04 Cobra Hesitation Under Load

99Venom

I ♥ Internal Combustion
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Oct 1, 2004
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Got to the dyno today ( a hub dyno) and the current tune looks good, here's the results.

Peak Boost = 13 PSI @ 4500 RPM
AFR (Sniffer in tailpipe) = 13.2 at peak boost but averaged around 12.5
Peak Torque = 390 @ 3500 RPM
Peak HP = 382 @ 6200 RPM

Power seems low, like 10-15% low maybe. But I think the tune is safe as the first run the AFR never got above 12.5. The 13.2 was a brief spike in the second run around max boost.

Did some logging as well and the spark advance was around 15 or 16 degrees.
 

99Venom

I ♥ Internal Combustion
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Maine
So this issue came roaring back this morning on the way to work. About 20 minutes from home on the highway, the rain started to come down hard. The the car fell on it's face continuously, bucking all over the place. I was slowing down and saw the battery light come on briefly, then a few seconds later it stalled while I was still going about 20 mph. Mind you, the whole time I was slowing down there was little to no power when I pressed on the gas. It started back up just barely.

I was still 40 minutes from work so I pulled a U-turn and headed home to get my other car. The rest of the way on the highway it kept hesitating. I pulled over a few times when people loaded up behind me cause I literally couldn't go faster than 40ish. When I did pull over it seemed to idle ok. Once I got onto surface streets, cruising easily at 40 mph it smoothed out and didn't hiccup much until I got home.

Obviously, something is getting wet. My first thought is the coil cover gasket or maybe the grommet at the back where the harness slips through. Any other ideas?
 

01yellercobra

AKA slo984now
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Oct 5, 2005
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Check your alternator. That's exactly how my car would act when my my last alternator got hot and couldn't keep up. I could see the FPDC jump to 100%. Maybe the best is slipping when things get wet.

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99Venom

I ♥ Internal Combustion
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Oct 1, 2004
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Could it have anything to do with the alternator on these motors being mounted so low on the engine? It seems to only happen when it's raining buckets, and the alternator is going to pick up water from the road.
 

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