Ford Mustang Forum banner

Status
Not open for further replies.
1 - 8 of 8 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
I have a odd idle issue ever since I swapped to a 5 speed and I don't know how to resolve it. I idle surge (occasionally but enough to want it to stop) after I come to a stop light from driving. Sometimes it will drop to low idle perfectly, others it will drop straight to dieing, AND sometimes it will drop, almost die, then start surging. If I am just sitting and crack on it, it drops to smooth low idle nearly every time. TPS is at .96, Idle set to 800rpm (when it idles), fuel pressure set to 40 psi with no vac and drops to 38 with, timing set to 10 degrees with the pill out. I checked for vac leaks and none found. Not that I really think it matters, but I got new plugs/ wires/ cap/ rotor, coil, hell even a whole new distributor. Module on the dist. is one I've had for years so I don't know about it. My real question is about the computer. I didn't change from my A9P when I did the swap and I know the timing curves/ fuel maps are a little different. Can the computer be changing the timing to abruptly with no load on the engine causeing it to die? I assume the eec is set to expect a small load on the engine with an auto trans and it adjusts the timing to drop at a different rate. Right or wrong? I've tried doing little experiments by letting the clutch slip some as I slowly come to a complete stop and push in the clutch just as I reach a stand still but I don't quite have it down well enough to prove or disprove my theory on load affecting fast idle drop. BTW, fast idle as I slow down is around 1500 rpm and stays there till I stop and then SLAM down to around 600 which either the car recovers or dies. I've been in factory 5 speed cars and don't remember there being such a harsh drop in rpm as I was stopping. It's aggravating and somewhat embarrassing to be in the middle of town and die at 3 out of 5 stoplights!!! OK, thats the problem; here is the list of mods!!! 351 bored 40 over(357), Trick Flow Street heat intake, AFR185 heads, Comp Cams XE274h cam (230-236 duration 519-523 lift on 110* lobe seperation), 1.7 roller rockers, 24lb inj, 70mm TB, 80mm Mass, 1 5/8" BBK unequal length headers, 2 1/2" off road X-pipe into Flowmaster 40 series cat back (full tailpipes). ANY SUGGESTIONS?!?!
 

·
Registered
Joined
·
223 Posts
I did the AOD to 5 speed swap last summer,and retained the A9P.It's worked like a charm.
 

·
Registered
Joined
·
46 Posts
The A9P will work in either 5 speed or auto, the A9l will only work in the 5 speed. have you checked your IAC to see if it is working right, if not that, it sounds like the TPS isnt set right or is going bad
 

·
Registered
Joined
·
1,855 Posts
The A9P will work in either 5 speed or auto, the A9l will only work in the 5 speed. have you checked your IAC to see if it is working right, if not that, it sounds like the TPS isnt set right or is going bad

yepper when i did my MAF conversion i used a A9P in my 5 speed
 

·
Registered
Joined
·
1,520 Posts
My suggestion is I hope we never line up at a red light!!! Helluva set up....
 
R

·
Guest
Joined
·
0 Posts
the computer is not your problem....

try bumping the timing & fuel pressure.....
 

·
Registered
Joined
·
19 Posts
Discussion Starter #7
Thanx for the help. I readjusted the TPS to .97 volts, idle speed to 900rpm, and timing to base 10*. It still does it but not as bad as it was. I think its just a combination of new parts and not enough drive time to re-learn the parameters. I googled earlier and found a couple of threads on different forums from guys with heavily modded 'stangs and they had to move the idle up to 1000rpm before it finally quit surging. I REALLY don't want to idle that high just because you don't hear the lope of the cam as much. I know its retarded but DAMNIT I like it when I idle through a parking lot and the cam is jumping hard!! Oh well if it keeps me from dieing at every freakin' stop light I guess I'll cope. I started another thread about the speedo cable jumping on here if anybody has an idea on that one
 

·
Registered
Joined
·
2,975 Posts
I have a odd idle issue ever since I swapped to a 5 speed and I don't know how to resolve it. I idle surge (occasionally but enough to want it to stop) after I come to a stop light from driving. Sometimes it will drop to low idle perfectly, others it will drop straight to dieing, AND sometimes it will drop, almost die, then start surging. If I am just sitting and crack on it, it drops to smooth low idle nearly every time. TPS is at .96, Idle set to 800rpm (when it idles), fuel pressure set to 40 psi with no vac and drops to 38 with, timing set to 10 degrees with the pill out. I checked for vac leaks and none found. Not that I really think it matters, but I got new plugs/ wires/ cap/ rotor, coil, hell even a whole new distributor. Module on the dist. is one I've had for years so I don't know about it. My real question is about the computer. I didn't change from my A9P when I did the swap and I know the timing curves/ fuel maps are a little different. Can the computer be changing the timing to abruptly with no load on the engine causeing it to die? I assume the eec is set to expect a small load on the engine with an auto trans and it adjusts the timing to drop at a different rate. Right or wrong? I've tried doing little experiments by letting the clutch slip some as I slowly come to a complete stop and push in the clutch just as I reach a stand still but I don't quite have it down well enough to prove or disprove my theory on load affecting fast idle drop. BTW, fast idle as I slow down is around 1500 rpm and stays there till I stop and then SLAM down to around 600 which either the car recovers or dies. I've been in factory 5 speed cars and don't remember there being such a harsh drop in rpm as I was stopping. It's aggravating and somewhat embarrassing to be in the middle of town and die at 3 out of 5 stoplights!!! OK, thats the problem; here is the list of mods!!! 351 bored 40 over(357), Trick Flow Street heat intake, AFR185 heads, Comp Cams XE274h cam (230-236 duration 519-523 lift on 110* lobe seperation), 1.7 roller rockers, 24lb inj, 70mm TB, 80mm Mass, 1 5/8" BBK unequal length headers, 2 1/2" off road X-pipe into Flowmaster 40 series cat back (full tailpipes). ANY SUGGESTIONS?!?!
I think you are on to something. I have a friend who reports that a computer swap after the auto to 5 speed swap cured his strange idle problems like you describe.
 
1 - 8 of 8 Posts
Status
Not open for further replies.
Top