2007 Q7 4.2 - runs crappy, cleaned valves, new plugs, etc....could it be the ECU?

[flat12]

Hello Audi Gang. You may recall I had another thread going titled..."2007 4.2; suddenly ESP and EPC...all kinds of issues". We went to church one morning with no issues, then we went to breakfast and as we were leaving the restaurant, the Q7 started running a little rough. It was only a couple of miles to get home, and by the time we arrived, I had the EPC warning light on and the engine was running quite a bit rougher than just minutes ago. I decided to go ahead and clean the intake system and the valves as well. After getting everything back together, new plugs, new gaskets, etc....I hesitantly started the Q7 up. My hopes and prayers were dashed as the Audi still runs like crap! I suspected the throttle valve so I swapped it out and no change. I also did the same for the throttle pedal...nothing. All of this work did clear up the misfires I was getting so it wasn't all for nothing. But as you can imagine I'm a bit down in the dumps now. Any help is appreciated....thank you.

Using Vag-Com I did a scan and here is what shows up.

Summary of "malfunctioning" systems. I'm not so worried right now about the HVAC systems....
1) ABS Brakes
2) Auto HVAC
3) Instruments
4) CAN Gateway
5) HVAC Rear

Here are the codes:
Address: 03: ABS Brakes
Component: ESP ALLRAD MK25E1 0140
Code: 01826 Sensor for steering angle (G85) supply voltage terminal 30000

Address: 17 Instruments
Component: KOMBIINSTR. M73 H16 0070
Code: 01044 Control Module Incorrectly Coded.

Address: 19 CAN Gateway
Component: J533 Gateway H06 0040
Code: 01044 Control Module Incorrectly Coded.

[AudiTechS4]

since you have vagcom are you watching mvb's for misfires to see if you can see something going on if its a few or all cylinders

[flat12]

Spent the afternoon on Father's day chasing my tail on the Audi, much to my family's disappointment. The Q7 starts up and revs for a few seconds and then settles down to a horrible 600rpm idle. I can hold the rpms at 2000 and it's smooth. I've had some codes come an go....doesn't make sense. Most of the codes are related to the fuel delivery system and EVAP system, things like "short to ground" and "intermittent signal" for all of the various sensors, etc.

I'm thinking of pulling the ECU to see if it can be tested....can this be done at a dealer? Had another problem show back up today, the oil leak at the right rear timing chain cover is back. Getting to this leak is a total pain to do with the engine in the vehicle. There is no gasket for this cover, just sealant. I'm just horrified that it is leaking again. I was very particular when I resealed this cover since it was so hard to access. I just can't believe it.

I'm stepping back from the Q7 to gather my thoughts on what to do next. I will try and see if the ECU is good or not. I don't have years of tinkering time to spend on this vehicle, so I have to consider flat bedding it to the nearest Audi dealership about 75 miles away. I'll need to take out a second mortgage to pay the bill on a vehicle with a market value of maybe $15k if I'm lucky. I've been a die hard Audi owner and enthusiast for many years but this Q7 may just be the last straw for me....it saddens me to say it....

[RSFourMe]

I had a few issues like this on my RS4, turned out to be the battery. Have you checked that? The key was the intermittent effects on random systems.

[flat12]

I have been wondering about the battery. During the start up I had a charger at 2 amps output hooked up to the Q7. A check of the battery before start up showed 12.5 volts. That would seem to be okay.

[aluthman]

Just because you are seeing 12.5 volts on the battery doesn't necessarily mean it's good. You need to do a load test on it. Pull it out and bring it to pretty much any autoparts store and they can check it for you (generally for free).

[flat12]

Okay Audi Gang....here a long over due update:
I spent days and days trying to find the issue, using vag-com extensively. The issue seemed to vary from a slightly rough idle to bad running and stalling. Then sometimes it would almost go completely away. I replaced relays, verified continuity of wiring, etc. I removed the ECU and sent it out for testing - and they report it is good. I took the battery to 2 places for checking and it is good. After weeks of frustration, I took the Q7 to our local import specialists. They have had it for almost 3 weeks, they have named the Q7 "nightmare on elm street". They have been working with Audi-North America and also Audi-Europe...but still do not know what's going on. Both the import shop and Audi say they have never seen so many codes on a Q7.

We have purchased 10 Audi & VW vehicles in the last 8 years....5 of them were new. I'm thinking of writing Audi a letter and asking them for any assistance they can offer. Needless to say I'm very fed up with this situation...which has been going on since March. I just wanted to inform you good folks. Pardon me if I'm not stating things clearly or I'm rambling....but I'm at the end of my rope.

[acoleman]

Sorry to hear about your mess. I know the early Q7s were prone to weird issues like this. I hope you get it resolved!

[flat12]

Problem Fixed...!!! High Pressure Fuel Pump on Cylinder Head #2, the fuel pressure regulator was intermittently shorting out. When it shorted it dropped voltage to many other components and resulted in many fault codes.

[ZR1 DREAMING]

How did you/they track it to HPFP? Glad you found the culprit!


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