'99 GT Stalling, No CEL
06-24-2012, 02:10 PM
#1
Thread Starter
Join Date: Dec 2011
Location: Ohio
Posts: 7
'99 GT Stalling, No CEL
Greetings all,
I've had this car since November, have only run a couple of tanks full of gas through it, not that familiar with it yet, hoping you can give me some ideas on where to start looking.
I have a 99 GT 5-speed. It does a few things that I don't like, and I'm guessing they are all related:
1) When I turn the key, it fires immediately, revs to maybe 1500 rpm instantly, then basically "shuts off" until it catches itself around 500 rpm or so. Sometimes it just stalls, but usually the idle settles out okay. This whole sequence from key turn to idle (or stall) is maybe 2-3 seconds. It acts the same, warm or cold.
2) Sometimes it will just stall when I throw in the clutch, when it is at normal operating temperature.
3) If I rev it, it does not settle back to idle very quickly. It kind of sounds as if it has a 300 lb. flywheel on it when I take my foot off the pedal (note that it revs UP quickly... it just doesn't settle back to idle quickly).
Other than those three things, it runs great, pulls strong, etc. As far as I know it is 100% stock. I run it hard enough that there's no way it's loaded up with carbon.
Do these symptoms point to a 'typical' 4.6 problem, like maybe IAC problem or vacuum leak?
Thanks for any and all help!
I've had this car since November, have only run a couple of tanks full of gas through it, not that familiar with it yet, hoping you can give me some ideas on where to start looking.
I have a 99 GT 5-speed. It does a few things that I don't like, and I'm guessing they are all related:
1) When I turn the key, it fires immediately, revs to maybe 1500 rpm instantly, then basically "shuts off" until it catches itself around 500 rpm or so. Sometimes it just stalls, but usually the idle settles out okay. This whole sequence from key turn to idle (or stall) is maybe 2-3 seconds. It acts the same, warm or cold.
2) Sometimes it will just stall when I throw in the clutch, when it is at normal operating temperature.
3) If I rev it, it does not settle back to idle very quickly. It kind of sounds as if it has a 300 lb. flywheel on it when I take my foot off the pedal (note that it revs UP quickly... it just doesn't settle back to idle quickly).
Other than those three things, it runs great, pulls strong, etc. As far as I know it is 100% stock. I run it hard enough that there's no way it's loaded up with carbon.
Do these symptoms point to a 'typical' 4.6 problem, like maybe IAC problem or vacuum leak?
Thanks for any and all help!
06-26-2012, 05:55 PM
#3
3rd Gear Member
Join Date: Aug 2011
Location: Nebraska
Posts: 814
A. Just because no one has posted yet doesnt mean some one isnt thinking on your issue.
B. Even if no one posts back, no need to be a jerk about it.
C. You would have gotten faster help in the 99-04 4.6L section. More populated than General tech.
D. The stalling issue does sound like an IAC issue to me. However, the RPM's do not fall back after revving because it is designed that way, as there is no brake booster for vacuum when the idle is down low.. The Hydraboost is connected to the power steering and therefore the idel stays higher after revving until the nehicle is basically stock.
E. This forum has a search function...all this has been posted on before. Just sayin.
B. Even if no one posts back, no need to be a jerk about it.
C. You would have gotten faster help in the 99-04 4.6L section. More populated than General tech.
D. The stalling issue does sound like an IAC issue to me. However, the RPM's do not fall back after revving because it is designed that way, as there is no brake booster for vacuum when the idle is down low.. The Hydraboost is connected to the power steering and therefore the idel stays higher after revving until the nehicle is basically stock.
E. This forum has a search function...all this has been posted on before. Just sayin.
06-27-2012, 05:04 AM
#4
Thread Starter
Join Date: Dec 2011
Location: Ohio
Posts: 7
Thanks for your reply, Steve. My 2nd post was an attempt at humor and also an attempt to elicit a response after 75 views and zero replies.
It has been my feeling all along that what I am experiencing is "typical" 4.6 Mustang stuff, which was the gist of my post. I did search before I posted. There is a lot of "noise" to weed through, but my search resulted in my belief (and suggestion) that it's probably vacuum and/or IAC related. I felt that if I put together a concise post, that perhaps a straight forward easy answer would be forthcoming, since, again I believe I'm dealing with 'typical' 4.6 headaches.
After posting, I continued my search on the revving issue both here and on other sites. It seems that many have had luck with restriciting the IAC flow, either through a modified gasket, or some other means of restriction (drilled sheetmetal plate or copper pipe cap, etc.)
Do you have an opinion of the effectiveness or "worthwhile-ness" of that mod?
Thanks again,
Garry
It has been my feeling all along that what I am experiencing is "typical" 4.6 Mustang stuff, which was the gist of my post. I did search before I posted. There is a lot of "noise" to weed through, but my search resulted in my belief (and suggestion) that it's probably vacuum and/or IAC related. I felt that if I put together a concise post, that perhaps a straight forward easy answer would be forthcoming, since, again I believe I'm dealing with 'typical' 4.6 headaches.
After posting, I continued my search on the revving issue both here and on other sites. It seems that many have had luck with restriciting the IAC flow, either through a modified gasket, or some other means of restriction (drilled sheetmetal plate or copper pipe cap, etc.)
Do you have an opinion of the effectiveness or "worthwhile-ness" of that mod?
Thanks again,
Garry
06-27-2012, 04:19 PM
#7
3rd Gear Member
Join Date: Aug 2011
Location: Nebraska
Posts: 814
You have my apologies then...Ive seen many posts like yours that that is not the case.
I you can try cleaning it, but that doesn usually work for very long if at all. As far as the cap in the IAC line, I havent done it myself, It doesnt bother me now that im used to it and now that I know why it does what it does. Alot of people have had good luck with the mod though, so its really your call. If you do and dont like it its easily removable so what could it hurt right? I would pin down the stalling issue first though and go from there.
Its not very expensive to have your car smoke tested, I think around 60 bucks. That can eiminate the vacuum leak a source of your issue fairly quickly in one shot.
I you can try cleaning it, but that doesn usually work for very long if at all. As far as the cap in the IAC line, I havent done it myself, It doesnt bother me now that im used to it and now that I know why it does what it does. Alot of people have had good luck with the mod though, so its really your call. If you do and dont like it its easily removable so what could it hurt right? I would pin down the stalling issue first though and go from there.
Its not very expensive to have your car smoke tested, I think around 60 bucks. That can eiminate the vacuum leak a source of your issue fairly quickly in one shot.
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