[Luky]

So I have thrown a engine code a few times while driving with my JB4. It happens at moderate speed with mild acceleration. Have not had it happen when accelerating aggressively. Happened again yesterday morning. I was going through a parking lot maybe 10-15 mph, slowed at the corner and turned right onto the street while giving it a little gas (not punching it) and it threw a CEL and started running really rough. I continued 1/2 block and went down the ramp onto the freeway and pulled over.

I was on the side of the freeway on my way to work and left it idling (running really rough) while I popped the hood and read the code with my laptop. I don't remember the exact code number but when I checked, it said something like "Cyl #1 misfire". As soon as I cleared the code the engine went back to idling/running fine. It seems strange to me that just clearing a code would "fix" a problem like this... Any ideas?

I am either running map 1 or map 5 as it is stock with just the DCI (I have been mixing 91 and 100 octane so I have been running between 94 and 96 octane) when this happens. It has happened twice before this and I just cleared the code while driving as I still am not sure how to "read" the code off the speedo cluster (especially while driving...) and have not had time to stop and screw with it (why does it always happen when you need to be somewhere?)

I have to take the car in to the dealer to get the brakes done tomorrow (dash light came on for this a few days ago and I have the CPO warranty and extended Maintenance plan) so I am pulling the JB4 out.

Is there anything I need to do before I pull it to make sure they cannot see I had a tune installed?

My car is a 2008 and I have no idea what FW my ECU has. Since I have cleared the CEL light/code I was not going to mention it to the dealer as I figure there is nothing they can do without seeing the code for themselves. Or should I bring it up to them?

[Terry @ BMS]

Misfire codes are very common on the N54 motor and are generally either a defective plug, coil, injector, or if the misfires happen across multiple cylinders could be an o2 sensor or high pressure fuel pump. If your plugs have over 15k miles on them I'd suggest switching them out. If that doesn't do the trick you can switch the coil on the misfiring cylinder over to another cylinder to see if the misfire moves with it. If it does, then replace that coil.

[Luky]

Since it is still under warranty and full maintenance, I don't want to mess with it. I'll just put the JB4 back and when it thows a code again I'll have to pull it but leave the code and take it to the dealer. Will the dealer be able to see anything from having the JB4 installed? Is it likely to do damage if I keep driving it while it is miss firing?

If I set "enable auto code clear" what exactly does this do?

Where can I find out how to read codes from the cluster and what they mean? (So I can check without my laptop). Is there a pdf I can get?

Thanks!

[Terry @ BMS]

See FAQ in the JB4 sticky for code reading directions. For misfires I'd probably just swap the plugs myself and/or replace that coil if needed. Easier that way than messing around with the dealer. If plugs and/or coils don't do it, then its likely injectors and you'll want to dealer it for those.

[az335iat]

Originally Posted by Luky

Since it is still under warranty and full maintenance, I don't want to mess with it. I'll just put the JB4 back and when it thows a code again I'll have to pull it but leave the code and take it to the dealer. Will the dealer be able to see anything from having the JB4 installed? Is it likely to do damage if I keep driving it while it is miss firing?

If I set "enable auto code clear" what exactly does this do?

Where can I find out how to read codes from the cluster and what they mean? (So I can check without my laptop). Is there a pdf I can get?

Thanks!

When the code comes up, pull to the side of the road and shut the engine off.
Restarting the engine will generally clear the fault condition but NOT the fault code. That way you can dealer it with the code (if you want to) and still have a good running car in the meantime.