P1340: Multiple Cylinder Misfire During Start- Before I drop this at my indy for diag

[SpeedyE38]

before I drop this at my indy for diagnosis...what does our group think?

Here is what I have from the FB page:

Check coils (replace I suppose)
Replace plugs
Check for vacuum leaks
Check evaporate system for leaking purge valve

I have the M62U motor; 1/2 tank of gas and has 154K miles. I disconnected the battery for a few days (I don't drive the car much) and the Service Engine Soon light returned.

Thanks in advance for any guidance.

[MIKYZZ4]

P-codes can be very misleading, I suspect a CPS circuit error(bad connection,broken wire,bad sensor)
I would swap CPS(cam position sensors), observe if code changes.

[TheAngryBear]

First thing I would check is voltage, both resting battery and the voltage during start.
Then check fuel trims for evidence of vacuum leak with smooth/rough running values to see if it one bank or both.
Fuel pressure (total and hold time) at the rail would likely be next.
And of course all the normal visuals of plugs, coils, VCGs leaks, vacuum lines, etc.


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

[SpeedyE38]

Thank you both.

Here is what I did (don't shoot me)...I was driving by the local European auto repair place (who I had sent other people to, but never really needed them) and thought...I am going to be away for a week...why not let THEM figure it out? So, I pull in and what do I see? The only other 740 sport in my neighborhood is in the fenced in area. I took it as a sign. So, I left it. But not before I shared my thoughts on what I thought the issues were. That and a rattling shock in the rear. Being pretty chilly here and not having heat in my garage and with the state looking at me for a smog check...I needed to get this Service Engine Soon light off.

So now they have it. I will report out what they find. And yes, it kills me to not figure this out on my own.

[Mayorchuck]

Tis the season for vacuum leaks.

[SpeedyE38]

Tis the season for vacuum leaks.

I wonder why that is?

BTW, as I described a noise I was hearing, I felt like a sixteen year old again. "There is a sound coming from the passenger side of the motor that sounds like a rhythmic thump thump thump - or it could be an air sucking sound - either way, the car runs fine and I have this code that just popped up."

[rslifkin]

I wonder why that is?

Cold weather. Hoses, etc. all shrink in the cold, so leaks are more likely to show up.

[SpeedyE38]

Cold weather. Hoses, etc. all shrink in the cold, so leaks are more likely to show up.

Thanks. Makes sense.

[SpeedyE38]

Indy quoted me ~$800 to replace both CPS. I think I will go and collect my car from them and do it myself. I had wanted them to focus on vacuum leaks but they instead focused on the CPS solely. Since I can replace the parts in less than 30", why should I pay them for several hours labor? I'll pay them for the analysis and save their labor for something I cannot do in my garage.

[Mayorchuck]

Wow. That's insane. If you ask them to check for vacuum leaks, I would think the first thing they would want to do is a smoke test. Did they run a diagnostic with BMW software?

[MIKYZZ4]

Excellent strategy,
you'll save yourself a ton of ca$h with that DIY attitude.
Hopefully their diagnostics confirmed my CPS suspicions.

[SpeedyE38]

Excellent strategy,
you'll save yourself a ton of ca$h with that DIY attitude.
Hopefully their diagnostics confirmed my CPS suspicions.

Yeah, I wanted to build a relationship with these guys because they are close and I want to be able to use them for stuff I won't/can't do with my garage setup. I have replaced the front hubs, headlamp ballasts and the Nav. So, am a little handy, just not well-versed in all the systems this car has.

- - - Updated - - -

Wow. That's insane. If you ask them to check for vacuum leaks, I would think the first thing they would want to do is a smoke test. Did they run a diagnostic with BMW software?

I will get the codes from them. I think I will just pay them for the review and go back later after i rule out stuff I am willing to throw new parts at (i.e. CPS, maybe secondary air pump and valve.)

[SpeedyE38]

Parts ordered. Will ask them to do a smoke test and supply the codes from the diagnostic. That ought to earn them a couple hundred dollars and keep them happy. We will see!

[MIKYZZ4]

Cool,
Keep us in the loop.

[SpeedyE38]

Codes retrieved by the indy shop were P1340/P1341.
I bought both cam sensors for $123 delivered (OEM) and installed in under thirty minutes. Service Engine Soon light is no longer illuminated. Original quote was roughly $800. Being able to do the job was worth twice as much as any savings I earned. It really was kind of fun handling some of the parts that I had to take off. The MAF...seems fragile. The weaving of the wiring through and under the cover, interesting. Dropping a bolt and retrieving without opening up the bottom cover...ego-inspiring.

Now, I have to go back and understand the smoke test they did. I am still not sure what their notes state.

Thanks to all who helped and responded. This car is really fun to work on.

[Bagzebeamers]

Glad to hear the cam sensor replace kit fixed the problem. Curious if y’all think I should try the same. Got the light and ran the codes and got the P1340. But the car is running great. I just bought it so not sure what all has been replaced or when. But no idle issues or anything at all. The light went out for like a week and came back.