Boost stops at 1.4bar - N75?

[hunker7]

Not sure about the voltages im afraid. I just checked mine out using the resistance between pins 1+2 and found it was waaay above 1200 ohms. have a search on here and im sure you'll find some info

About that, I couldn't get resistance reading between 1 and 3, and between 2 and 3 it was something like 1080 Ohms

[mike74]

Not sure about the voltages im afraid. I just checked mine out using the resistance between pins 1+2 and found it was waaay above 1200 ohms. have a search on here and im sure you'll find some info

[hunker7]

beat me to it!

What now? It says there is problem with ECU voltage, is it fixable?

[mike74]

beat me to it!

[hunker7]

try unplugging the lambda sensor when idling and see if its any different. did you ever check out the altitude sensor btw?

Look above

[mike74]

try unplugging the lambda sensor when idling and see if its any different. did you ever check out the altitude sensor btw?

[hunker7]

So, I might have found the problem. Looked at one of the UrS4boy write ups about altitude sensor, and Bentley manual says

What the Bentley Manual says about the F96 is: with the three pin connector disconnected and with the wire bale up and the notch in the connector down, the three female connector pins are, left to right, 1, 2 and 3. With the ignition on, you should get 4.5 to 5.5 volts between pins 1 and 3 and pins 2 and 3, if not, there is a voltage issue related to the ECU. The only mention of ohms is 1 ohm maximum.

Between pins 2 and 3 I am getting 5v, but pins 1 and 3 it's only 3.98v.

[hunker7]

Just checked the ECU, that is all fine too.

MAP sensor isn't dead as it reads 1025mbar and TPS works fine too.



Only thing I can do is leak test it again.

I have noticed that car runs rough when idling. Gear-stick is visibly shaking, and if you put hands on the dash the whole car shakes. Nothing like that in my dad's Octy, can't even feel the engine running on his... don't know if that's how it should be, or, knock sensor is half dead and limits the boost.

[hunker7]

List of things I've tried.

• Boost test (leaks fixed)
• Checked all clips
• Checked N75
• Done output test

[hunker7]

On page 11 you can see what we did and what we found out.

There are no more leaks, so it should hold more than 0.6

By saying 0.6 is nice, I mean it gets to 0.6 nicely, smooth and with no mishaps.

[UrS4boy]

Swapped over the N75, still no luck, but now it looks like N75 is fine, as it boost nicely to 0.6bar, whereas before it was just 0.4. I will take the ECU out tomorrow, open it up and see what's going on in there, check the hose that goes to MAP sensor. Is there any way of checking the actual MAP sensor?

LOL. 0.6 Bar is NOT NOT NOT fine or nice. It is about 50% of what a stock AAN ECU should boost to. True, the 0.4 bar = mechanical boost only, no N75 connection or failed N75, so 0.6 Bar is an improvement.

What happened to boost leak testing? Did I miss the results or did you ever do it?

G71 Manifold Absolute Pressure (MAP) sensor (any all the Engine Bay Devices needed to run our AANs (and ABYs and ADUs), for the "N"teenth time (recommend bookmarking and reading about the device(s) in question before asking questions here):

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

[hunker7]

Swapped over the N75, still no luck, but now it looks like N75 is fine, as it boost nicely to 0.6bar, whereas before it was just 0.4. I will take the ECU out tomorrow, open it up and see what's going on in there, check the hose that goes to MAP sensor.

Is there any way of checking the actual MAP sensor?

[hunker7]

Sure you can. Since it is idling okay (ish), it is likely a weak coil. Read this Missing and Hesitation Diagnostics post and focus on the testing of the coils, looking for the one that is weakest. Might be no. 1 for you.

http://forums.quattroworld.com/s4s6/msgs/22611.phtml

In the article it says when idling or under low boost coil would be fine, but under boost it would play up. Just went for a drive and it runs fine under boost too.. when i removed the spark plug it was quite wet (i washed the engine yesterday) I dried it and that might have fixed it?

[UrS4boy]

One missing and hesitation diagnostic

Thanks I've been reading through that Just came out to test the coils etc and it runs fine, so i I can't test anything

Sure you can. Since it is idling okay (ish), it is likely a weak coil. Read this Missing and Hesitation Diagnostics post and focus on the testing of the coils, looking for the one that is weakest. Might be no. 1 for you.

http://forums.quattroworld.com/s4s6/msgs/22611.phtml

[hunker7]

Thanks I've been rrading through that Just came out to test the coils etc and it runs fine, so i I can't test anything