Had the Cobra dyno tuned today

[Colt .45]

And I am a little disappointed with the results.

'03 Cobra
Whipple 2.3 (3.5 pulley)
EGR delete
60lb injectors
KB BAP
JLT High boost intake
SCT3000
Bassani offroad X
Bassani Catback

Made 505hp and 457 torque. :lol1:

The tuner said he was losing spark after 4k rpms. He couldnt get it to dyno high at all. It was in the 47x range. So he put a battery charger on the car while he was tuning and it jumped up to 505. Yet it is still having issues at 4k and up. So he is saying the alternator is the probem. Get that fixed and it should jumped back up to where it should be. 550 range.
Does that sound legit? I was not there at the time to confirm.
Here is a copy of the graph I was given. I do not know AFR or timing yet. I will find out tomorrow.

When I picked it up and drove off, the car was bucking and runnning pretty bad. Ended up finding the vacuum line to the bosst gauge was unplugged. Plugged it back in and it runs MUCH better.
So what are my options?

 

[gabe1530]

get a new alternator asap.
what are your plugs and whats the gap?

 

[Colt .45]

get a new alternator asap.
what are your plugs and whats the gap?

NGK TR6 gapped at about .32
Put them in right before the whipple.

 

[05satinGT]

^ +1 with what he said. Those numbers are extremely low. I'd do new plugs, alternator, and check the coils, then go back for a retune. Have fun with the alternator though, they are a bitch.

 

[Colt .45]

Can I trust a new alternator from the local auto parts store or do I need to order a special one online?

 

[gabe1530]

this is the one i bought and it has been running amazing. they have amazing reviews. NEW ALTERNATOR FORD MUSTANG COBRA 2003-2004 4.6L 160 HIGH amp 8-Groove Pulley | eBay

changing it out isnt that hard, just takes some patience. if i remember correctly, you have to remove the battery and a bolt from the lower pulley cage to get access to it. then its just getting it out and vice versa.

 

[hiimdrummer03]

The alternators are a pain. Trying to get pass the one spots of the fender well is the hardest

 

[Nitrous SSC]

If your alternator still has a factory sized pulley on it will be overspun past 4000rpm and not charge worth a damn. This also burns them up quick. I ran into the same issue on our last 03' setup. I now run a 3.2" Alt pulley with the stock lower. Charges everything at idle perfect and provides power all the way to redline.

Swapping the alts is cake. 45-60 min tops.

 

[perry2k12]

I had a friend who had his 2.2kb tuned last year and it was loosing it's power after 5000 rpm on the dyno. Changed the alternator and all is well.

I went to a 3.2" alt pulley when I did my lower, I actually didn't think it was too bad of a job to remove the alternator. Just have to finnagle it a bit once it is unbolted. Definitely remove the battery tray to get to the top bolt.