jagerocks

Duncan, Parts show motronic flap style from 89-94 911 C2/C4. 993 have round air mass meter.?? I just looked it up useing Metric parts Catalog.
Jason

Dunasso

I am not sure, because there were alot of changes between 90 & 92 that may need to be addressed. Again I am not familiar with all the differences but I do know the DME, intake system, and there were some cylinderhead differences (gaskets I think) that were made between 90&91. So with that said it may be possible to buy the MAF for your car but there is no way I could tell you what the end result would turn out to be.

The MAF that I purchased was from Autothority and from what I understand the company has been bought out by another. I'm not sure who. My install of the MAF was very straight forward and fairly effortless. However, there have been other Rennlisters that did not have it as easy. I would suggest doing a search on the Rennlist search to help youself with this.

It is my beleife in theory, due to some info that I've read and by deduction, that I've come the statement I am about to make. My personal feeling is that the HotWire MAF gives a more constant realtime reading for air movement. The vane MAF is hard pressed to do this, especially if the engine is surging wildly. The time interval for the flap to move back and forth as the engine surges is too slow and inaccurate to aid in correcting this, and you stall. I know that under normal conditions this does not occure due to the added weight of the DMFW. That extra weight flying around allows the DME to recognize that the engine slowing down in time to make the neccessary changes, which it has a hard time doing w/the SMFW. The RPMs drop off too rapidly and when they reach the critical low, thats when the DME realises it and opens the the Idle-air. But the MAF is showing little to no air movement because by now the flap is shut, and the cycle begins. RPMs go Up and down Etc... until it get so far off it stalls. Now this is just an opinion not fact, but I believe that the HotWire MAF, sense it has no flap, sends a much more accurate realtime signal to the DME which gives it that few millisecs of an advantage over the flap.

Duncan

jagerocks

Yes your statement is correct, Mass air flow is much much better and correct. Funny you should say Autothority was the company you bought product from. They are the ones who installed the turbo clutch and LFW in the car. $4,700 bill. I would think they have would have dealt with this problem before and corrected it. I live now on Vancouver Island BC, Canada but I bought the car from Virginia and got it shipped up so I never knew about this problem (I still would have bought the car).
I think I don't really want to mess around with DME anymore and Mass air flow, I heard that adding weight to make the flywheel 19lb will fix the problem. This would still be lighter than factory but heavier than the 12lb that is in it now. WHY WOULD ANYONE MAKE OR INSTALL A LFW WITH THIS KNOW PROBLEM. What a waste of time and $$. The real waste is the clutch & LFW have only 500mile on it. And to re-due the job again. The hole thing just ticks me! Any how tomorrow I will call around Autothority and see what they have to say. The car is basically not drivable, it doesn't even surge, just totally craps out and stalls. Kind of ambarising.
Thanks for all who gave me your thoughts, I will post my feedback on monday 7th.

Jason

JasonAndreas

Did your RS chip also come from Autothority? Don't waste your money hoping their MAF will solve your problem, the issue is with the software in the DME and not the hardware (AFM) that measures airflow. If you run a system adaptation with a Bosch Hammer on a 964 with a LWF and no other issues you will have NO STALLING PROBLEMS until the DME recalculates the adaptation parameters. (it surprised me the first time I did it) You'll then eventually have stalling issues again but nothing as bad as you describe (i.e. its a temporary solution for those with KTS300 but it proves the problem is with the regular 964 software and not something else). Do I understand you correctly, you don't even get a bounce back surge when you let off the throttle? The RPMs just drop and the car stalls? Have you cleaned your ISV? A clean ISV won't come close to solving your problem but it will make the car at least driveable.

Adrian

Dear Jason,
I am interested in this "Turbo clutch". Seeing as the 964 Turbo has a DMF with a DMF clutch assembly I wonder what they used?
I also strongly recommend you purchase my book Jason. Most if not all the questions you ask are in the book.
What you can do is put the script on the back Carrera 4RS. Then it will be okay because your 964 seems to have the characteristics of this special 964 that needs 7000 rpm to keep going (just kidding of course)
You have to fix the car properly and I strongly advise you NOT to spend any money on gadgets to try and fix the unfixable. The LWF was not designed for your 964 and it will be cheaper returning it to standard than trying to eliminate the stalling issue.
Ciao,
Adrian.

