Odd Behavior post timing belt / waterpump etc - Kris? JimR? 4Driver4?
07-20-2005, 02:21 PM
#1
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Odd Behavior post timing belt / waterpump etc - Kris? JimR? 4Driver4?
New thread...<a href="https://forums.audiworld.com/a6/msgs/538811.phtml">here's</a> some background, but I'll start over.
Ok. Monday I began the timing belt, waterpump, thermostat, cam seals, tensioners, spark plugs, and oil change maintenance on our 99 Avant.
All went well I thought - got the parts and rental tool set from Blau. I followed a combination of the Bentley instructions and the 2.8 timing belt change from the tech section here. I've got years and years of automotive wrench experience, all on Hondas so I'm no stranger to engine work/maintenance.
The only hitch in the whole operation (if you can even call it that) was I managed to break the small dia. plastic vacuum line that runs over the drivers side cylinder bank. The last 4 inches broke off where it meeds the braided line. I mended it by removing the broken off section and the Audi braided line near the framerail and replaced it with a longer piece of rubber vacuum line I had (from my vast collection of Honda spares).
This morning I was finishing up by bleeding the coolant system, again following the Bentley as best I could.
I started the car up with the heater on, heater hose buttoned back up and was bleeding air from the coolant pipe near the powersteering pump. I had started the whole bleeding process yesterday afternoon with the heater hose hole exposed.
The car was idling fine once started and then after maybe a minute the motor seemed to load up, or run out of fuel and it died.
I re-fired it, held it at 2000 RPM waiting for the thermostat to open, got out (motor still running), and bled more air out, and the motor died again. I bled some air out, closed the bleed and started the motor again. It did start hard, but fired up after a couple cranks. I probably did this 5 times until the car idled ok for a couple minutes and I was satisfied that all was well.
So, I packed up my Blau rented tools and got in the car to test drive and drop the box at FedEx.
The car runs fine, has all the power that it ever did, but leaving the house it would seem to load up and die (or run out of fuel?) So, I drove it around the neighborhood until I felt confident that it would make it to FedEx (about 30 miles round trip).
After leaving the neighborhood, the car did run fine - a combination of city & highway all the way there and it ran perfectly all the way.
On the way home from FedEx, on the highway, it started to act up again. The way it behaves, I want to say that the fuel pump is cutting out. It's hard for me to believe that since this started happening immediately after all this work.
No check engine light, I have VAG COM & a cable, but have never registered it because I've had no reason to. I just may have one now.
Any ideas? The car has run flawlessly since we bought it back in December. After all this work, I really hate the thought of taking it somewhere. I've never had anyone else work on a car for me...
Oh, I should add that the temperature in the shop was easily 90° when I started it this morning, and driving around today it was 105° indicated in our fading display.
Ok. Monday I began the timing belt, waterpump, thermostat, cam seals, tensioners, spark plugs, and oil change maintenance on our 99 Avant.
All went well I thought - got the parts and rental tool set from Blau. I followed a combination of the Bentley instructions and the 2.8 timing belt change from the tech section here. I've got years and years of automotive wrench experience, all on Hondas so I'm no stranger to engine work/maintenance.
The only hitch in the whole operation (if you can even call it that) was I managed to break the small dia. plastic vacuum line that runs over the drivers side cylinder bank. The last 4 inches broke off where it meeds the braided line. I mended it by removing the broken off section and the Audi braided line near the framerail and replaced it with a longer piece of rubber vacuum line I had (from my vast collection of Honda spares).
This morning I was finishing up by bleeding the coolant system, again following the Bentley as best I could.
I started the car up with the heater on, heater hose buttoned back up and was bleeding air from the coolant pipe near the powersteering pump. I had started the whole bleeding process yesterday afternoon with the heater hose hole exposed.
The car was idling fine once started and then after maybe a minute the motor seemed to load up, or run out of fuel and it died.
I re-fired it, held it at 2000 RPM waiting for the thermostat to open, got out (motor still running), and bled more air out, and the motor died again. I bled some air out, closed the bleed and started the motor again. It did start hard, but fired up after a couple cranks. I probably did this 5 times until the car idled ok for a couple minutes and I was satisfied that all was well.
So, I packed up my Blau rented tools and got in the car to test drive and drop the box at FedEx.
The car runs fine, has all the power that it ever did, but leaving the house it would seem to load up and die (or run out of fuel?) So, I drove it around the neighborhood until I felt confident that it would make it to FedEx (about 30 miles round trip).
