Dave Cantrell (Login dgcantrell) HyperScale Forums from IP address 188.8.131.52
Nothing serious, it just worries me sometimes when I get "undeliverable" replies from someone's work e-mail server......
Anyway, here's what I was trying to get a hold of you over. The Saga of the wife's A8L continues...
Still having the same problems that I was to start with on the car.
Heres a recap.
2003 A8L (AUX,FUN) started missing periodically at any speed. Even at idle. You can see the RPMs dip a few RPMs on the tach when it misses at idle. It cranks and runs fine. Ill be going down the road at speed and itll miss for a second or two and stop. Sometimes itll go a 5 or 10 minutes between missing spells, sometimes longer. Sometimes just a few sessions just a few seconds apart.. It seems to happen more often after applying throttle to adjust the speed.
The car had developed an exhaust leak at the passenger side flex joint in front of the cat. Just barely noticeable. This was causing the check engine light to come on (O2 sensor errors). I ordered a couple of flex joints to replace the ones on the car. Just a few weeks before, I thought I had a bad coil but it turned out to be a cracked insulator on the spark plug. All spark plugs have been replaced with new.. It ran fine for the 2 or 3 weeks afterwards.
First we thought it might be the transmission and I order some of that liquid platinum fluid and a filter. Replaced a leaking rear trans seal while I had the exhaust off replacing that flex joint. I welded it as best I could due to the fact I couldnt completely remove it from the car thanks to Audis habit of putting large objects in small places that can only be taken out by completely disassembling the front end of the car Well, ok, Im exaggerating a little but I still have a couple of pin holes in the weld as I could see a little moisture bubbling out of a couple of spots when I cranked the car to inspect it I figure Ill take it down to my local service shop and have friend hit better with the car on the lift and his welder isnt a POS like the one my Dad has.
In the beginning of this latest saga, I bought a $200+ OBD reader to check the codes. After getting misfire codes on random cylinders you and I agree that we may have a fuel pump/fuel pressure issue..
I plunk down $200 for the pump and $140 for the gasket set and replace the pump and hoses inside the pump assembly. (The pump assembly from Audi OEMs has gone up $200 to around $900 from last year) Did you know that SAE-30R10 hose is over $20 a foot? Luckily I only needed about 16inches (thats what she said) Fresh gas and the car started right up. Once it came down off of the start up fast idle, I let if run for 2 or 3 minutes. Hit the throttle and almost immediately, it started the periodic miss. Kind of like a bump. You can see the RPMs drop off and come right back up. I can put my hand over the exhaust at the rear of the car and feel it puff when it misses. But now the car yields NO OBD trouble codes. None, nil, nada
Thats when I had a thought Do you think that the tiny exhaust leak in the weld might be causing a small backfire of sorts? There could possibly be another small leak on the driver side flex joint that I havent yet replaced..
Now Im right at $800 (that's a handful of 1/35 B-25s kits I coulda had....) in on the repair of this car and its driving me nuts Im ready to burn if you know what I mean.. Anyway, Im going to call my friends shop and have him replace that other flex joint and re-weld the one I put on and see if that fixes the problem.. Ive put off changing the fluid in the trans because Ive come to the conclusion that this is NOT a trans issue and I want to eliminate the problem before I change the fluid.
Let me know what you can gather from that information.
This message has been edited by dgcantrell from IP address 184.108.40.206 on May 5, 2012 1:58 PM