dfinnegan

I did replace the battery earth wire back when I got the car. Purchased 2005. Maybe 2006 for the new earth wire. I'll check the connection again, and the starter connections. Thanks.

I did check the AFM again. I pulled the air box, double checked the tech bulletin fix. Then wire wraped the ruber hose back to the piping. I'm fairly certain that is not the issue. At least, not the wire touching. Could be the AFM, itself. Although, that, too, has been replaced. I was after an un-drilled airbox and got the AFM with it. I installed the new airbox/AFM as it appeared in better shape than mine. That doesn't seem a likely culprit as the issue is not pedal position related. The cut-outs occur at different rpm and pedal positions. Though, I suppose I could give that greater thought. I could replace with my old AFM and see if that changes anything.

As far as cracked wires go, is that visible with the engine in? I do not have the engine out and would rather leave it in for now.

So, here's my list of things to test/try:

- check battery voltage - motor off, at idle
- check generator output - shld be 13.8-13.4V
- check battery earth wire
- check starter connections
- try old AFM/airbox
- unplug o2 sensor (test drive only)

Anything else?

I'm out tomorrow. May have some time on Mon. Out Tue. Working from home office again on Wed and Thu (1st time in 5 months!), so may have time to do some testing.

Will post as I'm able.

Thanks again!

ras62

Ideal if you could put the hammer on the car to see if any fault codes can point you in the right direction.
I also had similar issues and it was the O2 sensor although it was reading fine both static and on the hammer, sometimes it would breakdown causing hesitation/hunting etc. It would record as O2 sensor fault on the DME. IIRC my car did not run with it disconnected.

gchristofi

IIRC, there is a jumper on the ECU to set the car up for running with no O2 sensor.

I had very similar symptoms (although not on the 964 but on an e30 with similar Bosch motronic) which turned out to be failing solder joints within the ECU. Replacement solved all the issues. With the faulty ecu in place and the car idling, a very gentle tap to the ecu casing would cause the engine to stutter. Might be worth a similar "scientific" test or finding a known good ecu to test with.

Simc964

Had the air flow meter and fuel filter replaced today. Could immediately feel the difference. Much smoother power delivery, no hesitation, perfect idle. Fuel filter was nearly new but dealer fitted a replacement as a precaution. His thought was the air flow meter and fingers crossed this has permanently solved the problem. Just had the best drive since collecting 2 months ago. Very happy boy this evening, hoping it lasts!

Vandit

Definitely keep us updated to see if this clears up the issue.

What are you doing w/ the old AFM? You can open them up and check the condition of the internals and even adjust the resistor arm to give it a new/unworn contact area.

Simc964

Dealer kept the old one since he switched it with one he had in stock. There seems to be a few people with the same problem so let's hope this has resolved it and give some hope to the others. Early days though!

Simc964

To update. Despite it being night, cold, slightly wet, I could not resist going for a drive on some empty country roads to really make sure it's fixed. Just did 30 miles of smiley face driving. Car was perfect and is so much more responsive, faster, just better in every way. The problem had been there from day one of collection but having not driven a 64 just presumed that was how it was. My god, I loved the car anyway. Now I am totally smitten! Hope this is the problem with the others facing similar symptoms and you can get your cars back to health. Will sleep well tonight

dfinnegan

Simc964: Congrats! Gotta' love that feeling with the car is "running on all cylinders". :-)

dfinnegan

Update to my cut-out issue:

+ Changed the DME relay for a spare. No change on test drive.
+ Checked battery voltage at idle (via Hammer) - 13.2V
+ Checked battery earth wire. No change on test drive.
+ Checked hall sensor connector, and all other connectors in engine bay; No change on test drive.

+ Re-positioned #6 upper plug wire (it was damaged and in a position where it could arc). Not sure if I test drove this change, or not.

+ Unplugged O2 sensor for test drive. No cut-outs on test drive!

I pushed it pretty well and had gotten lots of cut-outs on several test drives in this same time period. Encouraging. Part way through the test drive (maybe 5 miles out) the check engine light came on. Drove back home. Hammer said "O2 Open fault". No surprise. Reconnected O2 sensor. Still no cut-outs on test drive.

Also, the O2 readings on the Hammer were very erratic prior to this change. The values jumped so fast that it was difficult to determine any single 3-digit value. I could see the tens place changing and the hundredths place changing, but couldn't comfortably read any single value.

After the disconnect, test drive, and re-connect the O2 values are solid. Still moving fast, but I can very clearly read all digits between changes.

I drove the car into NYC today for an all day business meeting. It behaved flawlessly! 2 hrs each way with an hour of stop and go traffic going in and half an hour coming out, along with some open runs, as well.

I can't be sure if it was the "Italian Tune-up" on the O2 sensor (unplugged and thrashing it), or the #6 plug wire re-positioning. I'll keep monitoring and reporting as I learn more, but for now I'm very happy.

I can say that the car seems to perform much better now. Smooth, solid idle. No hesitation from idle - it used to be just a bit slow coming up on rpms from idle. More responsive overall. Of course, the more closely you analyze these cars the more pefromant they feel. Time will tell.

Thanks,
Dave

Simc964

Great news Dave. 2 happy people!