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Weird stutter problem

Old 01-23-2019, 05:43 PM
  #11  
casual man mann
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Hey Derf, seriously man I appreciate it. I have zero experience with the pcms I actually bought one on ebay so I'll check right now if it'll work.
Do you thi K that could cause the overheating that happened the other night? Maybe the coolant temp sensor was the culprit? Thanks again.
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Old 01-23-2019, 06:10 PM
  #12  
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Ok I'm looking at both the door jamb and pcm, what number am I looking for?
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Old 01-24-2019, 01:42 PM
  #13  
Derf00
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Overheating could be the thermostat or the temperature that the ECM has to turn on the fan is incorrect or doesn't jive with the signal it's getting, or it could just be a cooling system that needs cleaning out.


One problem at a time. First let's get the PCM/ECM issue figured out. Then you can see what problems still exist.

The good news is that if you bought a ECM and it was from/for a mustang of your era 96-98 it should be easy to have the dealer flash it to the correct calibration using the VIN off your car. I don't know enough about ECM/PCM interchangeability to give you a better answer than that.

This is a case of knowing just enough to know where to look and identify the problem but not knowing enough to go much further than that.

Maybe someone else can chime in?
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Old 01-24-2019, 02:23 PM
  #14  
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Agreed. Now that we've identified a PCM mismatch, we should put aside the overheat issue. It's something that will need to be addressed immediately once the car is able to stay running on its own, but for now I don't think it's directly related to the stutter problem.

To identify what PCM the car was originally built with, look inside the left (driver's side) rear door jamb. There will be small sticker there, what's known as the "emission calibration label". The code you're looking for should start with "6-", followed by two numbers and a letter.
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Old 01-25-2019, 05:41 PM
  #15  
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Ok I have the right pcm on the way from rock auto with the correct calibration code. The eBay one I ordered just showed up and it isn't the right code but I tried it anyway since it's from the same car. Car starts for a sec and dies, which is fine I'll just try to be patient and wait for the right one.
Since the other one I ordered has a matching calibration code will it need to be flashed?
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Old 01-30-2019, 05:19 PM
  #16  
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Update: This is getting insane. Just took the new pcm from rock auto to ford and they flashed it, but the car won't run. It starts for a second and turns off. They don't know why but they suspect it has something to do with pats, but again they still can't confirm. They want 750 bucks to get a pcm from them and new keys.
The lady I spoke to had no answers for me so my question is, why the hell didn't this work???
​​​​​​
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Old 01-31-2019, 01:52 PM
  #17  
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If it were pats, the car would not start at all. Is the Theft/Pats light blinking? I don't think your dealer has anyone there that knows what they are doing. (23 yr old car).

I would check around town for a auto electric specialist. They specialize in all electrical components of cars regardless of year/make/model including the PCMS.
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Old 01-31-2019, 03:15 PM
  #18  
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Yeah that's an idea, I'll look into a specialist today. I just pick the car up and talk to the guy that serviced it. He was very knowledgeable about the issue and said the IAC is what is causing my issues. Basically the computer doesn't know my RPMs or gear and makes the wrong adjustment at the IAC. He said if there were some way to stick the IAC half-open permanently it would run properly but that doesn't sound right to me.
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Old 01-31-2019, 04:21 PM
  #19  
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YO!! I Unplugged the IAC and she ****ing rips. Good enough for the drift car. I'll post again with cold start experience.
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Old 01-31-2019, 05:20 PM
  #20  
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That could be it (or at least part of the problem) right there, then. Good find!

Sometimes the IAC gets dirty and a quick cleaning will get it working again, but sometimes the little solenoid inside fails too. To test the solenoid, use a multimeter to check resistance across the terminals (you may have to reverse your leads to get a reading, on account of a diode inside). I'm not 100% sure of the spec, but I've heard that it's 7.0-13.0 ohms (on older 5.0s it's actually 6.0-13.0 ohms).
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