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Discussion Starter #1
Hey fellas...

I've been having a strange seemingly minor issue with my 2001 V6 GLX...

At precisely 14 minutes elapsed run-time I notice a very subtle engine stumble, and if driving at night I notice the headlights slightly dim...this happens so quickly it's like a brief pulse and then back to normal.
Any thoughts of the cause of this? Air conditioning is not running. Just me doing my daily commute.
The car doesn't seem to be affected at all... I'd really just like to know what's going on.

I appreciate any and all theories...thanks!

-Joe
 

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Ok, so a question back to you. Is it always 14 minutes regardless of outside air temperature?
My initial complete stab in the dark is the electric fan kicking in.

Or...
that might be when the flux capacitor takes over. :LOL:
 

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So regardless of ambient temperature, I would say that rules out the electric cooling fan.
Now I'm officially stumped.
 

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The SAIP runs for 65 (V6) or 100 (1.8T) seconds after cold start, then briefly again after the engine is at operating temperature (and at idle) to test the SAIP system. (The ECM looks for a spike in upstream O2 sensor output.)

My 1.8T would do that stumble at a stop sign a mile or so from home, but the V6 takes a while longer to warm up. I very much suspect the SAIP test is what's causing your stumble & headlight dim.

The SAIP doesn't operate if the starting coolant temperature is below 59°F (V6) or 41°F (1.8T), but I'm not sure whether the test is still performed.
 

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The SAIP runs for 65 (V6) or 100 (1.8T) seconds after cold start, then briefly again after the engine is at operating temperature (and at idle) to test the SAIP system. (The ECM looks for a spike in upstream O2 sensor output.)

My 1.8T would do that stumble at a stop sign a mile or so from home, but the V6 takes a while longer to warm up. I very much suspect the SAIP test is what's causing your stumble & headlight dim.

The SAIP doesn't operate if the starting coolant temperature is below 59°F (V6) or 41°F (1.8T), but I'm not sure whether the test is still performed.
I pondered this very briefly, I would think the engine would be at normal temp by the time 14 minutes rolls by, unless of course your in the arctic north.
 

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Caveat: when ambient temp is within the SAIP operating range.
At least on my B5.5 1.8T, the SAIP runs at start up for ~100 seconds and then approximately 60-90 seconds after the first run, but only if at idle. If not at idle within that time frame, I believe it never runs a second time. At least I don't hear anything different. When I had an auto, I could hear it kick on a second time and if I started moving while it was running, it would shut off. Likely to prevent back flow from the increased exhaust pressure at elevated RPMs.
 

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I never felt my SAIP on the V6, but it did work. That motor warmed up pretty quick, less than 4 minutes. I really feel it on the 1.8T, usually on start up and then within a mile at a stop.
I wonder if it's something weird with the a/c regulator?
 

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I never felt my SAIP on the V6, but it did work. That motor warmed up pretty quick, less than 4 minutes. I really feel it on the 1.8T, usually on start up and then within a mile at a stop.
I wonder if it's something weird with the a/c regulator?
You mean the voltage regulator on the alternator? When I had my 90a in there, it would dim the headlights when it came on a second time. With the 120a from the V6, the only thing I notice now is the vacuum on the gauge goes down a smidge while it does its second run.
 

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I had this issue last year on my 04 V6. I don't recall if it happened in the same spot on my religious drive. I think sometimes it did and at other times not. Only the lights dimmed. Nothing else.

I noticed a lag in starting and chalked it up with a dying battery. Replaced it with one from the dealer. Lag at starting went away and lights didn't dim till a few weeks ago. I don't actually know if it were the lights dimming again or a car behind me hitting a bump making it appear it was my lights. Hmmmm
 

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You mean the voltage regulator on the alternator? When I had my 90a in there, it would dim the headlights when it came on a second time. With the 120a from the V6, the only thing I notice now is the vacuum on the gauge goes down a smidge while it does its second run.
Yes, the voltage regulator. This fever has me a bit loopy.
 
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Experienced similar, though not sure if at exact time increments. Finally would not start or even make a noise. Mechanic traced it to a corroded and severed wire beneath the driver's side floor. I had inadequate floor mats, so moisture had seeped for years. I have a 2000 V6 sedan.
 

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If it does this consistently, then the idea that the SAI pump turning on is the cause, could be proved by disconnecting it or pulling the 40A fuse. But if the 'stumble' is due to brief low voltage, I would clean all the battery connections and grounds, just in case.
 

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Discussion Starter #14
Thanks everyone for your replies. I think the easiest bit of maintenance would be to clean the battery connections and see if that make this issue go away. While the battery cranks strong, it couldn't hurt to clean those terminals anyway.
 

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I don't know much about it, but did find this item that might be helpful:
 
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