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Discussion Starter #1
I have this problem since 2 weeks now:
I was coming back from work one evening and suddenly the car stalled in the middle on the interstate, the theft light came on and the odometer displayed dashes instead the regular mileage. While driving, I turned the ignition off, and back on then the car started again. No problem during the 15 miles left to home.

Next morning to go to work, no problem.
But the evening, the problem happened again on the interstate (70mph) almost at the same place.

It has been doing that a few time since last week... always king of scary when it happens but strangely only the evening.

But until today, the car could always start again.

Tonight, wanted to come back from work, the car didn't start. The engine cranked but the theft light was on AND the cooling fan was running ?!? (no reason as the car was cold). I waited a few minutes the contact off and the car started. I didn't drive it, thinking it would be too risky to get stuck somewhere.

I have seen a lot of posts but I don't have a clear idea what can be the root cause... The PATS, why not when the car is stalling in the middle of the intersate. But now, the fan is running, CCRM problem?
I checked most of the connectors (PCM, Fuses, relays). Not sure what to do now.

Please help !! A colleague lent me a 92 toyota corrola... I want my stang back and running ;)
 

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Pats and or ECU is malfunctioning, might have to resort to taking it to a dealer with the equipment to pinpoint it!
 

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IMO, this is a POWER problem to the PCM or a bad PCM. The all dashes on the cluster indicates that the cluster can not "see" the PCM. If the cluster and PCM are not exchanging information via the SCP data buss, then the theft system (PATS) will not "prove out".

Check the CCRM ground around the right hand radiator core support.

Check the ground to the left of the center console. This ground is shared by the cluster, GEM, AC/heater motor, and Radio.

Check the battery terminals. Are they CLEAN, corrosion free, and tight? Don't cut corners here.

Do you have any aftermarket chips installed in the PCM? Not a bad idea to pull and clean the PCM connector. Check the ground around the PCM as well.

If this is a power problem to the PCM, the challenge is to figure out where the power is being interrupted. It could be in the ignition switch, CCRM, or in the PCM itself.

Put a voltage tester on fuse F2.34. Best if a light that can be seen while driving. What we are trying to find out is if power is being interrupted to this circuit when the problem occurs.
 

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Discussion Starter #5
Well, first thanks wmburns for your wise advises ! :bigthumbsup
I believe you pinpointed out the problem:

Here is the story...
I finally didn't bring the car to the dealer... just for my ego and my wallet.
I talked to some budies at work, one of them told me mustangs have a very sensitive ground scheme. So first thing first, I took some heavy duty sand paper and made all the ground tabs and battery connection mirror clean.
That includes as wmburns say:
1/ the positive and the negative and the battery
2/ the two ground tabs close to the radiator
3/ the ground tab close to the MAF sensor
4/ the ground tab for the PCM (located in the foot panel passenger tab)
5 the ground tab for the radio/cluster (located passenger side of the central console)

I made sure to sand paper the tab, both side, the chassis connection ( sand until you see the chassis steel) and the head of the screw.

Per design, the ground tabs have little pins supposedly to bite through the paint. Well, that with time doesn't make a good contact at all. Some of the tooth got corroded and some didn't even contact the chassis steel.

Anyway, so basically, I spend lunch time on my work parking lot sanding and grinding all the GND tabs. Also, I discover my battery being loose, i mean moving in the brackets supporting it. The long screw holding the battery was extremely rusted and could not be tighten any more.
Long story short, I went to ford spare part and bought a new screw. I also tightened all the screw holding the battery holder. Now the battery doesn't move at all !

Now, the road test...
The car cranked without any issue. I drove an hour around town without any issue...
The time will tell if it was the problem. However, I will now sleep better knowing I have good GND contacts compared to before.
 

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Discussion Starter #6
suite of the story...
I replaced the battery yesterday as it was weak. 460 cold Amps instead of 760.
I drove 100+ miles without any issue. Also the weather was great, and warm, in the 60s.

This morning it was much colder, in the 40s.
I took the car and drove for about 2 miles. Suddenly this damn stall! Again What the F#$%!! It didn't start, the anti theft light blinking rapidly and the cooling fan on.

I finally could go back home after 20 tries.

Back home, I unplugged the PCM and found out some moisture in the connector. hmmmm, that's not good. Also I found out I have a Superchips, Had no cloue I had that ;)

So I clean everything, the connector with electronic cleaner and also the contacts of the chips. I put some tape to hold the chip in place. It was moving around in the PCB connector. I put back everything together and the car started without issue... so far.
I let is run idle for 30 minutes with heater MAX and now I let it run with AC max, just to make sure the influence of the temperature.

Do you guys know a bit about this superchips ? Not too familiar with that.
It is blue and connects on the PCM on the other side of the connector.
Can I just remove the chip ? Or do I need to reprogram something ?

Is it related to the 99 cobra recall or is it a aftermarket chip ?

Thanks for the help.
 

