What can happen? Code 1281

[E36JZwannabee]

Ok.. Odd thing. I replaced a MAF(Euro 3.5) today which was giving me code 1215. So before doing the work on the car I disconnected the positive side of the battery. Replaced the MAF (roughly 20 minutes) then hooked the battery back up.

I went to see if the code 1215 was cleared before I started the car and all the sudden I have no code 1215 but now I have code 1281. I look this up and it is something about the internal DME memory.

I diconnect the battery again for another 20 minutes and start the car up. No CEL no nothing. Car runs better than it ever has Yippy! Drive the car half the day, turning it on and off at various times and then I am driving down some road in third at a low speed and I step on the gas and ping there goes the code again.

So again I read through to see how to reset it and go through the proceedure of disconnecting the DME, then letting it idle for 5 mins then driving for 5 mins. After driving for about 25 mins and letting it idle for 15 mins previously the code goes away as I was driving. But then 5 minutes later comes back? WTF?

I dont understand what is going on with this thing? Could I have hurt something disconnecting the battery? Did I do it wrong? Did I toast the DME somehow? And what type of damage can I do driving the car around while it has code 1281? It still seems to run just as good?

Sorry that was so long winded. I just wanted to give as much info as possible. I have searched and all the posts I have seen are just asking what it is and how to clear it. I know that stuff. I just want to know how it happend, and could it hurt the car to drive with it on.

thanks a lot guys.

Matt

I just wanted to bump this once to see if I can get anyone to comment.

thanks for looking guys.

Just trying to get a little info.

thanks guys.

I just wanted to bump this real quick to see if I could get anby feedback on this.

thanks guys.

[E36JZwannabee]

Can I just bump this.. Wondering if anyone can give me some insight here.

What is happening internally? Why do I need to replace the ecu? Car seems to run perfectly fine.

[MauiM3Mania]

If you don't find help here, ask over in the General BMW Mechanical Help area...

http://forums.bimmerforums.com/forum...play.php?f=145

[E36JZwannabee]

Thanks I'll do that I guess.

People don't generally like double posts though and this is where I had seen most of the ECU info being asked.

[mikese36m]

I have had the same issue when i first bought my M3 and it took several days of trying to clear the memory in the DME before it cleared and the CEL stayed off. Sorry bro don't really have any useful info for ya. Good Luck

[VaTechE36]

don't you need to run some kind of ship to use the larger 3.5" MAF? Your stock ECU I dont think can accurately measure the amount of air moving through the intake.

Just a thought

[E36JZwannabee]

Just to clarify. Yes I am running a TMS chip for 24lbers, 3.5HFM, Intake, and exhaust. I was just having HFM problems and swapped it out to another one. Fixed the HFM problem but then the CEL came on code 1281.

As another note, as I was driving home tonight the CEL went off and hasnt come back on (crossing fingers) so we will see.

thanks again for giving me input.

[Crazy 13immer]

I have code 1281 also, but my car cranks and won't start. I think I"m going to try to see if I can disable EWS.. but I don't think that EWS is my problem.

I actually just bought a new ECU so hopefully this will fix it.

Bump for any extra help.

[Crazy 13immer]

Thought I'd post a follow up. The wiring to my fuel pump was bad, so thats why the car ran so poorly. New fuel pump and bam. No more CEL 1281, no more reliability issues.

[Ron97M3]

You should be disconnecting the black negative cable and leaving the red positive cable attached to the battery. Never allow positive the chance to
make contact to car metal with negative still in contact as that is a BIG SHORT.

[dude8383]

Thought I'd post a follow up. The wiring to my fuel pump was bad, so thats why the car ran so poorly. New fuel pump and bam. No more CEL 1281, no more reliability issues.

Bumping this because I wanted to know exactly what you meant by "the wiring to my fuel pump was bad."

I'm experiencing the same issue with mine.

Started it up on Wednesday night, ran for a good 15min and then died without any warning. Replaced fuel relay and ecu with my old one and car started back up without an issue. Ran for 10min without dying so I shut it down thinking all was well.

While the car was running though I wanted to rule out the possibility of it being the fuel pump, so as the car was running I pulled the power on it. Car slowly died, with warning basically.

Last night it just wouldn't start...although the first time I went to start it I heard the pump come on and the car just kept turning over.

Battery voltage is really low though...around 11v, but it started up Wednesday with the booster attached. I'm completely puzzled ???

[Crazy 13immer]

Bumping this because I wanted to know exactly what you meant by "the wiring to my fuel pump was bad."

I'm experiencing the same issue with mine.

Started it up on Wednesday night, ran for a good 15min and then died without any warning. Replaced fuel relay and ecu with my old one and car started back up without an issue. Ran for 10min without dying so I shut it down thinking all was well.

While the car was running though I wanted to rule out the possibility of it being the fuel pump, so as the car was running I pulled the power on it. Car slowly died, with warning basically.

Last night it just wouldn't start...although the first time I went to start it I heard the pump come on and the car just kept turning over.

Battery voltage is really low though...around 11v, but it started up Wednesday with the booster attached. I'm completely puzzled ???

I bought a Walbro 255lph (iirc) pump to replace my stock one. When I removed the stock pump, I did not solder and connect the wires running to the fuel pump like I should have and after driving for a day or so, the wires that I wound together backed out.

I wound up just going back to a stock pump so I could just drop it in and plug in the connectors instead of worrying about soldering the wires. Since then I've had no problems.

[dude8383]

I bought a Walbro 255lph (iirc) pump to replace my stock one. When I removed the stock pump, I did not solder and connect the wires running to the fuel pump like I should have and after driving for a day or so, the wires that I wound together backed out.

I wound up just going back to a stock pump so I could just drop it in and plug in the connectors instead of worrying about soldering the wires. Since then I've had no problems.

Ah seems you had a fueling issue though. I'm not getting any fuel OR spark now.

[Crazy 13immer]

Yeah. I was eventually able to verify that I had a fuel problem by cranking the car while spraying starter fluid in the TB. The car would start basically right up and then die.

[Jrdeamicis]

Ah seems you had a fueling issue though. I'm not getting any fuel OR spark now.

That is your crank sensor. The ECU needs to see a solid crank signal to turn on the fuel pump relay and start enabling spark. If you give the ECU a solid CPS signal it will spark no matter what (Proven by a powered ecu, a bench grinder and a timing wheel)

[dude8383]

That is your crank sensor. The ECU needs to see a solid crank signal to turn on the fuel pump relay and start enabling spark. If you give the ECU a solid CPS signal it will spark no matter what (Proven by a powered ecu, a bench grinder and a timing wheel)

This is really good to know. I figured that that was the method or rather the order in which the car would start. Checking resistance at the crank sensor yielded a big fat zero so it MUST be non-functional.

Will definitely be ordering a new one on Monday. Any recommendations, factory AB ELEKTRONIK or Hella? Meyle is one the cheaper end and I don't really want to skimp out on cost. I'd rather do it right.