Has anyone had or have this problem.."99 Cobra"

tommyboy2008 · March 2nd, 2011, 09:13 PM

ok, I put up a post before but didnt get any help. Here's the problem..
Just swapped my v6 with a 99 cobra engine a T-45. I got everything together, tuned it to turn pats off and exhaust upgrade. It fired up on the first try. Great rite? well now its time to work out the bugs. I got them all worked out except this one thats driving me crazy. ....When its at idle (about 850rpm) and I give just a tiny bit of throttle...its wants to stall out. Not completely, but damn near. So i thought it might have been the cop's since EVERY sensor is brand new. O2 sensors, IAC, TPS, ect. So I had an idea to unplug the MAF and bam problem disapeared! so wtf. Thats when I bought a new MAF and it still hesitates when you gas it and wants to stall when opening the throttle a little. Im at a dead end. I also checked and double check the vacuum lines and my pcv had a little leak so I fixed that and no help. I also reset the computer and ran the recon software that came with my special forces tuner and everything checks out. O2 sensors are running around 50 which is perfect, so I dont know. Is it running too rich or too lean maybe? How can I check that "besides puling a spark plug to see if its black or white", I want a number. whats the air fuel ratio supposed to be? The guy at special forces told me "Thats normal" This isnt normal...HELP IM GOING NUTS OVER THIS!!

mfj · March 2nd, 2011, 11:56 PM

Did you switch out the wiring harness and are you running the 99 Cobra computer?

na svt · March 3rd, 2011, 09:26 AM

the a/f should be 14.7:1 while cruising and at part throttle and 13.0:1 at full throttle.

tommyboy2008 · March 3rd, 2011, 07:40 PM

thanks guys...I got the problem fixed. Its was what I figured it would be. It was the tune..aparently the manifold air volume was off, so I sent special forces my tune by email and the guy changed that and something else..not sure what it was but the car runs PERFECT now! sweet! So if anyone has put a tune on their mustang and suddenly have hesitation problems, check the manifold volume...

tommyboy2008 · March 3rd, 2011, 07:41 PM

oh, and yes I changed every single wire in the car including the computer to 99 cobra..

March 2nd, 2011, 09:13 PM	#1
tommyboy2008 Regular 2004 mustang Join Date: Jan 2010 Location: dover, pa Posts: 66 iTrader: 0 reviews	Has anyone had or have this problem.."99 Cobra" ok, I put up a post before but didnt get any help. Here's the problem.. Just swapped my v6 with a 99 cobra engine a T-45. I got everything together, tuned it to turn pats off and exhaust upgrade. It fired up on the first try. Great rite? well now its time to work out the bugs. I got them all worked out except this one thats driving me crazy. ....When its at idle (about 850rpm) and I give just a tiny bit of throttle...its wants to stall out. Not completely, but damn near. So i thought it might have been the cop's since EVERY sensor is brand new. O2 sensors, IAC, TPS, ect. So I had an idea to unplug the MAF and bam problem disapeared! so wtf. Thats when I bought a new MAF and it still hesitates when you gas it and wants to stall when opening the throttle a little. Im at a dead end. I also checked and double check the vacuum lines and my pcv had a little leak so I fixed that and no help. I also reset the computer and ran the recon software that came with my special forces tuner and everything checks out. O2 sensors are running around 50 which is perfect, so I dont know. Is it running too rich or too lean maybe? How can I check that "besides puling a spark plug to see if its black or white", I want a number. whats the air fuel ratio supposed to be? The guy at special forces told me "Thats normal" This isnt normal...HELP IM GOING NUTS OVER THIS!!

March 2nd, 2011, 11:56 PM	#2
mfj Banned 2001 Cobra Join Date: Feb 2011 Location: Hot Town, AZ Posts: 416 iTrader: 0 reviews	Did you switch out the wiring harness and are you running the 99 Cobra computer? __________________ 2001 Cobra- Stroked/Poked/Cammed/Blown 1996 Cobra- CF Clutch/STS/Lowered/CAI- otherwise stock... The daily driver... [SIZE="5"][B][COLOR="Blue"]MM Cobra Club #3.4[/COLOR][/B][/SIZE] [SIGPIC][/SIGPIC]

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March 3rd, 2011, 09:26 AM	#3
na svt 4v Know-it-all Join Date: Jan 2011 Posts: 488 iTrader: 0 reviews	the a/f should be 14.7:1 while cruising and at part throttle and 13.0:1 at full throttle.

March 3rd, 2011, 07:40 PM	#4
tommyboy2008 Regular 2004 mustang Join Date: Jan 2010 Location: dover, pa Posts: 66 iTrader: 0 reviews	thanks guys...I got the problem fixed. Its was what I figured it would be. It was the tune..aparently the manifold air volume was off, so I sent special forces my tune by email and the guy changed that and something else..not sure what it was but the car runs PERFECT now! sweet! So if anyone has put a tune on their mustang and suddenly have hesitation problems, check the manifold volume...

March 3rd, 2011, 07:41 PM	#5
tommyboy2008 Regular 2004 mustang Join Date: Jan 2010 Location: dover, pa Posts: 66 iTrader: 0 reviews	oh, and yes I changed every single wire in the car including the computer to 99 cobra..

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