Christer

Motec

Adrian

Dear Jason,
You might want to check that the idle microswitch is making contact when you take your foot off the gas. If this switch is not made the ISV will not even work.
The MAF story is incorrect and as Jason A. says a complete waste of money. If you understood how the whole system worked things would be clearer for you and what you have to do to fix it.
There is NO cheap way out of this situation. You cannot adjust out faults, you have to bite the bullet and fix it properly.
Ciao,
Adrian.

jagerocks

DearJason & Adrian,
Autothority only installed the clutch kit, I bought the chip from a fellow that said it was a place to start to see about repairing the stalling problem, I can email install instructions if anyone wants to read them. Also what do you mean by

"If you run a system adaptation with a Bosch Hammer on a 964 with a LWF and no other issues you will have NO STALLING PROBLEMS until the DME recalculates the adaptation parameters."

Is Bosch Hammer a fault clearing method and can I do this? please tell how. I would love to try it even if it is a temporary solution repair. I will clean the ISV I have never cleaned it yet and don't know if it has ever been done.
If I can't fix this I must install reg flywheel, you just can't enjoy the car the way it is.

Adrian, I have no idea about how they installed the clutch kit at Autothority, but I will ask on monday and will let you know. Is it possible to call anyone about this prob to recap all? tring to read emails over and over is allot to draw in. Just a thought.

Thanks allot guys for you help.
Jason

Adrian

Dear Jason,
I did not ask how? But what? Because there is no such thing as a LWF with 964 Turbo clutch unless they magically got hold of a Turbo S (ROW only) kit from Porsche motorsports and seeing as this uses a RS clutch it still is not a Turbo clutch.
It is very frustrating for me sitting here in Switzerland (I shouldn't care I suppose but I do) reading a lot of the stuff in these threads and others about people adjusting out problems.
In the end it all comes down to your money but in the end you will NEVER be happy with the car until it works correctly.
I cannot offer you any more advice apart from what I already have.
I deliberately refrain to making comment about particular suppliers in public due to the threat of legal action.
Ciao,
Adrian.

JasonAndreas

Does the receipt from Autothority include part numbers?

The problem with buying eproms from a 3rd party is that without checking the contents with an eprom reader (and having something to compare to) you really won't have any clue what you've bought. Sometimes even chips from well-known tuners can be questionable.

I was just pointing out that there are ways around the problem (software), but that the bosch hammer solution is just not that useful on a daily driver.

A Bosch Hammer (KTS300) is the dealer diagnostic equipment for early motronic based Porsches, your local Porsche dealer should have one.

There are great instructions with pictures in the archives here.

In the long run you probably will end up doing that but before you spend another $3000USD to do so, clean the ISV, check the idle contact switch (and there are a few other things you can check that don't cost anything that can have an affect). We all have issues with our LWF but not to the degree you describe. What other work did Autothority do?

jagerocks

Adrian, I hear ya, Maybe there is no turbo clutch kit in my car, the fellow I bought it from said there was but maybe he misunderstood. That's all I was told. I will find true stroy out on monday, and post the answer. If you say it's impossible then it is, it's all 2nd hand infomation. I want to know 100% what I have, because it will problably make a difference in what were saying.
How do I run a system adaptation with a Bosch Hammer on a 964 with a LWF ? This may help me in the mean time to get car around. I will clean ISV & check idle microswitch, were is this switch located? at pedal? or throttle housing?
I found the papers on clutch job, the parts # are as follows:flywheel 96410223931, ring gear 96411414331, c.disc 96411601161, P.plate 96411602890
Does this help to see if turbo clutch kit is installed? or flywheel?

Jason

jagerocks

They performed clutch kit, flywheel, cap/rotors,s.wires, belts,alt belt sensor,s.rack boots and wheel align car to RS spec's , service trans with synth 75w90.

A IMPORTANT NOTE IS ON INVOICE, IT SAYS "cust requests we tune his software and install new idle sabilizer valve for light flywheel, We recommend breaking in the new clutch for 500 miles before tuningwork, Otherwise we may distroy the new clutch llining, Tec also recommends removal,cleaning and reinstalling of ISV. He also found that the belt tensioner switch needs replacement."

Now how is this for infomation, right from the invoice.

Jason

JasonAndreas

You'll have to drive to the local Porsche dealer or independent (if they have a hammer).

The switch is located ontop of the intake manifold. Check the archives here or even better, pick up Adrian's book it shows were everything is and gives an even better explanation of what, how and why things are.

Assuming Autothority installed genuine Porsche or OEM Sachs parts then those are just standard Carrera RS part numbers and not for the Turbo.

jagerocks

This is on the invoice, so if it says just reg clutch kit and what about flywheel? is this a reg # or lighten? I will call in morning.

JasonAndreas

Sorry about that, those are RS parts and the flywheel is lightweight. Is there a part number on your invoice for the idle speed stabilizer valve (ISV). The 993 version is adjustable but I have no clue if PCNA superceded the 964 part and if the 993 version is compatible. If you have a 993 part you might be able to do something.