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Looks like there is no substitute fuction for the G4. It's only used for starting and not needed for engine operation. Althought that doesen't explain what happens to your vehicle when you unplug it! Its the hall sender that ignores the knock sensor.
Well there are some cross-redundancies. The G4, G28 and G40 are all needed to start the car. If the G40 fails while the engine is running, the ECU will use the G4 signal. If the G40 is good and the G4 fails, the ECU will carry on based on the calcs it does. However, it won't restart. I am not sure what happens if the G40 fails first while running and then the G4 fails after that. Personally, I would duck and hide because you are about to be struck by lightning.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant
Been out in it today to log the data on the vag-com and it seems it hates the warm weather even more!!!
Timing retarding back to 15 btdc this time as opposed to 18.5 btdc when it was pulling well t'other day. What the F**k is causing it to run so lean?? Fuel pressure checked again and its still bang on!
Again if someone reading this, knows their stuff and is willing to look at it, please step forwards!!
What about the knock sensors? are they new? tightened to the right torque?
Good one Jamo. If the knock sensors (or even one them) are Fubar'd, the ECU dials back the timing (6 deg) and probably boost because it has no way of controlling pinking (pinging) without the G61 and G66 knock sensors.
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RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant
What about the knock sensors? are they new? tightened to the right torque?
Thanks Jamo. But the sensors were replaced for new and to make double sure i took them off the good runner i had at the time and torqued to the correct setting.
Am i right in thinking that 14 btdc is more retarded than normal??
I'm running out of ideas, i've checked and triple checked camshaft timing, fuel pressure and for boost and vacuum leaks. What the hell else can cause knock?
This might not have anything to do with knocking but it could do with running down on power:
Have you pressure tested (wait for it), the green pressure/vacuum tubing that goes from the AAN intake manifold to the ECU (via a moisture trap). If it had a split, it would hold boost to certain point and then the little hose would open and dump boost. As a result, the ECU would not tell the injectors to add more fuel (which could cause you to run lean and, hence, pinging). Do you have a boost gauge so you can tell us what boost levels you are getting.
What I am talking about are the green ones in this diagram:
They start at the intake manifold and then head to a moisture trap (in this case an UrS4 on the firewall):
or in the case of the UrS6 down in the footwell (like this LHD passenger side):
Once through the moisture trap, the hose connects to the ECU brass nipple and hence the MAP sensor, as shown in this photo of an opened Motronic ECU:
Unless you have a boost gauge and you have seen over 20 psi (say 1.5 Bar gauge) boost, AND you are sure you have no major boost leaks, you might have a leak in this intake to MAP sensor green plastic pipe/hose. To test, I would pressurize it to 25 psi (1.7 Bar) - if it doesn't hold, you *might* have your answer.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant
I had similar on my old astra turbo. Motronic ecu also. Cut power. It turned out the pipe to ecu was partly shut off by a elbow rubber connector to ecu being doubled back. It also had wiring issues to knock sensor. Replaced loom and found a split in the shielded wire
It took a fair bit of time to sort out......well find the problem.
Audi A6 AEL 5cyl Quattro breaking.
Audi A5 3.0tdi Quattro Stage 2
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You won't see timing retard due to knock in VAG-COM.
Now re-evaluate everything you said with that in mind.
Reading through the thread, you make a lot of assumptions based on very little information. Even though you say "everything is checked and is working" I am pretty sure there is something fairly simple that is wrong.
Log all the temperature sensors in the car and see if they all show correct readings, for starters.
I never said that i saw it via vag com being retarded due to knock! I said i could see it back off and HEAR it pinking with the window down!!
I have now checked the fuel pressure 5 times with 3 different gauges and had shown correct every time. I have also carried out 3 pressure tests with no leaks found. TPS is showing WOT at WOT, Engine temp is 94-97 depending on speed, Air temp looks to be correct (around 34 degrees at 70-100 mph, gradually coming down)
I really have no time to properly look at the car now, and am struggling to look into anything on it now at all. I believe Rich (hoffer76) is forwarding on my logs for you to look over anyway. I'm coming to the point where i can earn more in the time that i am spending on it than it will cost to have a specialist look at it. But don't know how to send it to!! I have been to MRC . . . . . say no more!!!!
I never said that i saw it via vag com being retarded due to knock! I said i could see it back off and HEAR it pinking with the window down!!
Sorry, but that's not happening. Only thing you can hear is wind noise with the windows down. You might be hearing some noise, but it sure as hell is not det.
I have mapped tons of these, and I always have a mic with an amp connected directly to the engine block. Not a single one of my customers has ever heard anything ever, and it is not that loud using an amp and a direct mic.
1. Timing you see in VAG-COM is not backed off. You only see requested timing sent to the knock/ldr processor, and that backs off timing, you get the value before that happens in VAG-COM. Displayed requested timing does not change even during heavy knock.
2. You are assuming the car is running lean, you have not done anything to verify this as a fact.
3. You said the car boosts 0.8 bar on standard ECU. It should be boosting 1 bar. Use only the standard ECU, don't use a chipped one, as there is no telling what is inside it.
Sorry, but that's not happening. Only thing you can hear is wind noise with the windows down. You might be hearing some noise, but it sure as hell is not det.
I have mapped tons of these, and I always have a mic with an amp connected directly to the engine block. Not a single one of my customers has ever heard anything ever, and it is not that loud using an amp and a direct mic.
No. I've worked on various cars for 15 years, i was the only car there. It was pinking i'm sure, was just coming on boost next to an armco just as it hung back the pinking stopped.
Its going down to Rich in late June anyway for him to look at, as, like i have said i'm too busy with customers cars to waste time on this one.
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