we're confused

asufordpimp

New Member
Apr 20, 2004
34
0
0
NC
well, my friend and i were working on his 99 cobra... not doing anything major, just a K&N and removing the silencer (finally convinced him to do it, been trying for almost 2 years since he got the car). when i put in the filter and took off the silencer he started it up and the thing would not idle at all.... it wouldnt even hang, just cut right off as soon as he let off the gas, i checked to make sure everything was plugged in and tightened down, and it still didnt idle. so we reset the computer in it and tried again, same thing. then, we put the extremely dirty paper filter back in it, and same thing, no idle.... so then we put the silencer back on and the thing ran beautifully.... both extremely confused by this point, we decided to put the k&n in with the silencer on to see what would happen... it ran great again.... then we were sitting there and i suggested that we pull the silencer back out just to see what would happen, and when we did, the thing ran wonderfully.... now, he and i are so confused about what caused it not to run that one time..... anybody have any idea what may have caused this?

also, if anybody needs this done, come see me cause after taking the thing apart about 12 times in an hour, ive got pretty good and can get the whole intake tube and air box off in less than a minute, so come see me.... j/k
 
  • Sponsors (?)


you talking about the mass air meter? we didnt put a cold air intake on it, we just removed that little rubber snorkle looking thing, and theres no sensor in it..... and the fact that its running great now with the k&n and no silencer is whats really confusing me.... ive done the same thing to about 8 other mustangs and not had this problem.... its crazy....
 
You probably wont' believe me, but it's most likely an un-metered air leak. Exact same thing happend to me on a different car. Ran like crap and would die when I let off the gas. Everything looked great from my point of view, but my uncle told me it was an air leak. So not wanting to offend him I checked everything out and found that I had not put everything back together properly, even though it looked correct. I have no doubt that it's an unmetered air problem. Weather it's an actual leak, shorted wires or broken sensor, I couldn't tell you.
 
asufordpimp said:
well, my friend and i were working on his 99 cobra... not doing anything major, just a K&N and removing the silencer (finally convinced him to do it, been trying for almost 2 years since he got the car). when i put in the filter and took off the silencer he started it up and the thing would not idle at all.... it wouldnt even hang, just cut right off as soon as he let off the gas, i checked to make sure everything was plugged in and tightened down, and it still didnt idle. so we reset the computer in it and tried again, same thing. then, we put the extremely dirty paper filter back in it, and same thing, no idle.... so then we put the silencer back on and the thing ran beautifully.... both extremely confused by this point, we decided to put the k&n in with the silencer on to see what would happen... it ran great again.... then we were sitting there and i suggested that we pull the silencer back out just to see what would happen, and when we did, the thing ran wonderfully.... now, he and i are so confused about what caused it not to run that one time..... anybody have any idea what may have caused this?

also, if anybody needs this done, come see me cause after taking the thing apart about 12 times in an hour, ive got pretty good and can get the whole intake tube and air box off in less than a minute, so come see me.... j/k

Sounds like a sticking idle air control that unstuck. I had exactly the same problem one time on my 96 GT. Didn't happen for a long time afterwards, then one day I started it and it wouldn't stay running unless I stayed on the gas. A couple hours later it started and idled fine. I replaced it anyway ($40 for the GT). The old one was nasty. These went out a lot on the the 96 GTs - don't know about the Cobras though.
 
Gonna have to agree with the IAC theory. Sometime that will just happen, then it will unstick and it takes starting the car up a couple times to get the computer to put it back to where it should be.
 
If you didn't allow the K&N proper drying time, the oil may have dirtied the MAF just enough to mess up the readings, causing it to stall.

Unmetered air would be another guess. If it doesn't pop back up in the next couple days/weeks, it was probably unmetered air entering.