New guy with interesting issue on 2002 Mustang GT

[Zorin]

Hi, everyone! My name's Tim. I own a small auto repair shop in south Kansas, and this post regards my personal car.

I have a 2002 Mustang GT, with a 5 speed manual. This car is all stock, down to the air intake and exhaust. I purchased it from the original owner, who was a lady that never even did a burnout in it, and it came with all service records.

For 6 months, it drove fantastic. No trouble lights, got good gas mileage, the whole bit. Then, it stopped running, wasn't getting fuel. In the process of testing the voltage to the fuel pump, the PCM went out, showing all dashes on the odometer, and refusing to communicate with the scan tool. At this point, I replaced the fuel pump, the PCM, and the CCRM, as when I was testing down there, the original showed to have signs of water intrusion, and I was right there.

The replacement PCM came from AutoZone, and is a Cardone remanufactured PCM. It was supposedly flashed to my VIN, with my original MDE2 strategy. Where the problem comes in, the idle completely sucks. It holds 2300 RPM until the car comes to a complete stop. Also, when you start it, the idle flares to 1650 RPM and immediately comes down to roughly 300 RPM. Sometimes the car catches itself and levels the idle back out to 750 or so, and sometimes it does not.

The larger issue revolves around the cooling fans. I understand Ford's strategy on these was to run the fan on low speed any time the A/C is on, and I believe the high speed is activated at 228 or so degrees. According to my scan tool, the PCM can see the ECT, and this does report correctly, as does the A/C status. However, the PCM commands the fan in very odd ways that do not fit the strategy. For instance, it will command the high speed fan sometimes at 200 degrees, sometimes 230. It cuts the fans on and off at various speeds, which I understand the stock strategy is supposed to cut the fan at 45 MPH - but sometimes it waits till 50 or 60, and sometimes it cuts it off at 30 MPH. My VSS is working as it should and reports correctly via my scan tool.

Even stranger, the car does not have the power it once did, and the gas mileage has gone down as well. Before it stopped running, the car was 100% reliable, got mileage in the 20's, and basically felt playful like a stock Mustang should. Now the car feels like a two door Crown Vic.

So, here's my questions - I'm HAPPY to buy this and rework my tune, but I do NOT know if the PCM itself has faulty hardware causing these issues, or if the flash that Cardone did was corrupt, or what. My first course of action here is to warranty the PCM. That will be here Tuesday or Wednesday, I'll swap it out, parameter reset, and see how it does.

My big question here, is the MDE2 strategy known for having defects or bugs? Have you guys heard anything about the Cardone reman PCM's? The next problem here is....I'm a repair guy. I'm not a tuner, LOL. I'm happy to learn some stuff from anyone I can on this, because I have spent probably 10 hours diagnosing this, and double checking the integrity of the SCP data lines, wiring to and from PCM, fan, IACV, etc. Nothing is showing to have a fault, and the PCM is reporting no CMDTC's.

Basically, my end game here is get my car back to where it once was, and maybe bump the power a little with the tune, because.....well....why not. But at the end of the day, this is still a stock car, with nothing fancy done to it.

Thanks again, and I appreciate any insight I can get that would help me understand the strategy here.

Tim

[radcartuning]

I am not sure what strategy mine is, but I have a 2002 GT with similar issues as well. If I shift into neutral and coast, the car will tend to die. I have idling issues as well for various reasons. I can't say with certainty that certain strategies have more problems than others, but what I can tell you is that these are not uncommon issues with these vehicles.

From research I've done in the past, its an electrical issue. When my AC fans kick on at idle the car almost dies as well. I've had shorts and numerous electrical problems with lights on the car, so it would make sense that the idling and stalling issues are electrically related. The PCM definitely could be bad, but it could also be that there is a deeper electrical issue causing connection issues with the PCM. I changed my target idle speeds and fixed the stalling issues on mine. It will still want to dip to 300 coming to a stop like on yours, but setting a higher rpm target has caused it to catch itself more quickly.

Now, as far as tuning with HPT, just look at some of the other forums on here. You can read and write the tune without problem, but you won't be able to datalog. I think others smarter than myself can weigh in on what your best options are to fix the problem.

[Zorin]

Radcartuning,

That is VERY fascinating! I will look more into the electricals, but as yet, I've turned up nothing.

I DID just go out to the car, and pull the ECU information with my scan tool.

My original ECU was a 2R3A-12A650-EC, with catchword MDE2.

