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See if they can test the alternator too.
 

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Discussion Starter #22
Forgot to mention the battery is only about 6 months old and when the rpms do their little dance at idle voltage drops and rises with the rpms
 

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Discussion Starter #23
I'll ask them to test the alternater too. Thanks for all your help so far! I'll post an update tomorrow
 

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take it apart and check all the wiring harnesses
Now the fun starts. All four of your symptoms (boost cut, idle stalls, hunting idle, and overall performance) could be coming from an intermittent open circuit between the battery/alternator and VPWR V monitoring point, or an intermittent short to ground somewhere in the car. It could also be something else, like a faulty regulator on the alternator (odds are the standard alternator test would not catch an intermittent of a few milliseconds' duration), a failing coil driver (built into the coil), or simply a loose connection, to name a few. What is VPWR V, exactly? Is it power to the ECU? Knowing this can help narrow the search.

Do you have anything that can measure instantaneous voltage, like a scope, or a meter with fast min/max hold or an instantaneous bar graph display? You've been lucky to catch the fault a fraction of the times it happens with your monitoring software, given the low sample rate.
By far the worst voltage I got was when I shifted into neutral and revs dropped. When they dropped i saw voltage drop to 13.0 - 13.1volts.

If voltage dropped below 13 to 12.9 or 12.8 thats when the car would stall on me and it would stay around 12.7 until the bump start took it back to 14.1
These measurements are probably not telling you the whole story. Here's why.

14.0-14.1V is nominal operation. However, you don't know if 13.1V is really 13.1V, or 14V for 93% of the sample time and 0V for 7% of the sample time, or something in between, if your instrumentation is averaging its readings. The same thing applies to the 12.7-12.9V readings. Could be 14V 90% of the time and 0V 10% of the time.

One last Q for now: Do you have a Tech 2? There might be stored ECU DTCs that could be helpful. The misfire and knock counts would also be good to know.
 

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Discussion Starter #26
): ): ): this is going to be something else. But anything for the love of my life I suppose. Interesting what you said about it being an average and it could be 0 volts momentarily. Thats a good observation.

I ordered a tech 2 and its in the mail from chinacardiags. Its been on its way for 4 weeks now and I've sent 2 emails. One 2 weeks after I ordered and one yesterday. So who knows when they will get back to me.

I guess this will be frustrating but a learning experience.

I also had my mechanic run the tech 2 diagnostics. They're awesome and help me out for nothing sometimes figuring out my issues before I fix. So no stored codes as of now.

Any recommendations on where to start??
 

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First place to start is to identify the point where VPWR V is being monitored. Is it the voltage reported by ECU?
 

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Discussion Starter #28
Ummm I have no idea. I was just watching it off my SID. Although I have some mechanical skills. My electrical skills and knowledge leave a lot to be desired
 

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How sure are you that E55Boost is actual boost and not the requested boost? I'm not familiar with that logging software but I find it hard to believe the sensor works in every range except for around 15 PSI. I'm curious if the ECM is sensing knock or a condition that merits dropping boost, and the E55Boost is the request not actual. If the car feels slower on both tunes you may want to make sure your cat isn't clogged or your purge valve isn't intermittently stuck open. A clogged cat isn't common, but could cause this issue. Really weird; can't wait to hear the outcome!
 

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Discussion Starter #30
Brian told me e55boost is actually boost, but i myself am no expert. I would believe Brian though.

I also don't have a clogged cat because I don't have a cat :)

I could definitely try to check the pruge valve. Although I always get full boost before it cuts away. So I feel its unlikely. But I am willing to try anything.
 

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How sure are you that E55Boost is actual boost and not the requested boost? I'm not familiar with that logging software but I find it hard to believe the sensor works in every range except for around 15 PSI. I'm curious if the ECM is sensing knock or a condition that merits dropping boost, and the E55Boost is the request not actual. If the car feels slower on both tunes you may want to make sure your cat isn't clogged or your purge valve isn't intermittently stuck open. A clogged cat isn't common, but could cause this issue. Really weird; can't wait to hear the outcome!
ECU is commanding the turbo bypass valve open when it cuts boost. That's usually the third and last thing it tries before dumping the throttle when it senses knock, but it might do that for any fault condition it deems severe enough.

