So last week I was on my way to the Jets game, and I was at this yield sign about to yield onto an interstate. Cars were flying by so I couldn't go. This is right outside NYC and there was a ton of cars behind me and I was holding everyone up.

All of a sudden a huge Cadillac FLEW UP ON MY RIGHT, trying to get around me, and I was like WTFFF so I FLOORED IT AND TOOK OFF FASTER THAN EVER BEFORE. I swear I've never done such a fast perfect launch with the Xfire EVER. It was perfect.

Then a few moments later I passed a bus and thats when my "Check Engine Light" came on. Damn was I pissed but it was running fine. I couldn't take it in for a week and a half because I had this state licensing class that they only run once a month! Plus it was running fine.

So this morning I got it in and they fixed it.. He said that "Cylinder 4 Misfired" and let me look into it a little more and see what happened, sometimes that happens. So eventually he said he found a TSB (Technical Service Bulletin) for my problem, and all he needed to do was flash and reprogram my ECU with the new codes.

So WHATEVER that means. It doesn't run like it used to AT ALL. Shifting even feels different. And only now the damn thing is running faster than ever before. I've got about 10k miles on her and now the transmission is broken in and silky smooth as well.

But like seriously, I have a few questions??

WTF is with the 4th Cylinder misfiring at all??

And WHY would I need a new ECU programming done at all..?

I remember one other guy on here saying something that the same thing was done to his.

 

Are you saying the car seems faster after the ECU reprogram?

 

Absolutely. It might have lost some torque though. The horsepower kick in is a lot more noticable.... and even shifting is better.

 

bump

I'm bumping this up just because I'd like some help from anyone who might have experience with this sorta thing..

Like how does a cylinder misfire?? Is it a bad thing? Should it happen from only peeling out? WTF is with an ECU flash, how does that make sense? And could there be something else wrong with my car?

 

You'll get your misfire code to pop up in the event that a plug either fails to fire or fires at the wrong time. Sometimes this is just a random occurence in engines - especially when being driven hard.

The fact that the dealer has a TSB on the incident and knew to flash the ECU means that there is a documented problem somewhere. It is likely that there was a batch of ECU's produced that had a less than optimal tune programmed into them. However, because this is a TSB and not a recall, most people won't hear a word about it unless they complain.

With your previous tune (and misfire) your car was probably defaulting back to a safer map where more fuel is dumped into the engine. This slows and cools the combustion process and helps to prevent damage. With your reflashed ECU you are probably running a leaner mix with better timing - this would account for your increase in performance.

Keep an eye on the car for a little while to make sure that your trouble light doesn't come back on. I wouldn't worry too much, though. Sometimes these things happen and it's unlikely that there's anything wrong with your car.

 

Cool, thanks TSaxMan. Makes sense....

My xfire is # 6060 just in case anyone's interested.

 

You're welcome.

 

OK so same problem however i have multiple cylinder misfires and the dealer has had it for a week now, and still can not pinpoint the problem they already re-input the new codes and when i picked it up i drove it home and the "WTF" light came back on and it broke down on me again, so i took it back to the dealer, and they still have it is there anything i can tell them to look for? Already replaced the plugs, wires, fuel filter, checked the injectors, intake leak test, put it under load Someone anyone Help!

My car will run fine between first start up and normal operating temperature, after the engine warms up it will have a multiple cylinder misfire and feel like its surging gas into the engine literally sitting at a redlight my whole car would jump back and forth like it had a crazy CAM package in it....