle control "something" ... I was so excited to get the car back, I wasn't fully listening ... but in a nutshell, he told me they did everything they could do to try to get it to idle better ...

Steve seemed pretty confident when I first approached with the programming solution I needed. Now he seems a little hesitant on wanting to do the free reprogram. He mentions that the potentiometer needs to be adjusted properly, which may be completely true. I'm sure he knows better than I do ... but, where and how do I adjust it, all I see is a little resistor on the wiring.

I'd rather not change my driving technique to one thats comparable to "walking on egg shells"

As far as the grid goes, its nothing too aggressive, and Steve took that into account already (at least I assume he did)

Pesty

I had a similar issue with my car.

A guy over here re programmed my chip. Is basically 'catches 'it as the revs drop. never stalled once since.

J richard

When you went to the autothority kit you dumped the original MAF and pot, so nothing to adjust. You can fool around with the ISV to try and get a slightly higher idle but you're fighting the DME which wants to make it idle back down.

The issue isn't A/F it's the fact that the DME can't keep up with the drop due to lower inertia of the LWF...additional load like lights or ac just make it worse. So there's driving style, which isn't that bad once you get used to it, or maybe a better MAF kit... I chased this around for a long time...

Paulie964

I sent over the above pic to Steve, and he thinks someone soldered on a fixed resistor. There is SUPPOSED to be an adjustable one. So, there's one question answered.

All of Steves chips come with a LWF fix programmed into them. This is why I'm leaning towards the issue being something else. After having a nice chat with Steve, he led me in some potential trouble shooting directions (if only I lived closer to his shop, I'd have my car over there now, or at least whenever he had a moment) ... I think the easiest solution would be to pop the stock intake components and chip back on and have him reprogram ...

crg53

For what it is worth, I have RS LWF and clutch and primary bypass, cat bypass with Steve Wong chip programmed for those mods and have absolutely no stalling issues, rock solid idle at 840 rpm, lights and ac on or off makes no difference, I would think your problems are else where.
Just my 2 c.

darth

Replace the resistor with a potentiometer?

tbennett017

I was exactly where you are, and the answer for me was to keep the Steve Wong chip, and go back to a stock Porsche AFM. I now have no issues at all. The Authothority setup isn't worth much without the custom Autothority chip. I sold them both off 2 years ago, and I am much happier for it.

Paulie964

its crossed my mind, but the logistics of doing so discourage me. This could potentially mean a few more dyno sessions and a couple more retunes.

I'm thinking the overall best solution is to go back to the stock intake and have the chip retuned. (if this is the issue)

I'm going to take it one step at a time. First, replace MAF with stock along with replacing the chip with stock. If that solves the problem, great, if not ... well ... I'll be back!!!


Again, thanks for all your input folks ... i'll keep you posted

J richard

I think that's the right track and FWIW I have the AT maf along with the install info and I can tell you there is no adjustable resistor, pot or reostat just a standard resistor...

I went through three chips from AT to deal with it to no avail... racecar runs a LWF and clutch open exhaust with a factory MAF...rock solid idle...