[Col Mustard]

Just installed the JDB tuner, and put everything back in place. Hit the start button, and the engine had a hard time turning over. It took 3 tries to get it to start.

The tuner was left at factory settings ~60%. I tuned it down to the min, but it still had a hard time. I had to hold the start button in.

I've taken it out, put everything back to spec, and there still seems to be a hesitation to turn over.

Any ideas what would cause this?

[Beemw335]

Originally Posted by Col Mustard

Just installed the JDB tuner, and put everything back in place. Hit the start button, and the engine had a hard time turning over. It took 3 tries to get it to start.

The tuner was left at factory settings ~60%. I tuned it down to the min, but it still had a hard time. I had to hold the start button in.

I've taken it out, put everything back to spec, and there still seems to be a hesitation to turn over.

Any ideas what would cause this?

Make sure the clips are in properly.

[Ron1n]

What he said. Check the connection into the ECU plug and make sure it's connected properly. On the flip side, when my car started doing this, it turned out to be my glow plugs and glow plug control unit, both of which got replaced.

[SomeRandomer123]

I had a new glow plug control unit when mine was rough starting.

[Col Mustard]

I tried a re-install of the unit this morning. Made sure the connections were seated properly and that I had them oriented correctly.

Not as much hesitation, but still some. I never had any issues with starting the car prior to this.

Does the chip do anything at idle? I thought it was all at the higher end.

[cssnms]

Contact Terry at BMS, he is very quick to respond, great customer service.

[crazyinp]

Do you have the same issue without the JBD? if you do than the problem is not your JBD. It might just been coincident that happened now

[Mike@N54Tuning.com]

The JBD is off at idle so it should not be related, but you can always remove it to see if the symptom goes away, etc. If it does contact BMS for technical support as a next step. If the problem is still there without the JBD check for any codes with the CAN Tool and then dealer it.

Mike

[Col Mustard]

I removed the JBD, and took it to the dealer. They found fault DDE FC-3F30. They're going to replace the rail pressure sensor, under warranty. I'm going to be sending the JDB back.

[EYE4SPEED]

If the sensor is faulty, why send back the JBD?

[Mike@N54Tuning.com]

Originally Posted by Col Mustard

I removed the JBD, and took it to the dealer. They found fault DDE FC-3F30. They're going to replace the rail pressure sensor, under warranty. I'm going to be sending the JDB back.

Makes sense. The dealer doesn't need to replace that sensor the code is from starting the car without the connector being on tight the first time. You really should have used the CT tool to read/delete any codes and engaged BMS for support prior to rushing in to the dealer. It would have saved you a lot of time. By going in with codes stored like that you really rolled the dice on your warranty. Sounds like you lucked out this time. Next time for for anyone else read codes first, ask for support if needed, then go to dealer.

Mike

[cssnms]

Yup lucky fella...

[sohcpunk]

Just experienced this after getting my JBD. One of the repliers was correct, the connection is loose. I re-clipped it and used a zip tie to tighten it up. Works great! No hesitation on start at all!

[Kaylin032]

Idk. My JBD broke after 12,000 miles of use and now it's only good as a necklace.

[cssnms]

Originally Posted by Kaylin032

Idk. My JBD broke after 12,000 miles of use and now it's only good as a necklace.

Broke? How so?

[coolchu001]

Originally Posted by cssnms

Broke? How so?

I had a JBD beta unit that fired up (needed to pull over and remove it in order to start the car again). But BMS replaced it with a new unit; so far so good with the new one (knock on wood).

[Jefarne]

So, I had a similar issue when I installed the JBD on my 2010. I actually did clear the codes and still had the half yellow engine..... Limped it into the dealer. My fuel pressure sensor had gone bad. They replaced it, but failed to tighten it completely...my fuel rail vented diesel at 1000 psi into my engine bay. I was NOT thrilled. Today I put in a new JBD thanks to Terry, I don't know wth happened, or why the sensor failed. This was the only post that I could find of issues with the box. I can say that Terry stood behind the product, hard to find nowadays. Seems great so far!

[daveN007]

I had similar issue.

Rough idle. Immediately shut down. Put back to stock.

Threw a code and went into limp mode. Codes not clearable with CAN tool.

Limped to dealer and they replaced "faulty fuel rail pressure sensor".

If I failed to install the JBD correctly, then it IS NOT A SIMPLE INSTALL. It is possible that it was my fault, but

There just isn't much that can go wrong as far as I can tell.

I would really like to install the unit, but I am spooked.

[daveN007]

Originally Posted by Jefarne

So, I had a similar issue when I installed the JBD on my 2010. I actually did clear the codes and still had the half yellow engine..... Limped it into the dealer. My fuel pressure sensor had gone bad. They replaced it, but failed to tighten it completely...my fuel rail vented diesel at 1000 psi into my engine bay. I was NOT thrilled. Today I put in a new JBD thanks to Terry, I don't know wth happened, or why the sensor failed. This was the only post that I could find of issues with the box. I can say that Terry stood behind the product, hard to find nowadays. Seems great so far!

Same here. Limp mode could not be "reset".

I am not sure about your comment about the sensor actually being "bad". I was able to hover over the guys in the garage while they looked at my car and they seemed to be practicing "swap-tronics" repaid.

Code says A and you replace part B. Period.

There was no real examination of anything aside from what the computer told them.

[AzureHaze]

There was only one time when I got a limp mode from a hard start that couldn't be cleared with a shut down/restart and my buddy's gf was driving it for the first time. Couldn't clear it from a shut down/restart after trying it a few times but luckily my buddy had a bluetooth ODBII tool handy and cleared it. Forgot what the codes were though. Very strange.

[daveN007]

Originally Posted by AzureHaze

There was only one time when I got a limp mode from a hard start that couldn't be cleared with a shut down/restart and my buddy's gf was driving it for the first time. Couldn't clear it from a shut down/restart after trying it a few times but luckily my buddy had a bluetooth ODBII tool handy and cleared it. Forgot what the codes were though. Very strange.

Just to be clear...

The limp mode was not something that the dealer could fix without replacing a part.

That probably means that the code thrown is deemed by BMW to be something that can't be the result of a fault that can simply be reset. So they don't let the dealer have the capability to do such a reset.

Whether the JBD actually caused a part to fail (the fuel rail pressure sensor) I do not know. If not installed correctly (which is like saying that someone didn't install the iPhone charger cable into their iPhone correctly) I would think that the car would sense a disconnected sensor...and interpret that as a failure since it can't just "disconnect" on it's own. That doesn't mean the sensor failed.

It would be like assuming that a light bulb is burned out because the light doesn't work...not knowing that someone unscrewed the perfectly good bulb.

The other possibility is some "partial disconnect" and "getting zapped" by the JBD...but as ignorant as I am to the inner workings of the device, I don't think it is capable of "zapping anything" unless you include zapping in extra torque.

People who talk about "resetting and moving on" are not talking about the same thing.

[Hoooper]

limp mode probably could have been reset/removed if the car had been left turned off for a bit or battery removed and allowed to reset. However, the dealership doesnt work that way, they get paid to replace parts under warranty, not to let cars sit around under warranty. Unless the JBD has an internal hardware issues and destroys the sensor, seems unlikely since sensors are usually fairly resistant to wiring mistakes, but definitely possible.