After leaving the neighborhood, the car did run fine - a combination of city & highway all the way there and it ran perfectly all the way.
On the way home from FedEx, on the highway, it started to act up again. The way it behaves, I want to say that the fuel pump is cutting out. It's hard for me to believe that since this started happening immediately after all this work.
No check engine light, I have VAG COM & a cable, but have never registered it because I've had no reason to. I just may have one now.
Any ideas? The car has run flawlessly since we bought it back in December. After all this work, I really hate the thought of taking it somewhere. I've never had anyone else work on a car for me...
Oh, I should add that the temperature in the shop was easily 90° when I started it this morning, and driving around today it was 105° indicated in our fading display.
07-20-2005, 02:29 PM
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I wouldn't mind finding out what that hose does but I doubt it's the source of your problems . .
Because . . . I broke the one on my 2.8 when I did my car recently with no ill effects to it (not even a change in fuel efficiency).
I've been meaning to check my Bently to see what the hose was for but never had a chance to.
I do remember thinking to myself, "why in the world would they use such a brittle plastic for this hose?" as I tried to trace it back far enough to repair it. Each time I tried to affix a patch of rubber hose over an unbroken section it would break further away until finally I gave up and moved on.
This is that brittle plastic hose that runs over the valve cover right behind the timing belt covers, right?
Now I have no doubt there's a use for this hose and I do intend to fix it some day but it's not critical to me at this point.
I've been meaning to check my Bently to see what the hose was for but never had a chance to.
I do remember thinking to myself, "why in the world would they use such a brittle plastic for this hose?" as I tried to trace it back far enough to repair it. Each time I tried to affix a patch of rubber hose over an unbroken section it would break further away until finally I gave up and moved on.
This is that brittle plastic hose that runs over the valve cover right behind the timing belt covers, right?
Now I have no doubt there's a use for this hose and I do intend to fix it some day but it's not critical to me at this point.
07-20-2005, 03:04 PM
#4
AudiWorld Super User
I would recheck the vacuum hose and a few other things again
Check the hose itself for any unexpected plugging, etc. Go back to the vacuum diagram under the hood and spend the time to check the suspect hose routing from end to end to see if it matches the diagram.
I have a 4.2, and the kind of hoses you describe sound like the ones that run the air (smog) pump controls. On the 2.8 C4 I had I remember the EGR was hose driven too. Particularly the EGR, but to some extent the air pump, could definitely cause rough engine running at lower RPM's.
If not there, per the other postings it does sound like you might have a coincidental fuel problem. You might also recheck all the electrical and other connections anywhere near where you were working in case something else came loose or you disconnected it to work on the motor--another hose, perhaps a plug connector for a sensor somewhere that ties into the ECU, etc.
I have a 4.2, and the kind of hoses you describe sound like the ones that run the air (smog) pump controls. On the 2.8 C4 I had I remember the EGR was hose driven too. Particularly the EGR, but to some extent the air pump, could definitely cause rough engine running at lower RPM's.
If not there, per the other postings it does sound like you might have a coincidental fuel problem. You might also recheck all the electrical and other connections anywhere near where you were working in case something else came loose or you disconnected it to work on the motor--another hose, perhaps a plug connector for a sensor somewhere that ties into the ECU, etc.
07-21-2005, 03:57 AM
#5
I agree. Gotta be a vacuum leak or the pump. Time to register the VAG-COM.
The hose you broke is the crankcase vent. I replaced the one on the sedan when I cracked it changing the plugs. It tends to get loaded up with crap and allows pressure to build.
07-21-2005, 06:35 AM
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I also broke that hose (it's just a vent hose) when I did my cam tensioner seal...
fixed it as you did with no problem.
What spark plugs did you replace the old ones with (brand, model#, type, etc.)?
I know it sounds silly, but I have experienced it before (so far only on domestic cars though) where using a different spark plug has caused similar symptoms.
What spark plugs did you replace the old ones with (brand, model#, type, etc.)?
I know it sounds silly, but I have experienced it before (so far only on domestic cars though) where using a different spark plug has caused similar symptoms.
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07-21-2005, 09:43 AM
#10
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SITUATION RECTIFIED!
After re-checking the easy stuff, I found that the parts counter guy at the local autoparts store gave me five Bosch 4417 plugs and one 4418. They look identical, but the ignition system apparently knows the difference.