EDIT: For sure it'll open the valve when you take your foot off the gas pedal after heavy acceleration.
 

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Ummm I have no idea. I was just watching it off my SID. Although I have some mechanical skills. My electrical skills and knowledge leave a lot to be desired
Do you have a modified SID, or other monitor display? Or is voltage monitor peculiar to V6 or XWD? Stock SID won't show system voltage according to WIS, my owner's manual, and checking on my car. Where is the data shown in EFILive in your first pic coming from? Can you confirm it is all coming from ECU?

The reason I'm being picky about this is that knowing at what point you are monitoring voltage is that gives a physical location in the car's wiring, from which to start troubleshooting.
 

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Discussion Starter #33
Okay I am using and eSID2 connected to the OBD2 to monitor votage as I drive in the SID. And I'm using a hand held tuner to record data logs through the OBD2 for EFIlive. I can only do one at a time but that's where I've collected all my data. I think it is all data pulled from the ECU
 

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Cool. Let's assume it's from ECU with reasonable confidence, then. One easy thing you could try quickly is wiggling and pushing against metal (ground) the part of the wiring harness leading from ECU connector B back towards UEC. Also wiggle the ECU B connector. B connector is the upper connector on ECU. Do this with engine idling (safely!), to see if you can induce stall or hunting idle at will.

Do you have the WIS? It's definitely time to get it if you don't. 👍
 

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Discussion Starter #35
I have the WIS. I wanted to start working on the car myself and my parents taught me to always use protection (; so I clearly needed it.

I think my next free day i have to muck about with the car is Wednesday next week. Ill start with your suggestions.

What does it tell me if the car does stall or have hinting idle after I push the connector to the ground? Just that it needs to be replaced?
 

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my parents taught me to always use protection
Best reason I have ever heard for getting a copy of the WIS, by miles! :)
What does it tell me if the car does stall or have hinting idle after I push the connector to the ground?
It tells you there's a fault in the harness (or something nearby that's connected to it). You can easily repair a frayed wire shorting to ground, and they are easier to see than internal breaks. You can also replace or splice around an internally broken wire as long as you can determine where the break is*. These are easier/cheaper alternatives to replacing harness.

While you're in there, if you have time, also check the parts of the harness coming off the coils and injectors the same way. Wiggle to find breaks, push against metal to find shorts to ground, usually where the harness is already near metal. Check for wires melted together in the harness, as well. <--- hopefully you don't find any of these!

* I do this using T-pins through the wire insulation to put my meter probes on, and at minimum put a dab of liquid electrical tape to seal the hole once I'm finished checking. People with deep pockets might use a fancy cable tester or time domain reflectometer.
 

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FWIW, I'm not sure you're seeing voltage monitored from ECU. Looking at the eSID2 docs, I think it's looking at the power feed from the OBD2 connector, which comes from the main +30 feed through fuse 11 in the dash. The handheld tuner is probably logging it the same way. So it's looking at overall system voltage, not power at ECU itself. It's still worth it to check harness as suggested, as a first step. B connector is where almost all 12V connections come into ECU.
 

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Discussion Starter #38
Alright I will get cracking next Wednesday. Thanks for all your advice! Glad you enjoyed my reason for getting the WIS.

I'll update this thread if I make any progress or figure out my issue. In the mean time if anyone thinks of anything else possible don't hesitate to let me know!
 

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The only test equipment I think you have right now is the eSID2 and the tuner, with the Tech 2 joining soon, hopefully. Please correct me if I'm wrong.

Unfortunately, none of these is particularly useful for troubleshooting what looks like an intermittent problem, and I don't think you want to throw random parts at the car. You could do a full car scan with the eSID to see if any modules have stored (historic) or pending (preliminary) codes that might shed some light on the problem. Record these, and clear all codes, if your mechanic hasn't done so already. That way, any new ones should relate to this issue. Beyond that, without gear to make real time measurements and transient captures, troubleshooting something like this necessarily has to rely on indirect methods like wiggling wires, checking ground connections, and reading codes, counters, and low sample rate data.

It would be really useful to see the misfire and knock counters. You'll have to wait for the Tech 2 to do that, though.
 

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Discussion Starter #40
I'll write my codes and clear them while I wait for next week and the tech 2 I guess. Maybe I'll get lucky in a few days
 
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