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Hey man I had the same exact issue you were having weeks ago searching threads I found info and cleaned terminals and all the grounds along with taking out the PCM I found a chip also I never new I had a u purchased the car with all mods. I cleaned the connections where the chip plugge in and no issues so far its been 2 weeks. Not sure what was the exact problem tho. But I will point out I purchased the car in the begging of the summer 6 months no problem an it started happening to mr egg the weather dropped also
 

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Same problem here I was having and listened to burns advice and cleaned all cubbyhole and replaced my terminals negative and positive and sanded my wires clean of corrosion. Along with battery terminal spray protection. Cleaned my chip and havnt had a problem since. I figured it might be something won bad chip connection so I'm getting a tuner and removing the chip. Next time if it doesn't start take the hip out see if it started up
 

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Discussion Starter #9
allright, I let the car idle for 2 hours, and no problem so far.
I drove a few blocks around my house and safely came back :)
Tomorrow should be even colder, I will see if I have issues.

Concerning the chip, what happen if I just unplug it and don't bring the car to a tuner ? Will the car start and be in stock or do I need to reprogram the PCM to bring it to stock? not clear with this chip...
 

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Well what modifications does your cobra have. I was told on this forum that if my injectors, fuel related were stock then unplugging the chip wouldn't harm the car. I have full exhaust no cats, intake and cams. So when when i unplug my chip it rubs alittle rougher an I get a check engine light because my chip enables he 02 sensor rears sovit won't read I have no cats. O would try tocontact the maker of the chip and see what's on it that will give you more of a idea o take it out or not. But if you know you have stock injectors ectt then sure started it up with chipped remove won't hurt
 

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suite of the story...
I replaced the battery yesterday as it was weak. 460 cold Amps instead of 760.
I drove 100+ miles without any issue. Also the weather was great, and warm, in the 60s.

This morning it was much colder, in the 40s.
I took the car and drove for about 2 miles. Suddenly this damn stall! Again What the F#$%!! It didn't start, the anti theft light blinking rapidly and the cooling fan on.

I finally could go back home after 20 tries.

Back home, I unplugged the PCM and found out some moisture in the connector. hmmmm, that's not good. Also I found out I have a Superchips, Had no cloue I had that ;)

So I clean everything, the connector with electronic cleaner and also the contacts of the chips. I put some tape to hold the chip in place. It was moving around in the PCB connector. I put back everything together and the car started without issue... so far.
I let is run idle for 30 minutes with heater MAX and now I let it run with AC max, just to make sure the influence of the temperature.

Do you guys know a bit about this superchips ? Not too familiar with that.
It is blue and connects on the PCM on the other side of the connector.
Can I just remove the chip ? Or do I need to reprogram something ?

Is it related to the 99 cobra recall or is it a aftermarket chip ?

Thanks for the help.
I just KNEW it wasn't a ground or connection problem!!
There's issues with your ECU and sorry I'd take it to the dealership like I first suggested!
And NO Ford didn't have superchips add one of their products to their computer, the "FIX" was an ECU reflash and intake Mod!
 

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Back home, I unplugged the PCM and found out some moisture in the connector. hmmmm, that's not good. Also I found out I have a Superchips, Had no cloue I had that ;)
so we don't think the moisture in the PCM connector is an issue?

Something is causing the PCM to "go stupid". It could be a bad ground, corrosion, bad chip, bad relay, ignition switch, rodent activity. Finding the cause is a PROCESS. It has to start somewhere.

To the OP, great work!!:bigthumbsup While cleaning the grounds didn't fix the problem, but now you know the grounds are in good condition. This allows you to focus on other possible causes.

Try putting a voltage tester to the PCM's power source. Use a set of leads long enough so that tester can be seen inside the car.

If you can prove that power is good to the PCM, then that means the problem is in the PCM.

If the power is being interrupted, then the focus can be in the supporting electronics.

However, based on the moisture in the connector and the superchip, I would be surprised if this didn't have some bearing on the problem.
 

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Discussion Starter #14
OK, I am not sure which mods I have on my cobra. For sure, I have a BBK cold intake. Then I don't know about the injectors. I bought the car used back in 2004.
I feel kind of stupid I never knew I had a chip in there.

Anyway, I cranked the car this morning, was pretty cold. No issue.
Tonight, I let the car idle again for an hour with heater max on the floor. (kind of thermal shock the PCM) No problem.
I even noticed the car is running smoother since I cleaned the connector.

I strongly believe the moisture was the issue. Most of the sensors are analog signals 0/5V with relatively high impedance. That can false the reading, potentially reset the PCM due to crazy sensors readings ??
Yes in fact, the dealership might fixed the problem by changing the PCM. No more moisture.
I would be surprised to have the PCM fried. I looked at it, all the components have conformal coating, it looks pretty clean inside. And of course no suspicious traces like burnt, etc.


The only think that sucks now... When unscrewing the the PCM connector, I dropped my 10mm socket in the underdoor body. Now I can hear the socket rolling all the way in the chassis when driving. I am pretty pissed.
Do you guys know a way to access and get it back ?
 

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To clarify, was the problem fixed by replacing the PCM or cleaning the connectors? I couldn't quite tell from your response above.

My 99 Cobra has a SuperChip as well. We have been encountering this problem for the past couple of years. Ironically, it got really bad (multiple highway stalls) the same week as yours.
 
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