marcus712

I have recently purchased a 04 6MT with 149k on it and it has this weird issue with the PCM. I was having intermittent starting when the weather is mild here in Dallas. It would turn everything on but not turn the engine over so I figured it was the Immobilizer kicking on and sure enough it was throwing P1260 code with "∩∩__∩∩∩______ = ID number data in the PCM and the keyless control module do not match" as the diagnosis.

As soon as the weather dropped into the sub 70°F range it would only start if I cleared the code with a reader and sometimes it would take 10+ clears for it to remove the Immobilizer. Once the car started and warmed up the issue was gone and would only pop back up once the car had cooled off fully.

So I ran an experiment where I pulled the PCM and put it in the sun for an hour and the car started right up. Once I let it cool the immobilizer was on again, I then pulled the PCM again but didn't warm it up and when reinstalled immobilizer was still on. So to confirm results I warmed the pcm up again with a heat gun and the car started right up.

So with that in mind I believe the PCM will likely need replaced, is this something I can just get used from a junkyard car and have a dealer program? Any other suggestions?

marcus712

Any ideas, thoughts, comments?

Tamas

iTrader: (1)

The PCM throwing a fault code when cold is not new. It happened to others (including me) but with a different code (P0610). Perhaps even with some other code.
Apparently, the solution is indeed to replace the PCM, which of course needs to be programmed to the car and keys - so it is a pain. It may be possible to clone your current PCM to another one based on this DIY post.
Alternatively, you could use VersaTuner or MazdaEdit to suppress the fault code if the PCM is working OK otherwise. VersaTuner is only $300 ($100 off) for a few more days, so that may be the most cost-effective solution.

marcus712

Thanks for the info!

marcus712

To update, found a used 04 PCM at nearby junkyard and swapped it into the car. This appears to have solved the immobilizer issue. I used Forscan with extended license for free with an OBDlink EX adapter. I copied all of the as-build data from the old PCM and then loaded/wrote it onto the new PCM. Most of the data was the same but I overwrote it any way to ensure it was copied. Once I loaded and saved the as built data, I ran Pats programming -> Module Initialization and the car now starts right up cold or warm!

Now I'm on to tracking down a P0455(Large) Evap code. Already replaced fuel cap so on to other issues here.

Also, when I cold start the car the front rotor misfires for about 5 seconds then smooths out so I think it may be flooding from a stuck injector. Any recommendations on checking the injectors for this? It only happens on a first start when when sitting 24+hours.

ZenVirZan

My car used to run on one rotor on startup for a bit before clearing up in exactly the same conditions, and I ended up having coolant seal failure. Just a heads up.

Loki

iTrader: (1)

+1. Poor cold starts are often coolant seeping into the chamber.

marcus712

That is what I am finding through my searching on here. Hoping it isn't this as the motor was rebuilt less than a year ago, have a block tester coming to confirm. The car did start with no issues yesterday after leaving the battery on a charger overnight so we will see what happens today. Also, pulled the APV motor as I am getting a P2010 and it was completely full of oil so wondering if the front rotor is partially flooding with that. Will update once I know more.

Loki

iTrader: (1)

Do you have warranty on that rebuild? Usually they're 1 year/12k miles. Simple way to confirm would be a chemical block test.

marcus712

Previous owner had the rebuild done so not sure if warranty or not. Will check for sure though. Chemical block test is on its way from amazon, will update with results once I get it.

marcus712

Latest Update: The weirdness continues.

APV motor died, so it has been replaced.

So with coolant in the car I am getting misfire on rotor 1 and lots of white smoke. Coolant getting in the rotor somehow. Drained the coolant and flushed, replaced with distilled water and no coolant. Leak resolves itself and car starts with no issues or misfires, no smoke. Repeated this test to confirm, smokes/misfire on start with coolant and no issues with water only.

Also, block test was negative as well and I pressure tested the coolant system and it holds 15 psi no problem.

Any thoughts or ideas as to why I would be getting this with coolant only? Because of lubricity of coolant vs water?

TeamRX8

iTrader: (25)

you only need ~30% coolant to avoid it freezing up if that’s an issue, but straight water is a long term issue with the iron engine plates. It will need something to prevent corrosion.

but water would evaporate into steam rather than smoke, not really sure otherwise
.

Loki

iTrader: (1)

That's not unreasonable if you had a hairline crack somewhere. Coolant mix has lower surface tension, so depending on where the crack/leak is, water would not seep into the rotor while the car sits, while coolant mix would. In both cases it would be ingested while the engine is turning, but in small volumes that you wouldn't notice. White smoke on start up is usually significant amounts of coolant accumulated while the car sits. Given that the block test is negative, I would guess the crack is somewhere on the induction side of the rotor, where exhaust wouldn't be pulled in. You might try to fill it with coolant, sit for a bit, remove the spark plugs and turn the engine over by hand to see if there is coolant there. Add dye to help see traces.

But, regardless, if it's under any warranty, it's up to the rebuilder to figure out why it smokes, don't waste your time. If it's not under warranty... yeah. There are no great options.