The replacement part is a 2U7A-12A650-EFA, with catchword FBD0.

No clue if this is where my issue lies, or if these are compatible, or what....

Thanks again!

Tim

[decipha]

yeah thats the same no worries there

Ive done thousands of new edges and never once had one that stalled or had driveability issues much less a stock one. You definitely have something going on.

I wouldnt be surprised if the water damaged some of those connections down there. Its extremely rare for an eec-v to go bad. In all my years Ive only come across a couple at most.

Reman ecus are not recommended as most of them have problems in my experiences. I highly recommend going to snatch one from a u pull it yard.

As has been said hpt doesnt support those older ecus correctly. Best tuning option for those is tunerpro and a moates quarterhorse. Even better its all free too.

[Zorin]

Ahahaha, Decipha posts! I was actually waiting on you to see this - matter of fact, I have your site open on another tab, LOL.

I have found NO evidence of water entry into the car, no evidence of corrosion on any interior electrical connector, no green crusties anywhere. Terminals look good, no terminal fretting, all pins engage nicely.

In my car's case, I had a rough time believing the PCM had failed as well. However, it certainly did. The odometer went to all dashes, my scan tool refused to communicate, and the fans defaulted to high speed. After checking powers, grounds, and SCP data line integrity, we ordered a PCM, and after a parameter reset to relearn the keys, it fired right up, everything was restored.

On your recommendation, I have begun looking for a used PCM, however, I am not sure I have a way to write the VIN to a used PCM. I don't think my scan tool has that capability.

I DID look into the QH and TunerPro, however, I am also concerned with MY ability. From the screenshots I saw, this looks a bit more involved, a lot more hex editing, if I am correct?

Thanks again!

Tim

[decipha]

VIN doesnt matter unless you need it to pass emissions. If so just ship me the ecu and I can put any VIN you want in it.

Nah no hex editing. If its all stock as you say you shouldnt have to do anything.

[Zorin]

Oh, OK, cool.

If it comes to that, I will definitely get with you! Right now, we'll try one more reman, as it is already on the way here. If it doesn't behave correctly, we'll step back and punt, as they say.

I did find a ECU in Nebraska with the same part number, catchword, and nearly the same mileage as mine, so if things get dicy, we'll go that way.

Thanks again!

Tim

[Zorin]

I would like to thank Decipha and Radcartuning for their time, as I think I found the issue.

Today, I had some free time, so I broke out the scan tool again, and went through the live data with a fine tooth comb. While not showing a P1000, I DID see that none of the self test monitors were ready, with no explanation for this, as I have not cleared codes in quite some time. Looking deeper into this, I found that the scan tool was reporting a KAM fault. I checked the fuse, battery voltage at all times on both sides of the fuse, and pulled the PCM real quick, and did a pinout on the harness to verify KAM power at the PCM, which I have.

As a back up, I pulled the KAM fuse, and turned the ignition on, and immediately set a P1633. Shows me that the PCM knows the KAM power is there, however there is some fault with the KAM memory itself. Oddly, I am NOT setting a P0603.

This is beginning to make a bit more sense now, and explains why the idle positively sucked - it was never learning how to idle! Also explains the piss poor gas mileage and the lack of power. This also explains why I was thinking there was a programming fault. The whole time, no CMDTC's found!

Radcartuning, check your car to make sure you don't have the same fault, or issue!

Thanks again.

Tim

[decipha]

No, a kam fault will not cause any of those issues.

[AlexanderOgden]

I also have a 2002 Mustang GT; I had a problem after installing a used PCM from a donor jeep, the engine stalled, and the diagnosis showed no power to the injectors on the second and eighth cylinders. I decided to install the old RCM all worked, but not for a long time; 25 km later lit up again. After that, I decided to go to the car repair shop Autoleap, as not once heard about their excellent quality work. The guys are ten minutes to solve the problem; it turned out the last mechanics are not clicked wiring in the gasoline injectors, and because of that, check popped up.

[decipha]

I think anyone here is more than capable of verifying the injectors are plugged all the way in.

[desecid]

Hi Tim! If you're still here, can you tell us about the tools in your workshop? My brother also thought about opening an auto repair shop. We live in a small town where residents prefer to buy old pickup trucks. Accordingly, the parts and requirements for repairs aren't as strict as they could be when repairing a Mustang But we can't yet make a clear list of what we can't work without. A neighbor advises us to buy this https://sandfieldengineering.com/wha...eding-systems/. But I'm not sure that this thing is necessary for our aim.