99 cobra hesitates after 4k rpms

01yellercobra

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Both of those timing numbers seem really low. I think I had my old set up in the high 20's when it was N/A. Could your knock sensors be giving false readings?
 

01yellercobra

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You can. But expect a CEL at the very least. And possibly the computer going into some kind of limp state.
 

006

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at the lip or the ribs?

are they smaller than the Mach 1 alt pulleys? my old stock Mach alt pulley measures 2.75 at the lip and 2.5 at the ribs. if his is 2.5 at the lip he could be over-spinning it, assuming they are supposed to be the same size as the Mach 1.

At the lip.

Correct! The Mach 1 alt pulley is larger than the 96-98 and 99-01 cobra. Also, the Mach alt uses a "clutch" type pulley, while ours are a slide in and bolt up. I know it's not much, but I was offering a 3.2" (lip) and 2.95" (ribs) pulley to help alleviate the possible over-spinning issue for our cobras (when super-charging) and to free up an extra hp or two for N/A applications.
 

006

Slow mustang :(
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You can. But expect a CEL at the very least. And possibly the computer going into some kind of limp state.

I recall someone unplugging the sensor and wrapping it up with foam padding of some sort and leaving it in the valley. There was no mention of any CEL codes.

If anyone needs a referral to a tuner who knows how to turn the KS off, let me know and I will post his link/info.
 

Roots-type

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I recall someone unplugging the sensor and wrapping it up with foam padding of some sort and leaving it in the valley.

My knock sensors were left in the valley when I eaton swapped. My tuner completely disabled them. No issues with limp mode or anything.
 

006

Slow mustang :(
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What else besides knock sensors can pull my timing so low?

Questions:
What brand of O2 sensors are on the vehicle right now?
You mentioned the exhaust temps pre and post cat being 50 deg different. This could be due to a fuel mixture and depending on what brand of sensors you have, it could eventually lead to clogged cats.
Does the vehicle have a tune on it? Can you check and if so, put it back to the stock program?
It is possible you're running in limp mode.
 

Justin Boisclaire

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I have some data logged info, I hope I have done this correctly so you can view it. I had a tuner turn my fuel up to get rid of my lean condition, and was hoping this would solve the spark advance issue too. I now have a sct x4 to data log with. so all help and advise would be appreciated!!!
 

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