Car is still running like crap

[795.0pacecar]

Here is the first thread on the issue, didn't get much help though http://forums.stangnet.com/showthread.php?t=656860

I tryed changing the ACT sensor and I got the same codes. Then I did a continuity test of the ACT sensor wires and they were fine. So I tried using a stock MAF and I still got the same codes and it didn't run any differen't. The codes Im getting are 24 and 54 but never at the same time. The car will run at about 900rpms great on the initial start up, it will stay there as long as I let it run. Then after I turn it off and turn it back on a few minutes later, it will idle at about 1000rpms for 30 seconds or so then just die or try to die, and sometimes it feels like theres a miss when its trying to die. Also on the initial start up it will run very rich untill it gets at or over 180 degrees. Driving down the road at part and full throttle the car runs great.

BTW I have the FMS conversion kit wiring harness, and A9P computer, and an 80mm Pro-M.

I am totaly lost here and starting to get frustrated, so if anyone has any advice I would love to hear it.

Thanks!!

 

[65ShelbyClone]

With the speed density computer I didn't get any codes.

Do you know someone that will let you try a different ECU to rule that out? Is your A9P new or used?

You shouldn't need to have the TPS voltage so low either. I remember when I had my '89 GT I set it at .90v and the idle was too high. I had to get the TB stop screw and TPS just right. The IAB should be unplugged when adjusting idle also.

On the running rich, it is supposed to do that, but it should come out of warmup enrichment around 140*, not 180.

How about your harness grounds?

 

[795.0pacecar]

Well I switched to the speed density ecu and I got the same codes as the mass air comp so Im pretty sure thats not the problem now. I will play with the idle and tps more tomorrow and try to set it with the IAC unplugged, I have it set at .70 right now and it still idles high but now instead of dieing it just tries to die. The harness grounds are good, I made sure they were all good when I did the head and intake swap last year, I checked them all over and they seemed to be fine. Is the map sensor for a speed density ecu the same as the baro sensor for the maf ecu? Tomorrow I will also try clocking the mass air meter a bit, I have a super short intake tube because being a 79 my battery is on the same side as the intake tube.

 

[795.0pacecar]

I set the idle at about 650 with the IAC unplugged and got the tps set at .75v. After it warms up it idles at about 750-850 pretty consistently so Im pretty content with that and its been running a bit better. Im still getting the same code 24 though. Im tempted to run my own wiring to the ACT from the computer. I checked the resistence on the ACT and ECT sensors and both were fine. I also had a new ACT sensor that I returned today because it didn't fix the problem.

The problem Im having now is the car dies when I come to a stop most of the time. Is this because I dont have a VSS? If so do I have to go to a junkyard to get the VSS wiring harness? Do I have to use a VSS specific speedo cable? I have a VSS I just dont have a harness for it so I never used it.

 

[65ShelbyClone]

1.) Im still getting the same code 24 though. Im tempted to run my own wiring to the ACT from the computer. I checked the resistence on the ACT and ECT sensors and both were fine. I also had a new ACT sensor that I returned today because it didn't fix the problem.

2.)The problem Im having now is the car dies when I come to a stop most of the time. Is this because I dont have a VSS? If so do I have to go to a junkyard to get the VSS wiring harness? Do I have to use a VSS specific speedo cable? I have a VSS I just dont have a harness for it so I never used it.

1.) I need my memory refreshed on what the code 24 is. Since the sensors are good, have you checked the "salt and pepper shakers" by the center/rear of the engine? The two big main harness plugs....one is white, one is black, and both are round. Quite a few have reported a better running engine my making sure all the pins in them are making good contact and are sealed with dielectric grease. Maybe the pins for those two sensors have a questionable contact there. Maybe have a look at the ECU pins/contacts as well, which should also be sealed with dielectric grease.

2. The VSS allows the ECU to open the IAB and raise the idle if you abruptly let off the throttle. This keeps the engine from stalling. Since your ECU isn't getting that signal, it is most likely the cause of your stalling when coming to a stop. I don't know about scavenging for VSS parts; I haven't needed to thus far.

 

[795.0pacecar]

Code 24 is ACT sensor out of self test range 0.3 to 3.7 volts. I have checked the connection at the computer and Im confident that its good. The salt&pepper shakers have never been apart. But I"ll give it a whirl tomorrow.

 

[vristang]

Subscribing
I would like to hear how this works out.

By-passing the ACT wiring to the ecu is a decent idea. It does sound like a continuity problem, in the wiring harness.
Either the salt n pepper shakers or a faulty wire?

good luck,
jason